1 | "use strict";
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2 | var __extends = (this && this.__extends) || (function () {
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3 | var extendStatics = function (d, b) {
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4 | extendStatics = Object.setPrototypeOf ||
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5 | ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
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6 | function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
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7 | return extendStatics(d, b);
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8 | }
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9 | return function (d, b) {
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10 | extendStatics(d, b);
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11 | function __() { this.constructor = d; }
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12 | d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
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13 | };
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14 | })();
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15 | Object.defineProperty(exports, "__esModule", { value: true });
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16 | var ts = require("typescript");
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17 | var Lint = require("tslint");
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18 | var tsutils = require("tsutils");
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19 | var FAILURE_STRING = 'Unnecessary local variable: ';
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20 | var Rule = (function (_super) {
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21 | __extends(Rule, _super);
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22 | function Rule() {
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23 | return _super !== null && _super.apply(this, arguments) || this;
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24 | }
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25 | Rule.prototype.apply = function (sourceFile) {
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26 | return this.applyWithFunction(sourceFile, walk);
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27 | };
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28 | Rule.metadata = {
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29 | ruleName: 'no-unnecessary-local-variable',
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30 | type: 'maintainability',
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31 | description: 'Do not declare a variable only to return it from the function on the next line.',
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32 | options: null,
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33 | optionsDescription: '',
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34 | typescriptOnly: true,
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35 | issueClass: 'Non-SDL',
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36 | issueType: 'Warning',
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37 | severity: 'Low',
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38 | level: 'Opportunity for Excellence',
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39 | group: 'Clarity',
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40 | commonWeaknessEnumeration: '563, 710'
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41 | };
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42 | return Rule;
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43 | }(Lint.Rules.AbstractRule));
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44 | exports.Rule = Rule;
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45 | function walk(ctx) {
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46 | var variableUsages = tsutils.collectVariableUsage(ctx.sourceFile);
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47 | function validateStatementArray(statements) {
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48 | if (statements === undefined || statements.length < 2) {
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49 | return;
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50 | }
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51 | var lastStatement = statements[statements.length - 1];
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52 | var nextToLastStatement = statements[statements.length - 2];
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53 | var returnedVariableName = tryToGetReturnedVariableName(lastStatement);
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54 | var declaredVariableIdentifier = tryToGetDeclaredVariable(nextToLastStatement);
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55 | if (declaredVariableIdentifier === undefined) {
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56 | return;
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57 | }
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58 | var declaredVariableName = declaredVariableIdentifier.text;
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59 | if (returnedVariableName !== undefined &&
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60 | declaredVariableName !== undefined &&
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61 | returnedVariableName === declaredVariableName &&
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62 | variableIsOnlyUsedOnce(declaredVariableIdentifier)) {
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63 | ctx.addFailureAt(nextToLastStatement.getStart(), nextToLastStatement.getWidth(), FAILURE_STRING + returnedVariableName);
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64 | }
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65 | }
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66 | function tryToGetDeclaredVariable(statement) {
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67 | if (statement !== undefined && tsutils.isVariableStatement(statement)) {
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68 | if (statement.declarationList.declarations.length === 1) {
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69 | var declaration = statement.declarationList.declarations[0];
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70 | if (declaration.name && tsutils.isIdentifier(declaration.name)) {
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71 | return declaration.name;
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72 | }
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73 | }
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74 | }
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75 | return undefined;
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76 | }
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77 | function tryToGetReturnedVariableName(statement) {
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78 | if (statement !== undefined && tsutils.isReturnStatement(statement)) {
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79 | if (statement.expression && tsutils.isIdentifier(statement.expression)) {
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80 | return statement.expression.text;
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81 | }
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82 | }
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83 | return undefined;
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84 | }
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85 | function variableIsOnlyUsedOnce(declaredVariableIdentifier) {
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86 | var usage = variableUsages.get(declaredVariableIdentifier);
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87 | return usage !== undefined && usage.uses.length === 1;
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88 | }
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89 | function cb(node) {
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90 | if (tsutils.isBlock(node) || tsutils.isSourceFile(node) || tsutils.isCaseClause(node) || tsutils.isDefaultClause(node)) {
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91 | validateStatementArray(node.statements);
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92 | }
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93 | if (tsutils.isModuleDeclaration(node)) {
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94 | if (node.body && tsutils.isModuleBlock(node.body)) {
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95 | validateStatementArray(node.body.statements);
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96 | }
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97 | }
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98 | return ts.forEachChild(node, cb);
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99 | }
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100 | return ts.forEachChild(ctx.sourceFile, cb);
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101 | }
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102 |
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