tslint-microsoft-contrib
Version:
TSLint Rules for Microsoft
102 lines • 4.41 kB
JavaScript
;
var __extends = (this && this.__extends) || (function () {
var extendStatics = function (d, b) {
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 extendStatics(d, b);
}
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("tslint");
var tsutils = require("tsutils");
var FAILURE_STRING = 'Unnecessary local variable: ';
var Rule = (function (_super) {
__extends(Rule, _super);
function Rule() {
return _super !== null && _super.apply(this, arguments) || this;
}
Rule.prototype.apply = function (sourceFile) {
return this.applyWithFunction(sourceFile, walk);
};
Rule.metadata = {
ruleName: 'no-unnecessary-local-variable',
type: 'maintainability',
description: 'Do not declare a variable only to return it from the function on the next line.',
options: null,
optionsDescription: '',
typescriptOnly: true,
issueClass: 'Non-SDL',
issueType: 'Warning',
severity: 'Low',
level: 'Opportunity for Excellence',
group: 'Clarity',
commonWeaknessEnumeration: '563, 710'
};
return Rule;
}(Lint.Rules.AbstractRule));
exports.Rule = Rule;
function walk(ctx) {
var variableUsages = tsutils.collectVariableUsage(ctx.sourceFile);
function validateStatementArray(statements) {
if (statements === undefined || statements.length < 2) {
return;
}
var lastStatement = statements[statements.length - 1];
var nextToLastStatement = statements[statements.length - 2];
var returnedVariableName = tryToGetReturnedVariableName(lastStatement);
var declaredVariableIdentifier = tryToGetDeclaredVariable(nextToLastStatement);
if (declaredVariableIdentifier === undefined) {
return;
}
var declaredVariableName = declaredVariableIdentifier.text;
if (returnedVariableName !== undefined &&
declaredVariableName !== undefined &&
returnedVariableName === declaredVariableName &&
variableIsOnlyUsedOnce(declaredVariableIdentifier)) {
ctx.addFailureAt(nextToLastStatement.getStart(), nextToLastStatement.getWidth(), FAILURE_STRING + returnedVariableName);
}
}
function tryToGetDeclaredVariable(statement) {
if (statement !== undefined && tsutils.isVariableStatement(statement)) {
if (statement.declarationList.declarations.length === 1) {
var declaration = statement.declarationList.declarations[0];
if (declaration.name && tsutils.isIdentifier(declaration.name)) {
return declaration.name;
}
}
}
return undefined;
}
function tryToGetReturnedVariableName(statement) {
if (statement !== undefined && tsutils.isReturnStatement(statement)) {
if (statement.expression && tsutils.isIdentifier(statement.expression)) {
return statement.expression.text;
}
}
return undefined;
}
function variableIsOnlyUsedOnce(declaredVariableIdentifier) {
var usage = variableUsages.get(declaredVariableIdentifier);
return usage !== undefined && usage.uses.length === 1;
}
function cb(node) {
if (tsutils.isBlock(node) || tsutils.isSourceFile(node) || tsutils.isCaseClause(node) || tsutils.isDefaultClause(node)) {
validateStatementArray(node.statements);
}
if (tsutils.isModuleDeclaration(node)) {
if (node.body && tsutils.isModuleBlock(node.body)) {
validateStatementArray(node.body.statements);
}
}
return ts.forEachChild(node, cb);
}
return ts.forEachChild(ctx.sourceFile, cb);
}
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