LTCN

LTCN or "Lua Table Constructor Notation" is a Lua library for parsing and deserializing Lua table syntax via an LPeg grammar. It's intended to parse a safe subset of the Lua language and to replace many common use cases of the load function for reading data and configuration files.

Features

• Parses any Lua table constructor that consists of string, number or boolean keys and string, number, boolean or table values.
• Handles unescaping of escape sequences in string literals.
• Discards single-line comments and long comments.
• Permits a single return keyword before the outermost opening brace, to enable drop-in replacement of the load function.
• Provides useful error messages for syntax errors, including line and column numbers.

Requirements

• Lua >= 5.1 or LuaJIT >= 2.0
• LPeg >= 0.12

Installation

There's no versioned release yet, but for now the SCM rock can be installed with:

luarocks --server=https://luarocks.org/dev install ltcn

Features Not Implemented

Lua 5.2+ features

The following are features that were added to Lua after version 5.1 and are deliberately not supported to simplify cross-version compatibility:

• Hexadecimal floating point literals (e.g. 0x1.5p-3).
• Hexadecimal escape sequences in strings (e.g. "\xFF")
• Whitespace escape sequences in strings (e.g. "\z")
• Unicode escape sequences in strings (e.g. "\u{1F311}")

Beyond the scope of LTCN

The following are syntactical constructs of Lua that could theoretically be supported, but are considered beyond the scope of the project:

• Tables as keys (not useful without considerable extra functionality).
• Tables that require more than a simple constructor to initialize (e.g. those with self references, shared references etc.).
• Expression evaluation.
• Metatables, functions, conditionals, etc. (just use the Lua load function for this).

License

ISC License (SPDX: ISC).