no-unnecessary-type-arguments.js
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"use strict";
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
Object.defineProperty(o, k2, { enumerable: true, get: function() { return m[k]; } });
}) : (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
o[k2] = m[k];
}));
var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
o["default"] = v;
});
var __importStar = (this && this.__importStar) || function (mod) {
if (mod && mod.__esModule) return mod;
var result = {};
if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
__setModuleDefault(result, mod);
return result;
};
Object.defineProperty(exports, "__esModule", { value: true });
const tsutils = __importStar(require("tsutils"));
const ts = __importStar(require("typescript"));
const util = __importStar(require("../util"));
const util_1 = require("../util");
exports.default = util.createRule({
name: 'no-unnecessary-type-arguments',
meta: {
docs: {
description: 'Enforces that type arguments will not be used if not required',
category: 'Best Practices',
recommended: false,
requiresTypeChecking: true,
},
fixable: 'code',
messages: {
unnecessaryTypeParameter: 'This is the default value for this type parameter, so it can be omitted.',
},
schema: [],
type: 'suggestion',
},
defaultOptions: [],
create(context) {
const parserServices = util.getParserServices(context);
const checker = parserServices.program.getTypeChecker();
const sourceCode = context.getSourceCode();
function checkTSArgsAndParameters(esParameters, typeParameters) {
// Just check the last one. Must specify previous type parameters if the last one is specified.
const i = esParameters.params.length - 1;
const arg = esParameters.params[i];
const param = typeParameters[i];
// TODO: would like checker.areTypesEquivalent. https://github.com/Microsoft/TypeScript/issues/13502
if (!(param === null || param === void 0 ? void 0 : param.default) ||
param.default.getText() !== sourceCode.getText(arg)) {
return;
}
context.report({
node: arg,
messageId: 'unnecessaryTypeParameter',
fix: fixer => fixer.removeRange(i === 0
? esParameters.range
: [esParameters.params[i - 1].range[1], arg.range[1]]),
});
}
return {
TSTypeParameterInstantiation(node) {
const expression = parserServices.esTreeNodeToTSNodeMap.get(node);
const typeParameters = getTypeParametersFromNode(expression, checker);
if (typeParameters) {
checkTSArgsAndParameters(node, typeParameters);
}
},
};
},
});
function getTypeParametersFromNode(node, checker) {
if (ts.isExpressionWithTypeArguments(node)) {
return getTypeParametersFromType(node.expression, checker);
}
if (ts.isTypeReferenceNode(node)) {
return getTypeParametersFromType(node.typeName, checker);
}
if (ts.isCallExpression(node) || ts.isNewExpression(node)) {
return getTypeParametersFromCall(node, checker);
}
return undefined;
}
function getTypeParametersFromType(type, checker) {
const symAtLocation = checker.getSymbolAtLocation(type);
if (!symAtLocation) {
return undefined;
}
const sym = getAliasedSymbol(symAtLocation, checker);
const declarations = sym.getDeclarations();
if (!declarations) {
return undefined;
}
return util_1.findFirstResult(declarations, decl => tsutils.isClassLikeDeclaration(decl) ||
ts.isTypeAliasDeclaration(decl) ||
ts.isInterfaceDeclaration(decl)
? decl.typeParameters
: undefined);
}
function getTypeParametersFromCall(node, checker) {
const sig = checker.getResolvedSignature(node);
const sigDecl = sig === null || sig === void 0 ? void 0 : sig.getDeclaration();
if (!sigDecl) {
return ts.isNewExpression(node)
? getTypeParametersFromType(node.expression, checker)
: undefined;
}
return sigDecl.typeParameters;
}
function getAliasedSymbol(symbol, checker) {
return tsutils.isSymbolFlagSet(symbol, ts.SymbolFlags.Alias)
? checker.getAliasedSymbol(symbol)
: symbol;
}
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