Current File : /var/www/html/node_modules/eslint/lib/linter/code-path-analysis/code-path-segment.js
/**
* @fileoverview A class of the code path segment.
* @author Toru Nagashima
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const debug = require("./debug-helpers");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Checks whether or not a given segment is reachable.
* @param {CodePathSegment} segment A segment to check.
* @returns {boolean} `true` if the segment is reachable.
*/
function isReachable(segment) {
return segment.reachable;
}
//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------
/**
* A code path segment.
*/
class CodePathSegment {
/**
* @param {string} id An identifier.
* @param {CodePathSegment[]} allPrevSegments An array of the previous segments.
* This array includes unreachable segments.
* @param {boolean} reachable A flag which shows this is reachable.
*/
constructor(id, allPrevSegments, reachable) {
/**
* The identifier of this code path.
* Rules use it to store additional information of each rule.
* @type {string}
*/
this.id = id;
/**
* An array of the next segments.
* @type {CodePathSegment[]}
*/
this.nextSegments = [];
/**
* An array of the previous segments.
* @type {CodePathSegment[]}
*/
this.prevSegments = allPrevSegments.filter(isReachable);
/**
* An array of the next segments.
* This array includes unreachable segments.
* @type {CodePathSegment[]}
*/
this.allNextSegments = [];
/**
* An array of the previous segments.
* This array includes unreachable segments.
* @type {CodePathSegment[]}
*/
this.allPrevSegments = allPrevSegments;
/**
* A flag which shows this is reachable.
* @type {boolean}
*/
this.reachable = reachable;
// Internal data.
Object.defineProperty(this, "internal", {
value: {
used: false,
loopedPrevSegments: []
}
});
/* istanbul ignore if */
if (debug.enabled) {
this.internal.nodes = [];
}
}
/**
* Checks a given previous segment is coming from the end of a loop.
* @param {CodePathSegment} segment A previous segment to check.
* @returns {boolean} `true` if the segment is coming from the end of a loop.
*/
isLoopedPrevSegment(segment) {
return this.internal.loopedPrevSegments.indexOf(segment) !== -1;
}
/**
* Creates the root segment.
* @param {string} id An identifier.
* @returns {CodePathSegment} The created segment.
*/
static newRoot(id) {
return new CodePathSegment(id, [], true);
}
/**
* Creates a segment that follows given segments.
* @param {string} id An identifier.
* @param {CodePathSegment[]} allPrevSegments An array of the previous segments.
* @returns {CodePathSegment} The created segment.
*/
static newNext(id, allPrevSegments) {
return new CodePathSegment(
id,
CodePathSegment.flattenUnusedSegments(allPrevSegments),
allPrevSegments.some(isReachable)
);
}
/**
* Creates an unreachable segment that follows given segments.
* @param {string} id An identifier.
* @param {CodePathSegment[]} allPrevSegments An array of the previous segments.
* @returns {CodePathSegment} The created segment.
*/
static newUnreachable(id, allPrevSegments) {
const segment = new CodePathSegment(id, CodePathSegment.flattenUnusedSegments(allPrevSegments), false);
/*
* In `if (a) return a; foo();` case, the unreachable segment preceded by
* the return statement is not used but must not be remove.
*/
CodePathSegment.markUsed(segment);
return segment;
}
/**
* Creates a segment that follows given segments.
* This factory method does not connect with `allPrevSegments`.
* But this inherits `reachable` flag.
* @param {string} id An identifier.
* @param {CodePathSegment[]} allPrevSegments An array of the previous segments.
* @returns {CodePathSegment} The created segment.
*/
static newDisconnected(id, allPrevSegments) {
return new CodePathSegment(id, [], allPrevSegments.some(isReachable));
}
/**
* Makes a given segment being used.
*
* And this function registers the segment into the previous segments as a next.
* @param {CodePathSegment} segment A segment to mark.
* @returns {void}
*/
static markUsed(segment) {
if (segment.internal.used) {
return;
}
segment.internal.used = true;
let i;
if (segment.reachable) {
for (i = 0; i < segment.allPrevSegments.length; ++i) {
const prevSegment = segment.allPrevSegments[i];
prevSegment.allNextSegments.push(segment);
prevSegment.nextSegments.push(segment);
}
} else {
for (i = 0; i < segment.allPrevSegments.length; ++i) {
segment.allPrevSegments[i].allNextSegments.push(segment);
}
}
}
/**
* Marks a previous segment as looped.
* @param {CodePathSegment} segment A segment.
* @param {CodePathSegment} prevSegment A previous segment to mark.
* @returns {void}
*/
static markPrevSegmentAsLooped(segment, prevSegment) {
segment.internal.loopedPrevSegments.push(prevSegment);
}
/**
* Replaces unused segments with the previous segments of each unused segment.
* @param {CodePathSegment[]} segments An array of segments to replace.
* @returns {CodePathSegment[]} The replaced array.
*/
static flattenUnusedSegments(segments) {
const done = Object.create(null);
const retv = [];
for (let i = 0; i < segments.length; ++i) {
const segment = segments[i];
// Ignores duplicated.
if (done[segment.id]) {
continue;
}
// Use previous segments if unused.
if (!segment.internal.used) {
for (let j = 0; j < segment.allPrevSegments.length; ++j) {
const prevSegment = segment.allPrevSegments[j];
if (!done[prevSegment.id]) {
done[prevSegment.id] = true;
retv.push(prevSegment);
}
}
} else {
done[segment.id] = true;
retv.push(segment);
}
}
return retv;
}
}
module.exports = CodePathSegment;
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