lib/display/xml_parser.js

/**
 * @licstart The following is the entire license notice for the
 * Javascript code in this page
 *
 * Copyright 2020 Mozilla Foundation
 *
 * 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.
 *
 * @licend The above is the entire license notice for the
 * Javascript code in this page
 */
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.SimpleXMLParser = void 0;
const XMLParserErrorCode = {
  NoError: 0,
  EndOfDocument: -1,
  UnterminatedCdat: -2,
  UnterminatedXmlDeclaration: -3,
  UnterminatedDoctypeDeclaration: -4,
  UnterminatedComment: -5,
  MalformedElement: -6,
  OutOfMemory: -7,
  UnterminatedAttributeValue: -8,
  UnterminatedElement: -9,
  ElementNeverBegun: -10
};

function isWhitespace(s, index) {
  const ch = s[index];
  return ch === " " || ch === "\n" || ch === "\r" || ch === "\t";
}

function isWhitespaceString(s) {
  for (let i = 0, ii = s.length; i < ii; i++) {
    if (!isWhitespace(s, i)) {
      return false;
    }
  }

  return true;
}

class XMLParserBase {
  _resolveEntities(s) {
    return s.replace(/&([^;]+);/g, (all, entity) => {
      if (entity.substring(0, 2) === "#x") {
        return String.fromCharCode(parseInt(entity.substring(2), 16));
      } else if (entity.substring(0, 1) === "#") {
        return String.fromCharCode(parseInt(entity.substring(1), 10));
      }

      switch (entity) {
        case "lt":
          return "<";

        case "gt":
          return ">";

        case "amp":
          return "&";

        case "quot":
          return '"';
      }

      return this.onResolveEntity(entity);
    });
  }

  _parseContent(s, start) {
    const attributes = [];
    let pos = start;

    function skipWs() {
      while (pos < s.length && isWhitespace(s, pos)) {
        ++pos;
      }
    }

    while (pos < s.length && !isWhitespace(s, pos) && s[pos] !== ">" && s[pos] !== "/") {
      ++pos;
    }

    const name = s.substring(start, pos);
    skipWs();

    while (pos < s.length && s[pos] !== ">" && s[pos] !== "/" && s[pos] !== "?") {
      skipWs();
      let attrName = "",
          attrValue = "";

      while (pos < s.length && !isWhitespace(s, pos) && s[pos] !== "=") {
        attrName += s[pos];
        ++pos;
      }

      skipWs();

      if (s[pos] !== "=") {
        return null;
      }

      ++pos;
      skipWs();
      const attrEndChar = s[pos];

      if (attrEndChar !== '"' && attrEndChar !== "'") {
        return null;
      }

      const attrEndIndex = s.indexOf(attrEndChar, ++pos);

      if (attrEndIndex < 0) {
        return null;
      }

      attrValue = s.substring(pos, attrEndIndex);
      attributes.push({
        name: attrName,
        value: this._resolveEntities(attrValue)
      });
      pos = attrEndIndex + 1;
      skipWs();
    }

    return {
      name,
      attributes,
      parsed: pos - start
    };
  }

  _parseProcessingInstruction(s, start) {
    let pos = start;

    function skipWs() {
      while (pos < s.length && isWhitespace(s, pos)) {
        ++pos;
      }
    }

    while (pos < s.length && !isWhitespace(s, pos) && s[pos] !== ">" && s[pos] !== "/") {
      ++pos;
    }

    const name = s.substring(start, pos);
    skipWs();
    const attrStart = pos;

    while (pos < s.length && (s[pos] !== "?" || s[pos + 1] !== ">")) {
      ++pos;
    }

    const value = s.substring(attrStart, pos);
    return {
      name,
      value,
      parsed: pos - start
    };
  }

  parseXml(s) {
    let i = 0;

    while (i < s.length) {
      const ch = s[i];
      let j = i;

      if (ch === "<") {
        ++j;
        const ch2 = s[j];
        let q;

        switch (ch2) {
          case "/":
            ++j;
            q = s.indexOf(">", j);

            if (q < 0) {
              this.onError(XMLParserErrorCode.UnterminatedElement);
              return;
            }

            this.onEndElement(s.substring(j, q));
            j = q + 1;
            break;

          case "?":
            ++j;

            const pi = this._parseProcessingInstruction(s, j);

            if (s.substring(j + pi.parsed, j + pi.parsed + 2) !== "?>") {
              this.onError(XMLParserErrorCode.UnterminatedXmlDeclaration);
              return;
            }

            this.onPi(pi.name, pi.value);
            j += pi.parsed + 2;
            break;

          case "!":
            if (s.substring(j + 1, j + 3) === "--") {
              q = s.indexOf("-->", j + 3);

              if (q < 0) {
                this.onError(XMLParserErrorCode.UnterminatedComment);
                return;
              }

              this.onComment(s.substring(j + 3, q));
              j = q + 3;
            } else if (s.substring(j + 1, j + 8) === "[CDATA[") {
              q = s.indexOf("]]>", j + 8);

              if (q < 0) {
                this.onError(XMLParserErrorCode.UnterminatedCdat);
                return;
              }

              this.onCdata(s.substring(j + 8, q));
              j = q + 3;
            } else if (s.substring(j + 1, j + 8) === "DOCTYPE") {
              const q2 = s.indexOf("[", j + 8);
              let complexDoctype = false;
              q = s.indexOf(">", j + 8);

              if (q < 0) {
                this.onError(XMLParserErrorCode.UnterminatedDoctypeDeclaration);
                return;
              }

              if (q2 > 0 && q > q2) {
                q = s.indexOf("]>", j + 8);

                if (q < 0) {
                  this.onError(XMLParserErrorCode.UnterminatedDoctypeDeclaration);
                  return;
                }

                complexDoctype = true;
              }

              const doctypeContent = s.substring(j + 8, q + (complexDoctype ? 1 : 0));
              this.onDoctype(doctypeContent);
              j = q + (complexDoctype ? 2 : 1);
            } else {
              this.onError(XMLParserErrorCode.MalformedElement);
              return;
            }

            break;

          default:
            const content = this._parseContent(s, j);

            if (content === null) {
              this.onError(XMLParserErrorCode.MalformedElement);
              return;
            }

            let isClosed = false;

            if (s.substring(j + content.parsed, j + content.parsed + 2) === "/>") {
              isClosed = true;
            } else if (s.substring(j + content.parsed, j + content.parsed + 1) !== ">") {
              this.onError(XMLParserErrorCode.UnterminatedElement);
              return;
            }

            this.onBeginElement(content.name, content.attributes, isClosed);
            j += content.parsed + (isClosed ? 2 : 1);
            break;
        }
      } else {
        while (j < s.length && s[j] !== "<") {
          j++;
        }

        const text = s.substring(i, j);
        this.onText(this._resolveEntities(text));
      }

      i = j;
    }
  }

  onResolveEntity(name) {
    return `&${name};`;
  }

  onPi(name, value) {}

  onComment(text) {}

  onCdata(text) {}

  onDoctype(doctypeContent) {}

  onText(text) {}

  onBeginElement(name, attributes, isEmpty) {}

  onEndElement(name) {}

  onError(code) {}

}

class SimpleDOMNode {
  constructor(nodeName, nodeValue) {
    this.nodeName = nodeName;
    this.nodeValue = nodeValue;
    Object.defineProperty(this, "parentNode", {
      value: null,
      writable: true
    });
  }

  get firstChild() {
    return this.childNodes && this.childNodes[0];
  }

  get nextSibling() {
    const childNodes = this.parentNode.childNodes;

    if (!childNodes) {
      return undefined;
    }

    const index = childNodes.indexOf(this);

    if (index === -1) {
      return undefined;
    }

    return childNodes[index + 1];
  }

  get textContent() {
    if (!this.childNodes) {
      return this.nodeValue || "";
    }

    return this.childNodes.map(function (child) {
      return child.textContent;
    }).join("");
  }

  hasChildNodes() {
    return this.childNodes && this.childNodes.length > 0;
  }

}

class SimpleXMLParser extends XMLParserBase {
  constructor() {
    super();
    this._currentFragment = null;
    this._stack = null;
    this._errorCode = XMLParserErrorCode.NoError;
  }

  parseFromString(data) {
    this._currentFragment = [];
    this._stack = [];
    this._errorCode = XMLParserErrorCode.NoError;
    this.parseXml(data);

    if (this._errorCode !== XMLParserErrorCode.NoError) {
      return undefined;
    }

    const [documentElement] = this._currentFragment;

    if (!documentElement) {
      return undefined;
    }

    return {
      documentElement
    };
  }

  onResolveEntity(name) {
    switch (name) {
      case "apos":
        return "'";
    }

    return super.onResolveEntity(name);
  }

  onText(text) {
    if (isWhitespaceString(text)) {
      return;
    }

    const node = new SimpleDOMNode("#text", text);

    this._currentFragment.push(node);
  }

  onCdata(text) {
    const node = new SimpleDOMNode("#text", text);

    this._currentFragment.push(node);
  }

  onBeginElement(name, attributes, isEmpty) {
    const node = new SimpleDOMNode(name);
    node.childNodes = [];

    this._currentFragment.push(node);

    if (isEmpty) {
      return;
    }

    this._stack.push(this._currentFragment);

    this._currentFragment = node.childNodes;
  }

  onEndElement(name) {
    this._currentFragment = this._stack.pop() || [];
    const lastElement = this._currentFragment[this._currentFragment.length - 1];

    if (!lastElement) {
      return;
    }

    for (let i = 0, ii = lastElement.childNodes.length; i < ii; i++) {
      lastElement.childNodes[i].parentNode = lastElement;
    }
  }

  onError(code) {
    this._errorCode = code;
  }

}

exports.SimpleXMLParser = SimpleXMLParser;