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View File Name : returnUndefinedRule.js

"use strict";
/**
 * @license
 * Copyright 2017 Palantir Technologies, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.Rule = void 0;
var tslib_1 = require("tslib");
var tsutils_1 = require("tsutils");
var ts = require("typescript");
var Lint = require("../index");
var Rule = /** @class */ (function (_super) {
    tslib_1.__extends(Rule, _super);
    function Rule() {
        return _super !== null && _super.apply(this, arguments) || this;
    }
    Rule.prototype.applyWithProgram = function (sourceFile, program) {
        return this.applyWithFunction(sourceFile, walk, undefined, program.getTypeChecker());
    };
    /* tslint:disable:object-literal-sort-keys */
    Rule.metadata = {
        ruleName: "return-undefined",
        description: "Prefer `return;` in void functions and `return undefined;` in value-returning functions.",
        optionsDescription: "Not configurable.",
        options: null,
        optionExamples: [true],
        type: "style",
        typescriptOnly: false,
        requiresTypeInfo: true,
    };
    /* tslint:enable:object-literal-sort-keys */
    Rule.FAILURE_STRING_VALUE_RETURN = "Value-returning function should use `return undefined;`, not just `return;`.";
    Rule.FAILURE_STRING_VOID_RETURN = "`void` function should use `return;`, not `return undefined;`.";
    return Rule;
}(Lint.Rules.TypedRule));
exports.Rule = Rule;
function walk(ctx, checker) {
    return ts.forEachChild(ctx.sourceFile, function cb(node) {
        if (tsutils_1.isReturnStatement(node)) {
            check(node);
        }
        return ts.forEachChild(node, cb);
    });
    function check(node) {
        var actualReturnKind = getReturnKindFromReturnStatement(node);
        if (actualReturnKind === undefined) {
            return;
        }
        var functionReturningFrom = Lint.ancestorWhere(node, isFunctionLike);
        if (functionReturningFrom === undefined) {
            // Return outside of function is invalid
            return;
        }
        var returnKindFromType = getReturnKindFromFunction(functionReturningFrom);
        if (returnKindFromType !== undefined && returnKindFromType !== actualReturnKind) {
            ctx.addFailureAtNode(node, returnKindFromType === "void" /* Void */
                ? Rule.FAILURE_STRING_VOID_RETURN
                : Rule.FAILURE_STRING_VALUE_RETURN);
        }
    }
    function getReturnKindFromFunction(node) {
        switch (node.kind) {
            case ts.SyntaxKind.Constructor:
            case ts.SyntaxKind.SetAccessor:
                return "void" /* Void */;
            case ts.SyntaxKind.GetAccessor:
                return "value" /* Value */;
        }
        // Handle generator functions/methods:
        if (node.asteriskToken !== undefined) {
            return "void" /* Void */;
        }
        var contextual = isFunctionExpressionLike(node) && node.type === undefined
            ? tryGetReturnType(checker.getContextualType(node), checker)
            : undefined;
        var returnType = contextual !== undefined
            ? contextual
            : tryGetReturnType(checker.getTypeAtLocation(node), checker);
        if (returnType === undefined || tsutils_1.isTypeFlagSet(returnType, ts.TypeFlags.Any)) {
            return undefined;
        }
        var effectivelyVoidChecker = tsutils_1.hasModifier(node.modifiers, ts.SyntaxKind.AsyncKeyword)
            ? isEffectivelyVoidPromise
            : isEffectivelyVoid;
        if (effectivelyVoidChecker(returnType)) {
            return "void" /* Void */;
        }
        return "value" /* Value */;
    }
    /** True for `void`, `undefined`, Promise<void>, or `void | undefined | Promise<void>`. */
    function isEffectivelyVoidPromise(type) {
        // Would need access to `checker.getPromisedTypeOfPromise` to do this properly.
        // Assume that the return type is the global Promise (since this is an async function) and get its type argument.
        if (
        // tslint:disable-next-line:no-bitwise
        tsutils_1.isTypeFlagSet(type, ts.TypeFlags.Void | ts.TypeFlags.Undefined) ||
            (tsutils_1.isUnionType(type) && type.types.every(isEffectivelyVoidPromise))) {
            return true;
        }
        var typeArguments = getTypeArgumentsOfType(type);
        return (typeArguments !== undefined &&
            typeArguments.length === 1 &&
            isEffectivelyVoidPromise(typeArguments[0]));
    }
    function getTypeArgumentsOfType(type) {
        if (!tsutils_1.isTypeReference(type)) {
            return undefined;
        }
        // tslint:disable:no-unsafe-any
        // Fixes for https://github.com/palantir/tslint/issues/4863
        // type.typeArguments was replaced with checker.getTypeArguments:
        // https://github.com/microsoft/TypeScript/commit/250d5a8229e17342f36fe52545bb68140db96a2e
        if (checker.getTypeArguments) {
            return checker.getTypeArguments(type);
        }
        return type.typeArguments;
        // tslint:enable:no-unsafe-any
    }
}
function getReturnKindFromReturnStatement(node) {
    if (node.expression === undefined) {
        return "void" /* Void */;
    }
    else if (tsutils_1.isIdentifier(node.expression) && node.expression.text === "undefined") {
        return "value" /* Value */;
    }
    else {
        return undefined;
    }
}
/** True for `void`, `undefined`, or `void | undefined`. */
function isEffectivelyVoid(type) {
    return (
    // tslint:disable-next-line:no-bitwise
    tsutils_1.isTypeFlagSet(type, ts.TypeFlags.Void | ts.TypeFlags.Undefined) ||
        (tsutils_1.isUnionType(type) && type.types.every(isEffectivelyVoid)));
}
function tryGetReturnType(fnType, checker) {
    if (fnType === undefined) {
        return undefined;
    }
    var sigs = checker.getSignaturesOfType(fnType, ts.SignatureKind.Call);
    if (sigs.length !== 1) {
        return undefined;
    }
    return checker.getReturnTypeOfSignature(sigs[0]);
}
function isFunctionLike(node) {
    switch (node.kind) {
        case ts.SyntaxKind.FunctionDeclaration:
        case ts.SyntaxKind.FunctionExpression:
        case ts.SyntaxKind.ArrowFunction:
        case ts.SyntaxKind.MethodDeclaration:
        case ts.SyntaxKind.Constructor:
        case ts.SyntaxKind.GetAccessor:
        case ts.SyntaxKind.SetAccessor:
            return true;
        default:
            return false;
    }
}
function isFunctionExpressionLike(node) {
    return (node.kind === ts.SyntaxKind.FunctionExpression || node.kind === ts.SyntaxKind.ArrowFunction);
}