comment-event-generator.js
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/**
* @fileoverview The event generator for comments.
* @author Toru Nagashima
*/
"use strict";
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Check collection of comments to prevent double event for comment as
* leading and trailing, then emit event if passing
* @param {ASTNode[]} comments - Collection of comment nodes
* @param {EventEmitter} emitter - The event emitter which is the destination of events.
* @param {Object[]} locs - List of locations of previous comment nodes
* @param {string} eventName - Event name postfix
* @returns {void}
*/
function emitComments(comments, emitter, locs, eventName) {
if (comments.length > 0) {
comments.forEach(node => {
const index = locs.indexOf(node.loc);
if (index >= 0) {
locs.splice(index, 1);
} else {
locs.push(node.loc);
emitter.emit(node.type + eventName, node);
}
});
}
}
/**
* Shortcut to check and emit enter of comment nodes
* @param {CommentEventGenerator} generator - A generator to emit.
* @param {ASTNode[]} comments - Collection of comment nodes
* @returns {void}
*/
function emitCommentsEnter(generator, comments) {
emitComments(
comments,
generator.emitter,
generator.commentLocsEnter,
"Comment");
}
/**
* Shortcut to check and emit exit of comment nodes
* @param {CommentEventGenerator} generator - A generator to emit.
* @param {ASTNode[]} comments Collection of comment nodes
* @returns {void}
*/
function emitCommentsExit(generator, comments) {
emitComments(
comments,
generator.emitter,
generator.commentLocsExit,
"Comment:exit");
}
//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------
/**
* The event generator for comments.
* This is the decorator pattern.
* This generates events of comments before/after events which are generated the original generator.
*
* Comment event generator class
*/
class CommentEventGenerator {
/**
* @param {EventGenerator} originalEventGenerator - An event generator which is the decoration target.
* @param {SourceCode} sourceCode - A source code which has comments.
*/
constructor(originalEventGenerator, sourceCode) {
this.original = originalEventGenerator;
this.emitter = originalEventGenerator.emitter;
this.sourceCode = sourceCode;
this.commentLocsEnter = [];
this.commentLocsExit = [];
}
/**
* Emits an event of entering comments.
* @param {ASTNode} node - A node which was entered.
* @returns {void}
*/
enterNode(node) {
const comments = this.sourceCode.getComments(node);
emitCommentsEnter(this, comments.leading);
this.original.enterNode(node);
emitCommentsEnter(this, comments.trailing);
}
/**
* Emits an event of leaving comments.
* @param {ASTNode} node - A node which was left.
* @returns {void}
*/
leaveNode(node) {
const comments = this.sourceCode.getComments(node);
emitCommentsExit(this, comments.trailing);
this.original.leaveNode(node);
emitCommentsExit(this, comments.leading);
}
}
module.exports = CommentEventGenerator;