Text.ParserCombinators.Poly.StateLazy

polyparse-1.13: A variety of alternative parser combinator libraries.

Safe Haskell | None
Language | Haskell98

Text.ParserCombinators.Poly.StateLazy

Contents

- The Parser datatype
  - Basic parsers
  - State-handling
  - Re-parsing
- Re-export all more general combinators

Synopsis

- newtype Parser s t a = P (Parser s t a)
- data Result z a
  - = Success z a
  - | Failure z String
  - | Committed (Result z a)
- runParser :: Parser s t a -> s -> [t] -> (a, s, [t])
- next :: Parser s t t
- eof :: Parser s t ()
- satisfy :: (t -> Bool) -> Parser s t t
- onFail :: Parser s t a -> Parser s t a -> Parser s t a
- manyFinally :: Parser s t a -> Parser s t z -> Parser s t [a]
- stUpdate :: (s -> s) -> Parser s t ()
- stQuery :: (s -> a) -> Parser s t a
- stGet :: Parser s t s
- reparse :: [t] -> Parser s t ()
- many1 :: PolyParse p => p a -> p [a]
- sepBy :: PolyParse p => p a -> p sep -> p [a]
- sepBy1 :: PolyParse p => p a -> p sep -> p [a]
- apply :: PolyParse p => p (a -> b) -> p a -> p b
- bracket :: PolyParse p => p bra -> p ket -> p a -> p a
- indent :: Int -> String -> String
- exactly :: PolyParse p => Int -> p a -> p [a]
- class Commitment (p :: Type -> Type) where
  - commit :: p a -> p a
  - adjustErr :: p a -> (String -> String) -> p a
  - oneOf' :: [(String, p a)] -> p a
- class (Functor p, Monad p, MonadFail p, Applicative p, Alternative p, Commitment p) => PolyParse (p :: Type -> Type)
- discard :: PolyParse p => p a -> p b -> p a
- failBad :: PolyParse p => String -> p a
- adjustErrBad :: PolyParse p => p a -> (String -> String) -> p a
- oneOf :: PolyParse p => [p a] -> p a
- upto :: PolyParse p => Int -> p a -> p [a]
- bracketSep :: PolyParse p => p bra -> p sep -> p ket -> p a -> p [a]
- manyFinally' :: (PolyParse p, Show a) => p a -> p z -> p [a]
- module Control.Applicative

# The Parser datatype

newtype Parser s t a #

The only differences between a State and a StateLazy parser are the instance of Applicative, and the type (and implementation) of runParser. We therefore need to newtype the original Parser type, to allow it to have a different instance.

Constructors

P (Parser s t a) |

#### Instances

Instances details

Alternative (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateLazy Methods empty :: Parser s t a # (<|>) :: Parser s t a -> Parser s t a -> Parser s t a # some :: Parser s t a -> Parser s t [a] # many :: Parser s t a -> Parser s t [a] #
Applicative (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateLazy Methods pure :: a -> Parser s t a # (<*>) :: Parser s t (a -> b) -> Parser s t a -> Parser s t b # liftA2 :: (a -> b -> c) -> Parser s t a -> Parser s t b -> Parser s t c # (*>) :: Parser s t a -> Parser s t b -> Parser s t b # (<*) :: Parser s t a -> Parser s t b -> Parser s t a #
Functor (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateLazy Methods fmap :: (a -> b) -> Parser s t a -> Parser s t b # (<$) :: a -> Parser s t b -> Parser s t a #
Monad (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateLazy Methods (>>=) :: Parser s t a -> (a -> Parser s t b) -> Parser s t b # (>>) :: Parser s t a -> Parser s t b -> Parser s t b # return :: a -> Parser s t a #
MonadFail (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateLazy Methods fail :: String -> Parser s t a #
Commitment (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateLazy Methods commit :: Parser s t a -> Parser s t a # adjustErr :: Parser s t a -> (String -> String) -> Parser s t a # oneOf' :: [(String, Parser s t a)] -> Parser s t a #
PolyParse (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateLazy

data Result z a #

A return type like Either, that distinguishes not only between right and wrong answers, but also has commitment, so that a failure cannot be undone. This should only be used for writing very primitive parsers - really it is an internal detail of the library. The z type is the remaining unconsumed input.

Constructors

Success z a |
Failure z String |
Committed (Result z a) |

#### Instances

Instances details

Functor (Result z) # |
Instance details Defined in Text.ParserCombinators.Poly.Result Methods fmap :: (a -> b) -> Result z a -> Result z b # (<$) :: a -> Result z b -> Result z a #

runParser :: Parser s t a -> s -> [t] -> (a, s, [t]) #

Apply a parser to an input token sequence.

## Basic parsers

next :: Parser s t t #

Simply return the next token in the input tokenstream.

eof :: Parser s t () #

Succeed if the end of file/input has been reached, fail otherwise.

satisfy :: (t -> Bool) -> Parser s t t #

Return the next token if it satisfies the given predicate.

onFail :: Parser s t a -> Parser s t a -> Parser s t a #

`p `onFail` q` means parse p, unless p fails, in which case parse q instead. Can be chained together to give multiple attempts to parse something. (Note that q could itself be a failing parser, e.g. to change the error message from that defined in p to something different.) However, a severe failure in p cannot be ignored.

manyFinally :: Parser s t a -> Parser s t z -> Parser s t [a] #

## State-handling

stUpdate :: (s -> s) -> Parser s t () #

Update the internal state.

stQuery :: (s -> a) -> Parser s t a #

Query the internal state.

stGet :: Parser s t s #

Deliver the entire internal state.

## Re-parsing

reparse :: [t] -> Parser s t () #

Push some tokens back onto the front of the input stream and reparse. This is useful e.g. for recursively expanding macros. When the user-parser recognises a macro use, it can lookup the macro expansion from the parse state, lex it, and then stuff the lexed expansion back down into the parser.

# Re-export all more general combinators

many1 :: PolyParse p => p a -> p [a] #

Parse a non-empty list of items.

sepBy :: PolyParse p => p a -> p sep -> p [a] #

Parse a list of items separated by discarded junk.

sepBy1 :: PolyParse p => p a -> p sep -> p [a] #

Parse a non-empty list of items separated by discarded junk.

apply :: PolyParse p => p (a -> b) -> p a -> p b infixl 3 #

Apply a parsed function to a parsed value. Rather like ordinary function application lifted into parsers.

bracket :: PolyParse p => p bra -> p ket -> p a -> p a #

Parse a bracketed item, discarding the brackets. If everything matches except the closing bracket, the whole parse fails soft, which can give less-than-satisfying error messages. If you want better error messages, try calling with e.g. `bracket open (commit close) item`

indent :: Int -> String -> String #

Helper for formatting error messages: indents all lines by a fixed amount.

exactly :: PolyParse p => Int -> p a -> p [a] #

'exactly n p' parses precisely n items, using the parser p, in sequence.

class Commitment (p :: Type -> Type) where #

The `Commitment` class is an abstraction over all the current concrete representations of monadic/applicative parser combinators in this package. The common feature is two-level error-handling. Some primitives must be implemented specific to each parser type (e.g. depending on whether the parser has a running state, or whether it is lazy). But given those primitives, large numbers of combinators do not depend any further on the internal structure of the particular parser.

Methods

commit :: p a -> p a #

Commit is a way of raising the severity of any errors found within its argument. Used in the middle of a parser definition, it means that any operations prior to commitment fail softly, but after commitment, they fail hard.

adjustErr :: p a -> (String -> String) -> p a #

`p `adjustErr` f` applies the transformation `f` to any error message generated in `p`, having no effect if `p` succeeds.

oneOf' :: [(String, p a)] -> p a #

Parse the first alternative that succeeds, but if none succeed, report only the severe errors, and if none of those, then report all the soft errors.

#### Instances

Instances details

Commitment Parser # |
Instance details Defined in Text.ParserCombinators.Poly.ByteString Methods commit :: Parser a -> Parser a # adjustErr :: Parser a -> (String -> String) -> Parser a # oneOf' :: [(String, Parser a)] -> Parser a #
Commitment Parser # |
Instance details Defined in Text.ParserCombinators.Poly.ByteStringChar Methods commit :: Parser a -> Parser a # adjustErr :: Parser a -> (String -> String) -> Parser a # oneOf' :: [(String, Parser a)] -> Parser a #
Commitment Parser # |
Instance details Defined in Text.ParserCombinators.Poly.Text Methods commit :: Parser a -> Parser a # adjustErr :: Parser a -> (String -> String) -> Parser a # oneOf' :: [(String, Parser a)] -> Parser a #
Commitment (Parser t) # |
Instance details Defined in Text.ParserCombinators.Poly.Lazy Methods commit :: Parser t a -> Parser t a # adjustErr :: Parser t a -> (String -> String) -> Parser t a # oneOf' :: [(String, Parser t a)] -> Parser t a #
Commitment (Parser t) # |
Instance details Defined in Text.ParserCombinators.Poly.Lex Methods commit :: Parser t a -> Parser t a # adjustErr :: Parser t a -> (String -> String) -> Parser t a # oneOf' :: [(String, Parser t a)] -> Parser t a #
Commitment (Parser t) # |
Instance details Defined in Text.ParserCombinators.Poly.Parser Methods commit :: Parser t a -> Parser t a # adjustErr :: Parser t a -> (String -> String) -> Parser t a # oneOf' :: [(String, Parser t a)] -> Parser t a #
Commitment (Parser s) # |
Instance details Defined in Text.ParserCombinators.Poly.StateText Methods commit :: Parser s a -> Parser s a # adjustErr :: Parser s a -> (String -> String) -> Parser s a # oneOf' :: [(String, Parser s a)] -> Parser s a #
Commitment (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateLazy Methods commit :: Parser s t a -> Parser s t a # adjustErr :: Parser s t a -> (String -> String) -> Parser s t a # oneOf' :: [(String, Parser s t a)] -> Parser s t a #
Commitment (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateParser Methods commit :: Parser s t a -> Parser s t a # adjustErr :: Parser s t a -> (String -> String) -> Parser s t a # oneOf' :: [(String, Parser s t a)] -> Parser s t a #

class (Functor p, Monad p, MonadFail p, Applicative p, Alternative p, Commitment p) => PolyParse (p :: Type -> Type) #

The `PolyParse` class is an abstraction gathering all of the common features that a two-level error-handling parser requires: the applicative parsing interface, the monadic interface, and commitment.

There are two additional basic combinators that we expect to be implemented afresh for every concrete type, but which (for technical reasons) cannot be class methods. They are `next` and `satisfy`.

#### Instances

Instances details

PolyParse Parser # |
Instance details Defined in Text.ParserCombinators.Poly.ByteString
PolyParse Parser # |
Instance details Defined in Text.ParserCombinators.Poly.ByteStringChar
PolyParse Parser # |
Instance details Defined in Text.ParserCombinators.Poly.Text
PolyParse (Parser t) # |
Instance details Defined in Text.ParserCombinators.Poly.Lazy
PolyParse (Parser t) # |
Instance details Defined in Text.ParserCombinators.Poly.Lex
PolyParse (Parser t) # |
Instance details Defined in Text.ParserCombinators.Poly.Parser
PolyParse (Parser s) # |
Instance details Defined in Text.ParserCombinators.Poly.StateText
PolyParse (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateLazy
PolyParse (Parser s t) # |
Instance details Defined in Text.ParserCombinators.Poly.StateParser

discard :: PolyParse p => p a -> p b -> p a infixl 3 #

`x `discard` y` parses both x and y, but discards the result of y. Rather like `const` lifted into parsers.

failBad :: PolyParse p => String -> p a #

When a simple fail is not strong enough, use failBad for emphasis. An emphasised (severe) error cannot be overridden by choice operators.

adjustErrBad :: PolyParse p => p a -> (String -> String) -> p a #

`adjustErrBad` is just like `adjustErr` except it also raises the severity of the error.

oneOf :: PolyParse p => [p a] -> p a #

Parse the first alternative in the list that succeeds.

upto :: PolyParse p => Int -> p a -> p [a] #

'upto n p' parses n or fewer items, using the parser p, in sequence.

bracketSep :: PolyParse p => p bra -> p sep -> p ket -> p a -> p [a] #

Parse a list of items, discarding the start, end, and separator items.

manyFinally' :: (PolyParse p, Show a) => p a -> p z -> p [a] #

`manyFinally'` is like `manyFinally`, except when the terminator parser overlaps with the element parser. In `manyFinally e t`, the parser `t` is tried only when parser `e` fails, whereas in `manyFinally' e t`, the parser `t` is always tried first, then parser `e` only if the terminator is not found. For instance, `manyFinally (accept "01") (accept "0")` on input `"0101010"` returns `["01","01","01"]`, whereas `manyFinally'` with the same arguments and input returns `[]`.

module Control.Applicative