JSON was boring so I made this
 

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MLEM is a human-oriented data format designed for readable and moddable configuration files and data.

This project was made for fun and is still in development. Expect bugs, changes and incomplete features. Please report any misbehavior

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Why not JSON or YAML ?

MLEM aims to provide a middle ground between JSON and YAML, less syntax-heavy than JSON, more predictable than YAML, and offers an alternative designed for human-written data.

The parser is currently only available in C, a port to C++ might happen in the future.

Any feedback or contributions are welcome!

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Goals

MLEM is designed for:

• Configuration files
• Game/modding data
• Human-edited data structures
• Lightweight C projects
   

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Features

• Minimal and readable syntax
• JSON-like data model, able to parse JSON and JSON5 files
• A fast single-pass parser written in C
• A small API to manipulate the data MLEM parses
• A serializer that tries its best to keep your values as they were originally

Syntax

• Newlines, indentation, commas and spacing don't matter.
• Most values are case-insensitive.
• Strings do not require quotes unless they contain spaces or special characters.
• Square brackets [] can be used for both arrays and objects. MLEM will automatically determine the intended structure.
• Equals = are used to determine key-value pairs.
• Comments starts with //, or /// on both ends for multiline comments.

Types

Of course, MLEM supports all the standard JSON types, plus some extras.

Type	C value	Example
Integer	int64_t	1, -3, 0xFFAA85, 3625304601213135
Float	double	3.14, -.6, 1.87e-3
String	char*	"Hello!" Not_even_quoted 'Spaced text\n'
Boolean	bool	True, False
Array	t_mlem_value[]	["MLEM" wow 147]
Object	t_mlem_pair[]	[key = value enabled = true] {other : format}
Constant	varies	NaN, Inf, Null
Reference	t_mlem_reference*	#reference
Template (WIP)	t_mlem_template*	<required INT[0 1] [ON OFF] = 1>

More information about types and syntax can be found on the wiki.

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Example

Here's what MLEM looks like:

// World settings
world = [
	name = MyWorld
	seed = 12345
	hard_mode = true
	playtime = 1.56
	
	spawn_point = [
		x = 128
		y = 64
	]
	players = [JohnZ lily123 _Horse]
]

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Usage

First of all, clone the repository and build it.

git clone git@github.com:DaemonicGh/MLEM.git MLEM
make -C MLEM

You can then include the header MLEM/include/mlem.h in your project.

Here's a simple example:

#include <stdio.h>
#include "mlem.h"

int	main(void) {
	t_mlem_value	constants;
	t_mlem_value	value;

	constants = mlem_parse("constants.mlem", NULL, (t_mlem_value){0});
	value = mlem_parse("example.mlem", NULL, constants);
	printf("Parsed value:\n");
	mlem_print(stdout, value);
	if (value.type)
	{
		// Assuming the mlem file is properly formatted
		t_mlem_value	cat = mlem_object_get(value, "cat");
		printf("The cat's name is %s\n", mlem_object_get(cat, "name").strv.value);
	}
	mlem_destroy(value);
	mlem_destroy(constants);
	return (0);
}

More information about the internals and API can be found on the wiki.