140 lines
5.3 KiB
JavaScript
140 lines
5.3 KiB
JavaScript
"use strict";
|
|
Object.defineProperty(exports, "__esModule", { value: true });
|
|
exports.PDFLoader = void 0;
|
|
const documents_1 = require("@langchain/core/documents");
|
|
const buffer_1 = require("langchain/document_loaders/fs/buffer");
|
|
/**
|
|
* A class that extends the `BufferLoader` class. It represents a document
|
|
* loader that loads documents from PDF files.
|
|
* @example
|
|
* ```typescript
|
|
* const loader = new PDFLoader("path/to/bitcoin.pdf");
|
|
* const docs = await loader.load();
|
|
* console.log({ docs });
|
|
* ```
|
|
*/
|
|
class PDFLoader extends buffer_1.BufferLoader {
|
|
constructor(filePathOrBlob, { splitPages = true, pdfjs = PDFLoaderImports, parsedItemSeparator = "", } = {}) {
|
|
super(filePathOrBlob);
|
|
Object.defineProperty(this, "splitPages", {
|
|
enumerable: true,
|
|
configurable: true,
|
|
writable: true,
|
|
value: void 0
|
|
});
|
|
Object.defineProperty(this, "pdfjs", {
|
|
enumerable: true,
|
|
configurable: true,
|
|
writable: true,
|
|
value: void 0
|
|
});
|
|
Object.defineProperty(this, "parsedItemSeparator", {
|
|
enumerable: true,
|
|
configurable: true,
|
|
writable: true,
|
|
value: void 0
|
|
});
|
|
this.splitPages = splitPages;
|
|
this.pdfjs = pdfjs;
|
|
this.parsedItemSeparator = parsedItemSeparator;
|
|
}
|
|
/**
|
|
* A method that takes a `raw` buffer and `metadata` as parameters and
|
|
* returns a promise that resolves to an array of `Document` instances. It
|
|
* uses the `getDocument` function from the PDF.js library to load the PDF
|
|
* from the buffer. It then iterates over each page of the PDF, retrieves
|
|
* the text content using the `getTextContent` method, and joins the text
|
|
* items to form the page content. It creates a new `Document` instance
|
|
* for each page with the extracted text content and metadata, and adds it
|
|
* to the `documents` array. If `splitPages` is `true`, it returns the
|
|
* array of `Document` instances. Otherwise, if there are no documents, it
|
|
* returns an empty array. Otherwise, it concatenates the page content of
|
|
* all documents and creates a single `Document` instance with the
|
|
* concatenated content.
|
|
* @param raw The buffer to be parsed.
|
|
* @param metadata The metadata of the document.
|
|
* @returns A promise that resolves to an array of `Document` instances.
|
|
*/
|
|
async parse(raw, metadata) {
|
|
const { getDocument, version } = await this.pdfjs();
|
|
const pdf = await getDocument({
|
|
data: new Uint8Array(raw.buffer),
|
|
useWorkerFetch: false,
|
|
isEvalSupported: false,
|
|
useSystemFonts: true,
|
|
}).promise;
|
|
const meta = await pdf.getMetadata().catch(() => null);
|
|
const documents = [];
|
|
for (let i = 1; i <= pdf.numPages; i += 1) {
|
|
const page = await pdf.getPage(i);
|
|
const content = await page.getTextContent();
|
|
if (content.items.length === 0) {
|
|
continue;
|
|
}
|
|
// Eliminate excessive newlines
|
|
// Source: https://github.com/albertcui/pdf-parse/blob/7086fc1cc9058545cdf41dd0646d6ae5832c7107/lib/pdf-parse.js#L16
|
|
let lastY;
|
|
const textItems = [];
|
|
for (const item of content.items) {
|
|
if ("str" in item) {
|
|
if (lastY === item.transform[5] || !lastY) {
|
|
textItems.push(item.str);
|
|
}
|
|
else {
|
|
textItems.push(`\n${item.str}`);
|
|
}
|
|
// eslint-disable-next-line prefer-destructuring
|
|
lastY = item.transform[5];
|
|
}
|
|
}
|
|
const text = textItems.join(this.parsedItemSeparator);
|
|
documents.push(new documents_1.Document({
|
|
pageContent: text,
|
|
metadata: {
|
|
...metadata,
|
|
pdf: {
|
|
version,
|
|
info: meta?.info,
|
|
metadata: meta?.metadata,
|
|
totalPages: pdf.numPages,
|
|
},
|
|
loc: {
|
|
pageNumber: i,
|
|
},
|
|
},
|
|
}));
|
|
}
|
|
if (this.splitPages) {
|
|
return documents;
|
|
}
|
|
if (documents.length === 0) {
|
|
return [];
|
|
}
|
|
return [
|
|
new documents_1.Document({
|
|
pageContent: documents.map((doc) => doc.pageContent).join("\n\n"),
|
|
metadata: {
|
|
...metadata,
|
|
pdf: {
|
|
version,
|
|
info: meta?.info,
|
|
metadata: meta?.metadata,
|
|
totalPages: pdf.numPages,
|
|
},
|
|
},
|
|
}),
|
|
];
|
|
}
|
|
}
|
|
exports.PDFLoader = PDFLoader;
|
|
async function PDFLoaderImports() {
|
|
try {
|
|
const { default: mod } = await import("pdf-parse/lib/pdf.js/v1.10.100/build/pdf.js");
|
|
const { getDocument, version } = mod;
|
|
return { getDocument, version };
|
|
}
|
|
catch (e) {
|
|
console.error(e);
|
|
throw new Error("Failed to load pdf-parse. Please install it with eg. `npm install pdf-parse`.");
|
|
}
|
|
}
|