CommentPlugin.ts

import * as ts from "typescript";

import { Comment, CommentTag } from "../../models/comments/index";
import {
    Reflection,
    ReflectionFlag,
    ReflectionKind,
    TypeParameterReflection,
    DeclarationReflection,
    SignatureReflection,
    ParameterReflection,
} from "../../models/reflections/index";
import { Component, ConverterComponent } from "../components";
import {
    parseComment,
    getRawComment,
    getJsDocCommentText,
} from "../factories/comment";
import { Converter } from "../converter";
import type { Context } from "../context";
import { ReflectionType, SourceReference } from "../../models";
import {
    BindOption,
    filterMap,
    removeIfPresent,
    unique,
    partition,
} from "../../utils";

/**
 * These tags are not useful to display in the generated documentation.
 * They should be ignored when parsing comments. Any relevant type information
 * (for JS users) will be consumed by TypeScript and need not be preserved
 * in the comment.
 *
 * Note that param/arg/argument/return/returns are not present.
 * These tags will have their type information stripped when parsing, but still
 * provide useful information for documentation.
 */
const TAG_BLACKLIST = [
    "augments",
    "callback",
    "class",
    "constructor",
    "enum",
    "extends",
    "this",
    "type",
    "typedef",
];

/**
 * A handler that parses TypeDoc comments and attaches {@link Comment} instances to
 * the generated reflections.
 */
@Component({ name: "comment" })
export class CommentPlugin extends ConverterComponent {
    @BindOption("excludeTags")
    excludeTags!: string[];

    /**
     * Create a new CommentPlugin instance.
     */
    override initialize() {
        this.listenTo(this.owner, {
            [Converter.EVENT_CREATE_DECLARATION]: this.onDeclaration,
            [Converter.EVENT_CREATE_SIGNATURE]: this.onDeclaration,
            [Converter.EVENT_CREATE_TYPE_PARAMETER]: this.onCreateTypeParameter,
            [Converter.EVENT_RESOLVE_BEGIN]: this.onBeginResolve,
            [Converter.EVENT_RESOLVE]: this.onResolve,
        });
    }

    /**
     * Apply all comment tag modifiers to the given reflection.
     *
     * @param reflection  The reflection the modifiers should be applied to.
     * @param comment  The comment that should be searched for modifiers.
     */
    private applyModifiers(reflection: Reflection, comment: Comment) {
        if (comment.hasTag("private")) {
            reflection.setFlag(ReflectionFlag.Private);
            if (reflection.kindOf(ReflectionKind.CallSignature)) {
                reflection.parent?.setFlag(ReflectionFlag.Private);
            }
            comment.removeTags("private");
        }

        if (comment.hasTag("protected")) {
            reflection.setFlag(ReflectionFlag.Protected);
            if (reflection.kindOf(ReflectionKind.CallSignature)) {
                reflection.parent?.setFlag(ReflectionFlag.Protected);
            }
            comment.removeTags("protected");
        }

        if (comment.hasTag("public")) {
            reflection.setFlag(ReflectionFlag.Public);
            if (reflection.kindOf(ReflectionKind.CallSignature)) {
                reflection.parent?.setFlag(ReflectionFlag.Public);
            }
            comment.removeTags("public");
        }

        if (comment.hasTag("event")) {
            if (reflection.kindOf(ReflectionKind.CallSignature)) {
                if (reflection.parent) {
                    reflection.parent.kind = ReflectionKind.Event;
                }
            }
            reflection.kind = ReflectionKind.Event;
            comment.removeTags("event");
        }

        if (
            reflection.kindOf(
                ReflectionKind.Module | ReflectionKind.Namespace
            ) ||
            reflection.kind === ReflectionKind.Project
        ) {
            comment.removeTags("module");
            comment.removeTags("packagedocumentation");
        }
    }

    /**
     * Triggered when the converter has created a type parameter reflection.
     *
     * @param context  The context object describing the current state the converter is in.
     * @param reflection  The reflection that is currently processed.
     */
    private onCreateTypeParameter(
        _context: Context,
        reflection: TypeParameterReflection,
        node?: ts.Node
    ) {
        if (node && ts.isJSDocTemplateTag(node.parent)) {
            const comment = getJsDocCommentText(node.parent.comment);
            if (comment) {
                reflection.comment = new Comment(comment);
            }
        }

        const comment = reflection.parent && reflection.parent.comment;
        if (comment) {
            let tag = comment.getTag("typeparam", reflection.name);
            if (!tag) {
                tag = comment.getTag("template", reflection.name);
            }
            if (!tag) {
                tag = comment.getTag("param", `<${reflection.name}>`);
            }
            if (!tag) {
                tag = comment.getTag("param", reflection.name);
            }

            if (tag) {
                reflection.comment = new Comment(tag.text);
                removeIfPresent(comment.tags, tag);
            }
        }
    }

    /**
     * Triggered when the converter has created a declaration or signature reflection.
     *
     * Invokes the comment parser.
     *
     * @param context  The context object describing the current state the converter is in.
     * @param reflection  The reflection that is currently processed.
     * @param node  The node that is currently processed if available.
     */
    private onDeclaration(
        context: Context,
        reflection: Reflection,
        node?: ts.Node
    ) {
        if (reflection.kindOf(ReflectionKind.FunctionOrMethod)) {
            // We only want a comment on functions/methods if this is a set of overloaded functions.
            // In that case, TypeDoc lets you put a comment on the implementation, and will copy it over to
            // the available signatures so that you can avoid documenting things multiple times.
            // Once TypeDoc has proper support for TSDoc, this will go away since the same thing will be
            // possible by using a @inheritDoc tag to specify that docs should be copied from a specific signature.
            let specialOverloadCase = false;
            if (
                node &&
                (ts.isFunctionDeclaration(node) || ts.isMethodDeclaration(node))
            ) {
                const symbol =
                    node.name && context.checker.getSymbolAtLocation(node.name);
                if (symbol && symbol.declarations) {
                    const declarations = symbol.declarations.filter(
                        (d) =>
                            ts.isFunctionDeclaration(d) ||
                            ts.isMethodDeclaration(d)
                    );
                    if (
                        declarations.length > 1 &&
                        "body" in declarations[declarations.length - 1]
                    ) {
                        node = declarations[declarations.length - 1];
                        specialOverloadCase = true;
                    }
                }
            }

            if (!specialOverloadCase) return;
        }

        // Clean this up in 0.23. We should really accept a ts.Symbol so we don't need exportSymbol on Context
        const exportNode = context.exportSymbol?.getDeclarations()?.[0];
        let rawComment =
            exportNode && getRawComment(exportNode, this.application.logger);
        rawComment ??= node && getRawComment(node, this.application.logger);
        if (!rawComment) {
            return;
        }

        const comment = parseComment(rawComment, reflection.comment);

        if (reflection.kindOf(ReflectionKind.Module)) {
            const tag = comment.getTag("module");
            if (tag) {
                // If no name is specified, this is a flag to mark a comment as a module comment
                // and should not result in a reflection rename.
                const newName = tag.text.trim();
                if (newName.length) {
                    reflection.name = newName;
                }
                removeIfPresent(comment.tags, tag);
            }
        }

        this.applyModifiers(reflection, comment);
        this.removeExcludedTags(comment);
        reflection.comment = comment;
    }

    /**
     * Triggered when the converter begins resolving a project.
     *
     * @param context  The context object describing the current state the converter is in.
     */
    private onBeginResolve(context: Context) {
        const excludeInternal =
            this.application.options.getValue("excludeInternal");
        const excludePrivate =
            this.application.options.getValue("excludePrivate");
        const excludeProtected =
            this.application.options.getValue("excludeProtected");

        const project = context.project;
        const reflections = Object.values(project.reflections);

        // Remove hidden reflections
        const hidden = reflections.filter((reflection) =>
            CommentPlugin.isHidden(
                reflection,
                excludeInternal,
                excludePrivate,
                excludeProtected
            )
        );
        hidden.forEach((reflection) => project.removeReflection(reflection));

        // remove functions with empty signatures after their signatures have been removed
        const [allRemoved, someRemoved] = partition(
            filterMap(hidden, (reflection) =>
                reflection.parent?.kindOf(
                    ReflectionKind.FunctionOrMethod | ReflectionKind.Constructor
                )
                    ? reflection.parent
                    : void 0
            ) as DeclarationReflection[],
            (method) => method.signatures?.length === 0
        );
        allRemoved.forEach((reflection) =>
            project.removeReflection(reflection)
        );
        someRemoved.forEach((reflection) => {
            reflection.sources = unique(
                reflection.signatures!.reduce<SourceReference[]>(
                    (c, s) => c.concat(s.sources || []),
                    []
                )
            );
        });
    }

    /**
     * Triggered when the converter resolves a reflection.
     *
     * Cleans up comment tags related to signatures like @param or @return
     * and moves their data to the corresponding parameter reflections.
     *
     * This hook also copies over the comment of function implementations to their
     * signatures.
     *
     * @param context  The context object describing the current state the converter is in.
     * @param reflection  The reflection that is currently resolved.
     */
    private onResolve(_context: Context, reflection: DeclarationReflection) {
        if (!(reflection instanceof DeclarationReflection)) {
            return;
        }

        if (reflection.type instanceof ReflectionType) {
            this.addCommentToSignatures(
                reflection,
                reflection.type.declaration.getNonIndexSignatures()
            );
        } else {
            this.addCommentToSignatures(
                reflection,
                reflection.getNonIndexSignatures()
            );
        }
    }

    private addCommentToSignatures(
        reflection: DeclarationReflection,
        signatures: SignatureReflection[]
    ) {
        if (!signatures.length) {
            return;
        }

        const comment = reflection.comment;
        if (comment && comment.hasTag("returns")) {
            comment.returns = comment.getTag("returns")!.text;
            comment.removeTags("returns");
        }

        signatures.forEach((signature) => {
            let childComment = signature.comment;
            if (childComment && childComment.hasTag("returns")) {
                childComment.returns = childComment.getTag("returns")!.text;
                childComment.removeTags("returns");
            }

            if (comment) {
                if (!childComment) {
                    childComment = signature.comment = new Comment();
                }

                childComment.shortText ||= comment.shortText;
                childComment.text ||= comment.text;
                childComment.returns ||= comment.returns;
                childComment.tags = childComment.tags.length
                    ? childComment.tags
                    : [...comment.tags];
            }

            signature.parameters?.forEach((parameter, index) => {
                let tag: CommentTag | undefined;
                if (childComment && parameter.name === "__namedParameters") {
                    const commentParams = childComment?.tags.filter(
                        (tag) =>
                            tag.tagName === "param" &&
                            !tag.paramName.includes(".")
                    );
                    if (
                        signature.parameters?.length === commentParams.length &&
                        commentParams[index].paramName
                    ) {
                        parameter.name = commentParams[index].paramName;
                    }
                }
                if (childComment) {
                    moveNestedParamTags(childComment, parameter);
                    tag = childComment.getTag("param", parameter.name);
                }
                if (comment && !tag) {
                    tag = comment.getTag("param", parameter.name);
                }
                if (tag) {
                    parameter.comment = new Comment(tag.text);
                }
            });

            signature.typeParameters?.forEach((parameter) => {
                let tag: CommentTag | undefined;
                if (childComment) {
                    tag =
                        childComment.getTag("typeparam", parameter.name) ||
                        childComment.getTag("template", parameter.name) ||
                        childComment.getTag("param", `<${parameter.name}>`);
                }
                if (comment && !tag) {
                    tag =
                        comment.getTag("typeparam", parameter.name) ||
                        comment.getTag("template", parameter.name) ||
                        comment.getTag("param", `<${parameter.name}>`);
                }
                if (tag) {
                    parameter.comment = new Comment(tag.text);
                }
            });

            childComment?.removeTags("param");
            childComment?.removeTags("typeparam");
            childComment?.removeTags("template");
        });

        delete reflection.comment;
    }

    private removeExcludedTags(comment: Comment) {
        for (const tag of TAG_BLACKLIST) {
            comment.removeTags(tag);
        }
        for (const tag of this.excludeTags) {
            comment.removeTags(tag);
        }
    }

    /**
     * Determines whether or not a reflection has been hidden
     *
     * @param reflection Reflection to check if hidden
     */
    private static isHidden(
        reflection: Reflection,
        excludeInternal: boolean,
        excludePrivate: boolean,
        excludeProtected: boolean
    ) {
        const comment = reflection.comment;

        if (
            reflection.flags.hasFlag(ReflectionFlag.Private) &&
            excludePrivate
        ) {
            return true;
        }

        if (
            reflection.flags.hasFlag(ReflectionFlag.Protected) &&
            excludeProtected
        ) {
            return true;
        }

        if (!comment) {
            return false;
        }

        return (
            comment.hasTag("hidden") ||
            comment.hasTag("ignore") ||
            (comment.hasTag("internal") && excludeInternal)
        );
    }
}

// Moves tags like `@param foo.bar docs for bar` into the `bar` property of the `foo` parameter.
function moveNestedParamTags(comment: Comment, parameter: ParameterReflection) {
    if (parameter.type instanceof ReflectionType) {
        const tags = comment.tags.filter(
            (t) =>
                t.tagName === "param" &&
                t.paramName.startsWith(`${parameter.name}.`)
        );

        for (const tag of tags) {
            const path = tag.paramName.split(".");
            path.shift();
            const child = parameter.type.declaration.getChildByName(path);

            if (child && !child.comment) {
                child.comment = new Comment(tag.text);
            }
        }
    }
}