🏷️ tagparse

Only suppports ESM

tagparse is a high-performance, stream-based lexer and parser library for Node.js, designed to handle asynchronous, memory-efficient parsing of custom tag-based syntax. It’s ideal for high-concurrency applications and real-time data processing where non-blocking, scalable parsing is essential.

Use Case: Quickly parse and process custom tags (e.g., {variable}, {function:arg1|arg2}) for templating engines, dashboards, and real-time applications.

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✨ Features

• Custom Tag Parsing: Handles tags with complex argument structures (e.g., {var}, {func:arg1|arg2}).
• Stream-Based, Asynchronous Design: Perfect for processing large datasets with minimal memory usage, supporting real-time and high-concurrency environments.
• Strict Mode for Syntax Validation: Ensures robust syntax adherence with optional strict validation.
• Flexible & Extensible: Customize tokens, tag formats, and parsing logic as needed.
• Ideal for Real-Time Applications: Powers templating engines, dynamic dashboards, and high-performance real-time data processing.

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📦 Installation

Install via npm:

npm install tagparse

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🚀 Usage

tagparse is particularly useful for custom syntax processing in templating engines, real-time chat systems, or data stream processing applications.

🛠️ Basic Example

import { Lexer, Parser, NodeType } from "tagparse";

const inputText = "Hello {user}, your balance is {balance}!";

// Step 1: Initialize the Parser
const parser = new Parser(inputText, {
    lexerOptions: { tagStart: "{{", tagEnd: "}}" },
    parseTags: true,
    strict: true,
});

// Step 2: Parse the text
(async () => {
    const nodes = await parser.parse();
    console.log(nodes); // Parsed tokens and nodes
})();

🔧 Customizing Tags and Syntax

Easily define custom tag formats, enable strict mode for syntax validation, and configure tag handling:

const parser = new Parser("Hello {{user}}", {
    lexerOptions: { tagStart: "{{", tagEnd: "}}" },
    parseTags: true,
    strict: true,
});

📄 Example Use Case: Template Processing

This example demonstrates how to use the parser to replace placeholders dynamically within a template:

(async () => {
    const values = {
        name: "John",
        orderId: "12345",
    };

    const parser = new Parser(inputText);
    const nodes = await parser.parse();

    // Implement an on-the-go interpreter via `variableParser` & `functionParser`
    const result = nodes
        .map((node) => {
            if (node.type === NodeType.Variable && node.raw in values) {
                return values[node.raw];
            }
            return node.value;
        })
        .join("");

    console.log(result); // Outputs: "Hello, John! Your order #12345 is confirmed."
})();

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📚 API Reference

Lexer

The Lexer class tokenizes a given input string, identifying tags, literals, and other specified tokens.

• Constructor: new Lexer(input: string, options: LexerOptions)
  • input: The string to tokenize.
  • options: Configuration options, like tagStart and tagEnd.

Parser

The Parser class consumes tokens from the lexer and constructs a structured representation of the text (AST).

• Constructor: new Parser(input: string, options: ParserOptions)

  • input: The input text.
  • options: Configuration options, including:
    • parseTags: Enable/disable tag parsing.
    • strict: Enable strict mode for syntax validation.
    • functionParser and variableParser: Optional handlers for custom tag logic.

• Methods:

  • parse(): Asynchronously parses the input and returns an array of nodes.

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🤝 Contributing

Contributions are welcomed! If you find a bug or want to suggest an improvement, feel free to open an issue or submit a pull request.

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📄 License

This library is licensed under the MIT License. See LICENSE for more information.

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🙏 Acknowledgments

Special thanks to @aelxxs/ikigai for inspiration.