pdf.js/src/core/xfa/xfa_object.js

/* Copyright 2021 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.
 */

import { getInteger, getKeyword } from "./utils.js";
import { shadow, warn } from "../../shared/util.js";
import { NamespaceIds } from "./namespaces.js";

// We use these symbols to avoid name conflict between tags
// and properties/methods names.
const $clean = Symbol();
const $cleanup = Symbol();
const $content = Symbol("content");
const $dump = Symbol();
const $finalize = Symbol();
const $isDataValue = Symbol();
const $getAttributeIt = Symbol();
const $getChildrenByClass = Symbol();
const $getChildrenByName = Symbol();
const $getChildrenByNameIt = Symbol();
const $getChildren = Symbol();
const $getParent = Symbol();
const $isTransparent = Symbol();
const $lastAttribute = Symbol();
const $namespaceId = Symbol("namespaceId");
const $nodeName = Symbol("nodeName");
const $onChild = Symbol();
const $onChildCheck = Symbol();
const $onText = Symbol();
const $resolvePrototypes = Symbol();
const $setId = Symbol();
const $setSetAttributes = Symbol();
const $text = Symbol();

const _applyPrototype = Symbol();
const _attributes = Symbol();
const _attributeNames = Symbol();
const _children = Symbol();
const _clone = Symbol();
const _cloneAttribute = Symbol();
const _defaultValue = Symbol();
const _getPrototype = Symbol();
const _getUnsetAttributes = Symbol();
const _hasChildren = Symbol();
const _max = Symbol();
const _options = Symbol();
const _parent = Symbol();
const _setAttributes = Symbol();
const _validator = Symbol();

class XFAObject {
  constructor(nsId, name, hasChildren = false) {
    this[$namespaceId] = nsId;
    this[$nodeName] = name;
    this[_hasChildren] = hasChildren;
    this[_parent] = null;
    this[_children] = [];
  }

  [$onChild](child) {
    if (!this[_hasChildren] || !this[$onChildCheck](child)) {
      return false;
    }

    const name = child[$nodeName];
    const node = this[name];

    if (node instanceof XFAObjectArray) {
      if (node.push(child)) {
        child[_parent] = this;
        this[_children].push(child);
        return true;
      }
    } else if (node === null) {
      this[name] = child;
      child[_parent] = this;
      this[_children].push(child);
      return true;
    }

    warn(`XFA - node "${this[$nodeName]}" has already enough "${name}"!`);
    return false;
  }

  [$onChildCheck](child) {
    return (
      this.hasOwnProperty(child[$nodeName]) &&
      child[$namespaceId] === this[$namespaceId]
    );
  }

  [$setId](ids) {
    if (this.id && this[$namespaceId] === NamespaceIds.template.id) {
      ids.set(this.id, this);
    }
  }

  [$onText](_) {}

  [$finalize]() {}

  [$clean](builder) {
    delete this[_hasChildren];
    if (this[$cleanup]) {
      builder.clean(this[$cleanup]);
      delete this[$cleanup];
    }
  }

  [$isTransparent]() {
    return this.name === "";
  }

  [$lastAttribute]() {
    return "";
  }

  get [_attributeNames]() {
    // Lazily get attributes names
    const proto = Object.getPrototypeOf(this);
    if (!proto._attributes) {
      const attributes = (proto._attributes = new Set());
      for (const name of Object.getOwnPropertyNames(this)) {
        if (
          this[name] === null ||
          this[name] instanceof XFAObject ||
          this[name] instanceof XFAObjectArray
        ) {
          break;
        }
        attributes.add(name);
      }
    }
    return shadow(this, _attributeNames, proto._attributes);
  }

  [$getParent]() {
    return this[_parent];
  }

  [$getChildren](name = null) {
    if (!name) {
      return this[_children];
    }

    return this[name];
  }

  [$dump]() {
    const dumped = Object.create(null);
    if (this[$content]) {
      dumped.$content = this[$content];
    }

    for (const name of Object.getOwnPropertyNames(this)) {
      const value = this[name];
      if (value === null) {
        continue;
      }
      if (value instanceof XFAObject) {
        dumped[name] = value[$dump]();
      } else if (value instanceof XFAObjectArray) {
        if (!value.isEmpty()) {
          dumped[name] = value.dump();
        }
      } else {
        dumped[name] = value;
      }
    }

    return dumped;
  }

  [$setSetAttributes](attributes) {
    if (attributes.use || attributes.id) {
      // Just keep set attributes because this node uses a proto or is a proto.
      this[_setAttributes] = new Set(Object.keys(attributes));
    }
  }

  /**
   * Get attribute names which have been set in the proto but not in this.
   */
  [_getUnsetAttributes](protoAttributes) {
    const allAttr = this[_attributeNames];
    const setAttr = this[_setAttributes];
    return [...protoAttributes].filter(x => allAttr.has(x) && !setAttr.has(x));
  }

  /**
   * Update the node with properties coming from a prototype and apply
   * this function recursivly to all children.
   */
  [$resolvePrototypes](ids, ancestors = new Set()) {
    for (const child of this[_children]) {
      const proto = child[_getPrototype](ids, ancestors);
      if (proto) {
        // _applyPrototype will apply $resolvePrototypes with correct ancestors
        // to avoid infinite loop.
        child[_applyPrototype](proto, ids, ancestors);
      } else {
        child[$resolvePrototypes](ids, ancestors);
      }
    }
  }

  [_getPrototype](ids, ancestors) {
    const { use } = this;
    if (use && use.startsWith("#")) {
      const id = use.slice(1);
      const proto = ids.get(id);
      this.use = "";
      if (!proto) {
        warn(`XFA - Invalid prototype id: ${id}.`);
        return null;
      }

      if (proto[$nodeName] !== this[$nodeName]) {
        warn(
          `XFA - Incompatible prototype: ${proto[$nodeName]} !== ${this[$nodeName]}.`
        );
        return null;
      }

      if (ancestors.has(proto)) {
        // We've a cycle so break it.
        warn(`XFA - Cycle detected in prototypes use.`);
        return null;
      }

      ancestors.add(proto);
      // The prototype can have a "use" attribute itself.
      const protoProto = proto[_getPrototype](ids, ancestors);
      if (!protoProto) {
        ancestors.delete(proto);
        return proto;
      }

      proto[_applyPrototype](protoProto, ids, ancestors);
      ancestors.delete(proto);

      return proto;
    }
    // TODO: handle SOM expressions.

    return null;
  }

  [_applyPrototype](proto, ids, ancestors) {
    if (ancestors.has(proto)) {
      // We've a cycle so break it.
      warn(`XFA - Cycle detected in prototypes use.`);
      return;
    }

    if (!this[$content] && proto[$content]) {
      this[$content] = proto[$content];
    }

    const newAncestors = new Set(ancestors);
    newAncestors.add(proto);

    for (const unsetAttrName of this[_getUnsetAttributes](
      proto[_setAttributes]
    )) {
      this[unsetAttrName] = proto[unsetAttrName];
      if (this[_setAttributes]) {
        this[_setAttributes].add(unsetAttrName);
      }
    }

    for (const name of Object.getOwnPropertyNames(this)) {
      if (this[_attributeNames].has(name)) {
        continue;
      }
      const value = this[name];
      const protoValue = proto[name];

      if (value instanceof XFAObjectArray) {
        for (const child of value[_children]) {
          child[$resolvePrototypes](ids, ancestors);
        }

        for (
          let i = value[_children].length, ii = protoValue[_children].length;
          i < ii;
          i++
        ) {
          const child = proto[_children][i][_clone]();
          if (value.push(child)) {
            child[_parent] = this;
            this[_children].push(child);
            child[$resolvePrototypes](ids, newAncestors);
          } else {
            // No need to continue: other nodes will be rejected.
            break;
          }
        }
        continue;
      }

      if (value !== null) {
        value[$resolvePrototypes](ids, ancestors);
        continue;
      }

      if (protoValue !== null) {
        const child = protoValue[_clone]();
        child[_parent] = this;
        this[name] = child;
        this[_children].push(child);
        child[$resolvePrototypes](ids, newAncestors);
      }
    }
  }

  static [_cloneAttribute](obj) {
    if (Array.isArray(obj)) {
      return obj.map(x => XFAObject[_cloneAttribute](x));
    }
    if (obj instanceof Object) {
      return Object.assign({}, obj);
    }
    return obj;
  }

  [_clone]() {
    const clone = Object.create(Object.getPrototypeOf(this));
    for (const $symbol of Object.getOwnPropertySymbols(this)) {
      try {
        clone[$symbol] = this[$symbol];
      } catch (_) {
        shadow(clone, $symbol, this[$symbol]);
      }
    }
    clone[_children] = [];

    for (const name of Object.getOwnPropertyNames(this)) {
      if (this[_attributeNames].has(name)) {
        clone[name] = XFAObject[_cloneAttribute](this[name]);
        continue;
      }
      const value = this[name];
      if (value instanceof XFAObjectArray) {
        clone[name] = new XFAObjectArray(value[_max]);
      } else {
        clone[name] = null;
      }
    }

    for (const child of this[_children]) {
      const name = child[$nodeName];
      const clonedChild = child[_clone]();
      clone[_children].push(clonedChild);
      clonedChild[_parent] = clone;
      if (clone[name] === null) {
        clone[name] = clonedChild;
      } else {
        clone[name][_children].push(clonedChild);
      }
    }

    return clone;
  }

  [$getChildren](name = null) {
    if (!name) {
      return this[_children];
    }

    return this[_children].filter(c => c[$nodeName] === name);
  }

  [$getChildrenByClass](name) {
    return this[name];
  }

  [$getChildrenByName](name, allTransparent, first = true) {
    return Array.from(this[$getChildrenByNameIt](name, allTransparent, first));
  }

  *[$getChildrenByNameIt](name, allTransparent, first = true) {
    if (name === "parent") {
      yield this[_parent];
      return;
    }

    for (const child of this[_children]) {
      if (child[$nodeName] === name) {
        yield child;
      }

      if (child.name === name) {
        yield child;
      }

      if (allTransparent || child[$isTransparent]()) {
        yield* child[$getChildrenByNameIt](name, allTransparent, false);
      }
    }

    if (first && this[_attributeNames].has(name)) {
      yield new XFAAttribute(this, name, this[name]);
    }
  }
}

class XFAObjectArray {
  constructor(max = Infinity) {
    this[_max] = max;
    this[_children] = [];
  }

  push(child) {
    const len = this[_children].length;
    if (len <= this[_max]) {
      this[_children].push(child);
      return true;
    }
    warn(
      `XFA - node "${child[$nodeName]}" accepts no more than ${this[_max]} children`
    );
    return false;
  }

  isEmpty() {
    return this[_children].length === 0;
  }

  dump() {
    return this[_children].length === 1
      ? this[_children][0][$dump]()
      : this[_children].map(x => x[$dump]());
  }

  [_clone]() {
    const clone = new XFAObjectArray(this[_max]);
    clone[_children] = this[_children].map(c => c[_clone]());
    return clone;
  }

  get children() {
    return this[_children];
  }
}

class XFAAttribute {
  constructor(node, name, value) {
    this[_parent] = node;
    this[$nodeName] = name;
    this[$content] = value;
  }

  [$getParent]() {
    return this[_parent];
  }

  [$isDataValue]() {
    return true;
  }

  [$text]() {
    return this[$content];
  }
}

class XmlObject extends XFAObject {
  constructor(nsId, name, attributes = null) {
    super(nsId, name);
    this[$content] = "";
    if (name !== "#text") {
      this[_attributes] = attributes;
    }
  }

  [$onChild](child) {
    if (this[$content]) {
      const node = new XmlObject(this[$namespaceId], "#text");
      node[_parent] = this;
      node[$content] = this[$content];
      this[$content] = "";
      this[_children].push(node);
    }
    child[_parent] = this;
    this[_children].push(child);
    return true;
  }

  [$onText](str) {
    this[$content] += str;
  }

  [$finalize]() {
    if (this[$content] && this[_children].length > 0) {
      const node = new XmlObject(this[$namespaceId], "#text");
      node[_parent] = this;
      node[$content] = this[$content];
      this[_children].push(node);
      delete this[$content];
    }
  }

  [$text]() {
    if (this[_children].length === 0) {
      return this[$content];
    }
    return this[_children].map(c => c[$text]()).join("");
  }

  [$getChildren](name = null) {
    if (!name) {
      return this[_children];
    }

    return this[_children].filter(c => c[$nodeName] === name);
  }

  [$getChildrenByClass](name) {
    const value = this[_attributes][name];
    if (value !== undefined) {
      return value;
    }
    return this[$getChildren](name);
  }

  *[$getChildrenByNameIt](name, allTransparent) {
    const value = this[_attributes][name];
    if (value !== undefined) {
      yield new XFAAttribute(this, name, value);
    }

    for (const child of this[_children]) {
      if (child[$nodeName] === name) {
        yield child;
      }

      if (allTransparent) {
        yield* child[$getChildrenByNameIt](name, allTransparent);
      }
    }
  }

  *[$getAttributeIt](name) {
    const value = this[_attributes][name];
    if (value !== undefined) {
      yield new XFAAttribute(this, name, value);
    }

    for (const child of this[_children]) {
      yield* child[$getAttributeIt](name);
    }
  }

  [$isDataValue]() {
    return this[_children].length === 0;
  }
}

class ContentObject extends XFAObject {
  constructor(nsId, name) {
    super(nsId, name);
    this[$content] = "";
  }

  [$onText](text) {
    this[$content] += text;
  }

  [$finalize]() {}
}

class OptionObject extends ContentObject {
  constructor(nsId, name, options) {
    super(nsId, name);
    this[_options] = options;
  }

  [$finalize]() {
    this[$content] = getKeyword({
      data: this[$content],
      defaultValue: this[_options][0],
      validate: k => this[_options].includes(k),
    });
  }

  [$clean](builder) {
    super[$clean](builder);
    delete this[_options];
  }
}

class StringObject extends ContentObject {
  [$finalize]() {
    this[$content] = this[$content].trim();
  }
}

class IntegerObject extends ContentObject {
  constructor(nsId, name, defaultValue, validator) {
    super(nsId, name);
    this[_defaultValue] = defaultValue;
    this[_validator] = validator;
  }

  [$finalize]() {
    this[$content] = getInteger({
      data: this[$content],
      defaultValue: this[_defaultValue],
      validate: this[_validator],
    });
  }

  [$clean](builder) {
    super[$clean](builder);
    delete this[_defaultValue];
    delete this[_validator];
  }
}

class Option01 extends IntegerObject {
  constructor(nsId, name) {
    super(nsId, name, 0, n => n === 1);
  }
}

class Option10 extends IntegerObject {
  constructor(nsId, name) {
    super(nsId, name, 1, n => n === 0);
  }
}

export {
  $clean,
  $cleanup,
  $content,
  $dump,
  $finalize,
  $getAttributeIt,
  $getChildren,
  $getChildrenByClass,
  $getChildrenByName,
  $getChildrenByNameIt,
  $getParent,
  $isDataValue,
  $isTransparent,
  $namespaceId,
  $nodeName,
  $onChild,
  $onChildCheck,
  $onText,
  $resolvePrototypes,
  $setId,
  $setSetAttributes,
  $text,
  ContentObject,
  IntegerObject,
  Option01,
  Option10,
  OptionObject,
  StringObject,
  XFAAttribute,
  XFAObject,
  XFAObjectArray,
  XmlObject,
};