215 lines
9.3 KiB
JavaScript
215 lines
9.3 KiB
JavaScript
"use strict";
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/**
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* @license
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* Copyright 2014 Palantir Technologies, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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Object.defineProperty(exports, "__esModule", { value: true });
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var tslib_1 = require("tslib");
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var tsutils_1 = require("tsutils");
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var ts = require("typescript");
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var Lint = require("../index");
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var ALLOW_FAST_NULL_CHECKS = "allow-fast-null-checks";
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var ALLOW_NEW = "allow-new";
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var ALLOW_TAGGED_TEMPLATE = "allow-tagged-template";
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var Rule = (function (_super) {
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tslib_1.__extends(Rule, _super);
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function Rule() {
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return _super !== null && _super.apply(this, arguments) || this;
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}
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Rule.prototype.apply = function (sourceFile) {
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return this.applyWithFunction(sourceFile, walk, {
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allowFastNullChecks: this.ruleArguments.indexOf(ALLOW_FAST_NULL_CHECKS) !== -1,
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allowNew: this.ruleArguments.indexOf(ALLOW_NEW) !== -1,
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allowTaggedTemplate: this.ruleArguments.indexOf(ALLOW_TAGGED_TEMPLATE) !== -1,
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});
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};
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return Rule;
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}(Lint.Rules.AbstractRule));
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/* tslint:disable:object-literal-sort-keys */
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Rule.metadata = {
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ruleName: "no-unused-expression",
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description: "Disallows unused expression statements.",
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descriptionDetails: (_a = ["\n Unused expressions are expression statements which are not assignments or function calls\n (and thus usually no-ops)."], _a.raw = ["\n Unused expressions are expression statements which are not assignments or function calls\n (and thus usually no-ops)."], Lint.Utils.dedent(_a)),
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rationale: (_b = ["\n Detects potential errors where an assignment or function call was intended."], _b.raw = ["\n Detects potential errors where an assignment or function call was intended."], Lint.Utils.dedent(_b)),
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optionsDescription: (_c = ["\n Two arguments may be optionally provided:\n\n * `", "` allows to use logical operators to perform fast null checks and perform\n method or function calls for side effects (e.g. `e && e.preventDefault()`).\n * `", "` allows 'new' expressions for side effects (e.g. `new ModifyGlobalState();`.\n * `", "` allows tagged templates for side effects (e.g. `this.add\\`foo\\`;`."], _c.raw = ["\n Two arguments may be optionally provided:\n\n * \\`", "\\` allows to use logical operators to perform fast null checks and perform\n method or function calls for side effects (e.g. \\`e && e.preventDefault()\\`).\n * \\`", "\\` allows 'new' expressions for side effects (e.g. \\`new ModifyGlobalState();\\`.\n * \\`", "\\` allows tagged templates for side effects (e.g. \\`this.add\\\\\\`foo\\\\\\`;\\`."], Lint.Utils.dedent(_c, ALLOW_FAST_NULL_CHECKS, ALLOW_NEW, ALLOW_TAGGED_TEMPLATE)),
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options: {
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type: "array",
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items: {
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type: "string",
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enum: [ALLOW_FAST_NULL_CHECKS, ALLOW_NEW, ALLOW_TAGGED_TEMPLATE],
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},
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minLength: 0,
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maxLength: 3,
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},
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optionExamples: [true, [true, ALLOW_FAST_NULL_CHECKS]],
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type: "functionality",
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typescriptOnly: false,
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};
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/* tslint:enable:object-literal-sort-keys */
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Rule.FAILURE_STRING = "unused expression, expected an assignment or function call";
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exports.Rule = Rule;
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function walk(ctx) {
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var checking = false;
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var allowFastNullChecks = true;
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return ts.forEachChild(ctx.sourceFile, cb);
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function cb(node) {
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if (checking) {
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if (tsutils_1.isParenthesizedExpression(node) || tsutils_1.isVoidExpression(node)) {
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return cb(node.expression);
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}
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else if (tsutils_1.isConditionalExpression(node)) {
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noCheck(node.condition, cb);
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return both(node.whenTrue, node.whenFalse);
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}
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else if (tsutils_1.isBinaryExpression(node)) {
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switch (node.operatorToken.kind) {
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case ts.SyntaxKind.CommaToken:
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if (isIndirectEval(node)) {
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return false;
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}
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return both(node.left, node.right);
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case ts.SyntaxKind.AmpersandAmpersandToken:
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case ts.SyntaxKind.BarBarToken:
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if (allowFastNullChecks) {
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noCheck(node.left, cb);
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return cb(node.right);
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}
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}
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}
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noCheck(node, forEachChild);
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return isUnusedExpression(node, ctx.options);
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}
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if (tsutils_1.isExpressionStatement(node)) {
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allowFastNullChecks = ctx.options.allowFastNullChecks;
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if (!isDirective(node)) {
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check(node.expression, node);
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}
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allowFastNullChecks = true;
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return false;
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}
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else if (tsutils_1.isVoidExpression(node)) {
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// allow `void 0` and `void(0)`
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if (!isLiteralZero(tsutils_1.isParenthesizedExpression(node.expression) ? node.expression.expression : node.expression)) {
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check(node.expression);
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}
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return false;
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}
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else if (tsutils_1.isBinaryExpression(node) && node.operatorToken.kind === ts.SyntaxKind.CommaToken && !isIndirectEval(node)) {
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check(node.left);
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return cb(node.right);
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}
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return ts.forEachChild(node, cb);
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}
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function forEachChild(node) {
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return ts.forEachChild(node, cb);
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}
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function check(node, failNode) {
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checking = true;
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if (cb(node)) {
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ctx.addFailureAtNode(failNode === undefined ? node : failNode, Rule.FAILURE_STRING);
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}
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checking = false;
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}
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function noCheck(node, callback) {
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var old = allowFastNullChecks;
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checking = false;
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allowFastNullChecks = true;
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callback(node);
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allowFastNullChecks = old;
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checking = true;
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}
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function both(one, two) {
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if (cb(one)) {
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if (cb(two)) {
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return true;
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}
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else {
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ctx.addFailureAtNode(one, Rule.FAILURE_STRING);
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}
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}
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else if (cb(two)) {
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ctx.addFailureAtNode(two, Rule.FAILURE_STRING);
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}
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return false;
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}
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}
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function isUnusedExpression(node, options) {
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switch (node.kind) {
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case ts.SyntaxKind.CallExpression:
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case ts.SyntaxKind.YieldExpression:
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case ts.SyntaxKind.DeleteExpression:
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case ts.SyntaxKind.AwaitExpression:
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case ts.SyntaxKind.PostfixUnaryExpression:
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return false;
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case ts.SyntaxKind.NewExpression:
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return !options.allowNew;
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case ts.SyntaxKind.TaggedTemplateExpression:
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return !options.allowTaggedTemplate;
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case ts.SyntaxKind.BinaryExpression:
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return !tsutils_1.isAssignmentKind(node.operatorToken.kind);
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case ts.SyntaxKind.PrefixUnaryExpression:
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return node.operator !== ts.SyntaxKind.PlusPlusToken &&
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node.operator !== ts.SyntaxKind.MinusMinusToken;
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default:
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return true;
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}
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}
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function isLiteralZero(node) {
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return tsutils_1.isNumericLiteral(node) && node.text === "0";
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}
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function isIndirectEval(node) {
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return tsutils_1.isIdentifier(node.right) && node.right.text === "eval" &&
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isLiteralZero(node.left) &&
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node.parent.kind === ts.SyntaxKind.ParenthesizedExpression &&
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node.parent.parent.kind === ts.SyntaxKind.CallExpression;
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}
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function isDirective(node) {
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if (node.expression.kind !== ts.SyntaxKind.StringLiteral || !canContainDirective(node.parent)) {
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return false;
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}
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var parent = node.parent;
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// check if all previous statements in block are also directives
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for (var i = parent.statements.indexOf(node) - 1; i >= 0; --i) {
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var statement = parent.statements[i];
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if (!tsutils_1.isExpressionStatement(statement) || statement.expression.kind !== ts.SyntaxKind.StringLiteral) {
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return false;
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}
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}
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return true;
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}
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function canContainDirective(node) {
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switch (node.kind) {
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case ts.SyntaxKind.SourceFile:
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case ts.SyntaxKind.ModuleBlock:
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return true;
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case ts.SyntaxKind.Block:
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switch (node.parent.kind) {
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case ts.SyntaxKind.ArrowFunction:
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case ts.SyntaxKind.FunctionExpression:
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case ts.SyntaxKind.FunctionDeclaration:
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case ts.SyntaxKind.MethodDeclaration:
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case ts.SyntaxKind.Constructor:
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case ts.SyntaxKind.GetAccessor:
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case ts.SyntaxKind.SetAccessor:
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return true;
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default:
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return false;
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}
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default:
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return false;
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}
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}
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var _a, _b, _c;
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