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eb39fafa DC |
1 | /** |
2 | * @fileoverview A class of the code path. | |
3 | * @author Toru Nagashima | |
4 | */ | |
5 | ||
6 | "use strict"; | |
7 | ||
8 | //------------------------------------------------------------------------------ | |
9 | // Requirements | |
10 | //------------------------------------------------------------------------------ | |
11 | ||
12 | const CodePathState = require("./code-path-state"); | |
13 | const IdGenerator = require("./id-generator"); | |
14 | ||
15 | //------------------------------------------------------------------------------ | |
16 | // Public Interface | |
17 | //------------------------------------------------------------------------------ | |
18 | ||
19 | /** | |
20 | * A code path. | |
21 | */ | |
22 | class CodePath { | |
23 | ||
eb39fafa | 24 | /** |
609c276f TL |
25 | * Creates a new instance. |
26 | * @param {Object} options Options for the function (see below). | |
27 | * @param {string} options.id An identifier. | |
28 | * @param {string} options.origin The type of code path origin. | |
29 | * @param {CodePath|null} options.upper The code path of the upper function scope. | |
30 | * @param {Function} options.onLooped A callback function to notify looping. | |
eb39fafa | 31 | */ |
609c276f | 32 | constructor({ id, origin, upper, onLooped }) { |
eb39fafa DC |
33 | |
34 | /** | |
35 | * The identifier of this code path. | |
36 | * Rules use it to store additional information of each rule. | |
37 | * @type {string} | |
38 | */ | |
39 | this.id = id; | |
40 | ||
609c276f TL |
41 | /** |
42 | * The reason that this code path was started. May be "program", | |
43 | * "function", "class-field-initializer", or "class-static-block". | |
44 | * @type {string} | |
45 | */ | |
46 | this.origin = origin; | |
47 | ||
eb39fafa DC |
48 | /** |
49 | * The code path of the upper function scope. | |
50 | * @type {CodePath|null} | |
51 | */ | |
52 | this.upper = upper; | |
53 | ||
54 | /** | |
55 | * The code paths of nested function scopes. | |
56 | * @type {CodePath[]} | |
57 | */ | |
58 | this.childCodePaths = []; | |
59 | ||
60 | // Initializes internal state. | |
61 | Object.defineProperty( | |
62 | this, | |
63 | "internal", | |
64 | { value: new CodePathState(new IdGenerator(`${id}_`), onLooped) } | |
65 | ); | |
66 | ||
67 | // Adds this into `childCodePaths` of `upper`. | |
68 | if (upper) { | |
69 | upper.childCodePaths.push(this); | |
70 | } | |
71 | } | |
72 | ||
73 | /** | |
74 | * Gets the state of a given code path. | |
75 | * @param {CodePath} codePath A code path to get. | |
76 | * @returns {CodePathState} The state of the code path. | |
77 | */ | |
78 | static getState(codePath) { | |
79 | return codePath.internal; | |
80 | } | |
81 | ||
82 | /** | |
83 | * The initial code path segment. | |
84 | * @type {CodePathSegment} | |
85 | */ | |
86 | get initialSegment() { | |
87 | return this.internal.initialSegment; | |
88 | } | |
89 | ||
90 | /** | |
91 | * Final code path segments. | |
92 | * This array is a mix of `returnedSegments` and `thrownSegments`. | |
93 | * @type {CodePathSegment[]} | |
94 | */ | |
95 | get finalSegments() { | |
96 | return this.internal.finalSegments; | |
97 | } | |
98 | ||
99 | /** | |
100 | * Final code path segments which is with `return` statements. | |
101 | * This array contains the last path segment if it's reachable. | |
102 | * Since the reachable last path returns `undefined`. | |
103 | * @type {CodePathSegment[]} | |
104 | */ | |
105 | get returnedSegments() { | |
106 | return this.internal.returnedForkContext; | |
107 | } | |
108 | ||
109 | /** | |
110 | * Final code path segments which is with `throw` statements. | |
111 | * @type {CodePathSegment[]} | |
112 | */ | |
113 | get thrownSegments() { | |
114 | return this.internal.thrownForkContext; | |
115 | } | |
116 | ||
117 | /** | |
118 | * Current code path segments. | |
119 | * @type {CodePathSegment[]} | |
120 | */ | |
121 | get currentSegments() { | |
122 | return this.internal.currentSegments; | |
123 | } | |
124 | ||
125 | /** | |
126 | * Traverses all segments in this code path. | |
127 | * | |
128 | * codePath.traverseSegments(function(segment, controller) { | |
129 | * // do something. | |
130 | * }); | |
131 | * | |
132 | * This method enumerates segments in order from the head. | |
133 | * | |
134 | * The `controller` object has two methods. | |
135 | * | |
136 | * - `controller.skip()` - Skip the following segments in this branch. | |
137 | * - `controller.break()` - Skip all following segments. | |
138 | * @param {Object} [options] Omittable. | |
139 | * @param {CodePathSegment} [options.first] The first segment to traverse. | |
140 | * @param {CodePathSegment} [options.last] The last segment to traverse. | |
141 | * @param {Function} callback A callback function. | |
142 | * @returns {void} | |
143 | */ | |
144 | traverseSegments(options, callback) { | |
145 | let resolvedOptions; | |
146 | let resolvedCallback; | |
147 | ||
148 | if (typeof options === "function") { | |
149 | resolvedCallback = options; | |
150 | resolvedOptions = {}; | |
151 | } else { | |
152 | resolvedOptions = options || {}; | |
153 | resolvedCallback = callback; | |
154 | } | |
155 | ||
156 | const startSegment = resolvedOptions.first || this.internal.initialSegment; | |
157 | const lastSegment = resolvedOptions.last; | |
158 | ||
159 | let item = null; | |
160 | let index = 0; | |
161 | let end = 0; | |
162 | let segment = null; | |
163 | const visited = Object.create(null); | |
164 | const stack = [[startSegment, 0]]; | |
165 | let skippedSegment = null; | |
166 | let broken = false; | |
167 | const controller = { | |
168 | skip() { | |
169 | if (stack.length <= 1) { | |
170 | broken = true; | |
171 | } else { | |
172 | skippedSegment = stack[stack.length - 2][0]; | |
173 | } | |
174 | }, | |
175 | break() { | |
176 | broken = true; | |
177 | } | |
178 | }; | |
179 | ||
180 | /** | |
181 | * Checks a given previous segment has been visited. | |
182 | * @param {CodePathSegment} prevSegment A previous segment to check. | |
183 | * @returns {boolean} `true` if the segment has been visited. | |
184 | */ | |
185 | function isVisited(prevSegment) { | |
186 | return ( | |
187 | visited[prevSegment.id] || | |
188 | segment.isLoopedPrevSegment(prevSegment) | |
189 | ); | |
190 | } | |
191 | ||
192 | while (stack.length > 0) { | |
193 | item = stack[stack.length - 1]; | |
194 | segment = item[0]; | |
195 | index = item[1]; | |
196 | ||
197 | if (index === 0) { | |
198 | ||
199 | // Skip if this segment has been visited already. | |
200 | if (visited[segment.id]) { | |
201 | stack.pop(); | |
202 | continue; | |
203 | } | |
204 | ||
205 | // Skip if all previous segments have not been visited. | |
206 | if (segment !== startSegment && | |
207 | segment.prevSegments.length > 0 && | |
208 | !segment.prevSegments.every(isVisited) | |
209 | ) { | |
210 | stack.pop(); | |
211 | continue; | |
212 | } | |
213 | ||
214 | // Reset the flag of skipping if all branches have been skipped. | |
8f9d1d4d | 215 | if (skippedSegment && segment.prevSegments.includes(skippedSegment)) { |
eb39fafa DC |
216 | skippedSegment = null; |
217 | } | |
218 | visited[segment.id] = true; | |
219 | ||
220 | // Call the callback when the first time. | |
221 | if (!skippedSegment) { | |
222 | resolvedCallback.call(this, segment, controller); | |
223 | if (segment === lastSegment) { | |
224 | controller.skip(); | |
225 | } | |
226 | if (broken) { | |
227 | break; | |
228 | } | |
229 | } | |
230 | } | |
231 | ||
232 | // Update the stack. | |
233 | end = segment.nextSegments.length - 1; | |
234 | if (index < end) { | |
235 | item[1] += 1; | |
236 | stack.push([segment.nextSegments[index], 0]); | |
237 | } else if (index === end) { | |
238 | item[0] = segment.nextSegments[index]; | |
239 | item[1] = 0; | |
240 | } else { | |
241 | stack.pop(); | |
242 | } | |
243 | } | |
244 | } | |
245 | } | |
246 | ||
247 | module.exports = CodePath; |