forked from palantir/tslint
-
Notifications
You must be signed in to change notification settings - Fork 0
/
noUnnecessaryQualifierRule.ts
154 lines (135 loc) · 5.68 KB
/
noUnnecessaryQualifierRule.ts
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
/**
* @license
* Copyright 2017 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.
*/
import * as utils from "tsutils";
import * as ts from "typescript";
import * as Lint from "../index";
export class Rule extends Lint.Rules.TypedRule {
/* tslint:disable:object-literal-sort-keys */
public static metadata: Lint.IRuleMetadata = {
ruleName: "no-unnecessary-qualifier",
description: "Warns when a namespace qualifier (`A.x`) is unnecessary.",
hasFix: true,
optionsDescription: "Not configurable.",
options: null,
optionExamples: [true],
type: "style",
typescriptOnly: true,
requiresTypeInfo: true,
};
/* tslint:enable:object-literal-sort-keys */
public static FAILURE_STRING(name: string) {
return `Qualifier is unnecessary since '${name}' is in scope.`;
}
public applyWithProgram(sourceFile: ts.SourceFile, program: ts.Program): Lint.RuleFailure[] {
return this.applyWithFunction(sourceFile, walk, undefined, program.getTypeChecker());
}
}
function walk(ctx: Lint.WalkContext, checker: ts.TypeChecker): void {
const namespacesInScope: Array<ts.ModuleDeclaration | ts.EnumDeclaration> = [];
ts.forEachChild(ctx.sourceFile, cb);
function cb(node: ts.Node): void {
switch (node.kind) {
case ts.SyntaxKind.ModuleDeclaration:
case ts.SyntaxKind.EnumDeclaration:
namespacesInScope.push(node as ts.ModuleDeclaration | ts.EnumDeclaration);
ts.forEachChild(node, cb);
namespacesInScope.pop();
break;
case ts.SyntaxKind.QualifiedName:
const { left, right } = node as ts.QualifiedName;
visitNamespaceAccess(node, left, right);
break;
case ts.SyntaxKind.PropertyAccessExpression:
const { expression, name } = node as ts.PropertyAccessExpression;
if (utils.isEntityNameExpression(expression) && !Lint.isPrivateIdentifier(name)) {
visitNamespaceAccess(node, expression, name);
break;
}
// falls through
default:
ts.forEachChild(node, cb);
}
}
function visitNamespaceAccess(
node: ts.Node,
qualifier: ts.EntityNameOrEntityNameExpression,
name: ts.Identifier,
): void {
if (qualifierIsUnnecessary(qualifier, name)) {
const fix = Lint.Replacement.deleteFromTo(qualifier.getStart(), name.getStart());
ctx.addFailureAtNode(qualifier, Rule.FAILURE_STRING(qualifier.getText()), fix);
} else {
// Only look for nested qualifier errors if we didn't already fail on the outer qualifier.
ts.forEachChild(node, cb);
}
}
function qualifierIsUnnecessary(
qualifier: ts.EntityNameOrEntityNameExpression,
name: ts.Identifier,
): boolean {
const namespaceSymbol = checker.getSymbolAtLocation(qualifier);
if (namespaceSymbol === undefined || !symbolIsNamespaceInScope(namespaceSymbol)) {
return false;
}
const accessedSymbol = checker.getSymbolAtLocation(name);
if (accessedSymbol === undefined) {
return false;
}
// If the symbol in scope is different, the qualifier is necessary.
const fromScope = getSymbolInScope(qualifier, accessedSymbol.flags, name.text);
return fromScope === undefined || symbolsAreEqual(accessedSymbol, fromScope);
}
function getSymbolInScope(
node: ts.Node,
flags: ts.SymbolFlags,
name: string,
): ts.Symbol | undefined {
// TODO:PERF `getSymbolsInScope` gets a long list. Is there a better way?
const scope = checker.getSymbolsInScope(node, flags);
return scope.find(scopeSymbol => scopeSymbol.name === name);
}
function symbolIsNamespaceInScope(symbol: ts.Symbol): boolean {
const symbolDeclarations = symbol.getDeclarations();
if (symbolDeclarations === undefined) {
return false;
} else if (symbolDeclarations.some(decl => namespacesInScope.some(ns => ns === decl))) {
return true;
}
const alias = tryGetAliasedSymbol(symbol, checker);
return alias !== undefined && symbolIsNamespaceInScope(alias);
}
function symbolsAreEqual(accessed: ts.Symbol, inScope: ts.Symbol): boolean {
if (checker.getExportSymbolOfSymbol !== undefined) {
inScope = checker.getExportSymbolOfSymbol(inScope);
return accessed === inScope;
}
return (
accessed === inScope ||
// For compatibility with typescript@2.5: compare declarations because the symbols don't have the same reference
Lint.Utils.arraysAreEqual(
accessed.declarations,
inScope.declarations,
(a, b) => a === b,
)
);
}
}
function tryGetAliasedSymbol(symbol: ts.Symbol, checker: ts.TypeChecker): ts.Symbol | undefined {
return utils.isSymbolFlagSet(symbol, ts.SymbolFlags.Alias)
? checker.getAliasedSymbol(symbol)
: undefined;
}