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Diffstat (limited to 'tools/node_modules/eslint/lib/code-path-analysis/code-path-segment.js')
-rw-r--r-- | tools/node_modules/eslint/lib/code-path-analysis/code-path-segment.js | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/code-path-analysis/code-path-segment.js b/tools/node_modules/eslint/lib/code-path-analysis/code-path-segment.js new file mode 100644 index 0000000000..8145f92801 --- /dev/null +++ b/tools/node_modules/eslint/lib/code-path-analysis/code-path-segment.js @@ -0,0 +1,245 @@ +/** + * @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 = []; + this.internal.exitNodes = []; + } + } + + /** + * 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; |