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
|
"use strict";
/**
* @license
* Copyright 2016 Palantir Technologies, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
Object.defineProperty(exports, "__esModule", { value: true });
var tslib_1 = require("tslib");
var tsutils_1 = require("tsutils");
var ts = require("typescript");
var Lint = require("../index");
var Rule = /** @class */ (function (_super) {
tslib_1.__extends(Rule, _super);
function Rule() {
return _super !== null && _super.apply(this, arguments) || this;
}
Rule.prototype.applyWithProgram = function (sourceFile, program) {
return this.applyWithWalker(new Walker(sourceFile, this.ruleName, this.ruleArguments, program.getTypeChecker()));
};
/* tslint:disable:object-literal-sort-keys */
Rule.metadata = {
ruleName: "no-unnecessary-type-assertion",
description: "Warns if a type assertion does not change the type of an expression.",
options: {
type: "list",
listType: {
type: "array",
items: { type: "string" },
},
},
optionsDescription: "A list of whitelisted assertion types to ignore",
type: "typescript",
hasFix: true,
typescriptOnly: true,
requiresTypeInfo: true,
};
/* tslint:enable:object-literal-sort-keys */
Rule.FAILURE_STRING = "This assertion is unnecessary since it does not change the type of the expression.";
return Rule;
}(Lint.Rules.TypedRule));
exports.Rule = Rule;
var Walker = /** @class */ (function (_super) {
tslib_1.__extends(Walker, _super);
function Walker(sourceFile, ruleName, options, checker) {
var _this = _super.call(this, sourceFile, ruleName, options) || this;
_this.checker = checker;
return _this;
}
Walker.prototype.walk = function (sourceFile) {
var _this = this;
var cb = function (node) {
switch (node.kind) {
case ts.SyntaxKind.NonNullExpression:
_this.checkNonNullAssertion(node);
break;
case ts.SyntaxKind.TypeAssertionExpression:
case ts.SyntaxKind.AsExpression:
_this.verifyCast(node);
}
return ts.forEachChild(node, cb);
};
return ts.forEachChild(sourceFile, cb);
};
Walker.prototype.checkNonNullAssertion = function (node) {
var type = this.checker.getTypeAtLocation(node.expression);
if (type === this.checker.getNonNullableType(type)) {
this.addFailureAtNode(node, Rule.FAILURE_STRING, Lint.Replacement.deleteFromTo(node.expression.end, node.end));
}
};
Walker.prototype.verifyCast = function (node) {
if (this.options.indexOf(node.type.getText(this.sourceFile)) !== -1) {
return;
}
var castType = this.checker.getTypeAtLocation(node);
if (tsutils_1.isTypeFlagSet(castType, ts.TypeFlags.Literal) ||
tsutils_1.isObjectType(castType) && (tsutils_1.isObjectFlagSet(castType, ts.ObjectFlags.Tuple) || couldBeTupleType(castType))) {
// It's not always safe to remove a cast to a literal type or tuple
// type, as those types are sometimes widened without the cast.
return;
}
var uncastType = this.checker.getTypeAtLocation(node.expression);
if (uncastType === castType) {
this.addFailureAtNode(node, Rule.FAILURE_STRING, node.kind === ts.SyntaxKind.TypeAssertionExpression
? Lint.Replacement.deleteFromTo(node.getStart(), node.expression.getStart())
: Lint.Replacement.deleteFromTo(node.expression.end, node.end));
}
};
return Walker;
}(Lint.AbstractWalker));
/**
* Sometimes tuple types don't have ObjectFlags.Tuple set, like when they're being matched against an inferred type.
* So, in addition, check if there are integer properties 0..n and no other numeric keys
*/
function couldBeTupleType(type) {
var properties = type.getProperties();
if (properties.length === 0) {
return false;
}
var i = 0;
for (; i < properties.length; ++i) {
var name = properties[i].name;
if (String(i) !== name) {
if (i === 0) {
// if there are no integer properties, this is not a tuple
return false;
}
break;
}
}
for (; i < properties.length; ++i) {
if (String(+properties[i].name) === properties[i].name) {
return false; // if there are any other numeric properties, this is not a tuple
}
}
return true;
}
|
