megaparsec/Text/Megaparsec.hs

-- |
-- Module      :  Text.Megaparsec
-- Copyright   :  © 2015 Megaparsec contributors
--                © 2007 Paolo Martini
--                © 1999–2001 Daan Leijen
-- License     :  BSD3
--
-- Maintainer  :  Mark Karpov <markkarpov@opmbx.org>
-- Stability   :  experimental
-- Portability :  portable
--
-- This module includes everything you need to get started writing a parser.
--
-- By default this module is set up to parse character data. If you'd like to
-- parse the result of your own tokenizer you should start with the following
-- imports:
--
-- > import Text.Megaparsec.Prim
-- > import Text.Megaparsec.Combinator
--
-- Then you can implement your own version of 'satisfy' on top of the
-- 'tokenPrim' primitive.
--
-- Typical import section looks like this:
--
-- > import Text.Megaparsec
-- > import Text.Megaparsec.String
-- > -- import Text.Megaparsec.ByteString
-- > -- import Text.Megaparsec.ByteString.Lazy
-- > -- import Text.Megaparsec.Text
-- > -- import Text.Megaparsec.Text.Lazy
--
-- As you can see the second import depends on data type you want to use as
-- input stream. It just defines useful type-synonyms @Parser@ and
-- @GenParser@ and @parseFromFile@ function.
--
-- Megaparsec is capable of a lot. Apart from this standard functionality
-- you can parse permutation phrases with "Text.Megaparsec.Perm" and even
-- entire languages with "Text.Megaparsec.Token". These modules should be
-- imported explicitly along with two modules mentioned above.

module Text.Megaparsec
  ( -- * Running parser
    Parsec
  , ParsecT
  , runParser
  , runParserT
  , parse
  , parse'
  , parseTest
    -- * Backtracking user state
  , getState
  , setState
  , modifyState
    -- * Combinators
  , (A.<|>)
  -- $assocbo
  , A.many
  -- $many
  , A.some
  -- $some
  , A.optional
  -- $optional
  , unexpected
  , (<?>)
  , label
  , hidden
  , try
  , lookAhead
  , notFollowedBy
  , eof
  , token
  , tokens
  , between
  , chainl
  , chainl1
  , chainr
  , chainr1
  , choice
  , count
  , count'
  , endBy
  , endBy1
  , manyTill
  , someTill
  , option
  , sepBy
  , sepBy1
  , sepEndBy
  , sepEndBy1
  , skipMany
  , skipSome
    -- * Character parsing
  , newline
  , crlf
  , eol
  , tab
  , space
  , controlChar
  , spaceChar
  , upperChar
  , lowerChar
  , letterChar
  , alphaNumChar
  , printChar
  , digitChar
  , octDigitChar
  , hexDigitChar
  , markChar
  , numberChar
  , punctuationChar
  , symbolChar
  , separatorChar
  , asciiChar
  , latin1Char
  , charCategory
  , char
  , anyChar
  , oneOf
  , noneOf
  , satisfy
  , string
    -- * Error messages
  , Message (..)
  , messageString
  , badMessage
  , ParseError
  , errorPos
  , errorMessages
  , errorIsUnknown
    -- * Position
  , SourcePos
  , SourceName
  , Line
  , Column
  , sourceName
  , sourceLine
  , sourceColumn
    -- * Low-level operations
  , Stream (..)
  , Consumed (..)
  , Reply (..)
  , State (..)
  , getPosition
  , setPosition
  , getInput
  , setInput
  , getParserState
  , setParserState
  , updateParserState )
where

import qualified Control.Applicative as A

import Text.Megaparsec.Char
import Text.Megaparsec.Combinator
import Text.Megaparsec.Error
import Text.Megaparsec.Pos
import Text.Megaparsec.Prim

-- $assocbo
--
-- This combinator implements choice. The parser @p \<|> q@ first applies
-- @p@. If it succeeds, the value of @p@ is returned. If @p@ fails
-- /without consuming any input/, parser @q@ is tried.
--
-- The parser is called /predictive/ since @q@ is only tried when parser @p@
-- didn't consume any input (i.e. the look ahead is 1). This
-- non-backtracking behaviour allows for both an efficient implementation of
-- the parser combinators and the generation of good error messages.

-- $many
--
-- @many p@ applies the parser @p@ /zero/ or more times. Returns a list of
-- the returned values of @p@.
--
-- > identifier = (:) <$> letter <*> many (alphaNum <|> char '_')

-- $some
--
-- @some p@ applies the parser @p@ /one/ or more times. Returns a list of
-- the returned values of @p@.
--
-- > word = some letter

-- $optional
--
-- @optional p@ tries to apply parser @p@. It will parse @p@ or nothing. It
-- only fails if @p@ fails after consuming input. On success result of @p@
-- is returned inside of 'Just', on failure 'Nothing' is returned.