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"use strict";
/**
* @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.
*/
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 = (function (_super) {
tslib_1.__extends(Rule, _super);
function Rule() {
return _super !== null && _super.apply(this, arguments) || this;
}
Rule.prototype.apply = function (sourceFile) {
return this.applyWithFunction(sourceFile, walk);
};
return Rule;
}(Lint.Rules.AbstractRule));
/* tslint:disable:object-literal-sort-keys */
Rule.metadata = {
ruleName: "prefer-object-spread",
description: "Enforces the use of the ES2015 object spread operator over `Object.assign()` where appropriate.",
rationale: "Object spread allows for better type checking and inference.",
optionsDescription: "Not configurable.",
options: null,
optionExamples: [true],
type: "functionality",
typescriptOnly: false,
hasFix: true,
};
/* tslint:enable:object-literal-sort-keys */
Rule.FAILURE_STRING = "Use the object spread operator instead.";
Rule.ASSIGNMENT_FAILURE_STRING = "'Object.assign' returns the first argument. Prefer object spread if you want a new object.";
exports.Rule = Rule;
function walk(ctx) {
return ts.forEachChild(ctx.sourceFile, function cb(node) {
if (tsutils_1.isCallExpression(node) && node.arguments.length !== 0 &&
tsutils_1.isPropertyAccessExpression(node.expression) && node.expression.name.text === "assign" &&
tsutils_1.isIdentifier(node.expression.expression) && node.expression.expression.text === "Object" &&
// Object.assign(...someArray) cannot be written as object spread
!node.arguments.some(tsutils_1.isSpreadElement)) {
if (node.arguments[0].kind === ts.SyntaxKind.ObjectLiteralExpression) {
ctx.addFailureAtNode(node, Rule.FAILURE_STRING, createFix(node, ctx.sourceFile));
}
else {
var parent = node.parent;
if (parent.kind === ts.SyntaxKind.VariableDeclaration ||
tsutils_1.isBinaryExpression(parent) && parent.operatorToken.kind === ts.SyntaxKind.EqualsToken) {
ctx.addFailureAtNode(node, Rule.ASSIGNMENT_FAILURE_STRING, createFix(node, ctx.sourceFile));
}
}
}
return ts.forEachChild(node, cb);
});
}
function createFix(node, sourceFile) {
var args = node.arguments;
var fix = [
Lint.Replacement.replaceFromTo(node.getStart(sourceFile), args[0].getStart(sourceFile), "{"),
new Lint.Replacement(node.end - 1, 1, "}"),
];
for (var i = 0; i < args.length; ++i) {
var arg = args[i];
if (tsutils_1.isObjectLiteralExpression(arg)) {
if (arg.properties.length === 0) {
var end = arg.end;
if (i !== args.length - 1) {
end = args[i + 1].getStart(sourceFile);
}
else if (args.hasTrailingComma === true) {
end = args.end;
}
// remove empty object iteral and the following comma if exists
fix.push(Lint.Replacement.deleteFromTo(arg.getStart(sourceFile), end));
}
else {
fix.push(
// remove open brace
Lint.Replacement.deleteText(arg.getStart(sourceFile), 1),
// remove trailing comma if exists and close brace
Lint.Replacement.deleteFromTo(arg.properties[arg.properties.length - 1].end, arg.end));
}
}
else {
var parens = needsParens(arg);
fix.push(Lint.Replacement.appendText(arg.getStart(sourceFile), parens ? "...(" : "..."));
if (parens) {
fix.push(Lint.Replacement.appendText(arg.end, ")"));
}
}
}
return fix;
}
function needsParens(node) {
switch (node.kind) {
case ts.SyntaxKind.ConditionalExpression:
case ts.SyntaxKind.BinaryExpression:
return true;
default:
return false;
}
}
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