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Covert the ObjectLoader to a "normal" class

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This commit is contained in:
Jonas Jenwald 2021-04-13 18:25:42 +02:00
parent 604cd6d600
commit 6a935682fd
1 changed files with 112 additions and 117 deletions
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229
src/core/object_loader.js
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@ -17,6 +17,30 @@ import { Dict, isStream, Ref, RefSet } from "./primitives.js";
import { MissingDataException } from "./core_utils.js";
import { warn } from "../shared/util.js";
function mayHaveChildren(value) {
return (
value instanceof Ref ||
value instanceof Dict ||
Array.isArray(value) ||
isStream(value)
);
}
function addChildren(node, nodesToVisit) {
if (node instanceof Dict) {
node = node.getRawValues();
} else if (isStream(node)) {
node = node.dict.getRawValues();
} else if (!Array.isArray(node)) {
return;
}
for (const rawValue of node) {
if (mayHaveChildren(rawValue)) {
nodesToVisit.push(rawValue);
}
}
}
/**
* A helper for loading missing data in `Dict` graphs. It traverses the graph
* depth first and queues up any objects that have missing data. Once it has
@ -28,130 +52,101 @@ import { warn } from "../shared/util.js";
* that have references to the catalog or other pages since that will cause the
* entire PDF document object graph to be traversed.
*/
const ObjectLoader = (function () {
function mayHaveChildren(value) {
return (
value instanceof Ref ||
value instanceof Dict ||
Array.isArray(value) ||
isStream(value)
);
}
function addChildren(node, nodesToVisit) {
if (node instanceof Dict) {
node = node.getRawValues();
} else if (isStream(node)) {
node = node.dict.getRawValues();
} else if (!Array.isArray(node)) {
return;
}
for (const rawValue of node) {
if (mayHaveChildren(rawValue)) {
nodesToVisit.push(rawValue);
}
}
}
// eslint-disable-next-line no-shadow
function ObjectLoader(dict, keys, xref) {
class ObjectLoader {
constructor(dict, keys, xref) {
this.dict = dict;
this.keys = keys;
this.xref = xref;
this.refSet = null;
}
ObjectLoader.prototype = {
async load() {
// Don't walk the graph if all the data is already loaded; note that only
// `ChunkedStream` instances have a `allChunksLoaded` method.
if (
!this.xref.stream.allChunksLoaded ||
this.xref.stream.allChunksLoaded()
) {
return undefined;
}
const { keys, dict } = this;
this.refSet = new RefSet();
// Setup the initial nodes to visit.
const nodesToVisit = [];
for (let i = 0, ii = keys.length; i < ii; i++) {
const rawValue = dict.getRaw(keys[i]);
// Skip nodes that are guaranteed to be empty.
if (rawValue !== undefined) {
nodesToVisit.push(rawValue);
}
}
return this._walk(nodesToVisit);
},
async _walk(nodesToVisit) {
const nodesToRevisit = [];
const pendingRequests = [];
// DFS walk of the object graph.
while (nodesToVisit.length) {
let currentNode = nodesToVisit.pop();
// Only references or chunked streams can cause missing data exceptions.
if (currentNode instanceof Ref) {
// Skip nodes that have already been visited.
if (this.refSet.has(currentNode)) {
continue;
}
try {
this.refSet.put(currentNode);
currentNode = this.xref.fetch(currentNode);
} catch (ex) {
if (!(ex instanceof MissingDataException)) {
warn(`ObjectLoader._walk - requesting all data: "${ex}".`);
this.refSet = null;
const { manager } = this.xref.stream;
return manager.requestAllChunks();
}
nodesToRevisit.push(currentNode);
pendingRequests.push({ begin: ex.begin, end: ex.end });
}
}
if (currentNode && currentNode.getBaseStreams) {
const baseStreams = currentNode.getBaseStreams();
let foundMissingData = false;
for (let i = 0, ii = baseStreams.length; i < ii; i++) {
const stream = baseStreams[i];
if (stream.allChunksLoaded && !stream.allChunksLoaded()) {
foundMissingData = true;
pendingRequests.push({ begin: stream.start, end: stream.end });
}
}
if (foundMissingData) {
nodesToRevisit.push(currentNode);
}
}
addChildren(currentNode, nodesToVisit);
}
if (pendingRequests.length) {
await this.xref.stream.manager.requestRanges(pendingRequests);
for (let i = 0, ii = nodesToRevisit.length; i < ii; i++) {
const node = nodesToRevisit[i];
// Remove any reference nodes from the current `RefSet` so they
// aren't skipped when we revist them.
if (node instanceof Ref) {
this.refSet.remove(node);
}
}
return this._walk(nodesToRevisit);
}
// Everything is loaded.
this.refSet = null;
async load() {
// Don't walk the graph if all the data is already loaded; note that only
// `ChunkedStream` instances have a `allChunksLoaded` method.
if (
!this.xref.stream.allChunksLoaded ||
this.xref.stream.allChunksLoaded()
) {
return undefined;
},
};
}
return ObjectLoader;
})();
const { keys, dict } = this;
this.refSet = new RefSet();
// Setup the initial nodes to visit.
const nodesToVisit = [];
for (let i = 0, ii = keys.length; i < ii; i++) {
const rawValue = dict.getRaw(keys[i]);
// Skip nodes that are guaranteed to be empty.
if (rawValue !== undefined) {
nodesToVisit.push(rawValue);
}
}
return this._walk(nodesToVisit);
}
async _walk(nodesToVisit) {
const nodesToRevisit = [];
const pendingRequests = [];
// DFS walk of the object graph.
while (nodesToVisit.length) {
let currentNode = nodesToVisit.pop();
// Only references or chunked streams can cause missing data exceptions.
if (currentNode instanceof Ref) {
// Skip nodes that have already been visited.
if (this.refSet.has(currentNode)) {
continue;
}
try {
this.refSet.put(currentNode);
currentNode = this.xref.fetch(currentNode);
} catch (ex) {
if (!(ex instanceof MissingDataException)) {
warn(`ObjectLoader._walk - requesting all data: "${ex}".`);
this.refSet = null;
const { manager } = this.xref.stream;
return manager.requestAllChunks();
}
nodesToRevisit.push(currentNode);
pendingRequests.push({ begin: ex.begin, end: ex.end });
}
}
if (currentNode && currentNode.getBaseStreams) {
const baseStreams = currentNode.getBaseStreams();
let foundMissingData = false;
for (let i = 0, ii = baseStreams.length; i < ii; i++) {
const stream = baseStreams[i];
if (stream.allChunksLoaded && !stream.allChunksLoaded()) {
foundMissingData = true;
pendingRequests.push({ begin: stream.start, end: stream.end });
}
}
if (foundMissingData) {
nodesToRevisit.push(currentNode);
}
}
addChildren(currentNode, nodesToVisit);
}
if (pendingRequests.length) {
await this.xref.stream.manager.requestRanges(pendingRequests);
for (let i = 0, ii = nodesToRevisit.length; i < ii; i++) {
const node = nodesToRevisit[i];
// Remove any reference nodes from the current `RefSet` so they
// aren't skipped when we revist them.
if (node instanceof Ref) {
this.refSet.remove(node);
}
}
return this._walk(nodesToRevisit);
}
// Everything is loaded.
this.refSet = null;
return undefined;
}
}
export { ObjectLoader };