A high-performance, memory-free JSON parser for MQL5, based on a flat tape architecture.<br/> Single-pass iterative state machine (as is, without extra loops, "pure" o(n)): no recursion, no dynamic memory fragmentation, no overhead from function calls.
2026-06-03 09:20:57 -05:00
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---
## Main Features
- **Tape-based zero-alloc model**: the entire JSON is parsed into a single contiguous `long[]` array
- **Single flat loop**: one `switch` over a token enum, no helper function calls during parsing, strictly O(n)
- **FNV-1a key hashing**: key lookup in objects without string comparison
- **Handle-based navigation**: `CJsonNode` is a lightweight struct (pointer + two ints), copying is free
- **In-place mutation**: `SetInt`, `SetDbl`, `SetBool` modify the tape directly without re-parsing
- **Iterator support**: `CJsonIteratorObj` and `CJsonIteratorArray` for clean traversal
The gap comes from architecture, not micro-optimizations: one flat loop vs. a state machine with separate helper calls and per-iteration reserve checks.
---
## Repository Structure
```
JsonParserByLeo/
├── Src/ # Full code (Defines, Node, Parser)
└── Test/ # Test and Benchmarks (vs)
```
---
## License
**[Read Full License](./LICENSE)**
By downloading or using this repository, you accept the license terms.
---
## Requirements
See [dependencies.json](./dependencies.json) for the full list.
---
## Installation
```bash
cd "C:\Users\YOUR_USER\AppData\Roaming\MetaQuotes\Terminal\YOUR_ID\MQL5\Shared Projects"
Requires the `tsndep` package, available on [PyPI](https://pypi.org/project/tsndep). It automatically downloads and installs all declared dependencies.
---
## Quick Start
**1. Include the library:**
```mql5
#include "..\\JsonParserByLeo\\Src\\JsonNode.mqh"
```
**2. Parse and access:**
```mql5
TSN::CJsonParser parser;
parser.Assing(my_json_string);
if(parser.Parse())
{
TSN::CJsonNode root = parser.GetRoot();
double price = root["price"].ToDouble(0.0);
}
```
**3. Re-parse without re-copying (benchmark pattern):**
