260 lines
11 KiB
JavaScript
260 lines
11 KiB
JavaScript
/**
|
|
* @license
|
|
* Copyright 2013 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.
|
|
*/
|
|
"use strict";
|
|
var __extends = (this && this.__extends) || (function () {
|
|
var extendStatics = Object.setPrototypeOf ||
|
|
({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
|
|
function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
|
|
return function (d, b) {
|
|
extendStatics(d, b);
|
|
function __() { this.constructor = d; }
|
|
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
|
|
};
|
|
})();
|
|
Object.defineProperty(exports, "__esModule", { value: true });
|
|
var ts = require("typescript");
|
|
var Lint = require("../index");
|
|
var utils_1 = require("../language/utils");
|
|
var Rule = (function (_super) {
|
|
__extends(Rule, _super);
|
|
function Rule() {
|
|
return _super !== null && _super.apply(this, arguments) || this;
|
|
}
|
|
Rule.prototype.apply = function (sourceFile) {
|
|
var preferConstWalker = new PreferConstWalker(sourceFile, this.getOptions());
|
|
return this.applyWithWalker(preferConstWalker);
|
|
};
|
|
return Rule;
|
|
}(Lint.Rules.AbstractRule));
|
|
/* tslint:disable:object-literal-sort-keys */
|
|
Rule.metadata = {
|
|
ruleName: "prefer-const",
|
|
description: "Requires that variable declarations use `const` instead of `let` if possible.",
|
|
descriptionDetails: (_a = ["\n If a variable is only assigned to once when it is declared, it should be declared using 'const'"], _a.raw = ["\n If a variable is only assigned to once when it is declared, it should be declared using 'const'"], Lint.Utils.dedent(_a)),
|
|
hasFix: true,
|
|
optionsDescription: "Not configurable.",
|
|
options: null,
|
|
optionExamples: ["true"],
|
|
type: "maintainability",
|
|
typescriptOnly: false,
|
|
};
|
|
/* tslint:enable:object-literal-sort-keys */
|
|
Rule.FAILURE_STRING_FACTORY = function (identifier) {
|
|
return "Identifier '" + identifier + "' is never reassigned; use 'const' instead of 'let'.";
|
|
};
|
|
exports.Rule = Rule;
|
|
var PreferConstWalker = (function (_super) {
|
|
__extends(PreferConstWalker, _super);
|
|
function PreferConstWalker() {
|
|
return _super !== null && _super.apply(this, arguments) || this;
|
|
}
|
|
PreferConstWalker.collect = function (statements, scopeInfo) {
|
|
for (var _i = 0, statements_1 = statements; _i < statements_1.length; _i++) {
|
|
var s = statements_1[_i];
|
|
if (s.kind === ts.SyntaxKind.VariableStatement) {
|
|
PreferConstWalker.collectInVariableDeclarationList(s.declarationList, scopeInfo);
|
|
}
|
|
}
|
|
};
|
|
PreferConstWalker.collectInVariableDeclarationList = function (node, scopeInfo) {
|
|
var allowConst;
|
|
if (ts.getCombinedModifierFlags === undefined) {
|
|
// for back-compat, TypeScript < 2.1
|
|
allowConst = utils_1.isCombinedNodeFlagSet(node, ts.NodeFlags.Let)
|
|
&& !Lint.hasModifier(node.parent.modifiers, ts.SyntaxKind.ExportKeyword);
|
|
}
|
|
else {
|
|
allowConst = utils_1.isCombinedNodeFlagSet(node, ts.NodeFlags.Let) && !utils_1.isCombinedModifierFlagSet(node, ts.ModifierFlags.Export);
|
|
}
|
|
if (allowConst) {
|
|
for (var _i = 0, _a = node.declarations; _i < _a.length; _i++) {
|
|
var decl = _a[_i];
|
|
PreferConstWalker.addDeclarationName(decl.name, node, scopeInfo);
|
|
}
|
|
}
|
|
};
|
|
PreferConstWalker.addDeclarationName = function (node, container, scopeInfo) {
|
|
if (node.kind === ts.SyntaxKind.Identifier) {
|
|
scopeInfo.addVariable(node, container);
|
|
}
|
|
else {
|
|
for (var _i = 0, _a = node.elements; _i < _a.length; _i++) {
|
|
var el = _a[_i];
|
|
if (el.kind === ts.SyntaxKind.BindingElement) {
|
|
PreferConstWalker.addDeclarationName(el.name, container, scopeInfo);
|
|
}
|
|
}
|
|
}
|
|
};
|
|
PreferConstWalker.prototype.createScope = function () {
|
|
return {};
|
|
};
|
|
PreferConstWalker.prototype.createBlockScope = function (node) {
|
|
var scopeInfo = new ScopeInfo();
|
|
switch (node.kind) {
|
|
case ts.SyntaxKind.SourceFile:
|
|
PreferConstWalker.collect(node.statements, scopeInfo);
|
|
break;
|
|
case ts.SyntaxKind.Block:
|
|
PreferConstWalker.collect(node.statements, scopeInfo);
|
|
break;
|
|
case ts.SyntaxKind.ModuleDeclaration:
|
|
var body = node.body;
|
|
if (body && body.kind === ts.SyntaxKind.ModuleBlock) {
|
|
PreferConstWalker.collect(body.statements, scopeInfo);
|
|
}
|
|
break;
|
|
case ts.SyntaxKind.ForStatement:
|
|
case ts.SyntaxKind.ForOfStatement:
|
|
case ts.SyntaxKind.ForInStatement:
|
|
var initializer = node.initializer;
|
|
if (initializer && initializer.kind === ts.SyntaxKind.VariableDeclarationList) {
|
|
PreferConstWalker.collectInVariableDeclarationList(initializer, scopeInfo);
|
|
}
|
|
break;
|
|
case ts.SyntaxKind.SwitchStatement:
|
|
for (var _i = 0, _a = node.caseBlock.clauses; _i < _a.length; _i++) {
|
|
var caseClause = _a[_i];
|
|
PreferConstWalker.collect(caseClause.statements, scopeInfo);
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return scopeInfo;
|
|
};
|
|
PreferConstWalker.prototype.onBlockScopeEnd = function () {
|
|
var seenLetStatements = new Set();
|
|
for (var _i = 0, _a = this.getCurrentBlockScope().getConstCandiates(); _i < _a.length; _i++) {
|
|
var usage = _a[_i];
|
|
var fix = void 0;
|
|
if (!usage.reassignedSibling && !seenLetStatements.has(usage.letStatement)) {
|
|
// only fix if all variables in the `let` statement can use `const`
|
|
fix = this.createFix(this.createReplacement(usage.letStatement.getStart(), "let".length, "const"));
|
|
seenLetStatements.add(usage.letStatement);
|
|
}
|
|
this.addFailureAtNode(usage.identifier, Rule.FAILURE_STRING_FACTORY(usage.identifier.text), fix);
|
|
}
|
|
};
|
|
PreferConstWalker.prototype.visitBinaryExpression = function (node) {
|
|
if (utils_1.isAssignment(node)) {
|
|
this.handleLHSExpression(node.left);
|
|
}
|
|
_super.prototype.visitBinaryExpression.call(this, node);
|
|
};
|
|
PreferConstWalker.prototype.visitPrefixUnaryExpression = function (node) {
|
|
this.handleUnaryExpression(node);
|
|
_super.prototype.visitPrefixUnaryExpression.call(this, node);
|
|
};
|
|
PreferConstWalker.prototype.visitPostfixUnaryExpression = function (node) {
|
|
this.handleUnaryExpression(node);
|
|
_super.prototype.visitPostfixUnaryExpression.call(this, node);
|
|
};
|
|
PreferConstWalker.prototype.handleLHSExpression = function (node) {
|
|
var _this = this;
|
|
node = utils_1.unwrapParentheses(node);
|
|
if (node.kind === ts.SyntaxKind.Identifier) {
|
|
this.markAssignment(node);
|
|
}
|
|
else if (node.kind === ts.SyntaxKind.ArrayLiteralExpression) {
|
|
var deconstructionArray = node;
|
|
deconstructionArray.elements.forEach(function (child) {
|
|
// recursively unwrap destructuring arrays
|
|
_this.handleLHSExpression(child);
|
|
});
|
|
}
|
|
else if (node.kind === ts.SyntaxKind.ObjectLiteralExpression) {
|
|
for (var _i = 0, _a = node.properties; _i < _a.length; _i++) {
|
|
var prop = _a[_i];
|
|
switch (prop.kind) {
|
|
case ts.SyntaxKind.PropertyAssignment:
|
|
this.handleLHSExpression(prop.initializer);
|
|
break;
|
|
case ts.SyntaxKind.ShorthandPropertyAssignment:
|
|
this.handleLHSExpression(prop.name);
|
|
break;
|
|
case ts.SyntaxKind.SpreadAssignment:
|
|
this.handleLHSExpression(prop.expression);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
};
|
|
PreferConstWalker.prototype.handleUnaryExpression = function (node) {
|
|
if (node.operator === ts.SyntaxKind.PlusPlusToken || node.operator === ts.SyntaxKind.MinusMinusToken) {
|
|
this.handleLHSExpression(node.operand);
|
|
}
|
|
};
|
|
PreferConstWalker.prototype.markAssignment = function (identifier) {
|
|
var allBlockScopes = this.getAllBlockScopes();
|
|
// look through block scopes from local -> global
|
|
for (var i = allBlockScopes.length - 1; i >= 0; i--) {
|
|
if (allBlockScopes[i].incrementVariableUsage(identifier.text)) {
|
|
break;
|
|
}
|
|
}
|
|
};
|
|
return PreferConstWalker;
|
|
}(Lint.BlockScopeAwareRuleWalker));
|
|
var ScopeInfo = (function () {
|
|
function ScopeInfo() {
|
|
this.identifierUsages = new Map();
|
|
// variable names grouped by common `let` statements
|
|
this.sharedLetSets = new Map();
|
|
}
|
|
ScopeInfo.prototype.addVariable = function (identifier, letStatement) {
|
|
this.identifierUsages.set(identifier.text, { letStatement: letStatement, identifier: identifier, usageCount: 0 });
|
|
var shared = this.sharedLetSets.get(letStatement);
|
|
if (shared === undefined) {
|
|
shared = [];
|
|
this.sharedLetSets.set(letStatement, shared);
|
|
}
|
|
shared.push(identifier.text);
|
|
};
|
|
ScopeInfo.prototype.getConstCandiates = function () {
|
|
var _this = this;
|
|
var constCandidates = [];
|
|
this.sharedLetSets.forEach(function (variableNames) {
|
|
var anyReassigned = variableNames.some(function (key) { return _this.identifierUsages.get(key).usageCount > 0; });
|
|
for (var _i = 0, variableNames_1 = variableNames; _i < variableNames_1.length; _i++) {
|
|
var variableName = variableNames_1[_i];
|
|
var usage = _this.identifierUsages.get(variableName);
|
|
if (usage.usageCount === 0) {
|
|
constCandidates.push({
|
|
identifier: usage.identifier,
|
|
letStatement: usage.letStatement,
|
|
reassignedSibling: anyReassigned,
|
|
});
|
|
}
|
|
}
|
|
});
|
|
return constCandidates;
|
|
};
|
|
ScopeInfo.prototype.incrementVariableUsage = function (varName) {
|
|
var usages = this.identifierUsages.get(varName);
|
|
if (usages !== undefined) {
|
|
usages.usageCount++;
|
|
return true;
|
|
}
|
|
return false;
|
|
};
|
|
return ScopeInfo;
|
|
}());
|
|
var _a;
|