A zero-dependency, zero-allocation UTF-16 ANSI and VT100/VT220/Xterm escape sequence parser for Java, engineered for ultra-high-performance TUI layouts, terminal graphics, and console telemetry pipelines.

FastANSI is the dedicated high-speed text processing substrate of the FastJava ecosystem. It introduces a highly optimized, stack-free procedural state machine designed to parse raw terminal output streams containing styles, cursor movements, and custom colors into structured cell representations at the physical hardware level.

By operating with absolutely exactly zero object allocations on the Java heap, FastANSI is 100% garbage-collection-free and suited to run in demanding, high-throughput console-composing pipelines.

// Quick Start — Example
import fastansi.FastANSI;

public class Demo {
    public static void main(String[] args) {
        String ansiStream = "Hello \033[1;31mRed Bold\033[0m Text!";

        FastANSI.parse(ansiStream, new FastANSI.ANSIListener() {
            @Override
            public void onText(CharSequence text, int start, int end) {
                System.out.println("Text: " + text.subSequence(start, end));
            }

            @Override
            public void onReset() {
                System.out.println("Reset Styles");
            }

            @Override
            public void onBold(boolean enable) {
                System.out.println("Bold: " + enable);
            }

            @Override
            public void onForegroundColor(int colorType, int r, int g, int b) {
                System.out.println("FG Color - Type: " + colorType + ", R:" + r);
            }

            // ... Implement other low-overhead cursor & mode callbacks
        });
    }
}

• Mission
• Key Features
• Performance
• API Quick Reference
• Installation
• Documentation
• Platform Support
• Modular Ecosystem
• License

The mission is to establish the fastest, most comprehensive escape sequence parser in the JVM universe. FastANSI enables terminal viewports to consume raw external ANSI dumps dynamically, process global terminal styling, and support custom 24-bit True Color rendering with zero garbage collection overhead.

• 🚫 Zero Dependencies — Completely standalone, lightweight, pure Java 17 library.
• ⚡ Zero Heap Allocation — Renders cell properties purely using coordinate pointers (start, end) and primitives, avoiding all standard String splits or regex overhead.
• 🎨 Complete Color & Style Support — Full parsing of standard SGR parameters (bold, italic, underlines, standard 4-bit, 8-bit index, and 24-bit True Color RGB).
• 📏 Cursor & Erase Commands — Recognizes all standard VT navigation codes (Cursor up/down/forward/backward, cursor absolute, display/line erasing).
• 📺 Private & OSC Operating Modes — Detects alternate screen buffers (?1049h/l), cursor display toggles (?25h/l), and window title adjustments via Operating System Commands (OSC).

FastANSI is designed to process massive text buffers exponentially faster than traditional regex-based parser frameworks:

FastANSI is pure-Java and has zero external dependencies.

Add the JitPack repository and the dependency inside your pom.xml:

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

<dependencies>
    <dependency>
        <groupId>com.github.andrestubbe</groupId>
        <artifactId>FastANSI</artifactId>
        <version>v0.1.0</version>
    </dependency>
</dependencies>

Add this to your build.gradle file:

repositories {
    maven { url 'https://jitpack.io' }
}

dependencies {
    implementation 'com.github.andrestubbe:FastANSI:v0.1.0'
}

Download the pre-compiled JAR directly to add to your project's classpath:

• 📦 fastansi-v0.1.0.jar (Core Library)

• REFERENCE.md: Exhaustive catalog of SGR styles, OSC window parameters, and callback contracts.
• PHILOSOPHIE.md: Zero-allocation and low-overhead processing designs.
• ROADMAP.md: Planned milestone features and performance extensions.

FastANSI acts as the high-speed text stream processor across the FastJava line:

• FastTerminal — Multi-buffered True-Color console terminal rendering.

MIT License — See LICENSE file for details.

Part of the FastJava Ecosystem — Making the JVM faster.

Made with ⚡ by Andre Stubbe