forked from babel/eslint-plugin-babel
-
Notifications
You must be signed in to change notification settings - Fork 0
/
ast-utils.js
727 lines (642 loc) · 23.1 KB
/
ast-utils.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
/**
* @fileoverview Common utils for AST.
* @author Gyandeep Singh
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
const anyFunctionPattern = /^(?:Function(?:Declaration|Expression)|ArrowFunctionExpression)$/;
const anyLoopPattern = /^(?:DoWhile|For|ForIn|ForOf|While)Statement$/;
const arrayOrTypedArrayPattern = /Array$/;
const arrayMethodPattern = /^(?:every|filter|find|findIndex|forEach|map|some)$/;
const bindOrCallOrApplyPattern = /^(?:bind|call|apply)$/;
const breakableTypePattern = /^(?:(?:Do)?While|For(?:In|Of)?|Switch)Statement$/;
const thisTagPattern = /^[\s\*]*@this/m;
/**
* Checks reference if is non initializer and writable.
* @param {Reference} reference - A reference to check.
* @param {int} index - The index of the reference in the references.
* @param {Reference[]} references - The array that the reference belongs to.
* @returns {boolean} Success/Failure
* @private
*/
function isModifyingReference(reference, index, references) {
const identifier = reference.identifier;
/*
* Destructuring assignments can have multiple default value, so
* possibly there are multiple writeable references for the same
* identifier.
*/
const modifyingDifferentIdentifier = index === 0 ||
references[index - 1].identifier !== identifier;
return (identifier &&
reference.init === false &&
reference.isWrite() &&
modifyingDifferentIdentifier
);
}
/**
* Checks whether the given string starts with uppercase or not.
*
* @param {string} s - The string to check.
* @returns {boolean} `true` if the string starts with uppercase.
*/
function startsWithUpperCase(s) {
return s[0] !== s[0].toLocaleLowerCase();
}
/**
* Checks whether or not a node is a constructor.
* @param {ASTNode} node - A function node to check.
* @returns {boolean} Wehether or not a node is a constructor.
*/
function isES5Constructor(node) {
return (node.id && startsWithUpperCase(node.id.name));
}
/**
* Finds a function node from ancestors of a node.
* @param {ASTNode} node - A start node to find.
* @returns {Node|null} A found function node.
*/
function getUpperFunction(node) {
while (node) {
if (anyFunctionPattern.test(node.type)) {
return node;
}
node = node.parent;
}
return null;
}
/**
* Checks whether or not a node is `null` or `undefined`.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a `null` or `undefined`.
* @public
*/
function isNullOrUndefined(node) {
return (
(node.type === "Literal" && node.value === null) ||
(node.type === "Identifier" && node.name === "undefined") ||
(node.type === "UnaryExpression" && node.operator === "void")
);
}
/**
* Checks whether or not a node is callee.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is callee.
*/
function isCallee(node) {
return node.parent.type === "CallExpression" && node.parent.callee === node;
}
/**
* Checks whether or not a node is `Reclect.apply`.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a `Reclect.apply`.
*/
function isReflectApply(node) {
return (
node.type === "MemberExpression" &&
node.object.type === "Identifier" &&
node.object.name === "Reflect" &&
node.property.type === "Identifier" &&
node.property.name === "apply" &&
node.computed === false
);
}
/**
* Checks whether or not a node is `Array.from`.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a `Array.from`.
*/
function isArrayFromMethod(node) {
return (
node.type === "MemberExpression" &&
node.object.type === "Identifier" &&
arrayOrTypedArrayPattern.test(node.object.name) &&
node.property.type === "Identifier" &&
node.property.name === "from" &&
node.computed === false
);
}
/**
* Checks whether or not a node is a method which has `thisArg`.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a method which has `thisArg`.
*/
function isMethodWhichHasThisArg(node) {
while (node) {
if (node.type === "Identifier") {
return arrayMethodPattern.test(node.name);
}
if (node.type === "MemberExpression" && !node.computed) {
node = node.property;
continue;
}
break;
}
return false;
}
/**
* Checks whether or not a node has a `@this` tag in its comments.
* @param {ASTNode} node - A node to check.
* @param {SourceCode} sourceCode - A SourceCode instance to get comments.
* @returns {boolean} Whether or not the node has a `@this` tag in its comments.
*/
function hasJSDocThisTag(node, sourceCode) {
const jsdocComment = sourceCode.getJSDocComment(node);
if (jsdocComment && thisTagPattern.test(jsdocComment.value)) {
return true;
}
// Checks `@this` in its leading comments for callbacks,
// because callbacks don't have its JSDoc comment.
// e.g.
// sinon.test(/* @this sinon.Sandbox */function() { this.spy(); });
return sourceCode.getComments(node).leading.some(function(comment) {
return thisTagPattern.test(comment.value);
});
}
/**
* Determines if a node is surrounded by parentheses.
* @param {SourceCode} sourceCode The ESLint source code object
* @param {ASTNode} node The node to be checked.
* @returns {boolean} True if the node is parenthesised.
* @private
*/
function isParenthesised(sourceCode, node) {
const previousToken = sourceCode.getTokenBefore(node),
nextToken = sourceCode.getTokenAfter(node);
return Boolean(previousToken && nextToken) &&
previousToken.value === "(" && previousToken.range[1] <= node.range[0] &&
nextToken.value === ")" && nextToken.range[0] >= node.range[1];
}
//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------
module.exports = {
/**
* Determines whether two adjacent tokens are on the same line.
* @param {Object} left - The left token object.
* @param {Object} right - The right token object.
* @returns {boolean} Whether or not the tokens are on the same line.
* @public
*/
isTokenOnSameLine(left, right) {
return left.loc.end.line === right.loc.start.line;
},
isNullOrUndefined,
isCallee,
isES5Constructor,
getUpperFunction,
isArrayFromMethod,
isParenthesised,
/**
* Checks whether or not a given node is a string literal.
* @param {ASTNode} node - A node to check.
* @returns {boolean} `true` if the node is a string literal.
*/
isStringLiteral(node) {
return (
(node.type === "Literal" && typeof node.value === "string") ||
node.type === "TemplateLiteral"
);
},
/**
* Checks whether a given node is a breakable statement or not.
* The node is breakable if the node is one of the following type:
*
* - DoWhileStatement
* - ForInStatement
* - ForOfStatement
* - ForStatement
* - SwitchStatement
* - WhileStatement
*
* @param {ASTNode} node - A node to check.
* @returns {boolean} `true` if the node is breakable.
*/
isBreakableStatement(node) {
return breakableTypePattern.test(node.type);
},
/**
* Gets the label if the parent node of a given node is a LabeledStatement.
*
* @param {ASTNode} node - A node to get.
* @returns {string|null} The label or `null`.
*/
getLabel(node) {
if (node.parent.type === "LabeledStatement") {
return node.parent.label.name;
}
return null;
},
/**
* Gets references which are non initializer and writable.
* @param {Reference[]} references - An array of references.
* @returns {Reference[]} An array of only references which are non initializer and writable.
* @public
*/
getModifyingReferences(references) {
return references.filter(isModifyingReference);
},
/**
* Validate that a string passed in is surrounded by the specified character
* @param {string} val The text to check.
* @param {string} character The character to see if it's surrounded by.
* @returns {boolean} True if the text is surrounded by the character, false if not.
* @private
*/
isSurroundedBy(val, character) {
return val[0] === character && val[val.length - 1] === character;
},
/**
* Returns whether the provided node is an ESLint directive comment or not
* @param {LineComment|BlockComment} node The node to be checked
* @returns {boolean} `true` if the node is an ESLint directive comment
*/
isDirectiveComment(node) {
const comment = node.value.trim();
return (
node.type === "Line" && comment.indexOf("eslint-") === 0 ||
node.type === "Block" && (
comment.indexOf("global ") === 0 ||
comment.indexOf("eslint ") === 0 ||
comment.indexOf("eslint-") === 0
)
);
},
/**
* Finds the variable by a given name in a given scope and its upper scopes.
*
* @param {escope.Scope} initScope - A scope to start find.
* @param {string} name - A variable name to find.
* @returns {escope.Variable|null} A found variable or `null`.
*/
getVariableByName(initScope, name) {
let scope = initScope;
while (scope) {
const variable = scope.set.get(name);
if (variable) {
return variable;
}
scope = scope.upper;
}
return null;
},
/**
* Checks whether or not a given function node is the default `this` binding.
*
* First, this checks the node:
*
* - The function name does not start with uppercase (it's a constructor).
* - The function does not have a JSDoc comment that has a @this tag.
*
* Next, this checks the location of the node.
* If the location is below, this judges `this` is valid.
*
* - The location is not on an object literal.
* - The location is not assigned to a variable which starts with an uppercase letter.
* - The location is not on an ES2015 class.
* - Its `bind`/`call`/`apply` method is not called directly.
* - The function is not a callback of array methods (such as `.forEach()`) if `thisArg` is given.
*
* @param {ASTNode} node - A function node to check.
* @param {SourceCode} sourceCode - A SourceCode instance to get comments.
* @returns {boolean} The function node is the default `this` binding.
*/
isDefaultThisBinding(node, sourceCode) {
if (isES5Constructor(node) || hasJSDocThisTag(node, sourceCode)) {
return false;
}
const isAnonymous = node.id === null;
while (node) {
const parent = node.parent;
switch (parent.type) {
/*
* Looks up the destination.
* e.g., obj.foo = nativeFoo || function foo() { ... };
*/
case "LogicalExpression":
case "ConditionalExpression":
node = parent;
break;
// If the upper function is IIFE, checks the destination of the return value.
// e.g.
// obj.foo = (function() {
// // setup...
// return function foo() { ... };
// })();
case "ReturnStatement": {
const func = getUpperFunction(parent);
if (func === null || !isCallee(func)) {
return true;
}
node = func.parent;
break;
}
// e.g.
// var obj = { foo() { ... } };
// var obj = { foo: function() { ... } };
// class A { constructor() { ... } }
// class A { foo() { ... } }
// class A { get foo() { ... } }
// class A { set foo() { ... } }
// class A { static foo() { ... } }
case "Property":
case "MethodDefinition":
return parent.value !== node;
// e.g.
// obj.foo = function foo() { ... };
// Foo = function() { ... };
// [obj.foo = function foo() { ... }] = a;
// [Foo = function() { ... }] = a;
case "AssignmentExpression":
case "AssignmentPattern":
if (parent.right === node) {
if (parent.left.type === "MemberExpression") {
return false;
}
if (isAnonymous &&
parent.left.type === "Identifier" &&
startsWithUpperCase(parent.left.name)
) {
return false;
}
}
return true;
// e.g.
// var Foo = function() { ... };
case "VariableDeclarator":
return !(
isAnonymous &&
parent.init === node &&
parent.id.type === "Identifier" &&
startsWithUpperCase(parent.id.name)
);
// e.g.
// var foo = function foo() { ... }.bind(obj);
// (function foo() { ... }).call(obj);
// (function foo() { ... }).apply(obj, []);
case "MemberExpression":
return (
parent.object !== node ||
parent.property.type !== "Identifier" ||
!bindOrCallOrApplyPattern.test(parent.property.name) ||
!isCallee(parent) ||
parent.parent.arguments.length === 0 ||
isNullOrUndefined(parent.parent.arguments[0])
);
// e.g.
// Reflect.apply(function() {}, obj, []);
// Array.from([], function() {}, obj);
// list.forEach(function() {}, obj);
case "CallExpression":
if (isReflectApply(parent.callee)) {
return (
parent.arguments.length !== 3 ||
parent.arguments[0] !== node ||
isNullOrUndefined(parent.arguments[1])
);
}
if (isArrayFromMethod(parent.callee)) {
return (
parent.arguments.length !== 3 ||
parent.arguments[1] !== node ||
isNullOrUndefined(parent.arguments[2])
);
}
if (isMethodWhichHasThisArg(parent.callee)) {
return (
parent.arguments.length !== 2 ||
parent.arguments[0] !== node ||
isNullOrUndefined(parent.arguments[1])
);
}
return true;
// Otherwise `this` is default.
default:
return true;
}
}
/* istanbul ignore next */
return true;
},
/**
* Get the precedence level based on the node type
* @param {ASTNode} node node to evaluate
* @returns {int} precedence level
* @private
*/
getPrecedence(node) {
switch (node.type) {
case "SequenceExpression":
return 0;
case "AssignmentExpression":
case "ArrowFunctionExpression":
case "YieldExpression":
return 1;
case "ConditionalExpression":
return 3;
case "LogicalExpression":
switch (node.operator) {
case "||":
return 4;
case "&&":
return 5;
// no default
}
/* falls through */
case "BinaryExpression":
switch (node.operator) {
case "|":
return 6;
case "^":
return 7;
case "&":
return 8;
case "==":
case "!=":
case "===":
case "!==":
return 9;
case "<":
case "<=":
case ">":
case ">=":
case "in":
case "instanceof":
return 10;
case "<<":
case ">>":
case ">>>":
return 11;
case "+":
case "-":
return 12;
case "*":
case "/":
case "%":
return 13;
// no default
}
/* falls through */
case "UnaryExpression":
case "AwaitExpression":
return 14;
case "UpdateExpression":
return 15;
case "CallExpression":
// IIFE is allowed to have parens in any position (#655)
if (node.callee.type === "FunctionExpression") {
return -1;
}
return 16;
case "NewExpression":
return 17;
// no default
}
return 18;
},
/**
* Checks whether a given node is a loop node or not.
* The following types are loop nodes:
*
* - DoWhileStatement
* - ForInStatement
* - ForOfStatement
* - ForStatement
* - WhileStatement
*
* @param {ASTNode|null} node - A node to check.
* @returns {boolean} `true` if the node is a loop node.
*/
isLoop(node) {
return Boolean(node && anyLoopPattern.test(node.type));
},
/**
* Checks whether a given node is a function node or not.
* The following types are function nodes:
*
* - ArrowFunctionExpression
* - FunctionDeclaration
* - FunctionExpression
*
* @param {ASTNode|null} node - A node to check.
* @returns {boolean} `true` if the node is a function node.
*/
isFunction(node) {
return Boolean(node && anyFunctionPattern.test(node.type));
},
/**
* Gets the property name of a given node.
* The node can be a MemberExpression, a Property, or a MethodDefinition.
*
* If the name is dynamic, this returns `null`.
*
* For examples:
*
* a.b // => "b"
* a["b"] // => "b"
* a['b'] // => "b"
* a[`b`] // => "b"
* a[100] // => "100"
* a[b] // => null
* a["a" + "b"] // => null
* a[tag`b`] // => null
* a[`${b}`] // => null
*
* let a = {b: 1} // => "b"
* let a = {["b"]: 1} // => "b"
* let a = {['b']: 1} // => "b"
* let a = {[`b`]: 1} // => "b"
* let a = {[100]: 1} // => "100"
* let a = {[b]: 1} // => null
* let a = {["a" + "b"]: 1} // => null
* let a = {[tag`b`]: 1} // => null
* let a = {[`${b}`]: 1} // => null
*
* @param {ASTNode} node - The node to get.
* @returns {string|null} The property name if static. Otherwise, null.
*/
getStaticPropertyName(node) {
let prop;
switch (node && node.type) {
case "Property":
case "MethodDefinition":
prop = node.key;
break;
case "MemberExpression":
prop = node.property;
break;
// no default
}
switch (prop && prop.type) {
case "Literal":
return String(prop.value);
case "TemplateLiteral":
if (prop.expressions.length === 0 && prop.quasis.length === 1) {
return prop.quasis[0].value.cooked;
}
break;
case "Identifier":
if (!node.computed) {
return prop.name;
}
break;
// no default
}
return null;
},
/**
* Get directives from directive prologue of a Program or Function node.
* @param {ASTNode} node - The node to check.
* @returns {ASTNode[]} The directives found in the directive prologue.
*/
getDirectivePrologue(node) {
const directives = [];
// Directive prologues only occur at the top of files or functions.
if (
node.type === "Program" ||
node.type === "FunctionDeclaration" ||
node.type === "FunctionExpression" ||
// Do not check arrow functions with implicit return.
// `() => "use strict";` returns the string `"use strict"`.
(node.type === "ArrowFunctionExpression" && node.body.type === "BlockStatement")
) {
const statements = node.type === "Program" ? node.body : node.body.body;
for (const statement of statements) {
if (
statement.type === "ExpressionStatement" &&
statement.expression.type === "Literal"
) {
directives.push(statement);
} else {
break;
}
}
}
return directives;
},
/**
* Determines whether this node is a decimal integer literal. If a node is a decimal integer literal, a dot added
after the node will be parsed as a decimal point, rather than a property-access dot.
* @param {ASTNode} node - The node to check.
* @returns {boolean} `true` if this node is a decimal integer.
* @example
*
* 5 // true
* 5. // false
* 5.0 // false
* 05 // false
* 0x5 // false
* 0b101 // false
* 0o5 // false
* 5e0 // false
* '5' // false
*/
isDecimalInteger(node) {
return node.type === "Literal" && typeof node.value === "number" && /^(0|[1-9]\d*)$/.test(node.raw);
}
};