Copy readMaybe/readEither from base >= 4.7 for backwards compatibility

This commit is contained in:
Daniel Gröber 2014-05-10 13:36:54 +02:00
parent 5492f0c5d1
commit 96a85fe953
3 changed files with 112 additions and 11 deletions

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@ -6,6 +6,7 @@ module Language.Haskell.GhcMod.CabalConfig (
import Language.Haskell.GhcMod.GhcPkg import Language.Haskell.GhcMod.GhcPkg
import Language.Haskell.GhcMod.Utils import Language.Haskell.GhcMod.Utils
import Language.Haskell.GhcMod.Read
import Language.Haskell.GhcMod.Types import Language.Haskell.GhcMod.Types
import qualified Language.Haskell.GhcMod.Cabal16 as C16 import qualified Language.Haskell.GhcMod.Cabal16 as C16
@ -24,7 +25,6 @@ import Distribution.Simple.BuildPaths (defaultDistPref)
import Distribution.Simple.Configure (localBuildInfoFile) import Distribution.Simple.Configure (localBuildInfoFile)
import Distribution.Simple.LocalBuildInfo (ComponentName) import Distribution.Simple.LocalBuildInfo (ComponentName)
import System.FilePath ((</>)) import System.FilePath ((</>))
import Text.Read (readMaybe)
---------------------------------------------------------------- ----------------------------------------------------------------
type CabalConfig = String type CabalConfig = String
@ -94,7 +94,7 @@ configDependencies thisPkg config = map fromInstalledPackageId deps
clbi <- stripPrefix " = " field clbi <- stripPrefix " = " field
if "Nothing" `isPrefixOf` clbi if "Nothing" `isPrefixOf` clbi
then Nothing then Nothing
else case readMaybe <$> stripPrefix "Just " clbi of else case readMaybe =<< stripPrefix "Just " clbi of
Just x -> x Just x -> x
Nothing -> error $ "reading libraryConfig failed\n" ++ show (stripPrefix "Just " clbi) Nothing -> error $ "reading libraryConfig failed\n" ++ show (stripPrefix "Just " clbi)
@ -102,15 +102,9 @@ configDependencies thisPkg config = map fromInstalledPackageId deps
extract field = readConfigs field <$> extractField config field extract field = readConfigs field <$> extractField config field
readConfigs :: String -> String -> [(String, C16.ComponentLocalBuildInfo)] readConfigs :: String -> String -> [(String, C16.ComponentLocalBuildInfo)]
readConfigs f s = case readMaybe s of readConfigs f s = case readEither s of
Just x -> x Right x -> x
Nothing -> error $ "reading config " ++ f ++ " failed" Left msg -> error $ "reading config " ++ f ++ " failed ("++msg++")"
readEither :: Read r => String -> Either String r
readEither s = case readMaybe s of
Just x -> Right x
Nothing -> Left $ "read: failed on input:\n" ++ s
extractField :: CabalConfig -> String -> Either String String extractField :: CabalConfig -> String -> Either String String
extractField config field = extractField config field =

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@ -0,0 +1,106 @@
module Language.Haskell.GhcMod.Read where
import Text.Read (readPrec_to_S, readPrec, minPrec)
import qualified Text.ParserCombinators.ReadP as P
import Text.ParserCombinators.ReadPrec (lift)
-- This library (libraries/base) is derived from code from several
-- sources:
-- * Code from the GHC project which is largely (c) The University of
-- Glasgow, and distributable under a BSD-style license (see below),
-- * Code from the Haskell 98 Report which is (c) Simon Peyton Jones
-- and freely redistributable (but see the full license for
-- restrictions).
-- * Code from the Haskell Foreign Function Interface specification,
-- which is (c) Manuel M. T. Chakravarty and freely redistributable
-- (but see the full license for restrictions).
-- The full text of these licenses is reproduced below. All of the
-- licenses are BSD-style or compatible.
-- -----------------------------------------------------------------------------
-- The Glasgow Haskell Compiler License
-- Copyright 2004, The University Court of the University of Glasgow.
-- All rights reserved.
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions are met:
-- - Redistributions of source code must retain the above copyright notice,
-- this list of conditions and the following disclaimer.
-- - Redistributions in binary form must reproduce the above copyright notice,
-- this list of conditions and the following disclaimer in the documentation
-- and/or other materials provided with the distribution.
-- - Neither name of the University nor the names of its contributors may be
-- used to endorse or promote products derived from this software without
-- specific prior written permission.
-- THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY COURT OF THE UNIVERSITY OF
-- GLASGOW AND THE CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
-- INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
-- FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
-- UNIVERSITY COURT OF THE UNIVERSITY OF GLASGOW OR THE CONTRIBUTORS BE LIABLE
-- FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-- DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
-- SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-- CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
-- LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
-- OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
-- DAMAGE.
-- -----------------------------------------------------------------------------
-- Code derived from the document "Report on the Programming Language
-- Haskell 98", is distributed under the following license:
-- Copyright (c) 2002 Simon Peyton Jones
-- The authors intend this Report to belong to the entire Haskell
-- community, and so we grant permission to copy and distribute it for
-- any purpose, provided that it is reproduced in its entirety,
-- including this Notice. Modified versions of this Report may also be
-- copied and distributed for any purpose, provided that the modified
-- version is clearly presented as such, and that it does not claim to
-- be a definition of the Haskell 98 Language.
-- -----------------------------------------------------------------------------
-- Code derived from the document "The Haskell 98 Foreign Function
-- Interface, An Addendum to the Haskell 98 Report" is distributed under
-- the following license:
-- Copyright (c) 2002 Manuel M. T. Chakravarty
-- The authors intend this Report to belong to the entire Haskell
-- community, and so we grant permission to copy and distribute it for
-- any purpose, provided that it is reproduced in its entirety,
-- including this Notice. Modified versions of this Report may also be
-- copied and distributed for any purpose, provided that the modified
-- version is clearly presented as such, and that it does not claim to
-- be a definition of the Haskell 98 Foreign Function Interface.
-- -----------------------------------------------------------------------------
readEither :: Read a => String -> Either String a
readEither s =
case [ x | (x,"") <- readPrec_to_S read' minPrec s ] of
[x] -> Right x
[] -> Left "Prelude.read: no parse"
_ -> Left "Prelude.read: ambiguous parse"
where
read' =
do x <- readPrec
lift P.skipSpaces
return x
readMaybe :: Read a => String -> Maybe a
readMaybe s = case readEither s of
Left _ -> Nothing
Right a -> Just a

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@ -79,6 +79,7 @@ Library
Language.Haskell.GhcMod.PkgDoc Language.Haskell.GhcMod.PkgDoc
Language.Haskell.GhcMod.Utils Language.Haskell.GhcMod.Utils
Language.Haskell.GhcMod.Types Language.Haskell.GhcMod.Types
Language.Haskell.GhcMod.Read
Build-Depends: base >= 4.0 && < 5 Build-Depends: base >= 4.0 && < 5
, containers , containers
, deepseq , deepseq