fast_json - MQL5 High-Performance JSON Library (The "Bit-Banger" Edition V2)

"If your JSON parser needs recursion, you're doing it wrong."

Overview

fast_json is a production-grade, high-performance JSON library for MQL5, designed for high-frequency trading (HFT) environments where latency and memory fragmentation are critical.

Unlike standard libraries that abuse the heap with endless small allocations, fast_json uses a tape-based zero-allocation memory model and a SWAR (SIMD within a Register) scanner to parse gigabytes of data without triggering the garbage collector (or the equivalent memory pressure in MQL5).

Key Features

🚀 Zero-Alloc Tape Architecture: Parses the entire JSON into a single contiguous integer array (the "tape"). No objects are created during parsing.
⚡ SWAR Acceleration: Uses bit-manipulation hacks (Simulated 64-bit SWAR) to scan 8 bytes at a time for structural characters, drastically reducing branch misprediction.
🛡️ Stack-Safe Iterative Parser: Written as a finite state machine. Zero recursion. Immune to stack overflow attacks from deeply nested JSONs.
🔧 Handle-Based Navigation: Access data using lightweight CJsonNode structs that point to the tape. Copying nodes is free.
💾 Bit-Banged Serialization: Writing JSON is just as fast, filling a pre-allocated buffer with raw byte operations.

Performance

Metric	fast_json	Standard Libs
Allocation Strategy	1 big block (Tape)	N objects per node
Recursion Depth	Unlimited (Heap stack)	Limited (Call stack)
Parsing Speed	~300MB/s (Est.)	Snail pace
Memory Frag	Near Zero	High

Usage

Parsing

#include "fast_json.mqh"

CJsonContext ctx;
if (ctx.Parse(json_string)) {
    CJsonNode root = ctx.GetRoot();
    Print(root["price"].ToDouble());
} else {
    Print("Error: ", ctx.error_msg);
}

Building & Serializing

// Implicit serialization is supported via direct buffer writing
// (See implementation for details - this is for pros)

Why MQL5?

Because we trade here. And we don't tolerate latency.

License

MIT. Use it, profit, but don't blame me if your strategy fails.

2.2 KiB Raw 고유링크 Blame 히스토리