noRedundantJsdocRule.ts

/**
 * @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.
 */

import { canHaveJsDoc, getJsDoc } from "tsutils";
import * as ts from "typescript";

import * as Lint from "../index";

export class Rule extends Lint.Rules.AbstractRule {
    /* tslint:disable:object-literal-sort-keys */
    public static metadata: Lint.IRuleMetadata = {
        ruleName: "no-redundant-jsdoc",
        description: "Forbids JSDoc which duplicates TypeScript functionality.",
        optionsDescription: "Not configurable.",
        options: null,
        optionExamples: [true],
        type: "style",
        typescriptOnly: true,
    };
    /* tslint:enable:object-literal-sort-keys */

    public static FAILURE_STRING_REDUNDANT_TYPE =
        "Type annotation in JSDoc is redundant in TypeScript code.";
    public static FAILURE_STRING_REDUNDANT_TAG(tagName: string): string {
        return `JSDoc tag '@${tagName}' is redundant in TypeScript code.`;
    }
    public static FAILURE_STRING_NO_COMMENT(tagName: string): string {
        return `'@${tagName}' is redundant in TypeScript code if it has no description.`;
    }

    public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
        return this.applyWithFunction(sourceFile, walk);
    }
}

function walk(ctx: Lint.WalkContext): void {
    const { sourceFile } = ctx;
    // Intentionally exclude EndOfFileToken: it can have JSDoc, but it is only relevant in JavaScript files
    return sourceFile.statements.forEach(function cb(node: ts.Node): void {
        if (canHaveJsDoc(node)) {
            for (const { tags } of getJsDoc(node, sourceFile)) {
                if (tags !== undefined) {
                    for (const tag of tags) {
                        checkTag(tag);
                    }
                }
            }
        }
        return ts.forEachChild(node, cb);
    });

    function checkTag(tag: ts.JSDocTag): void {
        switch (tag.kind) {
            case ts.SyntaxKind.JSDocTag:
                if (redundantTags.has(tag.tagName.text)) {
                    ctx.addFailureAtNode(
                        tag.tagName,
                        Rule.FAILURE_STRING_REDUNDANT_TAG(tag.tagName.text),
                    );
                }
                break;
            case ts.SyntaxKind.JSDocDeprecatedTag:
            case ts.SyntaxKind.JSDocAugmentsTag:
            case ts.SyntaxKind.JSDocAuthorTag:
                // OK
                break;

            case ts.SyntaxKind.JSDocClassTag:
            case ts.SyntaxKind.JSDocThisTag:
            case ts.SyntaxKind.JSDocTypeTag:
            case ts.SyntaxKind.JSDocTypedefTag:
            case ts.SyntaxKind.JSDocPropertyTag:
                // Always redundant
                ctx.addFailureAtNode(
                    tag.tagName,
                    Rule.FAILURE_STRING_REDUNDANT_TAG(tag.tagName.text),
                );
                break;

            case ts.SyntaxKind.JSDocTemplateTag:
                if (
                    (tag as ts.JSDocTemplateTag).comment === undefined ||
                    (tag as ts.JSDocTemplateTag).comment === ""
                ) {
                    ctx.addFailureAtNode(
                        tag.tagName,
                        Rule.FAILURE_STRING_NO_COMMENT(tag.tagName.text),
                    );
                }
                break;

            case ts.SyntaxKind.JSDocReturnTag:
            case ts.SyntaxKind.JSDocParameterTag: {
                const { typeExpression, comment } = tag as ts.JSDocReturnTag | ts.JSDocParameterTag;
                if (typeExpression !== undefined) {
                    ctx.addFailureAtNode(typeExpression, Rule.FAILURE_STRING_REDUNDANT_TYPE);
                }
                if (comment === undefined || comment === "") {
                    // Redundant if no documentation
                    ctx.addFailureAtNode(
                        tag.tagName,
                        Rule.FAILURE_STRING_NO_COMMENT(tag.tagName.text),
                    );
                }
                break;
            }

            default:
                throw new Error(`Unexpected tag kind: ${ts.SyntaxKind[tag.kind]}`);
        }
    }
}

const redundantTags = new Set([
    "abstract",
    "access",
    "class",
    "constant",
    "constructs",
    "default",
    "enum",
    "exports",
    "function",
    "global",
    "implements",
    "interface",
    "instance",
    "member",
    "memberof",
    "mixes",
    "mixin",
    "module",
    "name",
    "namespace",
    "override",
    "private",
    "property",
    "protected",
    "public",
    "readonly",
    "requires",
    "static",
    "this",
]);