Text.Parsec.Indent
- type IndentParserT s u m a = ParsecT s u (StateT SourcePos m) a
- block :: (Stream s (StateT SourcePos m) Char, Monad m) => IndentParserT s u m a -> IndentParserT s u m [a]
- lineFold :: (Stream s (StateT SourcePos m) Char, Monad m) => IndentParserT s u m a -> IndentParserT s u m [a]
- manyLine :: (Stream s (StateT SourcePos m) Char, Monad m) => IndentParserT s u m a -> IndentParserT s u m [a]
- runIndent :: Monad m => SourceName -> StateT SourcePos m a -> m a
Documentation
type IndentParserT s u m a = ParsecT s u (StateT SourcePos m) aSource
A module to construct indentation aware parsers. Many programming language have indentation based syntax rules e.g. python and Haskell. This module exports combinators to create such parsers.
The input source can be thought of as a list of tokens. Abstractly each token occurs at a line and a column and has a width. The column number of a token measures is indentation. If t1 and t2 are two tokens then we say that indentation of t1 is more than t2 if the column number of occurrence of t1 is greater than that of t2.
Currently this module supports two kind of indentation based syntactic structures which we now describe:
- Block
- A block of indentation c is a sequence of tokens with indentation at least c. Examples for a block is a where clause of Haskell with no explicit braces.
- Line fold
- A line fold starting at line l and indentation c is a sequence of tokens that start at line l and possibly continue to subsequent lines as long as the indentation is greater than c. Such a sequence of lines need to be folded to a single line. An example is MIME headers. Line folding based binding separation is used in Haskell as well.
block :: (Stream s (StateT SourcePos m) Char, Monad m) => IndentParserT s u m a -> IndentParserT s u m [a]Source
Parses a block of lines at the same indentation level
lineFold :: (Stream s (StateT SourcePos m) Char, Monad m) => IndentParserT s u m a -> IndentParserT s u m [a]Source
Continues parsing indented below a line
manyLine :: (Stream s (StateT SourcePos m) Char, Monad m) => IndentParserT s u m a -> IndentParserT s u m [a]Source
Parses many occurances of p without using more than one line