[project @ 1999-05-13 10:45:03 by sof]

Fised & improved lexing of escaped numeric character literals + a regression
test.

diff --git a/ghc/lib/std/Char.lhs b/ghc/lib/std/Char.lhs
index a471bec..b00345d 100644 (file)
--- a/ghc/lib/std/Char.lhs
+++ b/ghc/lib/std/Char.lhs
@@ -33,20 +33,7 @@ module Char
     ) where
 
 import PrelBase
-import PrelRead (readLitChar, lexLitChar)
+import PrelRead (readLitChar, lexLitChar, digitToInt)
 import {-# SOURCE #-} PrelErr   ( error )
 
 \end{code}
-
-\begin{code}
--- Digit conversion operations
-
-digitToInt :: Char -> Int
-digitToInt c
- | isDigit c           =  fromEnum c - fromEnum '0'
- | c >= 'a' && c <= 'f' =  fromEnum c - fromEnum 'a' + 10
- | c >= 'A' && c <= 'F' =  fromEnum c - fromEnum 'A' + 10
- | otherwise           =  error ("Char.digitToInt: not a digit " ++ show c) -- sigh
-
-
-\end{code}

diff --git a/ghc/lib/std/PrelRead.lhs b/ghc/lib/std/PrelRead.lhs
index 1ef7b43..c298bcb 100644 (file)
--- a/ghc/lib/std/PrelRead.lhs
+++ b/ghc/lib/std/PrelRead.lhs
@@ -235,15 +235,17 @@ lexLitChar ('\\':s)     =  do
            (esc,t) <- lexEsc s
            return ('\\':esc, t)
        where
-        lexEsc (c:s)       | c `elem` "abfnrtv\\\"'" = return ([c],s)
-        lexEsc s@(d:_)     | isDigit d               = lexDecDigits s
-        lexEsc ('o':d:s) | isDigit d                 = lexOctDigits (d:s)
-        lexEsc ('O':d:s) | isDigit d                 = lexOctDigits (d:s)
-        lexEsc ('x':d:s) | isDigit d                 = lexHexDigits (d:s)
-        lexEsc ('X':d:s) | isDigit d                 = lexHexDigits (d:s)
-       lexEsc ('^':c:s) | '@' <= c && c <= '_'    = [(['^',c],s)] -- cf. cntrl in 2.6 of H. report.
-       lexEsc s@(c:_)   | isUpper c               = fromAsciiLab s
-        lexEsc _                                   = mzero
+        lexEsc (c:s)     | c `elem` escChars = return ([c],s)
+        lexEsc s@(d:_)   | isDigit d         = checkSize 10 lexDecDigits s
+        lexEsc ('o':d:s) | isOctDigit d      = checkSize  8 lexOctDigits (d:s)
+        lexEsc ('O':d:s) | isOctDigit d      = checkSize  8 lexOctDigits (d:s)
+        lexEsc ('x':d:s) | isHexDigit d      = checkSize 16 lexHexDigits (d:s)
+        lexEsc ('X':d:s) | isHexDigit d      = checkSize 16 lexHexDigits (d:s)
+       lexEsc ('^':c:s) | c >= '@' && c <= '_' = [(['^',c],s)] -- cf. cntrl in 2.6 of H. report.
+       lexEsc s@(c:_)   | isUpper c            = fromAsciiLab s
+        lexEsc _                                = mzero
+
+       escChars = "abfnrtv\\\"'"
 
         fromAsciiLab (x:y:z:ls) | isUpper y && (isUpper z || isDigit z) &&
                                   [x,y,z] `elem` asciiEscTab = return ([x,y,z], ls)
@@ -253,9 +255,36 @@ lexLitChar ('\\':s)     =  do
                                   
         asciiEscTab = "DEL" : asciiTab
 
+        {-
+          Check that the numerically escaped char literals are
+          within accepted boundaries.
+          
+          Note: this allows char lits with leading zeros, i.e.,
+                \0000000000000000000000000000001. 
+        -}
+        checkSize base f str = do
+          (num, res) <- f str
+             -- Note: this is assumes that a Char is 8 bits long.
+          if (toAnInt base num) > 255 then 
+             mzero
+           else
+             case base of
+                8  -> return ('o':num', res)
+                16 -> return ('x':num', res)
+                _  -> return (num, res)
+
+       toAnInt base xs = foldl (\ acc n -> acc*base + n) 0 (map digitToInt xs)
+
 
 lexLitChar (c:s)        =  return ([c],s)
 lexLitChar ""           =  mzero
+
+digitToInt :: Char -> Int
+digitToInt c
+ | isDigit c           =  fromEnum c - fromEnum '0'
+ | c >= 'a' && c <= 'f' =  fromEnum c - fromEnum 'a' + 10
+ | c >= 'A' && c <= 'F' =  fromEnum c - fromEnum 'A' + 10
+ | otherwise           =  error ("Char.digitToInt: not a digit " ++ show c) -- sigh
 \end{code}
 
 %*********************************************************

diff --git a/ghc/tests/lib/should_run/char001.hs b/ghc/tests/lib/should_run/char001.hs
new file mode 100644 (file)
index 0000000..ec4ae9b
--- /dev/null
+++ b/ghc/tests/lib/should_run/char001.hs
@@ -0,0 +1,39 @@
+-- !!! Testing the behaviour of Char.lexLitChar a little..
+module Main where
+
+import Char
+
+lex' str = do
+  putStr ("lex " ++ str ++ " = ")
+  print (lex str)
+
+hexes = do
+  lex' "'\\X00'"
+  lex' "'\\x0f2'"
+  lex' "'\\xf2'"
+  lex' "'\\xf2t'"
+  lex' "'\\X24'"
+  lex' "'\\x24b'"
+  lex' "'\\Xa4b'"
+  lex' "'\\xa4bg'"
+
+octs = do
+  lex' "'\\o00'"
+  lex' "'\\o05'"
+  lex' "'\\o50'"
+  lex' "'\\o72'"
+  lex' "'\\o82'"
+  lex' "'\\O24'"
+  lex' "'\\O000024'"
+  lex' "'\\024b'"
+  lex' "'\\o14b'"
+  lex' "'\\0a4bg'"
+
+main = do
+  hexes
+  octs
+
+
+
+
+

diff --git a/ghc/tests/lib/should_run/char001.stdout b/ghc/tests/lib/should_run/char001.stdout
new file mode 100644 (file)
index 0000000..c5d261e
--- /dev/null
+++ b/ghc/tests/lib/should_run/char001.stdout
@@ -0,0 +1,18 @@
+lex '\X00' = [("'\\x00'","")]
+lex '\x0f2' = [("'\\x0f2'","")]
+lex '\xf2' = [("'\\xf2'","")]
+lex '\xf2t' = []
+lex '\X24' = [("'\\x24'","")]
+lex '\x24b' = []
+lex '\Xa4b' = []
+lex '\xa4bg' = []
+lex '\o00' = [("'\\o00'","")]
+lex '\o05' = [("'\\o05'","")]
+lex '\o50' = [("'\\o50'","")]
+lex '\o72' = [("'\\o72'","")]
+lex '\o82' = []
+lex '\O24' = [("'\\o24'","")]
+lex '\O000024' = [("'\\o000024'","")]
+lex '\024b' = []
+lex '\o14b' = []
+lex '\0a4bg' = []