[ONOS-4744] Leafref implementation and UT

Change-Id: I151797185e0bb1695c0640b667ae76ef87c4d4b0

@@ -34,5 +34,10 @@ public enum ResolvableType {
     /**
     /**
      * Identifies the if-feature.
      * Identifies the if-feature.
      */
      */
-    YANG_IF_FEATURE
+    YANG_IF_FEATURE,
+
+    /**
+     * Identifies the leafref.
+     */
+    YANG_LEAFREF
 }
 }

@@ -24,6 +24,11 @@ import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
 
 
 import com.google.common.base.Strings;
 import com.google.common.base.Strings;
 
 
+import static org.onosproject.yangutils.datamodel.utils.ResolvableStatus.INTRA_FILE_RESOLVED;
+import static org.onosproject.yangutils.datamodel.utils.ResolvableStatus.RESOLVED;
+import static org.onosproject.yangutils.datamodel.utils.RestrictionResolver.processLengthRestriction;
+import static org.onosproject.yangutils.datamodel.utils.RestrictionResolver.processRangeRestriction;
+import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypeUtils.isOfRangeRestrictedType;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.BINARY;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.BINARY;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.BITS;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.BITS;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.BOOLEAN;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.BOOLEAN;
@@ -34,11 +39,6 @@ import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangData
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.LEAFREF;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.LEAFREF;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.STRING;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.STRING;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.UNION;
 import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes.UNION;
-import static org.onosproject.yangutils.datamodel.utils.ResolvableStatus.INTRA_FILE_RESOLVED;
-import static org.onosproject.yangutils.datamodel.utils.ResolvableStatus.RESOLVED;
-import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypeUtils.isOfRangeRestrictedType;
-import static org.onosproject.yangutils.datamodel.utils.RestrictionResolver.processLengthRestriction;
-import static org.onosproject.yangutils.datamodel.utils.RestrictionResolver.processRangeRestriction;
 
 
 /**
 /**
  * Represents the derived information.
  * Represents the derived information.
@@ -334,6 +334,9 @@ public class YangDerivedInfo<T>
                     return RESOLVED;
                     return RESOLVED;
                 }
                 }
             }
             }
+        } else if (baseType.getDataType() == LEAFREF) {
+            setEffectiveBuiltInType(baseType.getDataType());
+            return RESOLVED;
         } else {
         } else {
             setEffectiveBuiltInType(baseType.getDataType());
             setEffectiveBuiltInType(baseType.getDataType());
             /*
             /*
@@ -412,7 +415,6 @@ public class YangDerivedInfo<T>
                 }
                 }
             }
             }
         }
         }
-
         /*
         /*
          * Check if the data type is the one which can't be restricted, in this
          * Check if the data type is the one which can't be restricted, in this
          * case check whether no self restrictions should be present.
          * case check whether no self restrictions should be present.
@@ -426,7 +428,6 @@ public class YangDerivedInfo<T>
                 throw new DataModelException("YANG file error: Restrictions can't be applied to a given type");
                 throw new DataModelException("YANG file error: Restrictions can't be applied to a given type");
             }
             }
         }
         }
-
         // Throw exception for unsupported types
         // Throw exception for unsupported types
         throw new DataModelException("Linker error: Unable to process the derived type.");
         throw new DataModelException("Linker error: Unable to process the derived type.");
     }
     }

@@ -211,6 +211,11 @@ public class YangModule
     private List<YangResolutionInfo> ifFeatureResolutionList;
     private List<YangResolutionInfo> ifFeatureResolutionList;
 
 
     /**
     /**
+     * leafref resolution list.
+     */
+    private List<YangResolutionInfo> leafrefResolutionList;
+
+    /**
      * Creates a YANG node of module type.
      * Creates a YANG node of module type.
      */
      */
     public YangModule() {
     public YangModule() {
@@ -219,6 +224,7 @@ public class YangModule
         derivedTypeResolutionList = new LinkedList<>();
         derivedTypeResolutionList = new LinkedList<>();
         usesResolutionList = new LinkedList<>();
         usesResolutionList = new LinkedList<>();
         ifFeatureResolutionList = new LinkedList<>();
         ifFeatureResolutionList = new LinkedList<>();
+        leafrefResolutionList = new LinkedList<>();
         importList = new LinkedList<YangImport>();
         importList = new LinkedList<YangImport>();
         includeList = new LinkedList<YangInclude>();
         includeList = new LinkedList<YangInclude>();
         listOfLeaf = new LinkedList<YangLeaf>();
         listOfLeaf = new LinkedList<YangLeaf>();
@@ -589,8 +595,10 @@ public class YangModule
             return derivedTypeResolutionList;
             return derivedTypeResolutionList;
         } else if (type == ResolvableType.YANG_USES) {
         } else if (type == ResolvableType.YANG_USES) {
             return usesResolutionList;
             return usesResolutionList;
-        } else {
+        } else if (type == ResolvableType.YANG_IF_FEATURE) {
             return ifFeatureResolutionList;
             return ifFeatureResolutionList;
+        } else {
+            return leafrefResolutionList;
         }
         }
     }
     }
 
 
@@ -603,6 +611,8 @@ public class YangModule
             usesResolutionList.add(resolutionInfo);
             usesResolutionList.add(resolutionInfo);
         } else if (type == ResolvableType.YANG_IF_FEATURE) {
         } else if (type == ResolvableType.YANG_IF_FEATURE) {
             ifFeatureResolutionList.add(resolutionInfo);
             ifFeatureResolutionList.add(resolutionInfo);
+        } else {
+            leafrefResolutionList.add(resolutionInfo);
         }
         }
     }
     }
 
 
@@ -615,6 +625,8 @@ public class YangModule
             usesResolutionList = resolutionList;
             usesResolutionList = resolutionList;
         } else if (type == ResolvableType.YANG_IF_FEATURE) {
         } else if (type == ResolvableType.YANG_IF_FEATURE) {
             ifFeatureResolutionList.add((YangResolutionInfo) resolutionList);
             ifFeatureResolutionList.add((YangResolutionInfo) resolutionList);
+        } else if (type == ResolvableType.YANG_LEAFREF) {
+            leafrefResolutionList = resolutionList;
         }
         }
 
 
     }
     }

@@ -209,6 +209,11 @@ public class YangSubModule
     private List<YangResolutionInfo> ifFeatureResolutionList;
     private List<YangResolutionInfo> ifFeatureResolutionList;
 
 
     /**
     /**
+     * leafref resolution list.
+     */
+    private List<YangResolutionInfo> leafrefResolutionList;
+
+    /**
      * Creates a sub module node.
      * Creates a sub module node.
      */
      */
     public YangSubModule() {
     public YangSubModule() {
@@ -216,6 +221,7 @@ public class YangSubModule
         derivedTypeResolutionList = new LinkedList<>();
         derivedTypeResolutionList = new LinkedList<>();
         usesResolutionList = new LinkedList<>();
         usesResolutionList = new LinkedList<>();
         ifFeatureResolutionList = new LinkedList<>();
         ifFeatureResolutionList = new LinkedList<>();
+        leafrefResolutionList = new LinkedList<>();
         importList = new LinkedList<YangImport>();
         importList = new LinkedList<YangImport>();
         includeList = new LinkedList<YangInclude>();
         includeList = new LinkedList<YangInclude>();
         listOfLeaf = new LinkedList<YangLeaf>();
         listOfLeaf = new LinkedList<YangLeaf>();
@@ -551,8 +557,10 @@ public class YangSubModule
             return derivedTypeResolutionList;
             return derivedTypeResolutionList;
         } else if (type == ResolvableType.YANG_USES) {
         } else if (type == ResolvableType.YANG_USES) {
             return usesResolutionList;
             return usesResolutionList;
-        } else {
+        } else if (type == ResolvableType.YANG_IF_FEATURE) {
             return ifFeatureResolutionList;
             return ifFeatureResolutionList;
+        } else {
+            return leafrefResolutionList;
         }
         }
     }
     }
 
 
@@ -565,6 +573,8 @@ public class YangSubModule
             usesResolutionList.add(resolutionInfo);
             usesResolutionList.add(resolutionInfo);
         } else if (type == ResolvableType.YANG_IF_FEATURE) {
         } else if (type == ResolvableType.YANG_IF_FEATURE) {
             ifFeatureResolutionList.add(resolutionInfo);
             ifFeatureResolutionList.add(resolutionInfo);
+        } else {
+            leafrefResolutionList.add(resolutionInfo);
         }
         }
     }
     }
 
 
@@ -576,7 +586,9 @@ public class YangSubModule
         } else if (type == ResolvableType.YANG_USES) {
         } else if (type == ResolvableType.YANG_USES) {
             usesResolutionList = resolutionList;
             usesResolutionList = resolutionList;
         } else if (type == ResolvableType.YANG_IF_FEATURE) {
         } else if (type == ResolvableType.YANG_IF_FEATURE) {
-            ifFeatureResolutionList = resolutionList;
+            ifFeatureResolutionList.add((YangResolutionInfo) resolutionList);
+        } else if (type == ResolvableType.YANG_LEAFREF) {
+            leafrefResolutionList = resolutionList;
         }
         }
 
 
     }
     }

@@ -17,6 +17,7 @@
 package org.onosproject.yangutils.datamodel;
 package org.onosproject.yangutils.datamodel;
 
 
 import java.io.Serializable;
 import java.io.Serializable;
+
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.datamodel.utils.Parsable;
 import org.onosproject.yangutils.datamodel.utils.Parsable;
 import org.onosproject.yangutils.datamodel.utils.ResolvableStatus;
 import org.onosproject.yangutils.datamodel.utils.ResolvableStatus;
@@ -43,7 +44,7 @@ import static org.onosproject.yangutils.datamodel.utils.builtindatatype.YangData
  * | bit              | 9.7.4   | 0..n        | - YangBit used in YangBits         |
  * | bit              | 9.7.4   | 0..n        | - YangBit used in YangBits         |
  * | enum             | 9.6.4   | 0..n        | - YangEnum used in YangEnumeration |
  * | enum             | 9.6.4   | 0..n        | - YangEnum used in YangEnumeration |
  * | length           | 9.4.4   | 0..1        | - used for string                  |
  * | length           | 9.4.4   | 0..1        | - used for string                  |
- * | path             | 9.9.2   | 0..1        | - TODO leaf-ref                    |
+ * | path             | 9.9.2   | 0..1        | - path for referred leaf/leaf-list |
  * | pattern          | 9.4.6   | 0..n        | - used for string                  |
  * | pattern          | 9.4.6   | 0..n        | - used for string                  |
  * | range            | 9.2.4   | 0..1        | - used for integer data type       |
  * | range            | 9.2.4   | 0..1        | - used for integer data type       |
  * | require-instance | 9.13.2  | 0..1        | - TODO instance-identifier         |
  * | require-instance | 9.13.2  | 0..1        | - TODO instance-identifier         |
@@ -67,11 +68,6 @@ public class YangType<T>
     private YangNodeIdentifier nodeIdentifier;
     private YangNodeIdentifier nodeIdentifier;
 
 
     /**
     /**
-     * Java package in which the Java type is defined.
-     */
-    private String javaPackage;
-
-    /**
      * YANG data type.
      * YANG data type.
      */
      */
     private YangDataTypes dataType;
     private YangDataTypes dataType;
@@ -137,24 +133,6 @@ public class YangType<T>
     }
     }
 
 
     /**
     /**
-     * Returns the Java package where the type is defined.
-     *
-     * @return Java package where the type is defined
-     */
-    public String getJavaPackage() {
-        return javaPackage;
-    }
-
-    /**
-     * Sets Java package where the type is defined.
-     *
-     * @param javaPackage Java package where the type is defined
-     */
-    public void setJavaPackage(String javaPackage) {
-        this.javaPackage = javaPackage;
-    }
-
-    /**
      * Returns the type of data.
      * Returns the type of data.
      *
      *
      * @return the data type
      * @return the data type
@@ -209,6 +187,16 @@ public class YangType<T>
     }
     }
 
 
     /**
     /**
+     * Resets the class attributes to its default value.
+     */
+    public void resetYangType() {
+        nodeIdentifier = new YangNodeIdentifier();
+        resolvableStatus = ResolvableStatus.UNRESOLVED;
+        dataType = null;
+        dataTypeExtendedInfo = null;
+    }
+
+    /**
      * Returns the type of the parsed data.
      * Returns the type of the parsed data.
      *
      *
      * @return returns TYPE_DATA
      * @return returns TYPE_DATA

@@ -24,6 +24,7 @@ import org.onosproject.yangutils.datamodel.ResolvableType;
 import org.onosproject.yangutils.datamodel.YangIfFeature;
 import org.onosproject.yangutils.datamodel.YangIfFeature;
 import org.onosproject.yangutils.datamodel.YangLeaf;
 import org.onosproject.yangutils.datamodel.YangLeaf;
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.datamodel.YangLeafList;
+import org.onosproject.yangutils.datamodel.YangLeafRef;
 import org.onosproject.yangutils.datamodel.YangLeavesHolder;
 import org.onosproject.yangutils.datamodel.YangLeavesHolder;
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.YangReferenceResolver;
 import org.onosproject.yangutils.datamodel.YangReferenceResolver;
@@ -171,6 +172,10 @@ public final class DataModelUtils {
                 .getEntityToResolve() instanceof YangIfFeature) {
                 .getEntityToResolve() instanceof YangIfFeature) {
             resolutionNode.addToResolutionList(resolutionInfo,
             resolutionNode.addToResolutionList(resolutionInfo,
                     ResolvableType.YANG_IF_FEATURE);
                     ResolvableType.YANG_IF_FEATURE);
+        } else if (resolutionInfo.getEntityToResolveInfo()
+                .getEntityToResolve() instanceof YangLeafRef) {
+            resolutionNode.addToResolutionList(resolutionInfo,
+                    ResolvableType.YANG_LEAFREF);
         }
         }
     }
     }
 
 

@@ -25,14 +25,14 @@ public enum YangDataTypes {
      *
      *
      * int8 represents integer values between -128 and 127, inclusively.
      * int8 represents integer values between -128 and 127, inclusively.
      */
      */
-    INT8,
+    INT8("int8"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
      *
      *
      * int16 represents integer values between -32768 and 32767, inclusively.
      * int16 represents integer values between -32768 and 32767, inclusively.
      */
      */
-    INT16,
+    INT16("int16"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -40,7 +40,7 @@ public enum YangDataTypes {
      * int32 represents integer values between -2147483648 and 2147483647,
      * int32 represents integer values between -2147483648 and 2147483647,
      * inclusively.
      * inclusively.
      */
      */
-    INT32,
+    INT32("int32"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -48,28 +48,28 @@ public enum YangDataTypes {
      * int64 represents integer values between -9223372036854775808 and
      * int64 represents integer values between -9223372036854775808 and
      * 9223372036854775807, inclusively.
      * 9223372036854775807, inclusively.
      */
      */
-    INT64,
+    INT64("int64"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
      *
      *
      * uint8 represents integer values between 0 and 255, inclusively.
      * uint8 represents integer values between 0 and 255, inclusively.
      */
      */
-    UINT8,
+    UINT8("uint8"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
      *
      *
      * uint16 represents integer values between 0 and 65535, inclusively.
      * uint16 represents integer values between 0 and 65535, inclusively.
      */
      */
-    UINT16,
+    UINT16("uint16"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
      *
      *
      * uint32 represents integer values between 0 and 4294967295, inclusively.
      * uint32 represents integer values between 0 and 4294967295, inclusively.
      */
      */
-    UINT32,
+    UINT32("uint32"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -77,7 +77,7 @@ public enum YangDataTypes {
      * uint64 represents integer values between 0 and 18446744073709551615,
      * uint64 represents integer values between 0 and 18446744073709551615,
      * inclusively.
      * inclusively.
      */
      */
-    UINT64,
+    UINT64("uint64"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -88,7 +88,7 @@ public enum YangDataTypes {
      * a negative power of ten, i.e., expressible as "i x 10^-n" where i is an
      * a negative power of ten, i.e., expressible as "i x 10^-n" where i is an
      * integer64 and n is an integer between 1 and 18, inclusively.
      * integer64 and n is an integer between 1 and 18, inclusively.
      */
      */
-    DECIMAL64, // TODO: need to implement in type.
+    DECIMAL64("decimal64"), // TODO: need to implement in type.
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -97,14 +97,14 @@ public enum YangDataTypes {
      * characters are tab, carriage return, line feed, and the legal characters
      * characters are tab, carriage return, line feed, and the legal characters
      * of Unicode and ISO/IEC 10646
      * of Unicode and ISO/IEC 10646
      */
      */
-    STRING,
+    STRING("string"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
      *
      *
      * The boolean built-in type represents a boolean value.
      * The boolean built-in type represents a boolean value.
      */
      */
-    BOOLEAN,
+    BOOLEAN("boolean"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -112,7 +112,7 @@ public enum YangDataTypes {
      * The enumeration built-in type represents values from a set of assigned
      * The enumeration built-in type represents values from a set of assigned
      * names.
      * names.
      */
      */
-    ENUMERATION,
+    ENUMERATION("enumeration"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -121,7 +121,7 @@ public enum YangDataTypes {
      * set of flags identified by small integer position numbers starting at 0.
      * set of flags identified by small integer position numbers starting at 0.
      * Each bit number has an assigned name.
      * Each bit number has an assigned name.
      */
      */
-    BITS,
+    BITS("bits"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -129,7 +129,7 @@ public enum YangDataTypes {
      * The binary built-in type represents any binary data, i.e., a sequence of
      * The binary built-in type represents any binary data, i.e., a sequence of
      * octets.
      * octets.
      */
      */
-    BINARY,
+    BINARY("binary"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -150,14 +150,14 @@ public enum YangDataTypes {
      * more features, then the leaf with the leafref type MUST also be
      * more features, then the leaf with the leafref type MUST also be
      * conditional based on at least the same set of features.
      * conditional based on at least the same set of features.
      */
      */
-    LEAFREF, // TODO: need to implement in type.
+    LEAFREF("leafref"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
      *
      *
      * The identityref type is used to reference an existing identity.
      * The identityref type is used to reference an existing identity.
      */
      */
-    IDENTITYREF,
+    IDENTITYREF("identityref"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -167,7 +167,7 @@ public enum YangDataTypes {
      *
      *
      * An empty type cannot have a default value.
      * An empty type cannot have a default value.
      */
      */
-    EMPTY,
+    EMPTY("empty"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -189,7 +189,7 @@ public enum YangDataTypes {
      * Any default value or "units" property defined in the member types is not
      * Any default value or "units" property defined in the member types is not
      * inherited by the union type.
      * inherited by the union type.
      */
      */
-    UNION,
+    UNION("union"),
 
 
     /**
     /**
      * Reference:RFC 6020.
      * Reference:RFC 6020.
@@ -212,12 +212,26 @@ public enum YangDataTypes {
      * valid data. All such leaf nodes MUST reference existing nodes or leaf
      * valid data. All such leaf nodes MUST reference existing nodes or leaf
      * nodes with their default value in use for the data to be valid.
      * nodes with their default value in use for the data to be valid.
      */
      */
-    INSTANCE_IDENTIFIER,
+    INSTANCE_IDENTIFIER("instance-identifier"),
 
 
     /**
     /**
      * Derived data type.
      * Derived data type.
      */
      */
-    DERIVED;
+    DERIVED("derived");
+
+    /**
+     * Defined type from the enum value.
+     */
+    private String definedType;
+
+    /**
+     * Constructs type value from enum.
+     *
+     * @param definedType value of enum
+     */
+    YangDataTypes(String definedType) {
+        this.definedType = definedType;
+    }
 
 
     /**
     /**
      * Returns YANG data type for corresponding type name.
      * Returns YANG data type for corresponding type name.
@@ -228,7 +242,7 @@ public enum YangDataTypes {
     public static YangDataTypes getType(String name) {
     public static YangDataTypes getType(String name) {
         name = name.replace("\"", "");
         name = name.replace("\"", "");
         for (YangDataTypes yangDataType : values()) {
         for (YangDataTypes yangDataType : values()) {
-            if (yangDataType.name().toLowerCase().equals(name)) {
+            if (yangDataType.definedType.toLowerCase().equals(name)) {
                 return yangDataType;
                 return yangDataType;
             }
             }
         }
         }

@@ -161,6 +161,8 @@ public class YangLinkerManager
                 ((YangReferenceResolver) yangNode).resolveInterFileLinking(ResolvableType.YANG_USES);
                 ((YangReferenceResolver) yangNode).resolveInterFileLinking(ResolvableType.YANG_USES);
                 ((YangReferenceResolver) yangNode)
                 ((YangReferenceResolver) yangNode)
                         .resolveInterFileLinking(ResolvableType.YANG_DERIVED_DATA_TYPE);
                         .resolveInterFileLinking(ResolvableType.YANG_DERIVED_DATA_TYPE);
+                ((YangReferenceResolver) yangNode)
+                        .resolveInterFileLinking(ResolvableType.YANG_LEAFREF);
             } catch (DataModelException e) {
             } catch (DataModelException e) {
                 String errorInfo = "Error in file: " + yangNode.getName() + " at line: "
                 String errorInfo = "Error in file: " + yangNode.getName() + " at line: "
                         + e.getLineNumber() + " at position: " + e.getCharPositionInLine() + NEW_LINE + e.getMessage();
                         + e.getLineNumber() + " at position: " + e.getCharPositionInLine() + NEW_LINE + e.getMessage();

@@ -16,7 +16,6 @@
 
 
 // Generated from GeneratedYang.g4 by ANTLR 4.5
 // Generated from GeneratedYang.g4 by ANTLR 4.5
 
 
-
 package org.onosproject.yangutils.parser.antlrgencode;
 package org.onosproject.yangutils.parser.antlrgencode;
 
 
 import org.antlr.v4.runtime.tree.ParseTreeListener;
 import org.antlr.v4.runtime.tree.ParseTreeListener;
@@ -1950,4 +1949,18 @@ public interface GeneratedYangListener extends ParseTreeListener {
      */
      */
     void exitAnnotationIdentifier(GeneratedYangParser.AnnotationIdentifierContext
     void exitAnnotationIdentifier(GeneratedYangParser.AnnotationIdentifierContext
                                           currentContext);
                                           currentContext);
+
+    /**
+     * Enters a parse tree produced by GeneratedYangParser for grammar rule require instance.
+     *
+     * @param currentContext current context in the parsed tree
+     */
+    void enterRequireInstance(GeneratedYangParser.RequireInstanceContext currentContext);
+
+    /**
+     * Exits a parse tree produced by GeneratedYangParser for grammar require instance.
+     *
+     * @param currentContext current context in the parsed tree
+     */
+    void exitRequireInstance(GeneratedYangParser.RequireInstanceContext currentContext);
 }
 }

@@ -49,6 +49,7 @@ import org.onosproject.yangutils.parser.impl.listeners.InputListener;
 import org.onosproject.yangutils.parser.impl.listeners.KeyListener;
 import org.onosproject.yangutils.parser.impl.listeners.KeyListener;
 import org.onosproject.yangutils.parser.impl.listeners.LeafListListener;
 import org.onosproject.yangutils.parser.impl.listeners.LeafListListener;
 import org.onosproject.yangutils.parser.impl.listeners.LeafListener;
 import org.onosproject.yangutils.parser.impl.listeners.LeafListener;
+import org.onosproject.yangutils.parser.impl.listeners.LeafrefListener;
 import org.onosproject.yangutils.parser.impl.listeners.LengthRestrictionListener;
 import org.onosproject.yangutils.parser.impl.listeners.LengthRestrictionListener;
 import org.onosproject.yangutils.parser.impl.listeners.ListListener;
 import org.onosproject.yangutils.parser.impl.listeners.ListListener;
 import org.onosproject.yangutils.parser.impl.listeners.MandatoryListener;
 import org.onosproject.yangutils.parser.impl.listeners.MandatoryListener;
@@ -56,16 +57,18 @@ import org.onosproject.yangutils.parser.impl.listeners.MaxElementsListener;
 import org.onosproject.yangutils.parser.impl.listeners.MinElementsListener;
 import org.onosproject.yangutils.parser.impl.listeners.MinElementsListener;
 import org.onosproject.yangutils.parser.impl.listeners.ModuleListener;
 import org.onosproject.yangutils.parser.impl.listeners.ModuleListener;
 import org.onosproject.yangutils.parser.impl.listeners.MustListener;
 import org.onosproject.yangutils.parser.impl.listeners.MustListener;
-import org.onosproject.yangutils.parser.impl.listeners.NotificationListener;
 import org.onosproject.yangutils.parser.impl.listeners.NamespaceListener;
 import org.onosproject.yangutils.parser.impl.listeners.NamespaceListener;
+import org.onosproject.yangutils.parser.impl.listeners.NotificationListener;
 import org.onosproject.yangutils.parser.impl.listeners.OrganizationListener;
 import org.onosproject.yangutils.parser.impl.listeners.OrganizationListener;
 import org.onosproject.yangutils.parser.impl.listeners.OutputListener;
 import org.onosproject.yangutils.parser.impl.listeners.OutputListener;
+import org.onosproject.yangutils.parser.impl.listeners.PathListener;
 import org.onosproject.yangutils.parser.impl.listeners.PatternRestrictionListener;
 import org.onosproject.yangutils.parser.impl.listeners.PatternRestrictionListener;
 import org.onosproject.yangutils.parser.impl.listeners.PositionListener;
 import org.onosproject.yangutils.parser.impl.listeners.PositionListener;
 import org.onosproject.yangutils.parser.impl.listeners.PrefixListener;
 import org.onosproject.yangutils.parser.impl.listeners.PrefixListener;
 import org.onosproject.yangutils.parser.impl.listeners.PresenceListener;
 import org.onosproject.yangutils.parser.impl.listeners.PresenceListener;
 import org.onosproject.yangutils.parser.impl.listeners.RangeRestrictionListener;
 import org.onosproject.yangutils.parser.impl.listeners.RangeRestrictionListener;
 import org.onosproject.yangutils.parser.impl.listeners.ReferenceListener;
 import org.onosproject.yangutils.parser.impl.listeners.ReferenceListener;
+import org.onosproject.yangutils.parser.impl.listeners.RequireInstanceListener;
 import org.onosproject.yangutils.parser.impl.listeners.RevisionDateListener;
 import org.onosproject.yangutils.parser.impl.listeners.RevisionDateListener;
 import org.onosproject.yangutils.parser.impl.listeners.RevisionListener;
 import org.onosproject.yangutils.parser.impl.listeners.RevisionListener;
 import org.onosproject.yangutils.parser.impl.listeners.RpcListener;
 import org.onosproject.yangutils.parser.impl.listeners.RpcListener;
@@ -81,9 +84,9 @@ import org.onosproject.yangutils.parser.impl.listeners.ValueListener;
 import org.onosproject.yangutils.parser.impl.listeners.VersionListener;
 import org.onosproject.yangutils.parser.impl.listeners.VersionListener;
 import org.onosproject.yangutils.parser.impl.listeners.WhenListener;
 import org.onosproject.yangutils.parser.impl.listeners.WhenListener;
 
 
-import static org.onosproject.yangutils.utils.UtilConstants.UNSUPPORTED_YANG_CONSTRUCT;
-import static org.onosproject.yangutils.utils.UtilConstants.CURRENTLY_UNSUPPORTED;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerUtil.handleUnsupportedYangConstruct;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerUtil.handleUnsupportedYangConstruct;
+import static org.onosproject.yangutils.utils.UtilConstants.CURRENTLY_UNSUPPORTED;
+import static org.onosproject.yangutils.utils.UtilConstants.UNSUPPORTED_YANG_CONSTRUCT;
 
 
 /**
 /**
  * Represents ANTLR generates parse-tree. ANTLR generates a parse-tree listener interface that responds to events
  * Represents ANTLR generates parse-tree. ANTLR generates a parse-tree listener interface that responds to events
@@ -667,17 +670,17 @@ public class TreeWalkListener implements GeneratedYangListener {
 
 
     @Override
     @Override
     public void enterLeafrefSpecification(GeneratedYangParser.LeafrefSpecificationContext ctx) {
     public void enterLeafrefSpecification(GeneratedYangParser.LeafrefSpecificationContext ctx) {
-        // do nothing.
+        LeafrefListener.processLeafrefEntry(this, ctx);
     }
     }
 
 
     @Override
     @Override
     public void exitLeafrefSpecification(GeneratedYangParser.LeafrefSpecificationContext ctx) {
     public void exitLeafrefSpecification(GeneratedYangParser.LeafrefSpecificationContext ctx) {
-        // do nothing.
+        LeafrefListener.processLeafrefExit(this, ctx);
     }
     }
 
 
     @Override
     @Override
     public void enterPathStatement(GeneratedYangParser.PathStatementContext ctx) {
     public void enterPathStatement(GeneratedYangParser.PathStatementContext ctx) {
-        handleUnsupportedYangConstruct(YangConstructType.PATH_DATA, ctx, CURRENTLY_UNSUPPORTED);
+        PathListener.processPathEntry(this, ctx);
     }
     }
 
 
     @Override
     @Override
@@ -687,7 +690,7 @@ public class TreeWalkListener implements GeneratedYangListener {
 
 
     @Override
     @Override
     public void enterRequireInstanceStatement(GeneratedYangParser.RequireInstanceStatementContext ctx) {
     public void enterRequireInstanceStatement(GeneratedYangParser.RequireInstanceStatementContext ctx) {
-        handleUnsupportedYangConstruct(YangConstructType.REQUIRE_INSTANCE_DATA, ctx, UNSUPPORTED_YANG_CONSTRUCT);
+        RequireInstanceListener.processRequireInstanceEntry(this, ctx);
     }
     }
 
 
     @Override
     @Override
@@ -1489,6 +1492,16 @@ public class TreeWalkListener implements GeneratedYangListener {
     }
     }
 
 
     @Override
     @Override
+    public void enterRequireInstance(GeneratedYangParser.RequireInstanceContext ctx) {
+        // do nothing.
+    }
+
+    @Override
+    public void exitRequireInstance(GeneratedYangParser.RequireInstanceContext ctx) {
+        // do nothing.
+    }
+
+    @Override
     public void enterFraction(GeneratedYangParser.FractionContext ctx) {
     public void enterFraction(GeneratedYangParser.FractionContext ctx) {
         // TODO: implement the method.
         // TODO: implement the method.
     }
     }

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.onosproject.yangutils.datamodel.YangLeaf;
+import org.onosproject.yangutils.datamodel.YangLeafList;
+import org.onosproject.yangutils.datamodel.YangLeafRef;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.YangType;
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import org.onosproject.yangutils.datamodel.utils.Parsable;
+import org.onosproject.yangutils.linker.impl.YangResolutionInfoImpl;
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+import static org.onosproject.yangutils.datamodel.utils.DataModelUtils.addResolutionInfo;
+import static org.onosproject.yangutils.datamodel.utils.ResolvableStatus.UNRESOLVED;
+import static org.onosproject.yangutils.datamodel.utils.YangConstructType.LEAFREF_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructExtendedListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.UNHANDLED_PARSED_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * type-body-stmts     = numerical-restrictions /
+ *                       decimal64-specification /
+ *                       string-restrictions /
+ *                       enum-specification /
+ *                       leafref-specification /
+ *                       identityref-specification /
+ *                       instance-identifier-specification /
+ *                       bits-specification /
+ *                       union-specification
+ *
+ * leafref-specification =
+ *                         ;; these stmts can appear in any order
+ *                        path-stmt stmtsep
+ *                        [require-instance-stmt stmtsep]
+ *
+ * ANTLR grammar rule
+ *
+ * typeBodyStatements : numericalRestrictions | stringRestrictions | enumSpecification
+ *                 | leafrefSpecification | identityrefSpecification | instanceIdentifierSpecification
+ *                 | bitsSpecification | unionSpecification;
+ *
+ * leafrefSpecification : (pathStatement (requireInstanceStatement)?) | ((requireInstanceStatement)? pathStatement);
+ */
+
+/**
+ * Represents listener based call back function corresponding to the
+ * "leafref" rule defined in ANTLR grammar file for corresponding ABNF rule
+ * in RFC 6020.
+ */
+public final class LeafrefListener {
+
+    /**
+     * Creates a new leafref listener.
+     */
+    private LeafrefListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar rule
+     * (leafref), perform validations and updates the data model tree.
+     *
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
+     */
+    public static void processLeafrefEntry(TreeWalkListener listener,
+            GeneratedYangParser.LeafrefSpecificationContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAFREF_DATA, "", ENTRY);
+
+        int errorLine = ctx.getStart().getLine();
+        int errorPosition = ctx.getStart().getCharPositionInLine();
+
+        YangLeafRef<?> leafRef = new YangLeafRef<>();
+
+        Parsable typeData = listener.getParsedDataStack().pop();
+
+        if (!(typeData instanceof YangType)) {
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, LEAFREF_DATA,
+                    "", ENTRY));
+        }
+
+        YangType type = (YangType) typeData;
+        type.setDataTypeExtendedInfo(leafRef);
+
+        // Setting by default the value of require-instance as true.
+        leafRef.setRequireInstance(true);
+        Parsable tmpData = listener.getParsedDataStack().peek();
+
+        switch (tmpData.getYangConstructType()) {
+
+            case LEAF_DATA:
+
+                // Parent YANG node of leaf to be added in resolution information.
+                YangLeaf leaf = (YangLeaf) listener.getParsedDataStack().pop();
+                Parsable parentNodeOfLeaf = listener.getParsedDataStack().peek();
+                listener.getParsedDataStack().push(leaf);
+
+                // Verify parent node of leaf.
+                if (!(parentNodeOfLeaf instanceof YangNode)) {
+                    throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, LEAFREF_DATA,
+                            "", ENTRY));
+                }
+
+                leafRef.setResolvableStatus(UNRESOLVED);
+
+                // Add resolution information to the list.
+                YangResolutionInfoImpl resolutionInfo = new YangResolutionInfoImpl<YangLeafRef>(leafRef,
+                        (YangNode) parentNodeOfLeaf, errorLine, errorPosition);
+                addToResolutionList(resolutionInfo);
+                break;
+
+            case LEAF_LIST_DATA:
+
+                // Parent YANG node of leaf-list to be added in resolution information.
+                YangLeafList leafList = (YangLeafList) listener.getParsedDataStack().pop();
+                Parsable parentNodeOfLeafList = listener.getParsedDataStack().peek();
+                listener.getParsedDataStack().push(leafList);
+
+                // Verify parent node of leaf-list.
+                if (!(parentNodeOfLeafList instanceof YangNode)) {
+                    throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, LEAFREF_DATA,
+                            "", ENTRY));
+                }
+
+                leafRef.setResolvableStatus(UNRESOLVED);
+
+                // Add resolution information to the list.
+                YangResolutionInfoImpl resolutionInfoImpl = new YangResolutionInfoImpl<YangLeafRef>(leafRef,
+                        (YangNode) parentNodeOfLeafList, errorLine, errorPosition);
+                addToResolutionList(resolutionInfoImpl);
+                break;
+
+            case TYPEDEF_DATA:
+                /*
+                 * Do not add the leaf ref to resolution list. It needs to be
+                 * added to resolution list, when leaf/leaf list references to
+                 * this typedef. At this time that leaf/leaf-list becomes the
+                 * parent for the leafref.
+                 */
+                break;
+
+            default:
+                throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, LEAFREF_DATA,
+                        "", ENTRY));
+        }
+        listener.getParsedDataStack().push(typeData);
+        listener.getParsedDataStack().push(leafRef);
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (leafref), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
+     */
+    public static void processLeafrefExit(TreeWalkListener listener,
+            GeneratedYangParser.LeafrefSpecificationContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_CURRENT_HOLDER, LEAFREF_DATA, "", EXIT);
+
+        Parsable parsableType = listener.getParsedDataStack().pop();
+        if (!(parsableType instanceof YangLeafRef)) {
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, LEAFREF_DATA,
+                    "", EXIT));
+        }
+    }
+
+    /**
+     * Adds to resolution list.
+     *
+     * @param resolutionInfo resolution information
+     */
+    private static void addToResolutionList(YangResolutionInfoImpl resolutionInfo) {
+
+        try {
+            addResolutionInfo(resolutionInfo);
+        } catch (DataModelException e) {
+            throw new ParserException(constructExtendedListenerErrorMessage(UNHANDLED_PARSED_DATA,
+                    LEAFREF_DATA, "", ENTRY, e.getMessage()));
+        }
+    }
+}

@@ -128,6 +128,8 @@ public final class ModuleListener {
                     .peek()).resolveSelfFileLinking(ResolvableType.YANG_USES);
                     .peek()).resolveSelfFileLinking(ResolvableType.YANG_USES);
             ((YangReferenceResolver) listener.getParsedDataStack()
             ((YangReferenceResolver) listener.getParsedDataStack()
                     .peek()).resolveSelfFileLinking(ResolvableType.YANG_DERIVED_DATA_TYPE);
                     .peek()).resolveSelfFileLinking(ResolvableType.YANG_DERIVED_DATA_TYPE);
+            ((YangReferenceResolver) listener.getParsedDataStack()
+                    .peek()).resolveSelfFileLinking(ResolvableType.YANG_LEAFREF);
         } catch (DataModelException e) {
         } catch (DataModelException e) {
             LinkerException linkerException = new LinkerException(e.getMessage());
             LinkerException linkerException = new LinkerException(e.getMessage());
             linkerException.setLine(e.getLineNumber());
             linkerException.setLine(e.getLineNumber());

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.onosproject.yangutils.datamodel.YangLeafRef;
+import org.onosproject.yangutils.datamodel.utils.Parsable;
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerUtil.validatePathArgument;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.datamodel.utils.YangConstructType.PATH_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  leafref-specification =
+ *                        ;; these stmts can appear in any order
+ *                        path-stmt stmtsep
+ *                        [require-instance-stmt stmtsep]
+ *
+ * path-stmt           = path-keyword sep path-arg-str stmtend
+ *
+ * ANTLR grammar rule
+ *
+ * leafrefSpecification : (pathStatement (requireInstanceStatement)?) | ((requireInstanceStatement)? pathStatement);
+ *
+ * pathStatement : PATH_KEYWORD path STMTEND;
+ */
+
+/**
+ * Represents listener based call back function corresponding to the
+ * "path" rule defined in ANTLR grammar file for corresponding ABNF rule
+ * in RFC 6020.
+ */
+public final class PathListener {
+
+    /**
+     * Creates a new path listener.
+     */
+    private PathListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar rule
+     * (path), performs validation and updates the data model tree.
+     *
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
+     */
+    public static void processPathEntry(TreeWalkListener listener,
+            GeneratedYangParser.PathStatementContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, PATH_DATA, ctx.path().getText(), ENTRY);
+
+        Parsable curData = listener.getParsedDataStack().peek();
+
+        // Checks the holder of path as leafref, else throws error.
+        if (curData instanceof YangLeafRef) {
+
+            // Splitting the path argument and updating it in the datamodel tree.
+            validatePathArgument(ctx.path().getText(), PATH_DATA, ctx, (YangLeafRef) curData);
+        } else {
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, PATH_DATA,
+                    ctx.path().getText(), ENTRY));
+        }
+    }
+}

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.onosproject.yangutils.datamodel.YangLeafRef;
+import org.onosproject.yangutils.datamodel.YangType;
+import org.onosproject.yangutils.datamodel.utils.Parsable;
+import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+import static org.onosproject.yangutils.datamodel.utils.YangConstructType.REQUIRE_INSTANCE_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerUtil.getValidBooleanValue;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * require-instance-stmt = require-instance-keyword sep
+ *                            require-instance-arg-str stmtend
+ *
+ * require-instance-arg-str = < a string that matches the rule
+ *                            require-instance-arg >
+ *
+ * require-instance-arg = true-keyword / false-keyword
+ *
+ * ANTLR grammar rule
+ *
+ * requireInstanceStatement : REQUIRE_INSTANCE_KEYWORD requireInstance STMTEND;
+ *
+ * requireInstance : string;
+ */
+
+/**
+ * Represents listener based call back function corresponding to the
+ * "require-instance" rule defined in ANTLR grammar file for corresponding ABNF rule
+ * in RFC 6020.
+ */
+public final class RequireInstanceListener {
+
+    /**
+     * Creates a new require instance listener.
+     */
+    private RequireInstanceListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar rule
+     * (require-instance), performs validation and updates the data model tree.
+     *
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
+     */
+    public static void processRequireInstanceEntry(TreeWalkListener listener,
+            GeneratedYangParser.RequireInstanceStatementContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, REQUIRE_INSTANCE_DATA, "", ENTRY);
+
+        Parsable curData = listener.getParsedDataStack().peek();
+
+        // Gets the status of require instance
+        boolean isRequireInstance = getValidBooleanValue(ctx.requireInstance().getText(), REQUIRE_INSTANCE_DATA, ctx);
+
+        // Checks the holder of require-instance as leafref or type, else throws error.
+        if (curData instanceof YangLeafRef) {
+
+            // Sets the require-instance status to leafref.
+            ((YangLeafRef) curData).setRequireInstance(isRequireInstance);
+        } else if (curData instanceof YangType) {
+
+            // Checks type should be instance-identifier, else throw error.
+            if (((YangType) curData).getDataType() == YangDataTypes.INSTANCE_IDENTIFIER) {
+
+                // Sets the require-instance status to instance-identifier type.
+                ((YangType) curData).setDataTypeExtendedInfo(isRequireInstance);
+            } else {
+                throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, REQUIRE_INSTANCE_DATA,
+                        ctx.getText(), ENTRY));
+            }
+        } else {
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, REQUIRE_INSTANCE_DATA,
+                    ctx.getText(), ENTRY));
+        }
+    }
+}

@@ -133,6 +133,8 @@ public final class SubModuleListener {
                     .resolveSelfFileLinking(ResolvableType.YANG_USES);
                     .resolveSelfFileLinking(ResolvableType.YANG_USES);
             ((YangReferenceResolver) listener.getParsedDataStack().peek())
             ((YangReferenceResolver) listener.getParsedDataStack().peek())
                     .resolveSelfFileLinking(ResolvableType.YANG_DERIVED_DATA_TYPE);
                     .resolveSelfFileLinking(ResolvableType.YANG_DERIVED_DATA_TYPE);
+            ((YangReferenceResolver) listener.getParsedDataStack().peek())
+                    .resolveSelfFileLinking(ResolvableType.YANG_LEAFREF);
         } catch (DataModelException e) {
         } catch (DataModelException e) {
             LinkerException linkerException = new LinkerException(e.getMessage());
             LinkerException linkerException = new LinkerException(e.getMessage());
             linkerException.setLine(e.getLineNumber());
             linkerException.setLine(e.getLineNumber());

@@ -101,6 +101,9 @@ public final class TypeListener {
         type.setNodeIdentifier(nodeIdentifier);
         type.setNodeIdentifier(nodeIdentifier);
         type.setDataType(yangDataTypes);
         type.setDataType(yangDataTypes);
 
 
+        // Set default require instance value as true for instance identifier.
+        setDefaultRequireInstanceForInstanceIdentifier(type);
+
         int errorLine = ctx.getStart().getLine();
         int errorLine = ctx.getStart().getLine();
         int errorPosition = ctx.getStart().getCharPositionInLine();
         int errorPosition = ctx.getStart().getCharPositionInLine();
 
 
@@ -233,6 +236,18 @@ public final class TypeListener {
     }
     }
 
 
     /**
     /**
+     * Sets the default require instance value as true when the type is instance identifier.
+     *
+     * @param type type to which the value has to be set
+     */
+    private static void setDefaultRequireInstanceForInstanceIdentifier(YangType<?> type) {
+
+        if (type.getDataType() == YangDataTypes.INSTANCE_IDENTIFIER) {
+            ((YangType<Boolean>) type).setDataTypeExtendedInfo(true);
+        }
+    }
+
+    /**
      * It is called when parser exits from grammar rule (type), it perform
      * It is called when parser exits from grammar rule (type), it perform
      * validations and update the data model tree.
      * validations and update the data model tree.
      *
      *
@@ -291,7 +306,11 @@ public final class TypeListener {
                     parserException = new ParserException("YANG file error : a type bits" +
                     parserException = new ParserException("YANG file error : a type bits" +
                             " must have atleast one bit statement.");
                             " must have atleast one bit statement.");
                     break;
                     break;
-                // TODO : decimal64, identity ref, leafref
+                case LEAFREF:
+                    parserException = new ParserException("YANG file error : a type leafref" +
+                            " must have one path statement.");
+                    break;
+                // TODO : decimal64, identity ref
                 default:
                 default:
                     return;
                     return;
             }
             }

@@ -19,6 +19,8 @@ package org.onosproject.yangutils.translator.tojava;
 import java.io.IOException;
 import java.io.IOException;
 
 
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.YangTypeDef;
+import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
 import org.onosproject.yangutils.translator.exception.TranslatorException;
 import org.onosproject.yangutils.translator.exception.TranslatorException;
 import org.onosproject.yangutils.utils.io.impl.YangPluginConfig;
 import org.onosproject.yangutils.utils.io.impl.YangPluginConfig;
 
 
@@ -80,7 +82,20 @@ public final class JavaCodeGeneratorUtil {
                 if (!(codeGenNode instanceof JavaCodeGenerator)) {
                 if (!(codeGenNode instanceof JavaCodeGenerator)) {
                     throw new TranslatorException("Unsupported node to generate code");
                     throw new TranslatorException("Unsupported node to generate code");
                 }
                 }
-
+                if (codeGenNode instanceof YangTypeDef) {
+                    YangTypeDef typeDef = (YangTypeDef) codeGenNode;
+                    if (typeDef.getTypeDefBaseType().getDataType() == YangDataTypes.LEAFREF
+                            || typeDef.getTypeDefBaseType().getDataType() == YangDataTypes.IDENTITYREF) {
+                        if (codeGenNode.getNextSibling() != null) {
+                            curTraversal = SIBILING;
+                            codeGenNode = codeGenNode.getNextSibling();
+                        } else {
+                            curTraversal = PARENT;
+                            codeGenNode = codeGenNode.getParent();
+                        }
+                        continue;
+                    }
+                }
                 setCurNode(codeGenNode);
                 setCurNode(codeGenNode);
                 try {
                 try {
                     generateCodeEntry(codeGenNode, yangPlugin);
                     generateCodeEntry(codeGenNode, yangPlugin);

@@ -17,13 +17,15 @@
 package org.onosproject.yangutils.translator.tojava.javamodel;
 package org.onosproject.yangutils.translator.tojava.javamodel;
 
 
 import java.util.Stack;
 import java.util.Stack;
-import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
+
 import org.onosproject.yangutils.datamodel.YangDerivedInfo;
 import org.onosproject.yangutils.datamodel.YangDerivedInfo;
 import org.onosproject.yangutils.datamodel.YangEnumeration;
 import org.onosproject.yangutils.datamodel.YangEnumeration;
+import org.onosproject.yangutils.datamodel.YangLeafRef;
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.YangType;
 import org.onosproject.yangutils.datamodel.YangType;
 import org.onosproject.yangutils.datamodel.YangTypeDef;
 import org.onosproject.yangutils.datamodel.YangTypeDef;
 import org.onosproject.yangutils.datamodel.YangUnion;
 import org.onosproject.yangutils.datamodel.YangUnion;
+import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
 import org.onosproject.yangutils.translator.exception.TranslatorException;
 import org.onosproject.yangutils.translator.exception.TranslatorException;
 import org.onosproject.yangutils.translator.tojava.JavaCodeGeneratorInfo;
 import org.onosproject.yangutils.translator.tojava.JavaCodeGeneratorInfo;
 import org.onosproject.yangutils.translator.tojava.JavaFileInfo;
 import org.onosproject.yangutils.translator.tojava.JavaFileInfo;
@@ -101,6 +103,10 @@ public final class AttributesJavaDataType {
                 return STRING_DATA_TYPE;
                 return STRING_DATA_TYPE;
             case BOOLEAN:
             case BOOLEAN:
                 return BOOLEAN_DATA_TYPE;
                 return BOOLEAN_DATA_TYPE;
+            case INSTANCE_IDENTIFIER:
+                return STRING_DATA_TYPE;
+            case LEAFREF:
+                return getJavaDataType(getReferredTypeFromLeafref(yangType));
             default:
             default:
                 throw new TranslatorException("given data type is not supported.");
                 throw new TranslatorException("given data type is not supported.");
         }
         }
@@ -152,8 +158,8 @@ public final class AttributesJavaDataType {
                 case BINARY:
                 case BINARY:
                     return YANG_BINARY_CLASS;
                     return YANG_BINARY_CLASS;
                 case LEAFREF:
                 case LEAFREF:
-                    //TODO:LEAFREF
-                    break;
+                    YangType<?> referredType = getReferredTypeFromLeafref(yangType);
+                    return getJavaImportClass(referredType, isListAttr, pluginConfig);
                 case IDENTITYREF:
                 case IDENTITYREF:
                     //TODO:IDENTITYREF
                     //TODO:IDENTITYREF
                     break;
                     break;
@@ -163,8 +169,7 @@ public final class AttributesJavaDataType {
                     return getCapitalCase(getCamelCase(((YangJavaUnion) yangType.getDataTypeExtendedInfo()).getName(),
                     return getCapitalCase(getCamelCase(((YangJavaUnion) yangType.getDataTypeExtendedInfo()).getName(),
                             pluginConfig));
                             pluginConfig));
                 case INSTANCE_IDENTIFIER:
                 case INSTANCE_IDENTIFIER:
-                    //TODO:INSTANCE_IDENTIFIER
-                    break;
+                    return STRING_DATA_TYPE;
                 case DERIVED:
                 case DERIVED:
                     return getCapitalCase(
                     return getCapitalCase(
                             getCamelCase(yangType.getDataTypeName(), pluginConfig));
                             getCamelCase(yangType.getDataTypeName(), pluginConfig));
@@ -188,8 +193,8 @@ public final class AttributesJavaDataType {
                 case BINARY:
                 case BINARY:
                     return YANG_BINARY_CLASS;
                     return YANG_BINARY_CLASS;
                 case LEAFREF:
                 case LEAFREF:
-                    //TODO:LEAFREF
-                    break;
+                    YangType<?> referredType = getReferredTypeFromLeafref(yangType);
+                    return getJavaImportClass(referredType, isListAttr, pluginConfig);
                 case IDENTITYREF:
                 case IDENTITYREF:
                     //TODO:IDENTITYREF
                     //TODO:IDENTITYREF
                     break;
                     break;
@@ -199,8 +204,7 @@ public final class AttributesJavaDataType {
                     return getCapitalCase(getCamelCase(((YangJavaUnion) yangType.getDataTypeExtendedInfo()).getName(),
                     return getCapitalCase(getCamelCase(((YangJavaUnion) yangType.getDataTypeExtendedInfo()).getName(),
                             pluginConfig));
                             pluginConfig));
                 case INSTANCE_IDENTIFIER:
                 case INSTANCE_IDENTIFIER:
-                    //TODO:INSTANCE_IDENTIFIER
-                    break;
+                    return STRING_DATA_TYPE;
                 case DERIVED:
                 case DERIVED:
                     return getCapitalCase(
                     return getCapitalCase(
                             getCamelCase(yangType.getDataTypeName(), pluginConfig));
                             getCamelCase(yangType.getDataTypeName(), pluginConfig));
@@ -246,16 +250,15 @@ public final class AttributesJavaDataType {
                 case BINARY:
                 case BINARY:
                     return YANG_TYPES_PKG;
                     return YANG_TYPES_PKG;
                 case LEAFREF:
                 case LEAFREF:
-                    //TODO:LEAFREF
-                    break;
+                    YangType<?> referredType = getReferredTypeFromLeafref(yangType);
+                    return getJavaImportPackage(referredType, isListAttr, conflictResolver);
                 case IDENTITYREF:
                 case IDENTITYREF:
                     //TODO:IDENTITYREF
                     //TODO:IDENTITYREF
                     break;
                     break;
                 case UNION:
                 case UNION:
                     return getUnionPackage(yangType, conflictResolver);
                     return getUnionPackage(yangType, conflictResolver);
                 case INSTANCE_IDENTIFIER:
                 case INSTANCE_IDENTIFIER:
-                    //TODO:INSTANCE_IDENTIFIER
-                    break;
+                    return JAVA_LANG;
                 case DERIVED:
                 case DERIVED:
                     return getTypDefsPackage(yangType, conflictResolver);
                     return getTypDefsPackage(yangType, conflictResolver);
                 default:
                 default:
@@ -274,8 +277,8 @@ public final class AttributesJavaDataType {
                 case BINARY:
                 case BINARY:
                     return YANG_TYPES_PKG;
                     return YANG_TYPES_PKG;
                 case LEAFREF:
                 case LEAFREF:
-                    //TODO:LEAFREF
-                    break;
+                    YangType<?> referredType = getReferredTypeFromLeafref(yangType);
+                    return getJavaImportPackage(referredType, isListAttr, conflictResolver);
                 case IDENTITYREF:
                 case IDENTITYREF:
                     //TODO:IDENTITYREF
                     //TODO:IDENTITYREF
                     break;
                     break;
@@ -284,8 +287,7 @@ public final class AttributesJavaDataType {
                 case UNION:
                 case UNION:
                     return getUnionPackage(yangType, conflictResolver);
                     return getUnionPackage(yangType, conflictResolver);
                 case INSTANCE_IDENTIFIER:
                 case INSTANCE_IDENTIFIER:
-                    //TODO:INSTANCE_IDENTIFIER
-                    break;
+                    return JAVA_LANG;
                 case DERIVED:
                 case DERIVED:
                     return getTypDefsPackage(yangType, conflictResolver);
                     return getTypDefsPackage(yangType, conflictResolver);
                 default:
                 default:
@@ -444,4 +446,15 @@ public final class AttributesJavaDataType {
                                     .getPackage()));
                                     .getPackage()));
         }
         }
     }
     }
+
+    /**
+     * Returns the referred type from leaf/leaf-list.
+     *
+     * @param type current type in leaf
+     * @return type from the leafref
+     */
+    private static YangType<?> getReferredTypeFromLeafref(YangType type) {
+        YangLeafRef<?> leafRefInfo = (YangLeafRef<?>) type.getDataTypeExtendedInfo();
+        return leafRefInfo.getEffectiveDataType();
+    }
 }
 }

@@ -18,8 +18,9 @@ package org.onosproject.yangutils.translator.tojava.utils;
 
 
 import java.util.List;
 import java.util.List;
 import java.util.Map;
 import java.util.Map;
-import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
+
 import org.onosproject.yangutils.datamodel.YangType;
 import org.onosproject.yangutils.datamodel.YangType;
+import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
 import org.onosproject.yangutils.translator.exception.TranslatorException;
 import org.onosproject.yangutils.translator.exception.TranslatorException;
 import org.onosproject.yangutils.translator.tojava.JavaAttributeInfo;
 import org.onosproject.yangutils.translator.tojava.JavaAttributeInfo;
 import org.onosproject.yangutils.utils.io.impl.JavaDocGen;
 import org.onosproject.yangutils.utils.io.impl.JavaDocGen;
@@ -118,6 +119,7 @@ import static org.onosproject.yangutils.utils.UtilConstants.TWELVE_SPACE_INDENTA
 import static org.onosproject.yangutils.utils.UtilConstants.VALUE;
 import static org.onosproject.yangutils.utils.UtilConstants.VALUE;
 import static org.onosproject.yangutils.utils.UtilConstants.VOID;
 import static org.onosproject.yangutils.utils.UtilConstants.VOID;
 import static org.onosproject.yangutils.utils.UtilConstants.YANG_UTILS_TODO;
 import static org.onosproject.yangutils.utils.UtilConstants.YANG_UTILS_TODO;
+import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.getJavaDoc;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.BUILD_METHOD;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.BUILD_METHOD;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.CONSTRUCTOR;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.CONSTRUCTOR;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.DEFAULT_CONSTRUCTOR;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.DEFAULT_CONSTRUCTOR;
@@ -127,7 +129,6 @@ import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.MAN
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.OF_METHOD;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.OF_METHOD;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.SETTER_METHOD;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.SETTER_METHOD;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.TYPE_CONSTRUCTOR;
 import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.JavaDocType.TYPE_CONSTRUCTOR;
-import static org.onosproject.yangutils.utils.io.impl.JavaDocGen.getJavaDoc;
 import static org.onosproject.yangutils.utils.io.impl.YangIoUtils.getCamelCase;
 import static org.onosproject.yangutils.utils.io.impl.YangIoUtils.getCamelCase;
 import static org.onosproject.yangutils.utils.io.impl.YangIoUtils.getCapitalCase;
 import static org.onosproject.yangutils.utils.io.impl.YangIoUtils.getCapitalCase;
 import static org.onosproject.yangutils.utils.io.impl.YangIoUtils.getSmallCase;
 import static org.onosproject.yangutils.utils.io.impl.YangIoUtils.getSmallCase;

@@ -282,6 +282,16 @@ public final class UtilConstants {
     public static final String INPUT = "input";
     public static final String INPUT = "input";
 
 
     /**
     /**
+     * Static attribute for output string.
+     */
+    public static final String OUTPUT = "output";
+
+    /**
+     * Static attribute for current string.
+     */
+    public static final String CURRENT = "current";
+
+    /**
      * Static attribute for leafref string.
      * Static attribute for leafref string.
      */
      */
     public static final String LEAFREF = "leafref";
     public static final String LEAFREF = "leafref";
@@ -342,6 +352,41 @@ public final class UtilConstants {
     public static final String COMMA = ",";
     public static final String COMMA = ",";
 
 
     /**
     /**
+     * Static attribute for slash character.
+     */
+    public static final char CHAR_OF_SLASH = '/';
+
+    /**
+     * Static attribute for open square bracket character.
+     */
+    public static final char CHAR_OF_OPEN_SQUARE_BRACKET = '[';
+
+    /**
+     * Static attribute for close square bracket character.
+     */
+    public static final char CHAR_OF_CLOSE_SQUARE_BRACKET = ']';
+
+    /**
+     * Static attribute for slash string.
+     */
+    public static final String SLASH_FOR_STRING = "/";
+
+    /**
+     * Static attribute for open square bracket.
+     */
+    public static final String OPEN_SQUARE_BRACKET = "[";
+
+    /**
+     * Static attribute for ancestor accessor.
+     */
+    public static final String ANCESTOR_ACCESSOR = "..";
+
+    /**
+     * Static attribute for ancestor accessor along with path.
+     */
+    public static final String ANCESTOR_ACCESSOR_IN_PATH = "../";
+
+    /**
      * Static attribute for add syntax.
      * Static attribute for add syntax.
      */
      */
     public static final String ADD_STRING = "add";
     public static final String ADD_STRING = "add";
@@ -1110,7 +1155,6 @@ public final class UtilConstants {
      */
      */
     public static final String YANG_DECIMAL64_CLASS = "YangDecimal64";
     public static final String YANG_DECIMAL64_CLASS = "YangDecimal64";
 
 
-
     /**
     /**
      * Static attribute for YANG file error.
      * Static attribute for YANG file error.
      */
      */
@@ -1140,12 +1184,18 @@ public final class UtilConstants {
             + "grouping for given uses";
             + "grouping for given uses";
 
 
     /**
     /**
-     * Static attribute for grouping linker error information.
+     * Static attribute for if-feature linker error information.
      */
      */
     public static final String FEATURE_LINKER_ERROR = "YANG file error: Unable to find feature "
     public static final String FEATURE_LINKER_ERROR = "YANG file error: Unable to find feature "
             + "for given if-feature";
             + "for given if-feature";
 
 
     /**
     /**
+     * Static attribute for leafref linker error information.
+     */
+    public static final String LEAFREF_LINKER_ERROR = "YANG file error: Unable to find base "
+            + "leaf/leaf-list for given leafref";
+
+    /**
      * Static attribute for reference.
      * Static attribute for reference.
      */
      */
     public static final String REFERENCE = "Reference";
     public static final String REFERENCE = "Reference";

@@ -534,7 +534,7 @@ package org.onosproject.yangutils.parser.antlrgencode;
      *                             require-instance-arg >
      *                             require-instance-arg >
      *  require-instance-arg = true-keyword / false-keyword
      *  require-instance-arg = true-keyword / false-keyword
      */
      */
-    requireInstanceStatement : REQUIRE_INSTANCE_KEYWORD (TRUE_KEYWORD | FALSE_KEYWORD) STMTEND;
+    requireInstanceStatement : REQUIRE_INSTANCE_KEYWORD requireInstance STMTEND;
 
 
     /**
     /**
      *  instance-identifier-specification =
      *  instance-identifier-specification =
@@ -1279,6 +1279,8 @@ package org.onosproject.yangutils.parser.antlrgencode;
 
 
     refine : string;
     refine : string;
 
 
+    requireInstance : string;
+
     augment : string;
     augment : string;
 
 
     deviation : string;
     deviation : string;

+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import java.io.IOException;
+import java.util.ListIterator;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import org.onosproject.yangutils.datamodel.YangContainer;
+import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
+import org.onosproject.yangutils.datamodel.YangLeaf;
+import org.onosproject.yangutils.datamodel.YangLeafRef;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.YangNodeType;
+import org.onosproject.yangutils.datamodel.YangType;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.core.Is.is;
+/**
+ * Test cases for require-instance listener.
+ */
+public class RequireInstanceListenerTest {
+
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks require-statement with true as status.
+     */
+    @Test
+    public void processRequireInstanceTrue() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RequireInstanceTrue.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.MODULE_NODE));
+
+        // Check whether the module name is set correctly.
+        YangModule yangNode = (YangModule) node;
+        assertThat(yangNode.getName(), is("PathListener"));
+
+        YangContainer container = (YangContainer) yangNode.getChild().getNextSibling();
+        ListIterator<YangLeaf> leafIterator = container.getListOfLeaf().listIterator();
+        YangLeaf leafInfo = leafIterator.next();
+
+        // Check whether the require-instance value is set correctly in leafref.
+        assertThat(leafInfo.getName(), is("ifname"));
+        YangLeafRef yangLeafRef = (YangLeafRef) leafInfo.getDataType().getDataTypeExtendedInfo();
+        assertThat(yangLeafRef.getRequireInstance(), is(true));
+    }
+
+    /**
+     * Checks require-statement with false as status.
+     */
+    @Test
+    public void processRequireInstanceFalse() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RequireInstanceFalse.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.MODULE_NODE));
+
+        // Check whether the module name is set correctly.
+        YangModule yangNode = (YangModule) node;
+        assertThat(yangNode.getName(), is("PathListener"));
+
+        ListIterator<YangLeaf> leafIterator = yangNode.getListOfLeaf().listIterator();
+        YangLeaf leafInfo = leafIterator.next();
+
+        // Check whether the require-instance value is set correctly in instance-identifier.
+        assertThat(leafInfo.getName(), is("admin-status"));
+
+        YangType type = leafInfo.getDataType();
+
+        assertThat(type.getDataType(), is(YangDataTypes.INSTANCE_IDENTIFIER));
+        boolean status = ((YangType<Boolean>) type).getDataTypeExtendedInfo();
+
+        assertThat(status, is(false));
+    }
+
+    /**
+     * Checks require-statement default value when its not there in YANG under instance-identifier.
+     */
+    @Test
+    public void processRequireInstanceDefaultValueInInstanceIdentifier() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RequireInstanceDefaultValueInInstanceIdentifier.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.MODULE_NODE));
+
+        // Check whether the module name is set correctly.
+        YangModule yangNode = (YangModule) node;
+        assertThat(yangNode.getName(), is("PathListener"));
+
+        ListIterator<YangLeaf> leafIterator = yangNode.getListOfLeaf().listIterator();
+        YangLeaf leafInfo = leafIterator.next();
+
+        // Check whether the require-instance value is set correctly in instance-identifier.
+        assertThat(leafInfo.getName(), is("admin-status"));
+
+        YangType type = leafInfo.getDataType();
+
+        assertThat(type.getDataType(), is(YangDataTypes.INSTANCE_IDENTIFIER));
+
+        boolean status = ((YangType<Boolean>) type).getDataTypeExtendedInfo();
+        assertThat(status, is(true));
+    }
+
+    /**
+     * Checks require-statement default value when its not there in YANG under leafref.
+     */
+    @Test
+    public void processRequireInstanceDefaultValueForLeafref() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RequireInstanceDefaultValueForLeafref.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.MODULE_NODE));
+
+        // Check whether the module name is set correctly.
+        YangModule yangNode = (YangModule) node;
+        assertThat(yangNode.getName(), is("PathListener"));
+
+        YangContainer container = (YangContainer) yangNode.getChild().getNextSibling();
+        ListIterator<YangLeaf> leafIterator = container.getListOfLeaf().listIterator();
+        YangLeaf leafInfo = leafIterator.next();
+
+        // Check whether the require-instance value is set correctly in leafref.
+        assertThat(leafInfo.getName(), is("ifname"));
+        YangLeafRef yangLeafRef = (YangLeafRef) leafInfo.getDataType().getDataTypeExtendedInfo();
+        assertThat(yangLeafRef.getRequireInstance(), is(true));
+    }
+}

@@ -20,6 +20,7 @@ import java.util.ListIterator;
 import org.junit.Rule;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.junit.rules.ExpectedException;
+import org.onosproject.yangutils.datamodel.YangContainer;
 import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
 import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
 import org.onosproject.yangutils.datamodel.YangLeaf;
 import org.onosproject.yangutils.datamodel.YangLeaf;
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.datamodel.YangLeafList;
@@ -121,20 +122,6 @@ public class TypeListenerTest {
     }
     }
 
 
     /**
     /**
-     * Checks for unsupported type leafref.
-     */
-    @Test
-    public void processLeafrefType() throws IOException, ParserException {
-
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("YANG file error : \"leafref\" is not supported in current version,"
-                + " please check wiki for YANG utils road map.");
-
-        YangNode node = manager
-                .getDataModel("src/test/resources/LeafrefInvalidIdentifier.yang");
-    }
-
-    /**
      * Checks for unsupported type identityref.
      * Checks for unsupported type identityref.
      */
      */
     @Test
     @Test
@@ -149,16 +136,29 @@ public class TypeListenerTest {
     }
     }
 
 
     /**
     /**
-     * Checks for unsupported type instance identifier.
+     * Checks for type instance-identifier.
      */
      */
     @Test
     @Test
     public void processInstanceIdentifierType() throws IOException, ParserException {
     public void processInstanceIdentifierType() throws IOException, ParserException {
 
 
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("YANG file error : \"instance-identifier\" is not supported in current version,"
-                + " please check wiki for YANG utils road map.");
-
         YangNode node = manager
         YangNode node = manager
-                .getDataModel("src/test/resources/InstanceIdentifierInvalidIdentifier.yang");
+                .getDataModel("src/test/resources/InstanceIdentifierListener.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.MODULE_NODE));
+
+        // Check whether the module name is set correctly.
+        YangModule yangNode = (YangModule) node;
+        assertThat(yangNode.getName(), is("Test"));
+        YangContainer container = (YangContainer) yangNode.getChild();
+        ListIterator<YangLeaf> leafIterator = container.getListOfLeaf().listIterator();
+        YangLeaf leafInfo = leafIterator.next();
+
+        assertThat(leafInfo.getName(), is("invalid-interval"));
+        assertThat(leafInfo.getDataType().getDataTypeName(), is("instance-identifier"));
+        assertThat(leafInfo.getDataType().getDataType(), is(YangDataTypes.INSTANCE_IDENTIFIER));
     }
     }
 }
 }

@@ -18,11 +18,15 @@ package org.onosproject.yangutils.plugin.manager;
 
 
 import java.io.IOException;
 import java.io.IOException;
 import java.util.List;
 import java.util.List;
+import java.util.ListIterator;
+
 import org.junit.Test;
 import org.junit.Test;
 import org.onosproject.yangutils.datamodel.YangContainer;
 import org.onosproject.yangutils.datamodel.YangContainer;
+import org.onosproject.yangutils.datamodel.utils.builtindatatype.YangDataTypes;
 import org.onosproject.yangutils.datamodel.YangFeature;
 import org.onosproject.yangutils.datamodel.YangFeature;
 import org.onosproject.yangutils.datamodel.YangIfFeature;
 import org.onosproject.yangutils.datamodel.YangIfFeature;
 import org.onosproject.yangutils.datamodel.YangLeaf;
 import org.onosproject.yangutils.datamodel.YangLeaf;
+import org.onosproject.yangutils.datamodel.YangLeafRef;
 import org.onosproject.yangutils.datamodel.YangModule;
 import org.onosproject.yangutils.datamodel.YangModule;
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.YangNodeType;
 import org.onosproject.yangutils.datamodel.YangNodeType;
@@ -217,4 +221,111 @@ public class IntraFileIfFeatureLinkingTest {
         assertThat(ifFeature.getName().getName(), is("local-storage"));
         assertThat(ifFeature.getName().getName(), is("local-storage"));
         assertThat(ifFeature.getResolvableStatus(), is(ResolvableStatus.RESOLVED));
         assertThat(ifFeature.getResolvableStatus(), is(ResolvableStatus.RESOLVED));
     }
     }
+
+    /**
+     * Checks addition of if-feature list to leafref.
+     */
+    @Test
+    public void processSelfFileLinkingWithFeatureReferredByLeafref()
+            throws IOException, ParserException {
+
+        YangNode node = manager
+                .getDataModel("src/test/resources/SelfFileLinkingWithFeatureReferredByLeafref.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.MODULE_NODE));
+
+        // Check whether the module name is set correctly.
+        YangModule yangNode = (YangModule) node;
+        assertThat(yangNode.getName(), is("syslog"));
+
+        List<YangFeature> featureList = yangNode.getFeatureList();
+        YangFeature feature = featureList.iterator().next();
+        assertThat(feature.getName(), is("local-storage"));
+
+        YangContainer container = (YangContainer) yangNode.getChild();
+        assertThat(container.getName(), is("speed"));
+
+        List<YangLeaf> listOfLeaf = container.getListOfLeaf();
+        YangLeaf leaf = listOfLeaf.iterator().next();
+        assertThat(leaf.getName(), is("local-storage-limit"));
+
+        List<YangIfFeature> ifFeatureList = leaf.getIfFeatureList();
+        YangIfFeature ifFeature = ifFeatureList.iterator().next();
+        assertThat(ifFeature.getName().getName(), is("local-storage"));
+        assertThat(ifFeature.getResolvableStatus(), is(ResolvableStatus.RESOLVED));
+
+        ListIterator<YangLeaf> listOfLeafInModule =  yangNode.getListOfLeaf().listIterator();
+        YangLeaf yangLeaf = listOfLeafInModule.next();
+        assertThat(yangLeaf.getName(), is("storage-value"));
+
+        YangLeafRef leafRef = (YangLeafRef) yangLeaf.getDataType().getDataTypeExtendedInfo();
+
+        assertThat(leafRef.getEffectiveDataType().getDataType(), is(YangDataTypes.UINT64));
+
+        List<YangIfFeature> ifFeatureListInLeafref = leafRef.getIfFeatureList();
+        YangIfFeature ifFeatureInLeafref = ifFeatureListInLeafref.iterator().next();
+        assertThat(ifFeatureInLeafref.getName().getName(), is("local-storage"));
+        assertThat(ifFeatureInLeafref.getResolvableStatus(), is(ResolvableStatus.RESOLVED));
+    }
+
+    /**
+     * Checks addition of if-feature list to leafref when referred leaf is again having leafref in it.
+     */
+    @Test
+    public void processSelfFileLinkingWithFeatureReferredByMultiLeafref()
+            throws IOException, ParserException {
+
+        YangNode node = manager
+                .getDataModel("src/test/resources/SelfFileLinkingWithFeatureReferredByMultiLeafref.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.MODULE_NODE));
+
+        // Check whether the module name is set correctly.
+        YangModule yangNode = (YangModule) node;
+        assertThat(yangNode.getName(), is("syslog"));
+
+        List<YangFeature> featureList = yangNode.getFeatureList();
+        YangFeature feature = featureList.iterator().next();
+        assertThat(feature.getName(), is("local-storage"));
+
+        YangContainer container = (YangContainer) yangNode.getChild();
+        assertThat(container.getName(), is("speed"));
+
+        List<YangLeaf> listOfLeaf = container.getListOfLeaf();
+        YangLeaf leaf = listOfLeaf.iterator().next();
+        assertThat(leaf.getName(), is("local-storage-limit"));
+
+        List<YangIfFeature> ifFeatureList = leaf.getIfFeatureList();
+        YangIfFeature ifFeature = ifFeatureList.iterator().next();
+        assertThat(ifFeature.getName().getName(), is("local-storage"));
+        assertThat(ifFeature.getResolvableStatus(), is(ResolvableStatus.RESOLVED));
+
+        ListIterator<YangLeaf> listOfLeafInModule =  yangNode.getListOfLeaf().listIterator();
+        YangLeaf yangLeaf = listOfLeafInModule.next();
+        assertThat(yangLeaf.getName(), is("storage-value"));
+
+        YangLeafRef leafRef = (YangLeafRef) yangLeaf.getDataType().getDataTypeExtendedInfo();
+
+        assertThat(leafRef.getEffectiveDataType().getDataType(), is(YangDataTypes.UINT64));
+
+        List<YangIfFeature> ifFeatureListInLeafref = leafRef.getIfFeatureList();
+        YangIfFeature ifFeatureInLeafref = ifFeatureListInLeafref.iterator().next();
+
+        assertThat(ifFeatureInLeafref.getName().getName(), is("main-storage"));
+        assertThat(ifFeatureInLeafref.getResolvableStatus(), is(ResolvableStatus.RESOLVED));
+
+        YangIfFeature ifFeatureInLeafref1 = ifFeatureListInLeafref.iterator().next();
+
+        assertThat(ifFeatureInLeafref1.getName().getName(), is("main-storage"));
+        assertThat(ifFeatureInLeafref1.getResolvableStatus(), is(ResolvableStatus.RESOLVED));
+
+    }
 }
 }

+module PathListener {
+    namespace "test";
+    prefix test;
+     list interface {
+         key "name";
+         leaf name {
+             type string;
+         }
+         leaf admin-status {
+             type string;
+         }
+         list address {
+             key "ip";
+             leaf ip {
+                 type string;
+             }
+         }
+     }
+     container default-address {
+         leaf ifname {
+             type leafref {
+                 path "../../test:interface/test:name";
+             }
+         }
+         leaf status {
+             type leafref {
+                 path "/test:interface[name = current()/../ifname]/test:admin-status";
+             }
+         }
+     }
+}
\ No newline at end of file

+module PathListener {
+    namespace "test";
+    prefix test;
+     list interface {
+         key "name";
+         leaf name {
+             type string;
+         }
+         leaf admin-status {
+             type string;
+         }
+         list address {
+             key "ip";
+             leaf ip {
+                 type string;
+             }
+         }
+     }
+     container default-address {
+         leaf ifname {
+             type leafref {
+                 path "../../test:interface/test:name";
+             }
+         }
+         leaf status {
+             type leafref {
+                 path "/test:interface[name = current()/../ifname]/test:admin-status";
+             }
+         }
+     }
+}
\ No newline at end of file

+module PathListener {
+    namespace "test";
+    prefix test;
+    leaf admin-status {
+        type instance-identifier;
+    }
+}
\ No newline at end of file

+module PathListener {
+    namespace "test";
+    prefix test;
+    leaf admin-status {
+        type instance-identifier {
+            require-instance "false";
+        }
+    }
+}
\ No newline at end of file

+module PathListener {
+    namespace "test";
+    prefix test;
+     list interface {
+         key "name";
+         leaf name {
+             type string;
+         }
+         leaf admin-status {
+             type string;
+         }
+         list address {
+             key "ip";
+             leaf ip {
+                 type string;
+             }
+         }
+     }
+     container default-address {
+         leaf ifname {
+             type leafref {
+                 path "../../test:interface/test:name";
+                 require-instance true;
+             }
+         }
+         leaf status {
+             type leafref {
+                 path "/test:interface[name = current()/../ifname]/test:admin-status";
+             }
+         }
+     }
+}
\ No newline at end of file

+module syslog {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix "sys";
+    feature local-storage {
+        description
+            "This feature means the device supports local
+             storage (memory, flash or disk) that can be used to
+             store syslog messages.";
+    }
+
+    container speed {
+        leaf local-storage-limit {
+             if-feature local-storage;
+             type uint64;
+             units "kilobyte";
+             config false;
+             description
+                  "The amount of local storage that can be
+                   used to hold syslog messages.";
+         }
+     }
+     leaf storage-value {
+         type leafref {
+             path "/speed/local-storage-limit";
+         }
+     }
+}

+module syslog {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix "sys";
+    feature local-storage {
+        description
+            "This feature means the device supports local
+             storage (memory, flash or disk) that can be used to
+             store syslog messages.";
+    }
+    feature main-storage {
+        description
+            "This feature means the device supports main
+             storage that can be used to
+             store syslog messages.";
+    }
+
+    container speed {
+        leaf local-storage-limit {
+             if-feature local-storage;
+             type leafref {
+                 path "/value";
+             }
+             units "kilobyte";
+             config false;
+             description
+                  "The amount of local storage that can be
+                   used to hold syslog messages.";
+        }
+    }
+    leaf storage-value {
+        type leafref {
+            path "/speed/local-storage-limit";
+        }
+    }
+    leaf value {
+        if-feature main-storage;
+        type uint64;
+    }
+}

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type status;
+            description
+            "Identifies a network.";
+        }
+    }
+    typedef status {
+        type uint8;
+    }
+    leaf network-ref {
+        type leafref {
+            path "/networks";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type uint8;
+            description
+            "Identifies a network.";
+        }
+    }
+    leaf-list network-ref {
+        type leafref;
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    rpc networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        grouping input {
+            leaf network-id {
+                type string;
+                description
+                "Identifies a network.";
+            }
+        }
+        input {
+            leaf network-id {
+                type uint8;
+                description
+                "Identifies a network.";
+            }
+        }
+        output {
+        }
+    }
+    leaf network-ref {
+        type leafref {
+        path "/networks/input/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    grouping networks {
+        leaf network-id {
+            type uint8;
+            description
+            "Identifies a network.";
+        }
+    }
+    container current {
+        leaf network-ref {
+            type leafref {
+            path "/networks/network-id";
+            }
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    rpc networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        grouping input {
+            leaf network-id {
+                type string;
+                description
+                "Identifies a network.";
+            }
+        }
+        input {
+            leaf network-id {
+                type uint8;
+                description
+                "Identifies a network.";
+            }
+        }
+    }
+    leaf network-ref {
+        type leafref {
+        path "/networks/input/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    rpc networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        grouping input {
+            leaf network-id {
+                type string;
+                description
+                "Identifies a network.";
+            }
+        }
+        input {
+            leaf network-id {
+                type uint8;
+                description
+                "Identifies a network.";
+            }
+        }
+    }
+    leaf network-ref {
+        type leafref {
+            path "../networks/input/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type uint8;
+            description
+            "Identifies a network.";
+        }
+    }
+    leaf network-ref {
+            type leafref {
+            path "/define/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type uint8;
+            description
+            "Identifies a network.";
+        }
+    }
+    leaf network-ref {
+            type leafref {
+            path "../define/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type uint8;
+            description
+            "Identifies a network.";
+        }
+    }
+    leaf network-ref {
+            type leafref {
+            path "../../../define/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    rpc networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        input {
+            leaf network-id {
+                type uint8;
+                description
+                "Identifies a network.";
+            }
+        }
+        output {
+        }
+    }
+    leaf network-ref {
+        type leafref {
+        path "/networks/input/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    rpc networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        input {
+            leaf-list network-id {
+                type uint8;
+                description
+                "Identifies a network.";
+            }
+        }
+        output {
+        }
+    }
+    leaf-list network-ref {
+        type leafref {
+        path "/networks/input/network-id";
+        }
+    }
+}
\ No newline at end of file

+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "define";
+        leaf define {
+            type string;
+        }
+        container standard {
+            typedef node {
+                type leafref {
+                    path "/invalid-interval";
+                }
+            }
+            container present {
+                typedef name {
+                    type node;
+                }
+                leaf interval {
+                    type name;
+                }
+            }
+        }
+    }
+    leaf-list invalid-interval {
+        type enumeration {
+            enum 10m;
+            enum 100m;
+            enum auto;
+        }
+    }
+}

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    rpc networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        input {
+            leaf-list network-id {
+                type network-ref;
+                description
+                "Identifies a network.";
+            }
+            leaf id {
+                type uint8;
+            }
+        }
+        output {
+        }
+    }
+    typedef network-ref {
+        type leafref {
+            path "/networks/input/id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type network-ref;
+            description
+            "Identifies a network.";
+        }
+        leaf id {
+            type uint8;
+        }
+    }
+    typedef network-ref {
+        type leafref {
+            path "/networks/id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type network-ref;
+            description
+            "Identifies a network.";
+        }
+        leaf id {
+            type uint8;
+        }
+    }
+    typedef network-ref {
+        type leafref {
+            path "../id";
+        }
+    }
+}
\ No newline at end of file

+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "define";
+        leaf define {
+            type string;
+        }
+        container standard {
+            container present {
+                leaf name {
+                    type leafref {
+                        path "/invalid-interval";
+                    }
+                }
+            }
+        }
+    }
+    leaf invalid-interval {
+        type union {
+            type int32;
+            type enumeration {
+                enum "unbounded";
+            }
+        }
+    }
+}

+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "define";
+        leaf define {
+            type string;
+        }
+        container standard {
+            container present {
+                leaf-list name {
+                    type leafref {
+                        path "/invalid-interval";
+                    }
+                }
+            }
+        }
+    }
+    leaf-list invalid-interval {
+        type enumeration {
+            enum 10m;
+            enum 100m;
+            enum auto;
+        }
+    }
+}

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type status;
+            description
+            "Identifies a network.";
+        }
+    }
+    typedef status {
+        type uint8;
+    }
+    leaf network-ref {
+        type leafref {
+            path "/networks/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type leafref {
+                path "/status/current";
+            }
+            description
+            "Identifies a network.";
+        }
+    }
+    container status {
+        leaf current {
+            type uint8;
+        }
+    }
+    leaf network-ref {
+        type leafref {
+            path "/networks/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type uint8;
+            description
+            "Identifies a network.";
+        }
+    }
+    leaf network-ref {
+        type leafref {
+        path "/networks/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type uint8;
+            description
+            "Identifies a network.";
+        }
+    }
+    leaf-list network-ref {
+        type leafref {
+        path "/networks/network-id";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type uint8;
+            description
+            "Identifies a network.";
+        }
+    }
+    leaf network-ref {
+        type leafref {
+            path "../networks/network-id";
+        }
+    }
+}
\ No newline at end of file

+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "define";
+        leaf define {
+            type string;
+        }
+        container standard {
+            container present {
+                leaf-list name {
+                    type transmitter;
+                }
+            }
+        }
+    }
+    container reference {
+        list found {
+            key "define";
+            leaf define {
+                type string;
+            }
+            container reciever {
+                leaf remove {
+                    type leafref {
+                        path "/valid/standard/present/name";
+                    }
+                }
+            }
+        }
+    }
+    typedef transmitter {
+        type leafref {
+            path "/invalid-interval";
+        }
+    }
+    leaf invalid-interval {
+        type enumeration {
+            enum 10m;
+            enum 100m;
+            enum auto;
+        }
+    }
+}

+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "define";
+        leaf define {
+            type string;
+        }
+        container standard {
+            container present {
+                leaf-list name {
+                    type transmitter;
+                }
+            }
+        }
+    }
+    container reference {
+        list found {
+            key "define";
+            leaf define {
+                type string;
+            }
+            container reciever {
+                leaf remove {
+                    type leafref {
+                        path "../../../../valid/standard/present/name";
+                    }
+                }
+            }
+        }
+    }
+    typedef transmitter {
+        type leafref {
+            path "../../../../invalid-interval";
+        }
+    }
+    leaf invalid-interval {
+        type enumeration {
+            enum 10m;
+            enum 100m;
+            enum auto;
+        }
+    }
+}

+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "define";
+        leaf define {
+            type string;
+        }
+        container standard {
+            container present {
+                leaf-list name {
+                    type leafref {
+                        path "/transmitter/send";
+                    }
+                }
+            }
+        }
+    }
+    container reference {
+        list found {
+            key "define";
+            leaf define {
+                type string;
+            }
+            container reciever {
+                leaf remove {
+                    type leafref {
+                        path "/valid/standard/present/name";
+                    }
+                }
+            }
+        }
+    }
+    list transmitter {
+        key "send";
+        leaf send {
+            type leafref {
+                path "/invalid-interval";
+            }
+        }
+    }
+    leaf-list invalid-interval {
+        type enumeration {
+            enum 10m;
+            enum 100m;
+            enum auto;
+        }
+    }
+}

+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "define";
+        leaf define {
+            type string;
+        }
+        container standard {
+            container present {
+                leaf-list name {
+                    type leafref {
+                        path "../../../../transmitter/send";
+                    }
+                }
+            }
+        }
+    }
+    container reference {
+        list found {
+            key "define";
+            leaf define {
+                type string;
+            }
+            container reciever {
+                leaf remove {
+                    type leafref {
+                        path "../../../../valid/standard/present/name";
+                    }
+                }
+            }
+        }
+    }
+    list transmitter {
+        key "send";
+        leaf send {
+            type leafref {
+                path "../../invalid-interval";
+            }
+        }
+    }
+    leaf-list invalid-interval {
+        type enumeration {
+            enum 10m;
+            enum 100m;
+            enum auto;
+        }
+    }
+}

+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "define";
+        leaf define {
+            type string;
+        }
+        container standard {
+            container present {
+                leaf-list name {
+                    type transmitter;
+                }
+            }
+        }
+    }
+    container reference {
+        list found {
+            key "define";
+            leaf define {
+                type string;
+            }
+            container reciever {
+                leaf remove {
+                    type leafref {
+                        path "/valid/standard/present/name";
+                    }
+                }
+            }
+        }
+    }
+    typedef transmitter {
+        type invalid-interval;
+    }
+    typedef invalid-interval {
+        type enumeration {
+            enum 10m;
+            enum 100m;
+            enum auto;
+        }
+    }
+}

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type uint8;
+            description
+            "Identifies a network.";
+        }
+    }
+    leaf network-ref {
+            type leafref {
+            path "/define/network-id";
+        }
+    }
+}
\ No newline at end of file

+module module1 {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    import module2 {
+        prefix p;
+    }
+    leaf invalid-interval {
+        type leafref {
+            path "/p:hello";
+        }
+    }
+    leaf hello {
+        type string;
+    }
+}
\ No newline at end of file

-module Test {
+module module2 {
     yang-version 1;
     yang-version 1;
     namespace http://huawei.com;
     namespace http://huawei.com;
-    prefix Ant;
-    leaf-list invalid-interval {
-        type leafref;
+    prefix Ant2;
+    leaf hello {
+        type string;
     }
     }
 }
 }

+module module1 {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-te-topology";
+    prefix "tet";
+    import module2 {
+        prefix "nt";
+    }
+    grouping te-node-tunnel-termination-capability {
+        description
+        "Termination capability of a tunnel termination point on a
+        TE node.";
+        list termination-capability {
+            key "link-tp";
+            description
+            "The termination capabilities between
+            tunnel-termination-point and link termination-point.
+            The capability information can be used to compute
+            the tunnel path.";
+            leaf link-tp {
+                type leafref {
+                    path "/nt:termination-point/nt:tp-id";
+                }
+                description
+                "Link termination point.";
+            }
+        } // termination-capability
+    } // te-node-tunnel-termination-capability
+}
\ No newline at end of file

+module module2 {
+    yang-version 1;
+    namespace
+      "urn:ietf:params:xml:ns:yang:ietf-inet-types";
+    prefix inet;
+    container termination-point {
+        leaf tp-id {
+            type string;
+        }
+    }
+}
\ No newline at end of file

+module ietf-inet-types {
+    yang-version 1;
+    namespace
+      "urn:ietf:params:xml:ns:yang:ietf-inet-types";
+    prefix inet;
+    typedef tp-ref {
+        type leafref {
+            path "/nwtp:value";
+        }
+    }
+}
\ No newline at end of file

+module ietf-network-topology {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-te-topology";
+    prefix "tet";
+    import ietf-network {
+        prefix "nt";
+    }
+    grouping te-node-tunnel-termination-capability {
+        description
+        "Termination capability of a tunnel termination point on a
+        TE node.";
+        list termination-capability {
+            key "link-tp";
+            description
+            "The termination capabilities between
+            tunnel-termination-point and link termination-point.
+            The capability information can be used to compute
+            the tunnel path.";
+            leaf link-tp {
+                type leafref {
+                    path "/nt:termination-point/nt:tp-id";
+                }
+                description
+                "Link termination point.";
+            }
+        } // termination-capability
+    } // te-node-tunnel-termination-capability
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace
+      "urn:ietf:params:xml:ns:yang:ietf-inet-types";
+    prefix nw;
+    import ietf-inet-types {
+       prefix inet;
+    }
+    container termination-point {
+        leaf tp-id {
+            type string;
+        }
+    }
+}
\ No newline at end of file

+module ietf-network {
+    yang-version 1;
+    namespace "urn:ietf:params:xml:ns:yang:ietf-network";
+    prefix nd;
+    container networks {
+        description
+        "Serves as top-level container for a list of networks.";
+        leaf network-id {
+            type status;
+            description
+            "Identifies a network.";
+        }
+    }
+    typedef status {
+        type uint8;
+    }
+    leaf network-ref {
+        type leafref {
+            path "/networks";
+        }
+    }
+}
\ No newline at end of file