Cabal-3.14.0.0: A framework for packaging Haskell software
Copyright(c) 2003-2005 Isaac Jones Malcolm Wallace
LicenseBSD3
Maintainercabal-devel@haskell.org
Portabilityportable
Safe HaskellNone
LanguageHaskell2010

Distribution.Simple.PreProcess.Types

Description

This defines a PreProcessor abstraction which represents a pre-processor that can transform one kind of file into another.

Synopsis

Documentation

newtype Suffix Source #

A suffix (or file extension).

Mostly used to decide which preprocessor to use, e.g. files with suffix "y" are usually processed by the "happy" build tool.

Constructors

Suffix String 

Instances

Instances details
Pretty Suffix Source # 
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Structured Suffix Source # 
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Binary Suffix Source # 
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Methods

put :: Suffix -> Put #

get :: Get Suffix #

putList :: [Suffix] -> Put #

IsString Suffix Source # 
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Methods

fromString :: String -> Suffix #

Generic Suffix Source # 
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Associated Types

type Rep Suffix 
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type Rep Suffix = D1 ('MetaData "Suffix" "Distribution.Simple.PreProcess.Types" "Cabal-3.14.0.0-7eed" 'True) (C1 ('MetaCons "Suffix" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 String)))

Methods

from :: Suffix -> Rep Suffix x #

to :: Rep Suffix x -> Suffix #

Show Suffix Source # 
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Eq Suffix Source # 
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Methods

(==) :: Suffix -> Suffix -> Bool #

(/=) :: Suffix -> Suffix -> Bool #

Ord Suffix Source # 
Instance details

Defined in Distribution.Simple.PreProcess.Types

type Rep Suffix Source # 
Instance details

Defined in Distribution.Simple.PreProcess.Types

type Rep Suffix = D1 ('MetaData "Suffix" "Distribution.Simple.PreProcess.Types" "Cabal-3.14.0.0-7eed" 'True) (C1 ('MetaCons "Suffix" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 String)))

data PreProcessor Source #

The interface to a preprocessor, which may be implemented using an external program, but need not be. The arguments are the name of the input file, the name of the output file and a verbosity level. Here is a simple example that merely prepends a comment to the given source file:

ppTestHandler :: PreProcessor
ppTestHandler =
  PreProcessor {
    platformIndependent = True,
    runPreProcessor = mkSimplePreProcessor $ \inFile outFile verbosity ->
      do info verbosity (inFile++" has been preprocessed to "++outFile)
         stuff <- readFile inFile
         writeFile outFile ("-- preprocessed as a test\n\n" ++ stuff)
         return ExitSuccess

We split the input and output file names into a base directory and the rest of the file name. The input base dir is the path in the list of search dirs that this file was found in. The output base dir is the build dir where all the generated source files are put.

The reason for splitting it up this way is that some pre-processors don't simply generate one output .hs file from one input file but have dependencies on other generated files (notably c2hs, where building one .hs file may require reading other .chi files, and then compiling the .hs file may require reading a generated .h file). In these cases the generated files need to embed relative path names to each other (eg the generated .hs file mentions the .h file in the FFI imports). This path must be relative to the base directory where the generated files are located, it cannot be relative to the top level of the build tree because the compilers do not look for .h files relative to there, ie we do not use "-I .", instead we use "-I dist/build" (or whatever dist dir has been set by the user)

Most pre-processors do not care of course, so mkSimplePreProcessor and runSimplePreProcessor functions handle the simple case.

Constructors

PreProcessor 

Fields

type PreProcessCommand Source #

Arguments

 = (FilePath, FilePath)

Location of the source file relative to a base dir

-> (FilePath, FilePath)

Output file name, relative to an output base dir

-> Verbosity 
-> IO () 

A command to run a given preprocessor on a single source file.

The input and output file paths are passed in as arguments, as it is the build system and not the package author which chooses the location of source files.