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/**
* @fileoverview A class of the code path.
* @author Toru Nagashima
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const CodePathState = require("./code-path-state");
const IdGenerator = require("./id-generator");
//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------
/**
* A code path.
*/
class CodePath {
// eslint-disable-next-line jsdoc/require-description
/**
* @param {string} id An identifier.
* @param {CodePath|null} upper The code path of the upper function scope.
* @param {Function} onLooped A callback function to notify looping.
*/
constructor(id, upper, onLooped) {
/**
* The identifier of this code path.
* Rules use it to store additional information of each rule.
* @type {string}
*/
this.id = id;
/**
* The code path of the upper function scope.
* @type {CodePath|null}
*/
this.upper = upper;
/**
* The code paths of nested function scopes.
* @type {CodePath[]}
*/
this.childCodePaths = [];
// Initializes internal state.
Object.defineProperty(
this,
"internal",
{ value: new CodePathState(new IdGenerator(`${id}_`), onLooped) }
);
// Adds this into `childCodePaths` of `upper`.
if (upper) {
upper.childCodePaths.push(this);
}
}
/**
* Gets the state of a given code path.
* @param {CodePath} codePath A code path to get.
* @returns {CodePathState} The state of the code path.
*/
static getState(codePath) {
return codePath.internal;
}
/**
* The initial code path segment.
* @type {CodePathSegment}
*/
get initialSegment() {
return this.internal.initialSegment;
}
/**
* Final code path segments.
* This array is a mix of `returnedSegments` and `thrownSegments`.
* @type {CodePathSegment[]}
*/
get finalSegments() {
return this.internal.finalSegments;
}
/**
* Final code path segments which is with `return` statements.
* This array contains the last path segment if it's reachable.
* Since the reachable last path returns `undefined`.
* @type {CodePathSegment[]}
*/
get returnedSegments() {
return this.internal.returnedForkContext;
}
/**
* Final code path segments which is with `throw` statements.
* @type {CodePathSegment[]}
*/
get thrownSegments() {
return this.internal.thrownForkContext;
}
/**
* Current code path segments.
* @type {CodePathSegment[]}
*/
get currentSegments() {
return this.internal.currentSegments;
}
/**
* Traverses all segments in this code path.
*
* codePath.traverseSegments(function(segment, controller) {
* // do something.
* });
*
* This method enumerates segments in order from the head.
*
* The `controller` object has two methods.
*
* - `controller.skip()` - Skip the following segments in this branch.
* - `controller.break()` - Skip all following segments.
* @param {Object} [options] Omittable.
* @param {CodePathSegment} [options.first] The first segment to traverse.
* @param {CodePathSegment} [options.last] The last segment to traverse.
* @param {Function} callback A callback function.
* @returns {void}
*/
traverseSegments(options, callback) {
let resolvedOptions;
let resolvedCallback;
if (typeof options === "function") {
resolvedCallback = options;
resolvedOptions = {};
} else {
resolvedOptions = options || {};
resolvedCallback = callback;
}
const startSegment = resolvedOptions.first || this.internal.initialSegment;
const lastSegment = resolvedOptions.last;
let item = null;
let index = 0;
let end = 0;
let segment = null;
const visited = Object.create(null);
const stack = [[startSegment, 0]];
let skippedSegment = null;
let broken = false;
const controller = {
skip() {
if (stack.length <= 1) {
broken = true;
} else {
skippedSegment = stack[stack.length - 2][0];
}
},
break() {
broken = true;
}
};
/**
* Checks a given previous segment has been visited.
* @param {CodePathSegment} prevSegment A previous segment to check.
* @returns {boolean} `true` if the segment has been visited.
*/
function isVisited(prevSegment) {
return (
visited[prevSegment.id] ||
segment.isLoopedPrevSegment(prevSegment)
);
}
while (stack.length > 0) {
item = stack[stack.length - 1];
segment = item[0];
index = item[1];
if (index === 0) {
// Skip if this segment has been visited already.
if (visited[segment.id]) {
stack.pop();
continue;
}
// Skip if all previous segments have not been visited.
if (segment !== startSegment &&
segment.prevSegments.length > 0 &&
!segment.prevSegments.every(isVisited)
) {
stack.pop();
continue;
}
// Reset the flag of skipping if all branches have been skipped.
if (skippedSegment && segment.prevSegments.indexOf(skippedSegment) !== -1) {
skippedSegment = null;
}
visited[segment.id] = true;
// Call the callback when the first time.
if (!skippedSegment) {
resolvedCallback.call(this, segment, controller);
if (segment === lastSegment) {
controller.skip();
}
if (broken) {
break;
}
}
}
// Update the stack.
end = segment.nextSegments.length - 1;
if (index < end) {
item[1] += 1;
stack.push([segment.nextSegments[index], 0]);
} else if (index === end) {
item[0] = segment.nextSegments[index];
item[1] = 0;
} else {
stack.pop();
}
}
}
}
module.exports = CodePath;
|
