Description

type2 is a slow, but versatile parser for context free languages (type 2 in the Chomsky hierarchy).

Being fed with a JSON file, specifying the language and a string via stdin, it decomposes the input, analyzes it and spits out its corresponding abstract syntax tree on stdout.

A typical call looks like this: type2 language.tp2.json < input.txt

Language specification

A language is specified by a JSON file containing a value of the following type:

record<
	lexer_rules:list<
		record<
			type:string,
			parameters:map<string,any>
		>
	>,
	parser_rules:list<
		record<
			label:string,
			premise:string,
			conclusion:list<
				record<
					type:string,
					parameters:map<string,any>
				>
			>
		>
	>,
	parser_start:string
>

The recommended extension for such files is .tp2.json.

Lexer rule types

type	meaning	parameters
ignore	disregard matching strings	pattern
void	do not assign a value to matching strings	pattern,id
boolean	interpret matching strings as boolean values	pattern,id,value
int	interpret matching strings as integer number values	pattern,id
float	interpret matching strings as floating point number values	pattern,id
string	interpret matching strings as string values	pattern,id

Conclusion element types

type	meaning	parameters
terminal		id
variable		id