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Diffstat (limited to 'tools/node_modules/eslint/lib/code-path-analysis/fork-context.js')
-rw-r--r-- | tools/node_modules/eslint/lib/code-path-analysis/fork-context.js | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/code-path-analysis/fork-context.js b/tools/node_modules/eslint/lib/code-path-analysis/fork-context.js new file mode 100644 index 0000000000..4fae6bbb1e --- /dev/null +++ b/tools/node_modules/eslint/lib/code-path-analysis/fork-context.js @@ -0,0 +1,262 @@ +/** + * @fileoverview A class to operate forking. + * + * This is state of forking. + * This has a fork list and manages it. + * + * @author Toru Nagashima + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const assert = require("assert"), + CodePathSegment = require("./code-path-segment"); + +//------------------------------------------------------------------------------ +// Helpers +//------------------------------------------------------------------------------ + +/** + * Gets whether or not a given segment is reachable. + * + * @param {CodePathSegment} segment - A segment to get. + * @returns {boolean} `true` if the segment is reachable. + */ +function isReachable(segment) { + return segment.reachable; +} + +/** + * Creates new segments from the specific range of `context.segmentsList`. + * + * When `context.segmentsList` is `[[a, b], [c, d], [e, f]]`, `begin` is `0`, and + * `end` is `-1`, this creates `[g, h]`. This `g` is from `a`, `c`, and `e`. + * This `h` is from `b`, `d`, and `f`. + * + * @param {ForkContext} context - An instance. + * @param {number} begin - The first index of the previous segments. + * @param {number} end - The last index of the previous segments. + * @param {Function} create - A factory function of new segments. + * @returns {CodePathSegment[]} New segments. + */ +function makeSegments(context, begin, end, create) { + const list = context.segmentsList; + + if (begin < 0) { + begin = list.length + begin; + } + if (end < 0) { + end = list.length + end; + } + + const segments = []; + + for (let i = 0; i < context.count; ++i) { + const allPrevSegments = []; + + for (let j = begin; j <= end; ++j) { + allPrevSegments.push(list[j][i]); + } + + segments.push(create(context.idGenerator.next(), allPrevSegments)); + } + + return segments; +} + +/** + * `segments` becomes doubly in a `finally` block. Then if a code path exits by a + * control statement (such as `break`, `continue`) from the `finally` block, the + * destination's segments may be half of the source segments. In that case, this + * merges segments. + * + * @param {ForkContext} context - An instance. + * @param {CodePathSegment[]} segments - Segments to merge. + * @returns {CodePathSegment[]} The merged segments. + */ +function mergeExtraSegments(context, segments) { + while (segments.length > context.count) { + const merged = []; + + for (let i = 0, length = segments.length / 2 | 0; i < length; ++i) { + merged.push(CodePathSegment.newNext( + context.idGenerator.next(), + [segments[i], segments[i + length]] + )); + } + segments = merged; + } + return segments; +} + +//------------------------------------------------------------------------------ +// Public Interface +//------------------------------------------------------------------------------ + +/** + * A class to manage forking. + */ +class ForkContext { + + /** + * @param {IdGenerator} idGenerator - An identifier generator for segments. + * @param {ForkContext|null} upper - An upper fork context. + * @param {number} count - A number of parallel segments. + */ + constructor(idGenerator, upper, count) { + this.idGenerator = idGenerator; + this.upper = upper; + this.count = count; + this.segmentsList = []; + } + + /** + * The head segments. + * @type {CodePathSegment[]} + */ + get head() { + const list = this.segmentsList; + + return list.length === 0 ? [] : list[list.length - 1]; + } + + /** + * A flag which shows empty. + * @type {boolean} + */ + get empty() { + return this.segmentsList.length === 0; + } + + /** + * A flag which shows reachable. + * @type {boolean} + */ + get reachable() { + const segments = this.head; + + return segments.length > 0 && segments.some(isReachable); + } + + /** + * Creates new segments from this context. + * + * @param {number} begin - The first index of previous segments. + * @param {number} end - The last index of previous segments. + * @returns {CodePathSegment[]} New segments. + */ + makeNext(begin, end) { + return makeSegments(this, begin, end, CodePathSegment.newNext); + } + + /** + * Creates new segments from this context. + * The new segments is always unreachable. + * + * @param {number} begin - The first index of previous segments. + * @param {number} end - The last index of previous segments. + * @returns {CodePathSegment[]} New segments. + */ + makeUnreachable(begin, end) { + return makeSegments(this, begin, end, CodePathSegment.newUnreachable); + } + + /** + * Creates new segments from this context. + * The new segments don't have connections for previous segments. + * But these inherit the reachable flag from this context. + * + * @param {number} begin - The first index of previous segments. + * @param {number} end - The last index of previous segments. + * @returns {CodePathSegment[]} New segments. + */ + makeDisconnected(begin, end) { + return makeSegments(this, begin, end, CodePathSegment.newDisconnected); + } + + /** + * Adds segments into this context. + * The added segments become the head. + * + * @param {CodePathSegment[]} segments - Segments to add. + * @returns {void} + */ + add(segments) { + assert(segments.length >= this.count, `${segments.length} >= ${this.count}`); + + this.segmentsList.push(mergeExtraSegments(this, segments)); + } + + /** + * Replaces the head segments with given segments. + * The current head segments are removed. + * + * @param {CodePathSegment[]} segments - Segments to add. + * @returns {void} + */ + replaceHead(segments) { + assert(segments.length >= this.count, `${segments.length} >= ${this.count}`); + + this.segmentsList.splice(-1, 1, mergeExtraSegments(this, segments)); + } + + /** + * Adds all segments of a given fork context into this context. + * + * @param {ForkContext} context - A fork context to add. + * @returns {void} + */ + addAll(context) { + assert(context.count === this.count); + + const source = context.segmentsList; + + for (let i = 0; i < source.length; ++i) { + this.segmentsList.push(source[i]); + } + } + + /** + * Clears all secments in this context. + * + * @returns {void} + */ + clear() { + this.segmentsList = []; + } + + /** + * Creates the root fork context. + * + * @param {IdGenerator} idGenerator - An identifier generator for segments. + * @returns {ForkContext} New fork context. + */ + static newRoot(idGenerator) { + const context = new ForkContext(idGenerator, null, 1); + + context.add([CodePathSegment.newRoot(idGenerator.next())]); + + return context; + } + + /** + * Creates an empty fork context preceded by a given context. + * + * @param {ForkContext} parentContext - The parent fork context. + * @param {boolean} forkLeavingPath - A flag which shows inside of `finally` block. + * @returns {ForkContext} New fork context. + */ + static newEmpty(parentContext, forkLeavingPath) { + return new ForkContext( + parentContext.idGenerator, + parentContext, + (forkLeavingPath ? 2 : 1) * parentContext.count + ); + } +} + +module.exports = ForkContext; |