Agda-2.3.2: A dependently typed functional programming language and proof assistant

Safe Haskell | None

Agda.Syntax.Parser.Comments

Description

This module defines the lex action to lex nested comments. As is well-known this cannot be done by regular expressions (which, incidently, is probably the reason why C-comments don't nest).

When scanning nested comments we simply keep track of the nesting level, counting up for open comments and down for close comments.

Synopsis

- keepComments :: LexPredicate
- keepCommentsM :: Parser Bool
- nestedComment :: LexAction Token
- hole :: LexAction Token
- skipBlock :: String -> String -> LookAhead ()

# Documentation

keepComments :: LexPredicate

Should comment tokens be output?

keepCommentsM :: Parser Bool

Should comment tokens be output?

nestedComment :: LexAction Token

Manually lexing a block comment. Assumes an open comment has been lexed. In the end the comment is discarded and `lexToken` is called to lex a real token.

hole :: LexAction Token

Lex a hole (`{! ... !}`). Holes can be nested. Returns ``TokSymbol` `SymQuestionMark``.

skipBlock :: String -> String -> LookAhead ()

Skip a block of text enclosed by the given open and close strings. Assumes the first open string has been consumed. Open-close pairs may be nested.