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authorAlec Theriault <alec.theriault@gmail.com>2018-06-05 10:47:16 -0700
committerAlexander Biehl <alexbiehl@gmail.com>2018-06-05 19:47:16 +0200
commitbea565ec5a029b8c19965aa22f34c23a112c0a7f (patch)
treea0a93b524acf85676c4e46206f73ce2a7a2aaa0f /haddock-api/src/Haddock/Backends
parentee1ce11ceaf41d05973bb2c9ca7abd41a2ad078c (diff)
Improve hyperlinker's 'spanToNewline' (#846)
'spanToNewline' is used to help break apart the source into lines which can then be partioned into CPP and non-CPP chunks. It is important that 'spanToNewline' not break apart tokens, so it needs to properly handle things like * block comments, possibly nested * string literals, possibly multi-line * CPP macros, possibly multi-line String literals in particular were not being properly handled. The fix is to to fall back in 'Text.Read.lex' to help lex things that are not comments. Fixes #837.
Diffstat (limited to 'haddock-api/src/Haddock/Backends')
-rw-r--r--haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs32
1 files changed, 25 insertions, 7 deletions
diff --git a/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs b/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs
index 277634b9..456050d1 100644
--- a/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs
+++ b/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs
@@ -3,6 +3,8 @@ module Haddock.Backends.Hyperlinker.Parser (parse) where
import Data.Either ( isRight, isLeft )
import Data.List ( foldl', isPrefixOf, isSuffixOf )
import Data.Maybe ( maybeToList )
+import Data.Char ( isSpace )
+import qualified Text.Read as R
import GHC ( DynFlags, addSourceToTokens )
import SrcLoc
@@ -109,12 +111,9 @@ isCPPline :: String -> Bool
isCPPline = isPrefixOf "#" . dropWhile (`elem` " \t") . take 5
--- | Split a "line" off the front of a string, supporting newline escapes.
---
--- By "line", we understand: the shortest substring ending in a '\n' that is not
---
--- 1. immediately preceded by a '\\'
--- 2. not inside some (possibly nested) block comment
+-- | Split a "line" off the front of a string, hopefully without cutting tokens
+-- in half. I say "hopefully" because knowing what a token is requires lexing,
+-- yet lexing depends on this function.
--
-- All characters in the input are present in the output:
--
@@ -122,17 +121,36 @@ isCPPline = isPrefixOf "#" . dropWhile (`elem` " \t") . take 5
spanToNewline :: Int -- ^ open '{-'
-> String -- ^ input
-> (String, String)
-spanToNewline _ [] = ([], [])
+
+-- Base case and space characters
+spanToNewline _ "" = ("", "")
+spanToNewline n ('\n':str) | n <= 0 = ("\n", str)
spanToNewline n ('\n':str) | n <= 0 = ("\n", str)
spanToNewline n ('\\':'\n':str) =
let (str', rest) = spanToNewline n str
in ('\\':'\n':str', rest)
+
+-- Block comments
spanToNewline n ('{':'-':str) =
let (str', rest) = spanToNewline (n+1) str
in ('{':'-':str', rest)
spanToNewline n ('-':'}':str) =
let (str', rest) = spanToNewline (n-1) str
in ('-':'}':str', rest)
+
+-- When not in a block comment, try to lex a Haskell token
+spanToNewline 0 str@(c:_) | ((lexed, str') : _) <- R.lex str, not (isSpace c) =
+ if all (== '-') lexed && length lexed >= 2
+ -- A Haskell line comment
+ then case span (/= '\n') str' of
+ (str'', '\n':rest) -> (lexed ++ str'' ++ "\n", rest)
+ (_, _) -> (str, "")
+
+ -- An actual Haskell token
+ else let (str'', rest) = spanToNewline 0 str'
+ in (lexed ++ str'', rest)
+
+-- In all other cases, advance one character at a time
spanToNewline n (c:str) =
let (str', rest) = spanToNewline n str
in (c:str', rest)