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app_vue/node_modules/eslint/lib/linter/code-path-analysis/code-path-segment.js

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+/**
+ * @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 {
+
+    // eslint-disable-next-line jsdoc/require-description
+    /**
+     * @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;