| 1 | 'use strict'; |
| 2 | |
| 3 | //------------------------------------------------------------------------------ |
| 4 | // Requirements |
| 5 | //------------------------------------------------------------------------------ |
| 6 | |
| 7 | // eslint-disable-next-line |
| 8 | const CodePathState = require('./code-path-state'); |
| 9 | // eslint-disable-next-line |
| 10 | const IdGenerator = require('./id-generator'); |
| 11 | |
| 12 | //------------------------------------------------------------------------------ |
| 13 | // Public Interface |
| 14 | //------------------------------------------------------------------------------ |
| 15 | |
| 16 | /** |
| 17 | * A code path. |
| 18 | */ |
| 19 | class CodePath { |
| 20 | /** |
| 21 | * Creates a new instance. |
| 22 | * @param {Object} options Options for the function (see below). |
| 23 | * @param {string} options.id An identifier. |
| 24 | * @param {string} options.origin The type of code path origin. |
| 25 | * @param {CodePath|null} options.upper The code path of the upper function scope. |
| 26 | * @param {Function} options.onLooped A callback function to notify looping. |
| 27 | */ |
| 28 | constructor({id, origin, upper, onLooped}) { |
| 29 | /** |
| 30 | * The identifier of this code path. |
| 31 | * Rules use it to store additional information of each rule. |
| 32 | * @type {string} |
| 33 | */ |
| 34 | this.id = id; |
| 35 | |
| 36 | /** |
| 37 | * The reason that this code path was started. May be "program", |
| 38 | * "function", "class-field-initializer", or "class-static-block". |
| 39 | * @type {string} |
| 40 | */ |
| 41 | this.origin = origin; |
| 42 | |
| 43 | /** |
| 44 | * The code path of the upper function scope. |
| 45 | * @type {CodePath|null} |
| 46 | */ |
| 47 | this.upper = upper; |
| 48 | |
| 49 | /** |
| 50 | * The code paths of nested function scopes. |
| 51 | * @type {CodePath[]} |
| 52 | */ |
| 53 | this.childCodePaths = []; |
| 54 | |
| 55 | // Initializes internal state. |
| 56 | Object.defineProperty(this, 'internal', { |
| 57 | value: new CodePathState(new IdGenerator(`${id}_`), onLooped), |
| 58 | }); |
| 59 | |
| 60 | // Adds this into `childCodePaths` of `upper`. |
| 61 | if (upper) { |
| 62 | upper.childCodePaths.push(this); |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | /** |
| 67 | * Gets the state of a given code path. |
| 68 | * @param {CodePath} codePath A code path to get. |
| 69 | * @returns {CodePathState} The state of the code path. |
| 70 | */ |
| 71 | static getState(codePath) { |
| 72 | return codePath.internal; |
| 73 | } |
| 74 | |
| 75 | /** |
| 76 | * The initial code path segment. |
| 77 | * @type {CodePathSegment} |
| 78 | */ |
| 79 | get initialSegment() { |
| 80 | return this.internal.initialSegment; |
| 81 | } |
| 82 | |
| 83 | /** |
| 84 | * Final code path segments. |
| 85 | * This array is a mix of `returnedSegments` and `thrownSegments`. |
| 86 | * @type {CodePathSegment[]} |
| 87 | */ |
| 88 | get finalSegments() { |
| 89 | return this.internal.finalSegments; |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * Final code path segments which is with `return` statements. |
| 94 | * This array contains the last path segment if it's reachable. |
| 95 | * Since the reachable last path returns `undefined`. |
| 96 | * @type {CodePathSegment[]} |
| 97 | */ |
| 98 | get returnedSegments() { |
| 99 | return this.internal.returnedForkContext; |
| 100 | } |
| 101 | |
| 102 | /** |
| 103 | * Final code path segments which is with `throw` statements. |
| 104 | * @type {CodePathSegment[]} |
| 105 | */ |
| 106 | get thrownSegments() { |
| 107 | return this.internal.thrownForkContext; |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * Current code path segments. |
| 112 | * @type {CodePathSegment[]} |
| 113 | */ |
| 114 | get currentSegments() { |
| 115 | return this.internal.currentSegments; |
| 116 | } |
| 117 | |
| 118 | /** |
| 119 | * Traverses all segments in this code path. |
| 120 | * |
| 121 | * codePath.traverseSegments(function(segment, controller) { |
| 122 | * // do something. |
| 123 | * }); |
| 124 | * |
| 125 | * This method enumerates segments in order from the head. |
| 126 | * |
| 127 | * The `controller` object has two methods. |
| 128 | * |
| 129 | * - `controller.skip()` - Skip the following segments in this branch. |
| 130 | * - `controller.break()` - Skip all following segments. |
| 131 | * @param {Object} [options] Omittable. |
| 132 | * @param {CodePathSegment} [options.first] The first segment to traverse. |
| 133 | * @param {CodePathSegment} [options.last] The last segment to traverse. |
| 134 | * @param {Function} callback A callback function. |
| 135 | * @returns {void} |
| 136 | */ |
| 137 | traverseSegments(options, callback) { |
| 138 | let resolvedOptions; |
| 139 | let resolvedCallback; |
| 140 | |
| 141 | if (typeof options === 'function') { |
| 142 | resolvedCallback = options; |
| 143 | resolvedOptions = {}; |
| 144 | } else { |
| 145 | resolvedOptions = options || {}; |
| 146 | resolvedCallback = callback; |
| 147 | } |
| 148 | |
| 149 | const startSegment = resolvedOptions.first || this.internal.initialSegment; |
| 150 | const lastSegment = resolvedOptions.last; |
| 151 | |
| 152 | let item = null; |
| 153 | let index = 0; |
| 154 | let end = 0; |
| 155 | let segment = null; |
| 156 | const visited = Object.create(null); |
| 157 | const stack = [[startSegment, 0]]; |
| 158 | let skippedSegment = null; |
| 159 | let broken = false; |
| 160 | const controller = { |
| 161 | skip() { |
| 162 | if (stack.length <= 1) { |
| 163 | broken = true; |
| 164 | } else { |
| 165 | skippedSegment = stack[stack.length - 2][0]; |
| 166 | } |
| 167 | }, |
| 168 | break() { |
| 169 | broken = true; |
| 170 | }, |
| 171 | }; |
| 172 | |
| 173 | /** |
| 174 | * Checks a given previous segment has been visited. |
| 175 | * @param {CodePathSegment} prevSegment A previous segment to check. |
| 176 | * @returns {boolean} `true` if the segment has been visited. |
| 177 | */ |
| 178 | function isVisited(prevSegment) { |
| 179 | return ( |
| 180 | visited[prevSegment.id] || segment.isLoopedPrevSegment(prevSegment) |
| 181 | ); |
| 182 | } |
| 183 | |
| 184 | while (stack.length > 0) { |
| 185 | item = stack[stack.length - 1]; |
| 186 | segment = item[0]; |
| 187 | index = item[1]; |
| 188 | |
| 189 | if (index === 0) { |
| 190 | // Skip if this segment has been visited already. |
| 191 | if (visited[segment.id]) { |
| 192 | stack.pop(); |
| 193 | continue; |
| 194 | } |
| 195 | |
| 196 | // Skip if all previous segments have not been visited. |
| 197 | if ( |
| 198 | segment !== startSegment && |
| 199 | segment.prevSegments.length > 0 && |
| 200 | !segment.prevSegments.every(isVisited) |
| 201 | ) { |
| 202 | stack.pop(); |
| 203 | continue; |
| 204 | } |
| 205 | |
| 206 | // Reset the flag of skipping if all branches have been skipped. |
| 207 | if (skippedSegment && segment.prevSegments.includes(skippedSegment)) { |
| 208 | skippedSegment = null; |
| 209 | } |
| 210 | visited[segment.id] = true; |
| 211 | |
| 212 | // Call the callback when the first time. |
| 213 | if (!skippedSegment) { |
| 214 | resolvedCallback.call(this, segment, controller); |
| 215 | if (segment === lastSegment) { |
| 216 | controller.skip(); |
| 217 | } |
| 218 | if (broken) { |
| 219 | break; |
| 220 | } |
| 221 | } |
| 222 | } |
| 223 | |
| 224 | // Update the stack. |
| 225 | end = segment.nextSegments.length - 1; |
| 226 | if (index < end) { |
| 227 | item[1] += 1; |
| 228 | stack.push([segment.nextSegments[index], 0]); |
| 229 | } else if (index === end) { |
| 230 | item[0] = segment.nextSegments[index]; |
| 231 | item[1] = 0; |
| 232 | } else { |
| 233 | stack.pop(); |
| 234 | } |
| 235 | } |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | module.exports = CodePath; |