pdf.js/src/core/primitives.js
Jonas Jenwald c0736647f9 Add general iteration support in the RefSet and RefSetCache classes
This patch removes the existing `forEach` methods, in favor of making the classes properly iterable instead. Given that the classes are using a `Set` respectively a `Map` internally, implementing this is very easy/efficient and allows us to simplify some existing code.
2022-03-18 14:27:34 +01:00

444 lines
11 KiB
JavaScript

/* Copyright 2012 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 { assert, shadow, unreachable } from "../shared/util.js";
const CIRCULAR_REF = Symbol("CIRCULAR_REF");
const EOF = Symbol("EOF");
const Name = (function NameClosure() {
let nameCache = Object.create(null);
// eslint-disable-next-line no-shadow
class Name {
constructor(name) {
if (
(typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")) &&
typeof name !== "string"
) {
unreachable('Name: The "name" must be a string.');
}
this.name = name;
}
static get(name) {
const nameValue = nameCache[name];
// eslint-disable-next-line no-restricted-syntax
return nameValue ? nameValue : (nameCache[name] = new Name(name));
}
static _clearCache() {
nameCache = Object.create(null);
}
}
return Name;
})();
const Cmd = (function CmdClosure() {
let cmdCache = Object.create(null);
// eslint-disable-next-line no-shadow
class Cmd {
constructor(cmd) {
if (
(typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")) &&
typeof cmd !== "string"
) {
unreachable('Cmd: The "cmd" must be a string.');
}
this.cmd = cmd;
}
static get(cmd) {
const cmdValue = cmdCache[cmd];
// eslint-disable-next-line no-restricted-syntax
return cmdValue ? cmdValue : (cmdCache[cmd] = new Cmd(cmd));
}
static _clearCache() {
cmdCache = Object.create(null);
}
}
return Cmd;
})();
const nonSerializable = function nonSerializableClosure() {
return nonSerializable; // Creating closure on some variable.
};
class Dict {
constructor(xref = null) {
// Map should only be used internally, use functions below to access.
this._map = Object.create(null);
this.xref = xref;
this.objId = null;
this.suppressEncryption = false;
this.__nonSerializable__ = nonSerializable; // Disable cloning of the Dict.
}
assignXref(newXref) {
this.xref = newXref;
}
get size() {
return Object.keys(this._map).length;
}
// Automatically dereferences Ref objects.
get(key1, key2, key3) {
let value = this._map[key1];
if (value === undefined && key2 !== undefined) {
if (
(typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")) &&
key2.length < key1.length
) {
unreachable("Dict.get: Expected keys to be ordered by length.");
}
value = this._map[key2];
if (value === undefined && key3 !== undefined) {
if (
(typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")) &&
key3.length < key2.length
) {
unreachable("Dict.get: Expected keys to be ordered by length.");
}
value = this._map[key3];
}
}
if (value instanceof Ref && this.xref) {
return this.xref.fetch(value, this.suppressEncryption);
}
return value;
}
// Same as get(), but returns a promise and uses fetchIfRefAsync().
async getAsync(key1, key2, key3) {
let value = this._map[key1];
if (value === undefined && key2 !== undefined) {
if (
(typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")) &&
key2.length < key1.length
) {
unreachable("Dict.getAsync: Expected keys to be ordered by length.");
}
value = this._map[key2];
if (value === undefined && key3 !== undefined) {
if (
(typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")) &&
key3.length < key2.length
) {
unreachable("Dict.getAsync: Expected keys to be ordered by length.");
}
value = this._map[key3];
}
}
if (value instanceof Ref && this.xref) {
return this.xref.fetchAsync(value, this.suppressEncryption);
}
return value;
}
// Same as get(), but dereferences all elements if the result is an Array.
getArray(key1, key2, key3) {
let value = this._map[key1];
if (value === undefined && key2 !== undefined) {
if (
(typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")) &&
key2.length < key1.length
) {
unreachable("Dict.getArray: Expected keys to be ordered by length.");
}
value = this._map[key2];
if (value === undefined && key3 !== undefined) {
if (
(typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")) &&
key3.length < key2.length
) {
unreachable("Dict.getArray: Expected keys to be ordered by length.");
}
value = this._map[key3];
}
}
if (value instanceof Ref && this.xref) {
value = this.xref.fetch(value, this.suppressEncryption);
}
if (Array.isArray(value)) {
value = value.slice(); // Ensure that we don't modify the Dict data.
for (let i = 0, ii = value.length; i < ii; i++) {
if (value[i] instanceof Ref && this.xref) {
value[i] = this.xref.fetch(value[i], this.suppressEncryption);
}
}
}
return value;
}
// No dereferencing.
getRaw(key) {
return this._map[key];
}
getKeys() {
return Object.keys(this._map);
}
// No dereferencing.
getRawValues() {
return Object.values(this._map);
}
set(key, value) {
if (
typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")
) {
if (typeof key !== "string") {
unreachable('Dict.set: The "key" must be a string.');
} else if (value === undefined) {
unreachable('Dict.set: The "value" cannot be undefined.');
}
}
this._map[key] = value;
}
has(key) {
return this._map[key] !== undefined;
}
forEach(callback) {
for (const key in this._map) {
callback(key, this.get(key));
}
}
static get empty() {
const emptyDict = new Dict(null);
emptyDict.set = (key, value) => {
unreachable("Should not call `set` on the empty dictionary.");
};
return shadow(this, "empty", emptyDict);
}
static merge({ xref, dictArray, mergeSubDicts = false }) {
const mergedDict = new Dict(xref),
properties = new Map();
for (const dict of dictArray) {
if (!(dict instanceof Dict)) {
continue;
}
for (const [key, value] of Object.entries(dict._map)) {
let property = properties.get(key);
if (property === undefined) {
property = [];
properties.set(key, property);
} else if (!mergeSubDicts || !(value instanceof Dict)) {
// Ignore additional entries, if either:
// - This is a "shallow" merge, where only the first element matters.
// - The value is *not* a `Dict`, since other types cannot be merged.
continue;
}
property.push(value);
}
}
for (const [name, values] of properties) {
if (values.length === 1 || !(values[0] instanceof Dict)) {
mergedDict._map[name] = values[0];
continue;
}
const subDict = new Dict(xref);
for (const dict of values) {
for (const [key, value] of Object.entries(dict._map)) {
if (subDict._map[key] === undefined) {
subDict._map[key] = value;
}
}
}
if (subDict.size > 0) {
mergedDict._map[name] = subDict;
}
}
properties.clear();
return mergedDict.size > 0 ? mergedDict : Dict.empty;
}
}
const Ref = (function RefClosure() {
let refCache = Object.create(null);
// eslint-disable-next-line no-shadow
class Ref {
constructor(num, gen) {
this.num = num;
this.gen = gen;
}
toString() {
// This function is hot, so we make the string as compact as possible.
// |this.gen| is almost always zero, so we treat that case specially.
if (this.gen === 0) {
return `${this.num}R`;
}
return `${this.num}R${this.gen}`;
}
static get(num, gen) {
const key = gen === 0 ? `${num}R` : `${num}R${gen}`;
const refValue = refCache[key];
// eslint-disable-next-line no-restricted-syntax
return refValue ? refValue : (refCache[key] = new Ref(num, gen));
}
static _clearCache() {
refCache = Object.create(null);
}
}
return Ref;
})();
// The reference is identified by number and generation.
// This structure stores only one instance of the reference.
class RefSet {
constructor(parent = null) {
if (
(typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")) &&
parent &&
!(parent instanceof RefSet)
) {
unreachable('RefSet: Invalid "parent" value.');
}
this._set = new Set(parent && parent._set);
}
has(ref) {
return this._set.has(ref.toString());
}
put(ref) {
this._set.add(ref.toString());
}
remove(ref) {
this._set.delete(ref.toString());
}
[Symbol.iterator]() {
return this._set.values();
}
clear() {
this._set.clear();
}
}
class RefSetCache {
constructor() {
this._map = new Map();
}
get size() {
return this._map.size;
}
get(ref) {
return this._map.get(ref.toString());
}
has(ref) {
return this._map.has(ref.toString());
}
put(ref, obj) {
this._map.set(ref.toString(), obj);
}
putAlias(ref, aliasRef) {
this._map.set(ref.toString(), this.get(aliasRef));
}
[Symbol.iterator]() {
return this._map.values();
}
clear() {
this._map.clear();
}
}
function isName(v, name) {
return v instanceof Name && (name === undefined || v.name === name);
}
function isCmd(v, cmd) {
return v instanceof Cmd && (cmd === undefined || v.cmd === cmd);
}
function isDict(v, type) {
return (
v instanceof Dict && (type === undefined || isName(v.get("Type"), type))
);
}
function isRefsEqual(v1, v2) {
if (
typeof PDFJSDev === "undefined" ||
PDFJSDev.test("!PRODUCTION || TESTING")
) {
assert(
v1 instanceof Ref && v2 instanceof Ref,
"isRefsEqual: Both parameters should be `Ref`s."
);
}
return v1.num === v2.num && v1.gen === v2.gen;
}
function clearPrimitiveCaches() {
Cmd._clearCache();
Name._clearCache();
Ref._clearCache();
}
export {
CIRCULAR_REF,
clearPrimitiveCaches,
Cmd,
Dict,
EOF,
isCmd,
isDict,
isName,
isRefsEqual,
Name,
Ref,
RefSet,
RefSetCache,
};