commentFormatRule.ts

/**
 * @license
 * Copyright 2013 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 * as utils from "tsutils";
import * as ts from "typescript";

import { ENABLE_DISABLE_REGEX } from "../enableDisableRules";
import * as Lint from "../index";
import { escapeRegExp, isLowerCase, isUpperCase } from "../utils";

interface IExceptionsObject {
    "ignore-words"?: string[];
    "ignore-pattern"?: string;
}

interface Options {
    space: boolean;
    case: Case;
    exceptions?: RegExp;
    failureSuffix: string;
}

const enum Case {
    None,
    Lower,
    Upper,
}

const OPTION_SPACE = "check-space";
const OPTION_LOWERCASE = "check-lowercase";
const OPTION_UPPERCASE = "check-uppercase";

export class Rule extends Lint.Rules.AbstractRule {
    /* tslint:disable:object-literal-sort-keys */
    public static metadata: Lint.IRuleMetadata = {
        ruleName: "comment-format",
        description: "Enforces formatting rules for single-line comments.",
        rationale: "Helps maintain a consistent, readable style in your codebase.",
        optionsDescription: Lint.Utils.dedent`
            Three arguments may be optionally provided:

            * \`"check-space"\` requires that all single-line comments must begin with a space, as in \`// comment\`
                * note that for comments starting with multiple slashes, e.g. \`///\`, leading slashes are ignored
                * TypeScript reference comments are ignored completely
            * \`"check-lowercase"\` requires that the first non-whitespace character of a comment must be lowercase, if applicable.
            * \`"check-uppercase"\` requires that the first non-whitespace character of a comment must be uppercase, if applicable.

            Exceptions to \`"check-lowercase"\` or \`"check-uppercase"\` can be managed with object that may be passed as last argument.

            One of two options can be provided in this object:

                * \`"ignore-words"\`  - array of strings - words that will be ignored at the beginning of the comment.
                * \`"ignore-pattern"\` - string - RegExp pattern that will be ignored at the beginning of the comment.
            `,
        options: {
            type: "array",
            items: {
                anyOf: [
                    {
                        type: "string",
                        enum: ["check-space", "check-lowercase", "check-uppercase"],
                    },
                    {
                        type: "object",
                        properties: {
                            "ignore-words": {
                                type: "array",
                                items: {
                                    type: "string",
                                },
                            },
                            "ignore-pattern": {
                                type: "string",
                            },
                        },
                        minProperties: 1,
                        maxProperties: 1,
                    },
                ],
            },
            minLength: 1,
            maxLength: 4,
        },
        optionExamples: [
            [true, "check-space", "check-uppercase"],
            [true, "check-lowercase", { "ignore-words": ["TODO", "HACK"] }],
            [true, "check-lowercase", { "ignore-pattern": "STD\\w{2,3}\\b" }],
        ],
        type: "style",
        typescriptOnly: false,
        hasFix: true,
    };
    /* tslint:enable:object-literal-sort-keys */

    public static LOWERCASE_FAILURE = "comment must start with lowercase letter";
    public static UPPERCASE_FAILURE = "comment must start with uppercase letter";
    public static LEADING_SPACE_FAILURE = "comment must start with a space";
    public static IGNORE_WORDS_FAILURE_FACTORY = (words: string[]): string =>
        ` or the word(s): ${words.join(", ")}`;
    public static IGNORE_PATTERN_FAILURE_FACTORY = (pattern: string): string =>
        ` or its start must match the regex pattern "${pattern}"`;

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

function parseOptions(options: Array<string | IExceptionsObject>): Options {
    return {
        case:
            options.indexOf(OPTION_LOWERCASE) !== -1
                ? Case.Lower
                : options.indexOf(OPTION_UPPERCASE) !== -1
                ? Case.Upper
                : Case.None,
        failureSuffix: "",
        space: options.indexOf(OPTION_SPACE) !== -1,
        ...composeExceptions(options[options.length - 1]),
    };
}

function composeExceptions(
    option?: string | IExceptionsObject,
): undefined | { exceptions: RegExp; failureSuffix: string } {
    if (typeof option !== "object") {
        return undefined;
    }
    const ignorePattern = option["ignore-pattern"];
    if (ignorePattern !== undefined) {
        return {
            exceptions: new RegExp(`^\\s*(${ignorePattern})`),
            failureSuffix: Rule.IGNORE_PATTERN_FAILURE_FACTORY(ignorePattern),
        };
    }

    const ignoreWords = option["ignore-words"];
    if (ignoreWords !== undefined && ignoreWords.length !== 0) {
        return {
            exceptions: new RegExp(
                `^\\s*(?:${ignoreWords.map(word => escapeRegExp(word.trim())).join("|")})\\b`,
            ),
            failureSuffix: Rule.IGNORE_WORDS_FAILURE_FACTORY(ignoreWords),
        };
    }
    return undefined;
}

function walk(ctx: Lint.WalkContext<Options>) {
    utils.forEachComment(ctx.sourceFile, (fullText, { kind, pos, end }) => {
        let start = pos + 2;
        if (
            kind !== ts.SyntaxKind.SingleLineCommentTrivia ||
            // exclude empty comments
            start === end ||
            // exclude /// <reference path="...">
            (fullText[start] === "/" &&
                ctx.sourceFile.referencedFiles.some(ref => ref.pos >= pos && ref.end <= end))
        ) {
            return;
        }
        // skip all leading slashes
        while (fullText[start] === "/") {
            ++start;
        }
        if (start === end) {
            return;
        }
        const commentText = fullText.slice(start, end);
        // whitelist //#region and //#endregion and JetBrains IDEs' "//noinspection ...", "//region", "//endregion"
        if (/^(?:#?(?:end)?region|noinspection\s)/.test(commentText)) {
            return;
        }

        if (ctx.options.space && commentText[0] !== " ") {
            ctx.addFailure(start, end, Rule.LEADING_SPACE_FAILURE, [
                Lint.Replacement.appendText(start, " "),
            ]);
        }

        if (
            ctx.options.case === Case.None ||
            (ctx.options.exceptions !== undefined && ctx.options.exceptions.test(commentText)) ||
            ENABLE_DISABLE_REGEX.test(commentText)
        ) {
            return;
        }

        // search for first non-space character to check if lower or upper
        const charPos = commentText.search(/\S/);
        if (charPos === -1) {
            return;
        }
        if (ctx.options.case === Case.Lower) {
            if (!isLowerCase(commentText[charPos])) {
                ctx.addFailure(start, end, Rule.LOWERCASE_FAILURE + ctx.options.failureSuffix);
            }
        } else if (!isUpperCase(commentText[charPos])) {
            ctx.addFailure(start, end, Rule.UPPERCASE_FAILURE + ctx.options.failureSuffix);
        }
    });
}