prefer-reduce-type-parameter.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 experimental_utils_1 = require("@typescript-eslint/experimental-utils");
const util = __importStar(require("../util"));
const getMemberExpressionName = (member) => {
if (!member.computed) {
return member.property.name;
}
if (member.property.type === experimental_utils_1.AST_NODE_TYPES.Literal &&
typeof member.property.value === 'string') {
return member.property.value;
}
return null;
};
exports.default = util.createRule({
name: 'prefer-reduce-type-parameter',
meta: {
type: 'problem',
docs: {
category: 'Best Practices',
recommended: false,
description: 'Prefer using type parameter when calling `Array#reduce` instead of casting',
requiresTypeChecking: true,
},
messages: {
preferTypeParameter: 'Unnecessary cast: Array#reduce accepts a type parameter for the default value.',
},
fixable: 'code',
schema: [],
},
defaultOptions: [],
create(context) {
const service = util.getParserServices(context);
const checker = service.program.getTypeChecker();
return {
'CallExpression > MemberExpression.callee'(callee) {
if (getMemberExpressionName(callee) !== 'reduce') {
return;
}
const [, secondArg] = callee.parent.arguments;
if (callee.parent.arguments.length < 2 ||
!util.isTypeAssertion(secondArg)) {
return;
}
// Get the symbol of the `reduce` method.
const tsNode = service.esTreeNodeToTSNodeMap.get(callee.object);
const calleeObjType = util.getConstrainedTypeAtLocation(checker, tsNode);
// Check the owner type of the `reduce` method.
if (checker.isArrayType(calleeObjType)) {
context.report({
messageId: 'preferTypeParameter',
node: secondArg,
fix: fixer => [
fixer.removeRange([
secondArg.range[0],
secondArg.expression.range[0],
]),
fixer.removeRange([
secondArg.expression.range[1],
secondArg.range[1],
]),
fixer.insertTextAfter(callee, `<${context
.getSourceCode()
.getText(secondArg.typeAnnotation)}>`),
],
});
return;
}
},
};
},
});
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