*********************************************************************************
-* *
-* John Hughes's and Simon Peyton Jones's Pretty Printer Combinators *
-* *
-* based on "The Design of a Pretty-printing Library" *
-* in Advanced Functional Programming, *
-* Johan Jeuring and Erik Meijer (eds), LNCS 925 *
-* http://www.cs.chalmers.se/~rjmh/Papers/pretty.ps *
-* *
-* Heavily modified by Simon Peyton Jones, Dec 96 *
-* *
+* *
+* John Hughes's and Simon Peyton Jones's Pretty Printer Combinators *
+* *
+* based on "The Design of a Pretty-printing Library" *
+* in Advanced Functional Programming, *
+* Johan Jeuring and Erik Meijer (eds), LNCS 925 *
+* http://www.cs.chalmers.se/~rjmh/Papers/pretty.ps *
+* *
+* Heavily modified by Simon Peyton Jones, Dec 96 *
+* *
*********************************************************************************
-Version 2.0 24 April 1997
+Version 3.0 28 May 1997
+ * Cured massive performance bug. If you write
+
+ foldl <> empty (map (text.show) [1..10000])
+
+ you get quadratic behaviour with V2.0. Why? For just the same reason as you get
+ quadratic behaviour with left-associated (++) chains.
+
+ This is really bad news. One thing a pretty-printer abstraction should
+ certainly guarantee is insensivity to associativity. It matters: suddenly
+ GHC's compilation times went up by a factor of 100 when I switched to the
+ new pretty printer.
+
+ I fixed it with a bit of a hack (because I wanted to get GHC back on the
+ road). I added two new constructors to the Doc type, Above and Beside:
+
+ <> = Beside
+ $$ = Above
+
+ Then, where I need to get to a "TextBeside" or "NilAbove" form I "force"
+ the Doc to squeeze out these suspended calls to Beside and Above; but in so
+ doing I re-associate. It's quite simple, but I'm not satisfied that I've done
+ the best possible job. I'll send you the code if you are interested.
+
+ * Added new exports:
+ punctuate, hang
+ int, integer, float, double, rational,
+ lparen, rparen, lbrack, rbrack, lbrace, rbrace,
+
+ * fullRender's type signature has changed. Rather than producing a string it
+ now takes an extra couple of arguments that tells it how to glue fragments
+ of output together:
+
+ fullRender :: Mode
+ -> Int -- Line length
+ -> Float -- Ribbons per line
+ -> (TextDetails -> a -> a) -- What to do with text
+ -> a -- What to do at the end
+ -> Doc
+ -> a -- Result
+
+ The "fragments" are encapsulated in the TextDetails data type:
+ data TextDetails = Chr Char
+ | Str String
+ | PStr FastString
+
+ The Chr and Str constructors are obvious enough. The PStr constructor has a packed
+ string (FastString) inside it. It's generated by using the new "ptext" export.
+
+ An advantage of this new setup is that you can get the renderer to do output
+ directly (by passing in a function of type (TextDetails -> IO () -> IO ()),
+ rather than producing a string that you then print.
+
+
+Version 2.0 24 April 1997
* Made empty into a left unit for <> as well as a right unit;
it is also now true that
- nest k empty = empty
+ nest k empty = empty
which wasn't true before.
* Fixed an obscure bug in sep that occassionally gave very wierd behaviour
only it keeps fitting things on one line until itc can't fit any more.
3. Some random useful extra combinators are provided.
- <+> puts its arguments beside each other with a space between them,
- unless either argument is empty in which case it returns the other
-
-
- hcat is a list version of <>
- hsep is a list version of <+>
- vcat is a list version of $$
-
- sep (separate) is either like hsep or like vcat, depending on what fits
-
- cat is behaves like sep, but it uses <> for horizontal conposition
- fcat is behaves like fsep, but it uses <> for horizontal conposition
-
- These new ones do the obvious things:
- char, semi, comma, colon, space,
- parens, brackets, braces,
- quotes, doubleQuotes
-
-4. The "above" combinator, $$, now overlaps its two arguments if the
- last line of the top argument stops before the first line of the second begins.
- For example: text "hi" $$ nest 5 "there"
- lays out as
- hi there
- rather than
- hi
- there
-
- There are two places this is really useful
-
- a) When making labelled blocks, like this:
- Left -> code for left
- Right -> code for right
- LongLongLongLabel ->
- code for longlonglonglabel
- The block is on the same line as the label if the label is
- short, but on the next line otherwise.
-
- b) When laying out lists like this:
- [ first
- , second
- , third
- ]
- which some people like. But if the list fits on one line
- you want [first, second, third]. You can't do this with
- John's original combinators, but it's quite easy with the
- new $$.
-
- The combinator $+$ gives the original "never-overlap" behaviour.
-
-5. Several different renderers are provided:
- * a standard one
- * one that uses cut-marks to avoid deeply-nested documents
- simply piling up in the right-hand margin
- * one that ignores indentation (fewer chars output; good for machines)
- * one that ignores indentation and newlines (ditto, only more so)
-
-6. Numerous implementation tidy-ups
- Use of unboxed data types to speed up the implementation
+ <+> puts its arguments beside each other with a space between them,
+ unless either argument is empty in which case it returns the other
+
+
+ hcat is a list version of <>
+ hsep is a list version of <+>
+ vcat is a list version of $$
+
+ sep (separate) is either like hsep or like vcat, depending on what fits
+
+ cat is behaves like sep, but it uses <> for horizontal conposition
+ fcat is behaves like fsep, but it uses <> for horizontal conposition
+
+ These new ones do the obvious things:
+ char, semi, comma, colon, space,
+ parens, brackets, braces,
+ quotes, doubleQuotes
+
+4. The "above" combinator, $$, now overlaps its two arguments if the
+ last line of the top argument stops before the first line of the second begins.
+ For example: text "hi" $$ nest 5 "there"
+ lays out as
+ hi there
+ rather than
+ hi
+ there
+
+ There are two places this is really useful
+
+ a) When making labelled blocks, like this:
+ Left -> code for left
+ Right -> code for right
+ LongLongLongLabel ->
+ code for longlonglonglabel
+ The block is on the same line as the label if the label is
+ short, but on the next line otherwise.
+
+ b) When laying out lists like this:
+ [ first
+ , second
+ , third
+ ]
+ which some people like. But if the list fits on one line
+ you want [first, second, third]. You can't do this with
+ John's original combinators, but it's quite easy with the
+ new $$.
+
+ The combinator $+$ gives the original "never-overlap" behaviour.
+
+5. Several different renderers are provided:
+ * a standard one
+ * one that uses cut-marks to avoid deeply-nested documents
+ simply piling up in the right-hand margin
+ * one that ignores indentation (fewer chars output; good for machines)
+ * one that ignores indentation and newlines (ditto, only more so)
+
+6. Numerous implementation tidy-ups
+ Use of unboxed data types to speed up the implementation
\begin{code}
module Pretty (
- Doc, -- Abstract
- Mode(..), TextDetails(..),
-
- empty, nest,
-
- text, char, ptext,
- int, integer, float, double, rational,
- parens, brackets, braces, quotes, doubleQuotes,
- semi, comma, colon, space, equals,
- lparen, rparen, lbrack, rbrack, lbrace, rbrace,
-
- (<>), (<+>), hcat, hsep,
- ($$), ($+$), vcat,
- sep, cat,
- fsep, fcat,
-
- hang, punctuate,
-
--- renderStyle, -- Haskell 1.3 only
- render, fullRender
+ Doc, -- Abstract
+ Mode(..), TextDetails(..),
+
+ empty, isEmpty, nest,
+
+ text, char, ftext, ptext,
+ int, integer, float, double, rational,
+ parens, brackets, braces, quotes, doubleQuotes,
+ semi, comma, colon, space, equals,
+ lparen, rparen, lbrack, rbrack, lbrace, rbrace,
+
+ (<>), (<+>), hcat, hsep,
+ ($$), ($+$), vcat,
+ sep, cat,
+ fsep, fcat,
+
+ hang, punctuate,
+
+-- renderStyle, -- Haskell 1.3 only
+ render, fullRender, printDoc, showDocWith
) where
#include "HsVersions.h"
+import BufWrite
import FastString
-import GlaExts
+
+import GLAEXTS
+
+import Numeric (fromRat)
+import IO
+
+import System.IO ( hPutBuf )
+
+import GHC.Base ( unpackCString# )
+import GHC.Ptr ( Ptr(..) )
-- Don't import Util( assertPanic ) because it makes a loop in the module structure
*********************************************************
-* *
+* *
\subsection{CPP magic so that we can compile with both GHC and Hugs}
-* *
+* *
*********************************************************
The library uses unboxed types to get a bit more speed, but these CPP macros
allow you to use either GHC or Hugs. To get GHC, just set the CPP variable
- __GLASGOW_HASKELL__
+ __GLASGOW_HASKELL__
\begin{code}
#if defined(__GLASGOW_HASKELL__)
-
-- Glasgow Haskell
-- Disable ASSERT checks; they are expensive!
#define LOCAL_ASSERT(x)
-#define INT Int#
-#define MINUS -#
+#define ILIT(x) (x#)
+#define IBOX(x) (I# (x))
+#define INT Int#
+#define MINUS -#
#define NEGATE negateInt#
-#define PLUS +#
-#define GR >#
-#define GREQ >=#
-#define LT <#
-#define DIV `quotInt#`
+#define PLUS +#
+#define GR >#
+#define GREQ >=#
+#define LT <#
+#define DIV `quotInt#`
-#define SHOW Show
-#define MAXINT maxBound
+#define SHOW Show
+#define MAXINT maxBound
#else
#define LOCAL_ASSERT(x)
-#define INT Int
-#define IBOX(x) x
-#define MINUS -
+#define INT Int
+#define IBOX(x) x
+#define MINUS -
#define NEGATE negate
-#define PLUS +
-#define GR >
-#define GREQ >=
-#define LT <
-#define DIV `quot`
+#define PLUS +
+#define GR >
+#define GREQ >=
+#define LT <
+#define DIV `quot`
#define ILIT(x) x
-#define SHOW Show
-#define MAXINT maxBound
+#define SHOW Show
+#define MAXINT maxBound
#endif
*********************************************************
-* *
+* *
\subsection{The interface}
-* *
+* *
*********************************************************
The primitive @Doc@ values
\begin{code}
-empty :: Doc
-text :: String -> Doc
-char :: Char -> Doc
+empty :: Doc
+isEmpty :: Doc -> Bool
+text :: String -> Doc
+char :: Char -> Doc
-semi, comma, colon, space, equals :: Doc
+semi, comma, colon, space, equals :: Doc
lparen, rparen, lbrack, rbrack, lbrace, rbrace :: Doc
parens, brackets, braces :: Doc -> Doc
-quotes, doubleQuotes :: Doc -> Doc
+quotes, doubleQuotes :: Doc -> Doc
-int :: Int -> Doc
+int :: Int -> Doc
integer :: Integer -> Doc
-float :: Float -> Doc
-double :: Double -> Doc
+float :: Float -> Doc
+double :: Double -> Doc
rational :: Rational -> Doc
\end{code}
Combining @Doc@ values
\begin{code}
-(<>) :: Doc -> Doc -> Doc -- Beside
-hcat :: [Doc] -> Doc -- List version of <>
-(<+>) :: Doc -> Doc -> Doc -- Beside, separated by space
-hsep :: [Doc] -> Doc -- List version of <+>
+(<>) :: Doc -> Doc -> Doc -- Beside
+hcat :: [Doc] -> Doc -- List version of <>
+(<+>) :: Doc -> Doc -> Doc -- Beside, separated by space
+hsep :: [Doc] -> Doc -- List version of <+>
-($$) :: Doc -> Doc -> Doc -- Above; if there is no
- -- overlap it "dovetails" the two
-vcat :: [Doc] -> Doc -- List version of $$
+($$) :: Doc -> Doc -> Doc -- Above; if there is no
+ -- overlap it "dovetails" the two
+vcat :: [Doc] -> Doc -- List version of $$
-cat :: [Doc] -> Doc -- Either hcat or vcat
-sep :: [Doc] -> Doc -- Either hsep or vcat
-fcat :: [Doc] -> Doc -- ``Paragraph fill'' version of cat
-fsep :: [Doc] -> Doc -- ``Paragraph fill'' version of sep
+cat :: [Doc] -> Doc -- Either hcat or vcat
+sep :: [Doc] -> Doc -- Either hsep or vcat
+fcat :: [Doc] -> Doc -- ``Paragraph fill'' version of cat
+fsep :: [Doc] -> Doc -- ``Paragraph fill'' version of sep
-nest :: Int -> Doc -> Doc -- Nested
+nest :: Int -> Doc -> Doc -- Nested
\end{code}
GHC-specific ones.
\begin{code}
hang :: Doc -> Int -> Doc -> Doc
-punctuate :: Doc -> [Doc] -> [Doc] -- punctuate p [d1, ... dn] = [d1 <> p, d2 <> p, ... dn-1 <> p, dn]
+punctuate :: Doc -> [Doc] -> [Doc] -- punctuate p [d1, ... dn] = [d1 <> p, d2 <> p, ... dn-1 <> p, dn]
\end{code}
Displaying @Doc@ values.
instance SHOW Doc where
showsPrec prec doc cont = showDoc doc cont
-render :: Doc -> String -- Uses default style
+render :: Doc -> String -- Uses default style
fullRender :: Mode
- -> Int -- Line length
- -> Float -- Ribbons per line
- -> (TextDetails -> a -> a) -- What to do with text
- -> a -- What to do at the end
- -> Doc
- -> a -- Result
-
-{- When we start using 1.3
+ -> Int -- Line length
+ -> Float -- Ribbons per line
+ -> (TextDetails -> a -> a) -- What to do with text
+ -> a -- What to do at the end
+ -> Doc
+ -> a -- Result
+
+{- When we start using 1.3
renderStyle :: Style -> Doc -> String
-data Style = Style { lineLength :: Int, -- In chars
- ribbonsPerLine :: Float, -- Ratio of ribbon length to line length
- mode :: Mode
- }
-style :: Style -- The default style
+data Style = Style { lineLength :: Int, -- In chars
+ ribbonsPerLine :: Float, -- Ratio of ribbon length to line length
+ mode :: Mode
+ }
+style :: Style -- The default style
style = Style { lineLength = 100, ribbonsPerLine = 2.5, mode = PageMode }
-}
-data Mode = PageMode -- Normal
- | ZigZagMode -- With zig-zag cuts
- | LeftMode -- No indentation, infinitely long lines
- | OneLineMode -- All on one line
+data Mode = PageMode -- Normal
+ | ZigZagMode -- With zig-zag cuts
+ | LeftMode -- No indentation, infinitely long lines
+ | OneLineMode -- All on one line
\end{code}
*********************************************************
-* *
+* *
\subsection{The @Doc@ calculus}
-* *
+* *
*********************************************************
The @Doc@ combinators satisfy the following laws:
\begin{verbatim}
Laws for $$
~~~~~~~~~~~
-<a1> (x $$ y) $$ z = x $$ (y $$ z)
-<a2> empty $$ x = x
-<a3> x $$ empty = x
+<a1> (x $$ y) $$ z = x $$ (y $$ z)
+<a2> empty $$ x = x
+<a3> x $$ empty = x
- ...ditto $+$...
+ ...ditto $+$...
Laws for <>
~~~~~~~~~~~
-<b1> (x <> y) <> z = x <> (y <> z)
-<b2> empty <> x = empty
-<b3> x <> empty = x
+<b1> (x <> y) <> z = x <> (y <> z)
+<b2> empty <> x = empty
+<b3> x <> empty = x
- ...ditto <+>...
+ ...ditto <+>...
Laws for text
~~~~~~~~~~~~~
-<t1> text s <> text t = text (s++t)
-<t2> text "" <> x = x, if x non-empty
+<t1> text s <> text t = text (s++t)
+<t2> text "" <> x = x, if x non-empty
Laws for nest
~~~~~~~~~~~~~
-<n1> nest 0 x = x
-<n2> nest k (nest k' x) = nest (k+k') x
-<n3> nest k (x <> y) = nest k z <> nest k y
-<n4> nest k (x $$ y) = nest k x $$ nest k y
-<n5> nest k empty = empty
-<n6> x <> nest k y = x <> y, if x non-empty
+<n1> nest 0 x = x
+<n2> nest k (nest k' x) = nest (k+k') x
+<n3> nest k (x <> y) = nest k z <> nest k y
+<n4> nest k (x $$ y) = nest k x $$ nest k y
+<n5> nest k empty = empty
+<n6> x <> nest k y = x <> y, if x non-empty
** Note the side condition on <n6>! It is this that
** makes it OK for empty to be a left unit for <>.
Miscellaneous
~~~~~~~~~~~~~
-<m1> (text s <> x) $$ y = text s <> ((text "" <> x)) $$
- nest (-length s) y)
+<m1> (text s <> x) $$ y = text s <> ((text "" <> x)) $$
+ nest (-length s) y)
-<m2> (x $$ y) <> z = x $$ (y <> z)
- if y non-empty
+<m2> (x $$ y) <> z = x $$ (y <> z)
+ if y non-empty
Laws for list versions
~~~~~~~~~~~~~~~~~~~~~~
-<l1> sep (ps++[empty]++qs) = sep (ps ++ qs)
- ...ditto hsep, hcat, vcat, fill...
+<l1> sep (ps++[empty]++qs) = sep (ps ++ qs)
+ ...ditto hsep, hcat, vcat, fill...
-<l2> nest k (sep ps) = sep (map (nest k) ps)
- ...ditto hsep, hcat, vcat, fill...
+<l2> nest k (sep ps) = sep (map (nest k) ps)
+ ...ditto hsep, hcat, vcat, fill...
Laws for oneLiner
~~~~~~~~~~~~~~~~~
-<o1> oneLiner (nest k p) = nest k (oneLiner p)
-<o2> oneLiner (x <> y) = oneLiner x <> oneLiner y
+<o1> oneLiner (nest k p) = nest k (oneLiner p)
+<o2> oneLiner (x <> y) = oneLiner x <> oneLiner y
\end{verbatim}
You might think that the following verion of <m1> would
be neater:
\begin{verbatim}
-<3 NO> (text s <> x) $$ y = text s <> ((empty <> x)) $$
- nest (-length s) y)
+<3 NO> (text s <> x) $$ y = text s <> ((empty <> x)) $$
+ nest (-length s) y)
\end{verbatim}
But it doesn't work, for if x=empty, we would have
\begin{verbatim}
- text s $$ y = text s <> (empty $$ nest (-length s) y)
- = text s <> nest (-length s) y
+ text s $$ y = text s <> (empty $$ nest (-length s) y)
+ = text s <> nest (-length s) y
\end{verbatim}
*********************************************************
-* *
+* *
\subsection{Simple derived definitions}
-* *
+* *
*********************************************************
\begin{code}
lbrace = char '{'
rbrace = char '}'
-int n = text (show n)
+int n = text (show n)
integer n = text (show n)
float n = text (show n)
double n = text (show n)
---ORIG: rational n = text (show n)
-rational n = text (show (fromRationalX n)) -- _showRational 30 n)
+rational n = text (show (fromRat n))
+--rational n = text (show (fromRationalX n)) -- _showRational 30 n)
-quotes p = char '`' <> p <> char '\''
-doubleQuotes p = char '"' <> p <> char '"'
-parens p = char '(' <> p <> char ')'
-brackets p = char '[' <> p <> char ']'
-braces p = char '{' <> p <> char '}'
+quotes p = char '`' <> p <> char '\''
+doubleQuotes p = char '"' <> p <> char '"'
+parens p = char '(' <> p <> char ')'
+brackets p = char '[' <> p <> char ']'
+braces p = char '{' <> p <> char '}'
hcat = foldr (<>) empty
punctuate p [] = []
punctuate p (d:ds) = go d ds
- where
- go d [] = [d]
- go d (e:es) = (d <> p) : go e es
+ where
+ go d [] = [d]
+ go d (e:es) = (d <> p) : go e es
\end{code}
*********************************************************
-* *
+* *
\subsection{The @Doc@ data type}
-* *
+* *
*********************************************************
A @Doc@ represents a {\em set} of layouts. A @Doc@ with
no occurrences of @Union@ or @NoDoc@ represents just one layout.
\begin{code}
data Doc
- = Empty -- empty
- | NilAbove Doc -- text "" $$ x
- | TextBeside TextDetails INT Doc -- text s <> x
- | Nest INT Doc -- nest k x
- | Union Doc Doc -- ul `union` ur
- | NoDoc -- The empty set of documents
- | Beside Doc Bool Doc -- True <=> space between
- | Above Doc Bool Doc -- True <=> never overlap
+ = Empty -- empty
+ | NilAbove Doc -- text "" $$ x
+ | TextBeside !TextDetails INT Doc -- text s <> x
+ | Nest INT Doc -- nest k x
+ | Union Doc Doc -- ul `union` ur
+ | NoDoc -- The empty set of documents
+ | Beside Doc Bool Doc -- True <=> space between
+ | Above Doc Bool Doc -- True <=> never overlap
-type RDoc = Doc -- RDoc is a "reduced Doc", guaranteed not to have a top-level Above or Beside
+type RDoc = Doc -- RDoc is a "reduced Doc", guaranteed not to have a top-level Above or Beside
reduceDoc :: Doc -> RDoc
reduceDoc (Beside p g q) = beside p g (reduceDoc q)
reduceDoc (Above p g q) = above p g (reduceDoc q)
-reduceDoc p = p
+reduceDoc p = p
-data TextDetails = Chr Char
- | Str String
- | PStr FAST_STRING
+data TextDetails = Chr {-#UNPACK#-}!Char
+ | Str String
+ | PStr FastString -- a hashed string
+ | LStr Addr# Int# -- a '\0'-terminated array of bytes
+
space_text = Chr ' '
nl_text = Chr '\n'
\end{code}
\end{itemize}
\begin{code}
- -- Arg of a NilAbove is always an RDoc
+ -- Arg of a NilAbove is always an RDoc
nilAbove_ p = LOCAL_ASSERT( ok p ) NilAbove p
- where
- ok Empty = False
- ok other = True
+ where
+ ok Empty = False
+ ok other = True
- -- Arg of a TextBeside is always an RDoc
+ -- Arg of a TextBeside is always an RDoc
textBeside_ s sl p = TextBeside s sl (LOCAL_ASSERT( ok p ) p)
- where
- ok (Nest _ _) = False
- ok other = True
+ where
+ ok (Nest _ _) = False
+ ok other = True
- -- Arg of Nest is always an RDoc
+ -- Arg of Nest is always an RDoc
nest_ k p = Nest k (LOCAL_ASSERT( ok p ) p)
- where
- ok Empty = False
- ok other = True
+ where
+ ok Empty = False
+ ok other = True
- -- Args of union are always RDocs
+ -- Args of union are always RDocs
union_ p q = Union (LOCAL_ASSERT( ok p ) p) (LOCAL_ASSERT( ok q ) q)
- where
- ok (TextBeside _ _ _) = True
- ok (NilAbove _) = True
- ok (Union _ _) = True
- ok other = False
+ where
+ ok (TextBeside _ _ _) = True
+ ok (NilAbove _) = True
+ ok (Union _ _) = True
+ ok other = False
\end{code}
Notice the difference between
- * NoDoc (no documents)
- * Empty (one empty document; no height and no width)
- * text "" (a document containing the empty string;
- one line high, but has no width)
+ * NoDoc (no documents)
+ * Empty (one empty document; no height and no width)
+ * text "" (a document containing the empty string;
+ one line high, but has no width)
*********************************************************
-* *
+* *
\subsection{@empty@, @text@, @nest@, @union@}
-* *
+* *
*********************************************************
\begin{code}
empty = Empty
+isEmpty Empty = True
+isEmpty _ = False
+
char c = textBeside_ (Chr c) 1# Empty
text s = case length s of {IBOX(sl) -> textBeside_ (Str s) sl Empty}
-ptext s = case _LENGTH_ s of {IBOX(sl) -> textBeside_ (PStr s) sl Empty}
+ftext s = case lengthFS s of {IBOX(sl) -> textBeside_ (PStr s) sl Empty}
+ptext (Ptr s) = case strLength (Ptr s) of {IBOX(sl) -> textBeside_ (LStr s sl) sl Empty}
+
+-- RULE that turns (text "abc") into (ptext (A# "abc"#)) to avoid the
+-- intermediate packing/unpacking of the string.
+{-# RULES
+ "text/str" forall a. text (unpackCString# a) = ptext (Ptr a)
+ #-}
-nest IBOX(k) p = mkNest k (reduceDoc p) -- Externally callable version
+nest IBOX(k) p = mkNest k (reduceDoc p) -- Externally callable version
-- mkNest checks for Nest's invariant that it doesn't have an Empty inside it
mkNest k (Nest k1 p) = mkNest (k PLUS k1) p
mkNest k NoDoc = NoDoc
mkNest k Empty = Empty
-mkNest ILIT(0) p = p -- Worth a try!
-mkNest k p = nest_ k p
+mkNest ILIT(0) p = p -- Worth a try!
+mkNest k p = nest_ k p
-- mkUnion checks for an empty document
mkUnion Empty q = Empty
\end{code}
*********************************************************
-* *
+* *
\subsection{Vertical composition @$$@}
-* *
+* *
*********************************************************
above :: Doc -> Bool -> RDoc -> RDoc
above (Above p g1 q1) g2 q2 = above p g1 (above q1 g2 q2)
above p@(Beside _ _ _) g q = aboveNest (reduceDoc p) g ILIT(0) (reduceDoc q)
-above p g q = aboveNest p g ILIT(0) (reduceDoc q)
+above p g q = aboveNest p g ILIT(0) (reduceDoc q)
aboveNest :: RDoc -> Bool -> INT -> RDoc -> RDoc
-- Specfication: aboveNest p g k q = p $g$ (nest k q)
aboveNest NoDoc g k q = NoDoc
aboveNest (p1 `Union` p2) g k q = aboveNest p1 g k q `union_`
- aboveNest p2 g k q
-
+ aboveNest p2 g k q
+
aboveNest Empty g k q = mkNest k q
aboveNest (Nest k1 p) g k q = nest_ k1 (aboveNest p g (k MINUS k1) q)
- -- p can't be Empty, so no need for mkNest
-
+ -- p can't be Empty, so no need for mkNest
+
aboveNest (NilAbove p) g k q = nilAbove_ (aboveNest p g k q)
aboveNest (TextBeside s sl p) g k q = textBeside_ s sl rest
- where
- k1 = k MINUS sl
- rest = case p of
- Empty -> nilAboveNest g k1 q
- other -> aboveNest p g k1 q
+ where
+ k1 = k MINUS sl
+ rest = case p of
+ Empty -> nilAboveNest g k1 q
+ other -> aboveNest p g k1 q
\end{code}
\begin{code}
nilAboveNest :: Bool -> INT -> RDoc -> RDoc
-- Specification: text s <> nilaboveNest g k q
--- = text s <> (text "" $g$ nest k q)
+-- = text s <> (text "" $g$ nest k q)
-nilAboveNest g k Empty = Empty -- Here's why the "text s <>" is in the spec!
+nilAboveNest g k Empty = Empty -- Here's why the "text s <>" is in the spec!
nilAboveNest g k (Nest k1 q) = nilAboveNest g (k PLUS k1) q
-nilAboveNest g k q | (not g) && (k GR ILIT(0)) -- No newline if no overlap
- = textBeside_ (Str (spaces k)) k q
- | otherwise -- Put them really above
- = nilAbove_ (mkNest k q)
+nilAboveNest g k q | (not g) && (k GR ILIT(0)) -- No newline if no overlap
+ = textBeside_ (Str (spaces k)) k q
+ | otherwise -- Put them really above
+ = nilAbove_ (mkNest k q)
\end{code}
*********************************************************
-* *
+* *
\subsection{Horizontal composition @<>@}
-* *
+* *
*********************************************************
\begin{code}
beside NoDoc g q = NoDoc
beside (p1 `Union` p2) g q = (beside p1 g q) `union_` (beside p2 g q)
beside Empty g q = q
-beside (Nest k p) g q = nest_ k (beside p g q) -- p non-empty
+beside (Nest k p) g q = nest_ k $! beside p g q -- p non-empty
beside p@(Beside p1 g1 q1) g2 q2
- {- (A `op1` B) `op2` C == A `op1` (B `op2` C) iff op1 == op2
- [ && (op1 == <> || op1 == <+>) ] -}
- | g1 == g2 = beside p1 g1 (beside q1 g2 q2)
+ {- (A `op1` B) `op2` C == A `op1` (B `op2` C) iff op1 == op2
+ [ && (op1 == <> || op1 == <+>) ] -}
+ | g1 == g2 = beside p1 g1 $! beside q1 g2 q2
| otherwise = beside (reduceDoc p) g2 q2
-beside p@(Above _ _ _) g q = beside (reduceDoc p) g q
-beside (NilAbove p) g q = nilAbove_ (beside p g q)
-beside (TextBeside s sl p) g q = textBeside_ s sl rest
- where
- rest = case p of
- Empty -> nilBeside g q
- other -> beside p g q
+beside p@(Above _ _ _) g q = let d = reduceDoc p in d `seq` beside d g q
+beside (NilAbove p) g q = nilAbove_ $! beside p g q
+beside (TextBeside s sl p) g q = textBeside_ s sl $! rest
+ where
+ rest = case p of
+ Empty -> nilBeside g q
+ other -> beside p g q
\end{code}
\begin{code}
nilBeside :: Bool -> RDoc -> RDoc
-- Specification: text "" <> nilBeside g p
--- = text "" <g> p
+-- = text "" <g> p
-nilBeside g Empty = Empty -- Hence the text "" in the spec
+nilBeside g Empty = Empty -- Hence the text "" in the spec
nilBeside g (Nest _ p) = nilBeside g p
-nilBeside g p | g = textBeside_ space_text ILIT(1) p
- | otherwise = p
+nilBeside g p | g = textBeside_ space_text ILIT(1) p
+ | otherwise = p
\end{code}
*********************************************************
-* *
+* *
\subsection{Separate, @sep@, Hughes version}
-* *
+* *
*********************************************************
\begin{code}
-- Specification: sep ps = oneLiner (hsep ps)
--- `union`
--- vcat ps
+-- `union`
+-- vcat ps
-sep = sepX True -- Separate with spaces
-cat = sepX False -- Don't
+sep = sepX True -- Separate with spaces
+cat = sepX False -- Don't
sepX x [] = empty
sepX x (p:ps) = sep1 x (reduceDoc p) ILIT(0) ps
-- Specification: sep1 g k ys = sep (x : map (nest k) ys)
--- = oneLiner (x <g> nest k (hsep ys))
--- `union` x $$ nest k (vcat ys)
+-- = oneLiner (x <g> nest k (hsep ys))
+-- `union` x $$ nest k (vcat ys)
sep1 :: Bool -> RDoc -> INT -> [Doc] -> RDoc
-sep1 g NoDoc k ys = NoDoc
+sep1 g NoDoc k ys = NoDoc
sep1 g (p `Union` q) k ys = sep1 g p k ys
- `union_`
- (aboveNest q False k (reduceDoc (vcat ys)))
+ `union_`
+ (aboveNest q False k (reduceDoc (vcat ys)))
sep1 g Empty k ys = mkNest k (sepX g ys)
sep1 g (Nest n p) k ys = nest_ n (sep1 g p (k MINUS n) ys)
sepNB g (Nest _ p) k ys = sepNB g p k ys
sepNB g Empty k ys = oneLiner (nilBeside g (reduceDoc rest))
- `mkUnion`
- nilAboveNest False k (reduceDoc (vcat ys))
- where
- rest | g = hsep ys
- | otherwise = hcat ys
+ `mkUnion`
+ nilAboveNest False k (reduceDoc (vcat ys))
+ where
+ rest | g = hsep ys
+ | otherwise = hcat ys
-sepNB g p k ys = sep1 g p k ys
+sepNB g p k ys = sep1 g p k ys
\end{code}
*********************************************************
-* *
+* *
\subsection{@fill@}
-* *
+* *
*********************************************************
\begin{code}
-- fill [] = empty
-- fill [p] = p
-- fill (p1:p2:ps) = oneLiner p1 <#> nest (length p1)
--- (fill (oneLiner p2 : ps))
--- `union`
--- p1 $$ fill ps
+-- (fill (oneLiner p2 : ps))
+-- `union`
+-- p1 $$ fill ps
fill g [] = empty
fill g (p:ps) = fill1 g (reduceDoc p) ILIT(0) ps
fill1 :: Bool -> RDoc -> INT -> [Doc] -> Doc
-fill1 g NoDoc k ys = NoDoc
+fill1 g NoDoc k ys = NoDoc
fill1 g (p `Union` q) k ys = fill1 g p k ys
- `union_`
- (aboveNest q False k (fill g ys))
+ `union_`
+ (aboveNest q False k (fill g ys))
fill1 g Empty k ys = mkNest k (fill g ys)
fill1 g (Nest n p) k ys = nest_ n (fill1 g p (k MINUS n) ys)
fillNB g (Nest _ p) k ys = fillNB g p k ys
fillNB g Empty k [] = Empty
fillNB g Empty k (y:ys) = nilBeside g (fill1 g (oneLiner (reduceDoc y)) k1 ys)
- `mkUnion`
- nilAboveNest False k (fill g (y:ys))
- where
- k1 | g = k MINUS ILIT(1)
- | otherwise = k
+ `mkUnion`
+ nilAboveNest False k (fill g (y:ys))
+ where
+ k1 | g = k MINUS ILIT(1)
+ | otherwise = k
-fillNB g p k ys = fill1 g p k ys
+fillNB g p k ys = fill1 g p k ys
\end{code}
*********************************************************
-* *
+* *
\subsection{Selecting the best layout}
-* *
+* *
*********************************************************
\begin{code}
-best :: Mode
- -> Int -- Line length
- -> Int -- Ribbon length
+best :: Int -- Line length
+ -> Int -- Ribbon length
-> RDoc
- -> RDoc -- No unions in here!
+ -> RDoc -- No unions in here!
-best OneLineMode IBOX(w) IBOX(r) p
- = get p
- where
- get Empty = Empty
- get NoDoc = NoDoc
- get (NilAbove p) = nilAbove_ (get p)
- get (TextBeside s sl p) = textBeside_ s sl (get p)
- get (Nest k p) = get p -- Elide nest
- get (p `Union` q) = first (get p) (get q)
-
-best mode IBOX(w) IBOX(r) p
+best IBOX(w) IBOX(r) p
= get w p
where
- get :: INT -- (Remaining) width of line
+ get :: INT -- (Remaining) width of line
-> Doc -> Doc
get w Empty = Empty
get w NoDoc = NoDoc
get w (Nest k p) = nest_ k (get (w MINUS k) p)
get w (p `Union` q) = nicest w r (get w p) (get w q)
- get1 :: INT -- (Remaining) width of line
- -> INT -- Amount of first line already eaten up
- -> Doc -- This is an argument to TextBeside => eat Nests
- -> Doc -- No unions in here!
+ get1 :: INT -- (Remaining) width of line
+ -> INT -- Amount of first line already eaten up
+ -> Doc -- This is an argument to TextBeside => eat Nests
+ -> Doc -- No unions in here!
get1 w sl Empty = Empty
get1 w sl NoDoc = NoDoc
get1 w sl (TextBeside t tl p) = textBeside_ t tl (get1 w (sl PLUS tl) p)
get1 w sl (Nest k p) = get1 w sl p
get1 w sl (p `Union` q) = nicest1 w r sl (get1 w sl p)
- (get1 w sl q)
+ (get1 w sl q)
nicest w r p q = nicest1 w r ILIT(0) p q
nicest1 w r sl p q | fits ((w `minn` r) MINUS sl) p = p
- | otherwise = q
+ | otherwise = q
-fits :: INT -- Space available
+fits :: INT -- Space available
-> Doc
- -> Bool -- True if *first line* of Doc fits in space available
+ -> Bool -- True if *first line* of Doc fits in space available
fits n p | n LT ILIT(0) = False
fits n NoDoc = False
fits n (TextBeside _ sl p) = fits (n MINUS sl) p
minn x y | x LT y = x
- | otherwise = y
+ | otherwise = y
\end{code}
@first@ and @nonEmptySet@ are similar to @nicest@ and @fits@, only simpler.
\begin{code}
first p q | nonEmptySet p = p
- | otherwise = q
+ | otherwise = q
-nonEmptySet NoDoc = False
+nonEmptySet NoDoc = False
nonEmptySet (p `Union` q) = True
-nonEmptySet Empty = True
-nonEmptySet (NilAbove p) = True -- NoDoc always in first line
+nonEmptySet Empty = True
+nonEmptySet (NilAbove p) = True -- NoDoc always in first line
nonEmptySet (TextBeside _ _ p) = nonEmptySet p
nonEmptySet (Nest _ p) = nonEmptySet p
\end{code}
*********************************************************
-* *
+* *
\subsection{Displaying the best layout}
-* *
+* *
*********************************************************
= fullRender mode lineLength ribbonsPerLine doc ""
-}
-render doc = showDoc doc ""
-showDoc doc rest = fullRender PageMode 100 1.5 string_txt rest doc
+render doc = showDocWith PageMode doc
+showDoc doc rest = showDocWithAppend PageMode doc rest
+
+showDocWithAppend :: Mode -> Doc -> String -> String
+showDocWithAppend mode doc rest = fullRender mode 100 1.5 string_txt rest doc
+
+showDocWith :: Mode -> Doc -> String
+showDocWith mode doc = showDocWithAppend mode doc ""
string_txt (Chr c) s = c:s
string_txt (Str s1) s2 = s1 ++ s2
-string_txt (PStr s1) s2 = _UNPK_ s1 ++ s2
+string_txt (PStr s1) s2 = unpackFS s1 ++ s2
+string_txt (LStr s1 _) s2 = unpackLitString s1 ++ s2
+
+unpackLitString addr =
+ unpack 0#
+ where
+ unpack nh
+ | ch `eqChar#` '\0'# = []
+ | otherwise = C# ch : unpack (nh +# 1#)
+ where
+ ch = indexCharOffAddr# addr nh
\end{code}
\begin{code}
-fullRender OneLineMode _ _ txt end doc = easy_display space_text txt end (reduceDoc doc)
-fullRender LeftMode _ _ txt end doc = easy_display nl_text txt end (reduceDoc doc)
+fullRender OneLineMode _ _ txt end doc
+ = lay (reduceDoc doc)
+ where
+ lay NoDoc = cant_fail
+ lay (Union p q) = (lay q) -- Second arg can't be NoDoc
+ lay (Nest k p) = lay p
+ lay Empty = end
+ lay (NilAbove p) = space_text `txt` lay p -- NoDoc always on first line
+ lay (TextBeside s sl p) = s `txt` lay p
+
+fullRender LeftMode _ _ txt end doc
+ = lay (reduceDoc doc)
+ where
+ lay NoDoc = cant_fail
+ lay (Union p q) = lay (first p q)
+ lay (Nest k p) = lay p
+ lay Empty = end
+ lay (NilAbove p) = nl_text `txt` lay p -- NoDoc always on first line
+ lay (TextBeside s sl p) = s `txt` lay p
fullRender mode line_length ribbons_per_line txt end doc
= display mode line_length ribbon_length txt end best_doc
where
- best_doc = best mode hacked_line_length ribbon_length (reduceDoc doc)
+ best_doc = best hacked_line_length ribbon_length (reduceDoc doc)
hacked_line_length, ribbon_length :: Int
- ribbon_length = round (fromInt line_length / ribbons_per_line)
+ ribbon_length = round (fromIntegral line_length / ribbons_per_line)
hacked_line_length = case mode of { ZigZagMode -> MAXINT; other -> line_length }
display mode IBOX(page_width) IBOX(ribbon_width) txt end doc
= case page_width MINUS ribbon_width of { gap_width ->
case gap_width DIV ILIT(2) of { shift ->
let
- lay k (Nest k1 p) = lay (k PLUS k1) p
- lay k Empty = end
+ lay k (Nest k1 p) = lay (k PLUS k1) p
+ lay k Empty = end
- lay k (NilAbove p) = nl_text `txt` lay k p
+ lay k (NilAbove p) = nl_text `txt` lay k p
- lay k (TextBeside s sl p)
- = case mode of
- ZigZagMode | k GREQ gap_width
- -> nl_text `txt` (
- Str (multi_ch shift '/') `txt` (
- nl_text `txt` (
- lay1 (k MINUS shift) s sl p)))
-
- | k LT ILIT(0)
- -> nl_text `txt` (
- Str (multi_ch shift '\\') `txt` (
- nl_text `txt` (
- lay1 (k PLUS shift) s sl p )))
-
- other -> lay1 k s sl p
+ lay k (TextBeside s sl p)
+ = case mode of
+ ZigZagMode | k GREQ gap_width
+ -> nl_text `txt` (
+ Str (multi_ch shift '/') `txt` (
+ nl_text `txt` (
+ lay1 (k MINUS shift) s sl p)))
+
+ | k LT ILIT(0)
+ -> nl_text `txt` (
+ Str (multi_ch shift '\\') `txt` (
+ nl_text `txt` (
+ lay1 (k PLUS shift) s sl p )))
+
+ other -> lay1 k s sl p
- lay1 k s sl p = Str (indent k) `txt` (s `txt` lay2 (k PLUS sl) p)
+ lay1 k s sl p = Str (indent k) `txt` (s `txt` lay2 (k PLUS sl) p)
- lay2 k (NilAbove p) = nl_text `txt` lay k p
- lay2 k (TextBeside s sl p) = s `txt` (lay2 (k PLUS sl) p)
- lay2 k (Nest _ p) = lay2 k p
- lay2 k Empty = end
+ lay2 k (NilAbove p) = nl_text `txt` lay k p
+ lay2 k (TextBeside s sl p) = s `txt` (lay2 (k PLUS sl) p)
+ lay2 k (Nest _ p) = lay2 k p
+ lay2 k Empty = end
in
lay ILIT(0) doc
}}
cant_fail = error "easy_display: NoDoc"
-easy_display nl_text txt end doc
- = lay doc cant_fail
- where
- lay NoDoc no_doc = no_doc
- lay (Union p q) no_doc = {- lay p -} (lay q cant_fail) -- Second arg can't be NoDoc
- lay (Nest k p) no_doc = lay p no_doc
- lay Empty no_doc = end
- lay (NilAbove p) no_doc = nl_text `txt` lay p cant_fail -- NoDoc always on first line
- lay (TextBeside s sl p) no_doc = s `txt` lay p no_doc
indent n | n GREQ ILIT(8) = '\t' : indent (n MINUS ILIT(8))
- | otherwise = spaces n
+ | otherwise = spaces n
multi_ch ILIT(0) ch = ""
multi_ch n ch = ch : multi_ch (n MINUS ILIT(1)) ch
spaces n = ' ' : spaces (n MINUS ILIT(1))
\end{code}
-Doesn't really belong here..
-
------------------------------------
\begin{code}
--- from Lennart
-fromRationalX :: (RealFloat a) => Rational -> a
-
-fromRationalX r =
- let
- h = ceiling (huge `asTypeOf` x)
- b = toInteger (floatRadix x)
- x = fromRat 0 r
- fromRat e0 r' =
- let d = denominator r'
- n = numerator r'
- in if d > h then
- let e = integerLogBase b (d `div` h) + 1
- in fromRat (e0-e) (n % (d `div` (b^e)))
- else if abs n > h then
- let e = integerLogBase b (abs n `div` h) + 1
- in fromRat (e0+e) ((n `div` (b^e)) % d)
- else
- scaleFloat e0 (fromRational r')
- in x
-
--- Compute the discrete log of i in base b.
--- Simplest way would be just divide i by b until it's smaller then b, but that would
--- be very slow! We are just slightly more clever.
-integerLogBase :: Integer -> Integer -> Int
-integerLogBase b i =
- if i < b then
- 0
- else
- -- Try squaring the base first to cut down the number of divisions.
- let l = 2 * integerLogBase (b*b) i
-
- doDiv :: Integer -> Int -> Int
- doDiv j k = if j < b then k else doDiv (j `div` b) (k+1)
- in
- doDiv (i `div` (b^l)) l
-
-
-------------
-
--- Compute smallest and largest floating point values.
-{-
-tiny :: (RealFloat a) => a
-tiny =
- let (l, _) = floatRange x
- x = encodeFloat 1 (l-1)
- in x
--}
+pprCols = (120 :: Int) -- could make configurable
+
+printDoc :: Mode -> Handle -> Doc -> IO ()
+printDoc LeftMode hdl doc
+ = do { printLeftRender hdl doc; hFlush hdl }
+printDoc mode hdl doc
+ = do { fullRender mode pprCols 1.5 put done doc ;
+ hFlush hdl }
+ where
+ put (Chr c) next = hPutChar hdl c >> next
+ put (Str s) next = hPutStr hdl s >> next
+ put (PStr s) next = hPutFS hdl s >> next
+ put (LStr s l) next = hPutLitString hdl s l >> next
+
+ done = hPutChar hdl '\n'
+
+ -- some versions of hPutBuf will barf if the length is zero
+hPutLitString handle a# 0# = return ()
+hPutLitString handle a# l#
+#if __GLASGOW_HASKELL__ < 411
+ = hPutBuf handle (A# a#) (I# l#)
+#else
+ = hPutBuf handle (Ptr a#) (I# l#)
+#endif
+
+-- Printing output in LeftMode is performance critical: it's used when
+-- dumping C and assembly output, so we allow ourselves a few dirty
+-- hacks:
+--
+-- (1) we specialise fullRender for LeftMode with IO output.
+--
+-- (2) we add a layer of buffering on top of Handles. Handles
+-- don't perform well with lots of hPutChars, which is mostly
+-- what we're doing here, because Handles have to be thread-safe
+-- and async exception-safe. We only have a single thread and don't
+-- care about exceptions, so we add a layer of fast buffering
+-- over the Handle interface.
+--
+-- (3) a few hacks in layLeft below to convince GHC to generate the right
+-- code.
+
+printLeftRender :: Handle -> Doc -> IO ()
+printLeftRender hdl doc = do
+ b <- newBufHandle hdl
+ layLeft b (reduceDoc doc)
+ bFlush b
+
+-- HACK ALERT! the "return () >>" below convinces GHC to eta-expand
+-- this function with the IO state lambda. Otherwise we end up with
+-- closures in all the case branches.
+layLeft b _ | b `seq` False = undefined -- make it strict in b
+layLeft b NoDoc = cant_fail
+layLeft b (Union p q) = return () >> layLeft b (first p q)
+layLeft b (Nest k p) = return () >> layLeft b p
+layLeft b Empty = bPutChar b '\n'
+layLeft b (NilAbove p) = bPutChar b '\n' >> layLeft b p
+layLeft b (TextBeside s sl p) = put b s >> layLeft b p
+ where
+ put b _ | b `seq` False = undefined
+ put b (Chr c) = bPutChar b c
+ put b (Str s) = bPutStr b s
+ put b (PStr s) = bPutFS b s
+ put b (LStr s l) = bPutLitString b s l
+
+#if __GLASGOW_HASKELL__ < 503
+hPutBuf = hPutBufFull
+#endif
-huge :: (RealFloat a) => a
-huge =
- let (_, u) = floatRange x
- d = floatDigits x
- x = encodeFloat (floatRadix x ^ d - 1) (u - d)
- in x
\end{code}
projects / ghc-hetmet.git / blobdiff