amb-parser: Parser generator for ambiguous grammars🔗 i

1Introduction🔗 i

This is a very simple parser generator that mimics brag (and actually its built on top of it). It is designed for parsing English text.

I don’t know whether the implementation works correctly.

2Parser language🔗 i

Note: the parser does not support left-recursion. (Yet Another Parser that Doesn’t Support Left Recursion, yapdslr).

Note: the parser does not support grouping.

Note: you are allowed to combine question and star operators only in the order: rule*?.

3Parser interface🔗 i

• Firstly, import amb-parser in your Racket module.

• Then create a file with

  #lang amb-parser

  line and with your grammar and require it in your Racket module.

You will be provided with the parse function. You can use this function to parse your text. But before, your text should be separated into tokens.

For more details, refer to the parse documentation.

4Usage example🔗 i

Note how the star rule works.

5Parse tree structure🔗 i

In this section we will describe the structure of the parse tree without specifying that the parser returns multiple results and every parser-result contains the rest of tokens.

• Every rule name : expansion; will be parsed as (name expansion).

• Every expansion rule1 rule2 will be parsed as an association list, where keys and values are organized as list with two elements, keys are rule names and values are the result of parsing the rules.

• Every terminal terminal will be parsed as (list ’terminal token-str) where token-str is the string of the matched token.

If some parsing is failed then the parse returns empty (meaning there is no derivation trees and no parser results).

6Types and functions🔗 i