node.ts

import { ElementType, isTag as isTagRaw } from "domelementtype";

interface SourceCodeLocation {
    /** One-based line index of the first character. */
    startLine: number;
    /** One-based column index of the first character. */
    startCol: number;
    /** Zero-based first character index. */
    startOffset: number;
    /** One-based line index of the last character. */
    endLine: number;
    /** One-based column index of the last character. Points directly *after* the last character. */
    endCol: number;
    /** Zero-based last character index. Points directly *after* the last character. */
    endOffset: number;
}

interface TagSourceCodeLocation extends SourceCodeLocation {
    startTag?: SourceCodeLocation;
    endTag?: SourceCodeLocation;
}

/**
 * A node that can have children.
 */
export type ParentNode = Document | Element | CDATA;

/**
 * A node that can have a parent.
 */
export type ChildNode =
    | Text
    | Comment
    | ProcessingInstruction
    | Element
    | CDATA
    // `Document` is also used for document fragments, and can be a child node.
    | Document;
export type AnyNode = ParentNode | ChildNode;

/**
 * This object will be used as the prototype for Nodes when creating a
 * DOM-Level-1-compliant structure.
 */
export abstract class Node {
    /** The type of the node. */
    abstract readonly type: ElementType;

    /** Parent of the node */
    parent: ParentNode | null = null;

    /** Previous sibling */
    prev: ChildNode | null = null;

    /** Next sibling */
    next: ChildNode | null = null;

    /** The start index of the node. Requires `withStartIndices` on the handler to be `true. */
    startIndex: number | null = null;

    /** The end index of the node. Requires `withEndIndices` on the handler to be `true. */
    endIndex: number | null = null;

    /**
     * `parse5` source code location info.
     *
     * Available if parsing with parse5 and location info is enabled.
     */
    sourceCodeLocation?: SourceCodeLocation | null;

    // Read-only aliases

    /**
     * [DOM spec](https://dom.spec.whatwg.org/#dom-node-nodetype)-compatible
     * node {@link type}.
     */
    abstract readonly nodeType: number;

    // Read-write aliases for properties

    /**
     * Same as {@link parent}.
     * [DOM spec](https://dom.spec.whatwg.org)-compatible alias.
     */
    get parentNode(): ParentNode | null {
        return this.parent;
    }

    set parentNode(parent: ParentNode | null) {
        this.parent = parent;
    }

    /**
     * Same as {@link prev}.
     * [DOM spec](https://dom.spec.whatwg.org)-compatible alias.
     */
    get previousSibling(): ChildNode | null {
        return this.prev;
    }

    set previousSibling(prev: ChildNode | null) {
        this.prev = prev;
    }

    /**
     * Same as {@link next}.
     * [DOM spec](https://dom.spec.whatwg.org)-compatible alias.
     */
    get nextSibling(): ChildNode | null {
        return this.next;
    }

    set nextSibling(next: ChildNode | null) {
        this.next = next;
    }

    /**
     * Clone this node, and optionally its children.
     *
     * @param recursive Clone child nodes as well.
     * @returns A clone of the node.
     */
    cloneNode<T extends Node>(this: T, recursive = false): T {
        return cloneNode(this, recursive);
    }
}

/**
 * A node that contains some data.
 */
export abstract class DataNode extends Node {
    /**
     * @param data The content of the data node
     */
    constructor(public data: string) {
        super();
    }

    /**
     * Same as {@link data}.
     * [DOM spec](https://dom.spec.whatwg.org)-compatible alias.
     */
    get nodeValue(): string {
        return this.data;
    }

    set nodeValue(data: string) {
        this.data = data;
    }
}

/**
 * Text within the document.
 */
export class Text extends DataNode {
    type: ElementType.Text = ElementType.Text;

    get nodeType(): 3 {
        return 3;
    }
}

/**
 * Comments within the document.
 */
export class Comment extends DataNode {
    type: ElementType.Comment = ElementType.Comment;

    get nodeType(): 8 {
        return 8;
    }
}

/**
 * Processing instructions, including doc types.
 */
export class ProcessingInstruction extends DataNode {
    type: ElementType.Directive = ElementType.Directive;

    constructor(public name: string, data: string) {
        super(data);
    }

    override get nodeType(): 1 {
        return 1;
    }

    /** If this is a doctype, the document type name (parse5 only). */
    "x-name"?: string;
    /** If this is a doctype, the document type public identifier (parse5 only). */
    "x-publicId"?: string;
    /** If this is a doctype, the document type system identifier (parse5 only). */
    "x-systemId"?: string;
}

/**
 * A node that can have children.
 */
export abstract class NodeWithChildren extends Node {
    /**
     * @param children Children of the node. Only certain node types can have children.
     */
    constructor(public children: ChildNode[]) {
        super();
    }

    // Aliases
    /** First child of the node. */
    get firstChild(): ChildNode | null {
        return this.children[0] ?? null;
    }

    /** Last child of the node. */
    get lastChild(): ChildNode | null {
        return this.children.length > 0
            ? this.children[this.children.length - 1]
            : null;
    }

    /**
     * Same as {@link children}.
     * [DOM spec](https://dom.spec.whatwg.org)-compatible alias.
     */
    get childNodes(): ChildNode[] {
        return this.children;
    }

    set childNodes(children: ChildNode[]) {
        this.children = children;
    }
}

/**
 * CDATA nodes.
 */
export class CDATA extends NodeWithChildren {
    type: ElementType.CDATA = ElementType.CDATA;

    get nodeType(): 4 {
        return 4;
    }
}

/**
 * The root node of the document.
 */
export class Document extends NodeWithChildren {
    type: ElementType.Root = ElementType.Root;

    get nodeType(): 9 {
        return 9;
    }

    /** [Document mode](https://dom.spec.whatwg.org/#concept-document-limited-quirks) (parse5 only). */
    "x-mode"?: "no-quirks" | "quirks" | "limited-quirks";
}

/**
 * The description of an individual attribute.
 */
interface Attribute {
    name: string;
    value: string;
    namespace?: string;
    prefix?: string;
}

/**
 * An element within the DOM.
 */
export class Element extends NodeWithChildren {
    /**
     * @param name Name of the tag, eg. `div`, `span`.
     * @param attribs Object mapping attribute names to attribute values.
     * @param children Children of the node.
     */
    constructor(
        public name: string,
        public attribs: { [name: string]: string },
        children: ChildNode[] = [],
        public type:
            | ElementType.Tag
            | ElementType.Script
            | ElementType.Style = name === "script"
            ? ElementType.Script
            : name === "style"
            ? ElementType.Style
            : ElementType.Tag
    ) {
        super(children);
    }

    get nodeType(): 1 {
        return 1;
    }

    /**
     * `parse5` source code location info, with start & end tags.
     *
     * Available if parsing with parse5 and location info is enabled.
     */
    sourceCodeLocation?: TagSourceCodeLocation | null;

    // DOM Level 1 aliases

    /**
     * Same as {@link name}.
     * [DOM spec](https://dom.spec.whatwg.org)-compatible alias.
     */
    get tagName(): string {
        return this.name;
    }

    set tagName(name: string) {
        this.name = name;
    }

    get attributes(): Attribute[] {
        return Object.keys(this.attribs).map((name) => ({
            name,
            value: this.attribs[name],
            namespace: this["x-attribsNamespace"]?.[name],
            prefix: this["x-attribsPrefix"]?.[name],
        }));
    }

    /** Element namespace (parse5 only). */
    namespace?: string;
    /** Element attribute namespaces (parse5 only). */
    "x-attribsNamespace"?: Record<string, string>;
    /** Element attribute namespace-related prefixes (parse5 only). */
    "x-attribsPrefix"?: Record<string, string>;
}

/**
 * Checks if `node` is an element node.
 *
 * @param node Node to check.
 * @returns `true` if the node is an element node.
 */
export function isTag(node: Node): node is Element {
    return isTagRaw(node);
}

/**
 * Checks if `node` is a CDATA node.
 *
 * @param node Node to check.
 * @returns `true` if the node is a CDATA node.
 */
export function isCDATA(node: Node): node is CDATA {
    return node.type === ElementType.CDATA;
}

/**
 * Checks if `node` is a text node.
 *
 * @param node Node to check.
 * @returns `true` if the node is a text node.
 */
export function isText(node: Node): node is Text {
    return node.type === ElementType.Text;
}

/**
 * Checks if `node` is a comment node.
 *
 * @param node Node to check.
 * @returns `true` if the node is a comment node.
 */
export function isComment(node: Node): node is Comment {
    return node.type === ElementType.Comment;
}

/**
 * Checks if `node` is a directive node.
 *
 * @param node Node to check.
 * @returns `true` if the node is a directive node.
 */
export function isDirective(node: Node): node is ProcessingInstruction {
    return node.type === ElementType.Directive;
}

/**
 * Checks if `node` is a document node.
 *
 * @param node Node to check.
 * @returns `true` if the node is a document node.
 */
export function isDocument(node: Node): node is Document {
    return node.type === ElementType.Root;
}

/**
 * Checks if `node` has children.
 *
 * @param node Node to check.
 * @returns `true` if the node has children.
 */
export function hasChildren(node: Node): node is ParentNode {
    return Object.prototype.hasOwnProperty.call(node, "children");
}

/**
 * Clone a node, and optionally its children.
 *
 * @param recursive Clone child nodes as well.
 * @returns A clone of the node.
 */
export function cloneNode<T extends Node>(node: T, recursive = false): T {
    let result: Node;

    if (isText(node)) {
        result = new Text(node.data);
    } else if (isComment(node)) {
        result = new Comment(node.data);
    } else if (isTag(node)) {
        const children = recursive ? cloneChildren(node.children) : [];
        const clone = new Element(node.name, { ...node.attribs }, children);
        children.forEach((child) => (child.parent = clone));

        if (node.namespace != null) {
            clone.namespace = node.namespace;
        }
        if (node["x-attribsNamespace"]) {
            clone["x-attribsNamespace"] = { ...node["x-attribsNamespace"] };
        }
        if (node["x-attribsPrefix"]) {
            clone["x-attribsPrefix"] = { ...node["x-attribsPrefix"] };
        }

        result = clone;
    } else if (isCDATA(node)) {
        const children = recursive ? cloneChildren(node.children) : [];
        const clone = new CDATA(children);
        children.forEach((child) => (child.parent = clone));
        result = clone;
    } else if (isDocument(node)) {
        const children = recursive ? cloneChildren(node.children) : [];
        const clone = new Document(children);
        children.forEach((child) => (child.parent = clone));

        if (node["x-mode"]) {
            clone["x-mode"] = node["x-mode"];
        }

        result = clone;
    } else if (isDirective(node)) {
        const instruction = new ProcessingInstruction(node.name, node.data);

        if (node["x-name"] != null) {
            instruction["x-name"] = node["x-name"];
            instruction["x-publicId"] = node["x-publicId"];
            instruction["x-systemId"] = node["x-systemId"];
        }

        result = instruction;
    } else {
        throw new Error(`Not implemented yet: ${node.type}`);
    }

    result.startIndex = node.startIndex;
    result.endIndex = node.endIndex;

    if (node.sourceCodeLocation != null) {
        result.sourceCodeLocation = node.sourceCodeLocation;
    }

    return result as T;
}

/**
 * Clone a list of child nodes.
 *
 * @param childs The child nodes to clone.
 * @returns A list of cloned child nodes.
 */
function cloneChildren(childs: ChildNode[]): ChildNode[] {
    const children = childs.map((child) => cloneNode(child, true));

    for (let i = 1; i < children.length; i++) {
        children[i].prev = children[i - 1];
        children[i - 1].next = children[i];
    }

    return children;
}