Distribution.Parsec.Parser

Types

data Field ann

A Cabal-like file consists of a series of fields (foo: bar) and sections (library ...).

Constructors

Field !(Name ann) [FieldLine ann]

Section !(Name ann) [SectionArg ann] [Field ann]

Instances

Functor Field

Defined in Distribution.Parsec.Field

Methods

fmap :: (a -> b) -> Field a -> Field b

(<$) :: a -> Field b -> Field a

Eq ann => Eq (Field ann)

Defined in Distribution.Parsec.Field

Methods

(==) :: Field ann -> Field ann -> Bool

(/=) :: Field ann -> Field ann -> Bool

Show ann => Show (Field ann)

Defined in Distribution.Parsec.Field

Methods

showsPrec :: Int -> Field ann -> ShowS

show :: Field ann -> String

showList :: [Field ann] -> ShowS

data Name ann

A field name.

Invariant: ByteString is lower-case ASCII.

Constructors

Name !ann !FieldName

Instances

Functor Name

Defined in Distribution.Parsec.Field

Methods

fmap :: (a -> b) -> Name a -> Name b

(<$) :: a -> Name b -> Name a

Eq ann => Eq (Name ann)

Defined in Distribution.Parsec.Field

Methods

(==) :: Name ann -> Name ann -> Bool

(/=) :: Name ann -> Name ann -> Bool

Show ann => Show (Name ann)

Defined in Distribution.Parsec.Field

Methods

showsPrec :: Int -> Name ann -> ShowS

show :: Name ann -> String

showList :: [Name ann] -> ShowS

data FieldLine ann

A line of text representing the value of a field from a Cabal file. A field may contain multiple lines.

Invariant: ByteString has no newlines.

Constructors

FieldLine !ann !ByteString

Instances

Functor FieldLine

Defined in Distribution.Parsec.Field

Methods

fmap :: (a -> b) -> FieldLine a -> FieldLine b

(<$) :: a -> FieldLine b -> FieldLine a

Eq ann => Eq (FieldLine ann)

Defined in Distribution.Parsec.Field

Methods

(==) :: FieldLine ann -> FieldLine ann -> Bool

(/=) :: FieldLine ann -> FieldLine ann -> Bool

Show ann => Show (FieldLine ann)

Defined in Distribution.Parsec.Field

Methods

showsPrec :: Int -> FieldLine ann -> ShowS

show :: FieldLine ann -> String

showList :: [FieldLine ann] -> ShowS

data SectionArg ann

Section arguments, e.g. name of the library

Constructors

SecArgName !ann !ByteString

identifier, or omething which loos like number. Also many dot numbers, i.e. "7.6.3"

SecArgStr !ann !ByteString

quoted string

SecArgOther !ann !ByteString

everything else, mm. operators (e.g. in if-section conditionals)

Instances

Functor SectionArg

Defined in Distribution.Parsec.Field

Methods

fmap :: (a -> b) -> SectionArg a -> SectionArg b

(<$) :: a -> SectionArg b -> SectionArg a

Eq ann => Eq (SectionArg ann)

Defined in Distribution.Parsec.Field

Methods

(==) :: SectionArg ann -> SectionArg ann -> Bool

(/=) :: SectionArg ann -> SectionArg ann -> Bool

Show ann => Show (SectionArg ann)

Defined in Distribution.Parsec.Field

Methods

showsPrec :: Int -> SectionArg ann -> ShowS

show :: SectionArg ann -> String

showList :: [SectionArg ann] -> ShowS

Grammar and parsing

CabalStyleFile ::= SecElems

SecElems       ::= SecElem* '\n'?
SecElem        ::= '\n' SecElemLayout | SecElemBraces
SecElemLayout  ::= FieldLayout | FieldBraces | SectionLayout | SectionBraces
SecElemBraces  ::= FieldInline | FieldBraces |                 SectionBraces
FieldLayout    ::= name : line? ('\n' line)*
FieldBraces    ::= name : '\n'? '{' content '}'
FieldInline    ::= name : content
SectionLayout  ::= name arg* SecElems
SectionBraces  ::= name arg* '\n'? '{' SecElems '}'

and the same thing but left factored...

SecElems              ::= SecElem*
SecElem               ::= '\n' name SecElemLayout
                        |      name SecElemBraces
SecElemLayout         ::= :   FieldLayoutOrBraces
                        | arg*  SectionLayoutOrBraces
FieldLayoutOrBraces   ::= '\n'? '{' content '}'
                        | line? ('\n' line)*
SectionLayoutOrBraces ::= '\n'? '{' SecElems '\n'? '}'
                        | SecElems
SecElemBraces         ::= : FieldInlineOrBraces
                        | arg* '\n'? '{' SecElems '\n'? '}'
FieldInlineOrBraces   ::= '\n'? '{' content '}'
                        | content

Note how we have several productions with the sequence:

'\n'? '{'

That is, an optional newline (and indent) followed by a { token. In the SectionLayoutOrBraces case you can see that this makes it not fully left factored (because SecElems can start with a n). Fully left factoring here would be ugly, and though we could use a lookahead of two tokens to resolve the alternatives, we can't conveniently use Parsec's try here to get a lookahead of only two. So instead we deal with this case in the lexer by making a line where the first non-space is { lex as just the { token, without the usual indent token. Then in the parser we can resolve everything with just one token of lookahead and so without using try.

readFields :: ByteString -> Either ParseError [Field Position]

Parse cabal style ByteString into list of Fields, i.e. the cabal AST.

readFields' :: ByteString -> Either ParseError ([Field Position], [LexWarning])

Like readFields but also return lexer warnings