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eb39fafa DC |
1 | /** |
2 | * @fileoverview An object that caches and applies source code fixes. | |
3 | * @author Nicholas C. Zakas | |
4 | */ | |
5 | "use strict"; | |
6 | ||
7 | //------------------------------------------------------------------------------ | |
8 | // Requirements | |
9 | //------------------------------------------------------------------------------ | |
10 | ||
11 | const debug = require("debug")("eslint:source-code-fixer"); | |
12 | ||
13 | //------------------------------------------------------------------------------ | |
14 | // Helpers | |
15 | //------------------------------------------------------------------------------ | |
16 | ||
17 | const BOM = "\uFEFF"; | |
18 | ||
19 | /** | |
20 | * Compares items in a messages array by range. | |
21 | * @param {Message} a The first message. | |
22 | * @param {Message} b The second message. | |
23 | * @returns {int} -1 if a comes before b, 1 if a comes after b, 0 if equal. | |
24 | * @private | |
25 | */ | |
26 | function compareMessagesByFixRange(a, b) { | |
27 | return a.fix.range[0] - b.fix.range[0] || a.fix.range[1] - b.fix.range[1]; | |
28 | } | |
29 | ||
30 | /** | |
31 | * Compares items in a messages array by line and column. | |
32 | * @param {Message} a The first message. | |
33 | * @param {Message} b The second message. | |
34 | * @returns {int} -1 if a comes before b, 1 if a comes after b, 0 if equal. | |
35 | * @private | |
36 | */ | |
37 | function compareMessagesByLocation(a, b) { | |
38 | return a.line - b.line || a.column - b.column; | |
39 | } | |
40 | ||
41 | //------------------------------------------------------------------------------ | |
42 | // Public Interface | |
43 | //------------------------------------------------------------------------------ | |
44 | ||
45 | /** | |
46 | * Utility for apply fixes to source code. | |
47 | * @constructor | |
48 | */ | |
49 | function SourceCodeFixer() { | |
50 | Object.freeze(this); | |
51 | } | |
52 | ||
53 | /** | |
54 | * Applies the fixes specified by the messages to the given text. Tries to be | |
55 | * smart about the fixes and won't apply fixes over the same area in the text. | |
56 | * @param {string} sourceText The text to apply the changes to. | |
57 | * @param {Message[]} messages The array of messages reported by ESLint. | |
58 | * @param {boolean|Function} [shouldFix=true] Determines whether each message should be fixed | |
59 | * @returns {Object} An object containing the fixed text and any unfixed messages. | |
60 | */ | |
61 | SourceCodeFixer.applyFixes = function(sourceText, messages, shouldFix) { | |
62 | debug("Applying fixes"); | |
63 | ||
64 | if (shouldFix === false) { | |
65 | debug("shouldFix parameter was false, not attempting fixes"); | |
66 | return { | |
67 | fixed: false, | |
68 | messages, | |
69 | output: sourceText | |
70 | }; | |
71 | } | |
72 | ||
73 | // clone the array | |
74 | const remainingMessages = [], | |
75 | fixes = [], | |
76 | bom = sourceText.startsWith(BOM) ? BOM : "", | |
77 | text = bom ? sourceText.slice(1) : sourceText; | |
78 | let lastPos = Number.NEGATIVE_INFINITY, | |
79 | output = bom; | |
80 | ||
81 | /** | |
82 | * Try to use the 'fix' from a problem. | |
609c276f TL |
83 | * @param {Message} problem The message object to apply fixes from |
84 | * @returns {boolean} Whether fix was successfully applied | |
eb39fafa DC |
85 | */ |
86 | function attemptFix(problem) { | |
87 | const fix = problem.fix; | |
88 | const start = fix.range[0]; | |
89 | const end = fix.range[1]; | |
90 | ||
91 | // Remain it as a problem if it's overlapped or it's a negative range | |
92 | if (lastPos >= start || start > end) { | |
93 | remainingMessages.push(problem); | |
94 | return false; | |
95 | } | |
96 | ||
97 | // Remove BOM. | |
98 | if ((start < 0 && end >= 0) || (start === 0 && fix.text.startsWith(BOM))) { | |
99 | output = ""; | |
100 | } | |
101 | ||
102 | // Make output to this fix. | |
103 | output += text.slice(Math.max(0, lastPos), Math.max(0, start)); | |
104 | output += fix.text; | |
105 | lastPos = end; | |
106 | return true; | |
107 | } | |
108 | ||
109 | messages.forEach(problem => { | |
110 | if (Object.prototype.hasOwnProperty.call(problem, "fix")) { | |
111 | fixes.push(problem); | |
112 | } else { | |
113 | remainingMessages.push(problem); | |
114 | } | |
115 | }); | |
116 | ||
117 | if (fixes.length) { | |
118 | debug("Found fixes to apply"); | |
119 | let fixesWereApplied = false; | |
120 | ||
121 | for (const problem of fixes.sort(compareMessagesByFixRange)) { | |
122 | if (typeof shouldFix !== "function" || shouldFix(problem)) { | |
123 | attemptFix(problem); | |
124 | ||
125 | /* | |
126 | * The only time attemptFix will fail is if a previous fix was | |
127 | * applied which conflicts with it. So we can mark this as true. | |
128 | */ | |
129 | fixesWereApplied = true; | |
130 | } else { | |
131 | remainingMessages.push(problem); | |
132 | } | |
133 | } | |
134 | output += text.slice(Math.max(0, lastPos)); | |
135 | ||
136 | return { | |
137 | fixed: fixesWereApplied, | |
138 | messages: remainingMessages.sort(compareMessagesByLocation), | |
139 | output | |
140 | }; | |
141 | } | |
142 | ||
143 | debug("No fixes to apply"); | |
144 | return { | |
145 | fixed: false, | |
146 | messages, | |
147 | output: bom + text | |
148 | }; | |
149 | ||
150 | }; | |
151 | ||
152 | module.exports = SourceCodeFixer; |