index.js
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"use strict";
module.exports = codegen;
/**
* Begins generating a function.
* @memberof util
* @param {string[]} functionParams Function parameter names
* @param {string} [functionName] Function name if not anonymous
* @returns {Codegen} Appender that appends code to the function's body
*/
function codegen(functionParams, functionName) {
/* istanbul ignore if */
if (typeof functionParams === "string") {
functionName = functionParams;
functionParams = undefined;
}
var body = [];
/**
* Appends code to the function's body or finishes generation.
* @typedef Codegen
* @type {function}
* @param {string|Object.<string,*>} [formatStringOrScope] Format string or, to finish the function, an object of additional scope variables, if any
* @param {...*} [formatParams] Format parameters
* @returns {Codegen|Function} Itself or the generated function if finished
* @throws {Error} If format parameter counts do not match
*/
function Codegen(formatStringOrScope) {
// note that explicit array handling below makes this ~50% faster
// finish the function
if (typeof formatStringOrScope !== "string") {
var source = toString();
if (codegen.verbose)
console.log("codegen: " + source); // eslint-disable-line no-console
source = "return " + source;
if (formatStringOrScope) {
var scopeKeys = Object.keys(formatStringOrScope),
scopeParams = new Array(scopeKeys.length + 1),
scopeValues = new Array(scopeKeys.length),
scopeOffset = 0;
while (scopeOffset < scopeKeys.length) {
scopeParams[scopeOffset] = scopeKeys[scopeOffset];
scopeValues[scopeOffset] = formatStringOrScope[scopeKeys[scopeOffset++]];
}
scopeParams[scopeOffset] = source;
return Function.apply(null, scopeParams).apply(null, scopeValues); // eslint-disable-line no-new-func
}
return Function(source)(); // eslint-disable-line no-new-func
}
// otherwise append to body
var formatParams = new Array(arguments.length - 1),
formatOffset = 0;
while (formatOffset < formatParams.length)
formatParams[formatOffset] = arguments[++formatOffset];
formatOffset = 0;
formatStringOrScope = formatStringOrScope.replace(/%([%dfijs])/g, function replace($0, $1) {
var value = formatParams[formatOffset++];
switch ($1) {
case "d": case "f": return String(Number(value));
case "i": return String(Math.floor(value));
case "j": return JSON.stringify(value);
case "s": return String(value);
}
return "%";
});
if (formatOffset !== formatParams.length)
throw Error("parameter count mismatch");
body.push(formatStringOrScope);
return Codegen;
}
function toString(functionNameOverride) {
return "function " + (functionNameOverride || functionName || "") + "(" + (functionParams && functionParams.join(",") || "") + "){\n " + body.join("\n ") + "\n}";
}
Codegen.toString = toString;
return Codegen;
}
/**
* Begins generating a function.
* @memberof util
* @function codegen
* @param {string} [functionName] Function name if not anonymous
* @returns {Codegen} Appender that appends code to the function's body
* @variation 2
*/
/**
* When set to `true`, codegen will log generated code to console. Useful for debugging.
* @name util.codegen.verbose
* @type {boolean}
*/
codegen.verbose = false;