EBNF and Particple
I have been using the https://github.com/alecthomas/participle library for parsing a plain text accounting format and have learnt somethings. I decided to use the library rather than write my own parser as I am planning to extend the langauge with a number of new directives and wanted a good framework to describe and parse these.
I have learnt a number of things:
- indented syntax
- debugging
- strings
Indented syntax
Plain text account format uses indentation to describe blocks. In order to make this work with a Lexer and a Parser, a good solution is to have a pre lexer that converts the indentation to IDENT and DEDENT tokens.
For an example see the indentLexer in https://github.com/drummonds/luca/blob/master/internal/parser/parser.go.
Debugging
I found it worth creating a debugging parser that would turn on debugging and crucially let me look at the result of the tokenizer.
Strings
My first string parser return the whole string including the delimiters which was quite ugly. To get round this I used Claude which