Language.C.Inline.Internal

Context handling

setContext :: Context -> Q ()

Sets the Context for the current module. This function, if called, must be called before any of the other TH functions in this module. Fails if that's not the case.

getContext :: Q Context

Gets the current Context. Also makes sure that the current module is initialised.

Substitution

newtype Substitutions

Constructors

Substitutions

Fields

• unSubstitutions :: Map String (String -> String)

substitute :: [(String, String -> String)] -> Q a -> Q a

Define macros that can be used in the nested Template Haskell expression. Macros can be used as @MACRO_NAME(input) in inline-c quotes, and will transform their input with the given function. They can be useful for passing in types when defining Haskell instances for C++ template types.

getHaskellType :: Bool -> String -> TypeQ

Given a C type name, return the Haskell type in Template Haskell. The first parameter controls whether function pointers should be mapped as pure or IO functions.

Emitting and invoking C code

The functions in this section let us access more the C file associated with the current module. They can be used to build additional features on top of the basic machinery. All of inline-c is based upon the functions defined here.

Emitting C code

emitVerbatim :: String -> DecsQ

Simply appends some string to the module's C file. Use with care.

Inlining C code

We use the Code data structure to represent some C code that we want to emit to the module's C file and immediately generate a foreign call to. For this reason, Code includes both some C definition, and enough information to be able to generate a foreign call -- specifically the name of the function to call and the Haskell type.

All the quasi-quoters work by constructing a Code and calling inlineCode.

data Code

Data type representing a list of C definitions with a typed and named entry function.

We use it as a basis to inline and call C code.

Constructors

Code

Fields

• codeCallSafety :: Safety

  Safety of the foreign call.

• codeLoc :: Maybe Loc

  The haskell source location used for the #line directive

• codeType :: TypeQ

  Type of the foreign call.

• codeFunName :: String

  Name of the function to call in the code below.

• codeDefs :: String

  The C code.

• codeFunPtr :: Bool

  If True, the type will be wrapped in FunPtr, and the call will be static (e.g. prefixed by &).

inlineCode :: Code -> ExpQ

Inlines a piece of code inline. The resulting Exp will have the type specified in the codeType.

In practice, this function outputs the C code to the module's C file, and then inserts a foreign call of type codeType calling the provided codeFunName.

Example:

c_add :: Int -> Int -> Int
c_add = $(do
  here <- TH.location
  inlineCode $ Code
    TH.Unsafe                   -- Call safety
    (Just here)
    [t| Int -> Int -> Int |]    -- Call type
    "francescos_add"            -- Call name
    -- C Code
    "int francescos_add(int x, int y) { int z = x + y; return z; }")

inlineExp

Arguments

:: Safety

Safety of the foreign call

-> Loc

The location to report

-> TypeQ

Type of the foreign call

-> Type CIdentifier

Return type of the C expr

-> [(CIdentifier, Type CIdentifier)]

Parameters of the C expr

-> String

The C expression

-> ExpQ

Same as inlineCItems, but with a single expression.

c_cos :: Double -> Double
c_cos = $(do
  here <- TH.location
  inlineExp
    TH.Unsafe
    here
    [t| Double -> Double |]
    (quickCParser_ "double" parseType)
    [("x", quickCParser_ "double" parseType)]
    "cos(x)")

inlineItems

Arguments

:: Safety

Safety of the foreign call

-> Bool

Whether to return as a FunPtr or not

-> Maybe String

Optional postfix for the generated name

-> Loc

The location to report

-> TypeQ

Type of the foreign call

-> Type CIdentifier

Return type of the C expr

-> [(CIdentifier, Type CIdentifier)]

Parameters of the C expr

-> String

The C items

-> ExpQ

Same as inlineCode, but accepts a string containing a list of C statements instead instead than a full-blown Code. A function containing the provided statement will be automatically generated.

c_cos :: Double -> Double
c_cos = $(do
 here <- TH.location
 inlineItems
  TH.Unsafe
  False
  Nothing
  here
  [t| Double -> Double |]
  (quickCParser_ "double" parseType)
  [("x", quickCParser_ "double" parseType)]
  "return cos(x);")

Parsing

These functions are used to parse the anti-quotations. They're exposed for testing purposes, you really should not use them.

data SomeEq

Instances

Eq SomeEq

Defined in Language.C.Inline.Internal

Methods

(==) :: SomeEq -> SomeEq -> Bool

(/=) :: SomeEq -> SomeEq -> Bool

Show SomeEq

Defined in Language.C.Inline.Internal

Methods

showsPrec :: Int -> SomeEq -> ShowS

show :: SomeEq -> String

showList :: [SomeEq] -> ShowS

toSomeEq :: (Eq a, Typeable a) => a -> SomeEq

fromSomeEq :: (Eq a, Typeable a) => SomeEq -> Maybe a

data ParameterType

Constructors

Plain HaskellIdentifier

AntiQuote AntiQuoterId SomeEq

Instances

Eq ParameterType

Defined in Language.C.Inline.Internal

Methods

(==) :: ParameterType -> ParameterType -> Bool

(/=) :: ParameterType -> ParameterType -> Bool

Show ParameterType

Defined in Language.C.Inline.Internal

Methods

showsPrec :: Int -> ParameterType -> ShowS

show :: ParameterType -> String

showList :: [ParameterType] -> ShowS

data ParseTypedC

Constructors

ParseTypedC

Fields

• ptcReturnType :: Type CIdentifier
• ptcParameters :: [(CIdentifier, Type CIdentifier, ParameterType)]
• ptcBody :: String

parseTypedC

Arguments

:: CParser HaskellIdentifier m

=> Bool

-> AntiQuoters

-> m ParseTypedC

Returns the return type, the captured variables, and the body.

runParserInQ :: Hashable ident => String -> CParserContext ident -> (forall m. CParser ident m => m a) -> Q a

splitTypedC

Arguments

:: String

-> (String, String)

Returns the type and the body separately

Utility functions for writing quasiquoters

genericQuote

Arguments

:: Purity

-> (Loc -> TypeQ -> Type CIdentifier -> [(CIdentifier, Type CIdentifier)] -> String -> ExpQ)

Function building an Haskell expression, see inlineExp for guidance on the other args.

-> QuasiQuoter

funPtrQuote :: Safety -> QuasiQuoter