GPTify sax library

src/vs/workbench/contrib/void/electron-main/llmMessage/sax.ts

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+/*--------------------------------------------------------------------------------------
+ *  Copyright 2025 Glass Devtools, Inc. All rights reserved.
+ *  Licensed under the Apache License, Version 2.0. See LICENSE.txt for more information.
+ *--------------------------------------------------------------------------------------*/
+
+// Define options for the parser.
+export interface SaxParserOptions {
+	lowercase?: boolean;
+}
+
+// Define the structure for a parsed node.
+export interface SaxNode {
+	name: string;
+	attributes: { [key: string]: string };
+}
+
+// Define the interface for the SAX-like parser.
+export interface SaxParser {
+	// Event handlers that can be set by the consumer.
+	onopentag: ((node: SaxNode) => void) | null;
+	ontext: ((text: string) => void) | null;
+	onclosetag: ((tagName: string) => void) | null;
+	// Properties to track current positions (used for raw text extraction).
+	startTagPosition: number;
+	position: number;
+	// Processes a new chunk of text.
+	write(chunk: string): void;
+}
+
+/**
+ * Creates a minimal, event-driven SAX-like parser.
+ *
+ * @param options An object of type `SaxParserOptions`. Passing `{ lowercase: true }` will force all tag names to be lower-cased.
+ * @returns A parser object implementing the `SaxParser` interface.
+ */
+export function createSaxParser(options: SaxParserOptions = {}): SaxParser {
+	// Buffer to hold any leftover text (part of an incomplete tag).
+	let buffer: string = '';
+	// Global counter to track the total processed characters.
+	let globalPos: number = 0;
+
+	const parser: SaxParser = {
+		onopentag: null,
+		ontext: null,
+		onclosetag: null,
+		startTagPosition: 0,
+		position: 0,
+
+		write(chunk: string): void {
+			// Set the starting position before processing the new chunk.
+			this.startTagPosition = globalPos;
+			buffer += chunk;
+			globalPos += chunk.length;
+			// Set the current position to the end of the processed chunk.
+			this.position = globalPos - 1;
+
+			let cursor: number = 0;
+			while (cursor < buffer.length) {
+				// Look for the next opening '<' character.
+				const ltIndex = buffer.indexOf('<', cursor);
+				if (ltIndex === -1) {
+					// No more tags found. Emit any remaining text as a text node.
+					if (cursor < buffer.length && this.ontext) {
+						this.ontext(buffer.substring(cursor));
+					}
+					// Clear the buffer once all content is processed.
+					buffer = '';
+					break;
+				}
+
+				// Emit any text that appears before the tag.
+				if (ltIndex > cursor && this.ontext) {
+					this.ontext(buffer.substring(cursor, ltIndex));
+				}
+
+				// Look for the closing '>' character.
+				const gtIndex = buffer.indexOf('>', ltIndex);
+				if (gtIndex === -1) {
+					// Incomplete tag detected—retain the remaining content in the buffer.
+					buffer = buffer.substring(ltIndex);
+					break;
+				}
+
+				// Extract the tag content (excluding the '<' and '>').
+				let tagContent = buffer.substring(ltIndex + 1, gtIndex).trim();
+				if (!tagContent) {
+					cursor = gtIndex + 1;
+					continue;
+				}
+
+				// Check if this is a closing tag (starts with '/').
+				if (tagContent[0] === '/') {
+					let tagName = tagContent.substring(1).trim();
+					if (options.lowercase && tagName) {
+						tagName = tagName.toLowerCase();
+					}
+					if (this.onclosetag) {
+						this.onclosetag(tagName);
+					}
+				} else {
+					// Check for self-closing tags (ending with '/').
+					let selfClosing = false;
+					if (tagContent[tagContent.length - 1] === '/') {
+						selfClosing = true;
+						tagContent = tagContent.slice(0, -1).trim();
+					}
+					// Determine the tag name (first word before whitespace).
+					const spaceIndex = tagContent.indexOf(' ');
+					let tagName = (spaceIndex !== -1 ? tagContent.substring(0, spaceIndex) : tagContent).trim();
+					if (options.lowercase && tagName) {
+						tagName = tagName.toLowerCase();
+					}
+					// Call onopentag with a minimal node object.
+					if (this.onopentag) {
+						const node: SaxNode = { name: tagName, attributes: {} };
+						this.onopentag(node);
+					}
+					// If the tag is self-closing, immediately emit the closing tag event.
+					if (selfClosing && this.onclosetag) {
+						this.onclosetag(tagName);
+					}
+				}
+				// Move the cursor past the current tag.
+				cursor = gtIndex + 1;
+			}
+		},
+	};
+
+	return parser;
+}