----------------------------------------------------------------------------- -- | -- Module : Text.PrettyPrint.ANSI.Leijen -- Copyright : Daan Leijen (c) 2000, http://www.cs.uu.nl/~daan -- Max Bolingbroke (c) 2008, http://blog.omega-prime.co.uk -- License : BSD-style (see the file LICENSE) -- -- Maintainer : batterseapower@hotmail.com -- Stability : provisional -- Portability : portable -- -- Pretty print module based on Philip Wadler's \"prettier printer\" -- -- @ -- \"A prettier printer\" -- Draft paper, April 1997, revised March 1998. -- <http://cm.bell-labs.com/cm/cs/who/wadler/papers/prettier/prettier.ps> -- @ -- -- PPrint is an implementation of the pretty printing combinators -- described by Philip Wadler (1997). In their bare essence, the -- combinators of Wadler are not expressive enough to describe some -- commonly occurring layouts. The PPrint library adds new primitives -- to describe these layouts and works well in practice. -- -- The library is based on a single way to concatenate documents, -- which is associative and has both a left and right unit. This -- simple design leads to an efficient and short implementation. The -- simplicity is reflected in the predictable behaviour of the -- combinators which make them easy to use in practice. -- -- A thorough description of the primitive combinators and their -- implementation can be found in Philip Wadler's paper -- (1997). Additions and the main differences with his original paper -- are: -- -- * The nil document is called empty. -- -- * The above combinator is called '<$>'. The operator '</>' is used -- for soft line breaks. -- -- * There are three new primitives: 'align', 'fill' and -- 'fillBreak'. These are very useful in practice. -- -- * Lots of other useful combinators, like 'fillSep' and 'list'. -- -- * There are two renderers, 'renderPretty' for pretty printing and -- 'renderCompact' for compact output. The pretty printing algorithm -- also uses a ribbon-width now for even prettier output. -- -- * There are two displayers, 'displayS' for strings and 'displayIO' for -- file based output. -- -- * There is a 'Pretty' class. -- -- * The implementation uses optimised representations and strictness -- annotations. -- -- Full documentation for the original wl-pprint library available at -- <http://www.cs.uu.nl/~daan/download/pprint/pprint.html>. ----------------------------------------------------------- module Text.PrettyPrint.ANSI.Leijen ( -- * Documents Doc, putDoc, hPutDoc, -- * Basic combinators empty, char, text, (<>), nest, line, linebreak, group, softline, softbreak, -- * Alignment -- -- The combinators in this section can not be described by Wadler's -- original combinators. They align their output relative to the -- current output position - in contrast to @nest@ which always -- aligns to the current nesting level. This deprives these -- combinators from being \`optimal\'. In practice however they -- prove to be very useful. The combinators in this section should -- be used with care, since they are more expensive than the other -- combinators. For example, @align@ shouldn't be used to pretty -- print all top-level declarations of a language, but using @hang@ -- for let expressions is fine. align, hang, indent, encloseSep, list, tupled, semiBraces, -- * Operators (<+>), (<$>), (</>), (<$$>), (<//>), -- * List combinators hsep, vsep, fillSep, sep, hcat, vcat, fillCat, cat, punctuate, -- * Fillers fill, fillBreak, -- * Bracketing combinators enclose, squotes, dquotes, parens, angles, braces, brackets, -- * Character documents lparen, rparen, langle, rangle, lbrace, rbrace, lbracket, rbracket, squote, dquote, semi, colon, comma, space, dot, backslash, equals, -- * Primitive type documents string, int, integer, float, double, rational, -- * Primitive colorisation combinators black, red, green, yellow, blue, magenta, cyan, white, dullblack, dullred, dullgreen, dullyellow, dullblue, dullmagenta, dullcyan, dullwhite, onblack, onred, ongreen, onyellow, onblue, onmagenta, oncyan, onwhite, ondullblack, ondullred, ondullgreen, ondullyellow, ondullblue, ondullmagenta, ondullcyan, ondullwhite, -- * Pretty class Pretty(..), -- * Rendering SimpleDoc(..), renderPretty, renderCompact, displayS, displayIO -- * Undocumented , bool , column, nesting, width ) where import System.IO (Handle,hPutStr,hPutChar,stdout) import System.Console.ANSI (Color(..), ColorIntensity(..), ConsoleLayer(..), SGR(..), hSetSGR, setSGRCode) import Control.Monad (when) import Data.Maybe (isNothing, fromMaybe) infixr 5 </>,<//>,<$>,<$$> infixr 6 <>,<+> ----------------------------------------------------------- -- list, tupled and semiBraces pretty print a list of -- documents either horizontally or vertically aligned. ----------------------------------------------------------- -- | The document @(list xs)@ comma separates the documents @xs@ and -- encloses them in square brackets. The documents are rendered -- horizontally if that fits the page. Otherwise they are aligned -- vertically. All comma separators are put in front of the elements. list :: [Doc] -> Doc list = encloseSep lbracket rbracket comma -- | The document @(tupled xs)@ comma separates the documents @xs@ and -- encloses them in parenthesis. The documents are rendered -- horizontally if that fits the page. Otherwise they are aligned -- vertically. All comma separators are put in front of the elements. tupled :: [Doc] -> Doc tupled = encloseSep lparen rparen comma -- | The document @(semiBraces xs)@ separates the documents @xs@ with -- semi colons and encloses them in braces. The documents are rendered -- horizontally if that fits the page. Otherwise they are aligned -- vertically. All semi colons are put in front of the elements. semiBraces :: [Doc] -> Doc semiBraces = encloseSep lbrace rbrace semi -- | The document @(encloseSep l r sep xs)@ concatenates the documents -- @xs@ separated by @sep@ and encloses the resulting document by @l@ -- and @r@. The documents are rendered horizontally if that fits the -- page. Otherwise they are aligned vertically. All separators are put -- in front of the elements. For example, the combinator 'list' can be -- defined with @encloseSep@: -- -- > list xs = encloseSep lbracket rbracket comma xs -- > test = text "list" <+> (list (map int [10,200,3000])) -- -- Which is layed out with a page width of 20 as: -- -- @ -- list [10,200,3000] -- @ -- -- But when the page width is 15, it is layed out as: -- -- @ -- list [10 -- ,200 -- ,3000] -- @ encloseSep :: Doc -> Doc -> Doc -> [Doc] -> Doc encloseSep left right sep ds = case ds of [] -> left <> right [d] -> left <> d <> right _ -> align (cat (zipWith (<>) (left : repeat sep) ds) <> right) ----------------------------------------------------------- -- punctuate p [d1,d2,...,dn] => [d1 <> p,d2 <> p, ... ,dn] ----------------------------------------------------------- -- | @(punctuate p xs)@ concatenates all documents in @xs@ with -- document @p@ except for the last document. -- -- > someText = map text ["words","in","a","tuple"] -- > test = parens (align (cat (punctuate comma someText))) -- -- This is layed out on a page width of 20 as: -- -- @ -- (words,in,a,tuple) -- @ -- -- But when the page width is 15, it is layed out as: -- -- @ -- (words, -- in, -- a, -- tuple) -- @ -- -- (If you want put the commas in front of their elements instead of -- at the end, you should use 'tupled' or, in general, 'encloseSep'.) punctuate :: Doc -> [Doc] -> [Doc] punctuate p [] = [] punctuate p [d] = [d] punctuate p (d:ds) = (d <> p) : punctuate p ds ----------------------------------------------------------- -- high-level combinators ----------------------------------------------------------- -- | The document @(sep xs)@ concatenates all documents @xs@ either -- horizontally with @(\<+\>)@, if it fits the page, or vertically with -- @(\<$\>)@. -- -- > sep xs = group (vsep xs) sep :: [Doc] -> Doc sep = group . vsep -- | The document @(fillSep xs)@ concatenates documents @xs@ -- horizontally with @(\<+\>)@ as long as its fits the page, than -- inserts a @line@ and continues doing that for all documents in -- @xs@. -- -- > fillSep xs = foldr (\<\/\>) empty xs fillSep :: [Doc] -> Doc fillSep = fold (</>) -- | The document @(hsep xs)@ concatenates all documents @xs@ -- horizontally with @(\<+\>)@. hsep :: [Doc] -> Doc hsep = fold (<+>) -- | The document @(vsep xs)@ concatenates all documents @xs@ -- vertically with @(\<$\>)@. If a 'group' undoes the line breaks -- inserted by @vsep@, all documents are separated with a space. -- -- > someText = map text (words ("text to lay out")) -- > -- > test = text "some" <+> vsep someText -- -- This is layed out as: -- -- @ -- some text -- to -- lay -- out -- @ -- -- The 'align' combinator can be used to align the documents under -- their first element -- -- > test = text "some" <+> align (vsep someText) -- -- Which is printed as: -- -- @ -- some text -- to -- lay -- out -- @ vsep :: [Doc] -> Doc vsep = fold (<$>) -- | The document @(cat xs)@ concatenates all documents @xs@ either -- horizontally with @(\<\>)@, if it fits the page, or vertically with -- @(\<$$\>)@. -- -- > cat xs = group (vcat xs) cat :: [Doc] -> Doc cat = group . vcat -- | The document @(fillCat xs)@ concatenates documents @xs@ -- horizontally with @(\<\>)@ as long as its fits the page, than inserts -- a @linebreak@ and continues doing that for all documents in @xs@. -- -- > fillCat xs = foldr (\<\/\/\>) empty xs fillCat :: [Doc] -> Doc fillCat = fold (<//>) -- | The document @(hcat xs)@ concatenates all documents @xs@ -- horizontally with @(\<\>)@. hcat :: [Doc] -> Doc hcat = fold (<>) -- | The document @(vcat xs)@ concatenates all documents @xs@ -- vertically with @(\<$$\>)@. If a 'group' undoes the line breaks -- inserted by @vcat@, all documents are directly concatenated. vcat :: [Doc] -> Doc vcat = fold (<$$>) fold f [] = empty fold f ds = foldr1 f ds -- | The document @(x \<\> y)@ concatenates document @x@ and document -- @y@. It is an associative operation having 'empty' as a left and -- right unit. (infixr 6) (<>) :: Doc -> Doc -> Doc x <> y = x `beside` y -- | The document @(x \<+\> y)@ concatenates document @x@ and @y@ with a -- @space@ in between. (infixr 6) (<+>) :: Doc -> Doc -> Doc x <+> y = x <> space <> y -- | The document @(x \<\/\> y)@ concatenates document @x@ and @y@ with a -- 'softline' in between. This effectively puts @x@ and @y@ either -- next to each other (with a @space@ in between) or underneath each -- other. (infixr 5) (</>) :: Doc -> Doc -> Doc x </> y = x <> softline <> y -- | The document @(x \<\/\/\> y)@ concatenates document @x@ and @y@ with -- a 'softbreak' in between. This effectively puts @x@ and @y@ either -- right next to each other or underneath each other. (infixr 5) (<//>) :: Doc -> Doc -> Doc x <//> y = x <> softbreak <> y -- | The document @(x \<$\> y)@ concatenates document @x@ and @y@ with a -- 'line' in between. (infixr 5) (<$>) :: Doc -> Doc -> Doc x <$> y = x <> line <> y -- | The document @(x \<$$\> y)@ concatenates document @x@ and @y@ with -- a @linebreak@ in between. (infixr 5) (<$$>) :: Doc -> Doc -> Doc x <$$> y = x <> linebreak <> y -- | The document @softline@ behaves like 'space' if the resulting -- output fits the page, otherwise it behaves like 'line'. -- -- > softline = group line softline :: Doc softline = group line -- | The document @softbreak@ behaves like 'empty' if the resulting -- output fits the page, otherwise it behaves like 'line'. -- -- > softbreak = group linebreak softbreak :: Doc softbreak = group linebreak -- | Document @(squotes x)@ encloses document @x@ with single quotes -- \"'\". squotes :: Doc -> Doc squotes = enclose squote squote -- | Document @(dquotes x)@ encloses document @x@ with double quotes -- '\"'. dquotes :: Doc -> Doc dquotes = enclose dquote dquote -- | Document @(braces x)@ encloses document @x@ in braces, \"{\" and -- \"}\". braces :: Doc -> Doc braces = enclose lbrace rbrace -- | Document @(parens x)@ encloses document @x@ in parenthesis, \"(\" -- and \")\". parens :: Doc -> Doc parens = enclose lparen rparen -- | Document @(angles x)@ encloses document @x@ in angles, \"\<\" and -- \"\>\". angles :: Doc -> Doc angles = enclose langle rangle -- | Document @(brackets x)@ encloses document @x@ in square brackets, -- \"[\" and \"]\". brackets :: Doc -> Doc brackets = enclose lbracket rbracket -- | The document @(enclose l r x)@ encloses document @x@ between -- documents @l@ and @r@ using @(\<\>)@. -- -- > enclose l r x = l <> x <> r enclose :: Doc -> Doc -> Doc -> Doc enclose l r x = l <> x <> r -- | The document @lparen@ contains a left parenthesis, \"(\". lparen :: Doc lparen = char '(' -- | The document @rparen@ contains a right parenthesis, \")\". rparen :: Doc rparen = char ')' -- | The document @langle@ contains a left angle, \"\<\". langle :: Doc langle = char '<' -- | The document @rangle@ contains a right angle, \">\". rangle :: Doc rangle = char '>' -- | The document @lbrace@ contains a left brace, \"{\". lbrace :: Doc lbrace = char '{' -- | The document @rbrace@ contains a right brace, \"}\". rbrace :: Doc rbrace = char '}' -- | The document @lbracket@ contains a left square bracket, \"[\". lbracket :: Doc lbracket = char '[' -- | The document @rbracket@ contains a right square bracket, \"]\". rbracket :: Doc rbracket = char ']' -- | The document @squote@ contains a single quote, \"'\". squote :: Doc squote = char '\'' -- | The document @dquote@ contains a double quote, '\"'. dquote :: Doc dquote = char '"' -- | The document @semi@ contains a semi colon, \";\". semi :: Doc semi = char ';' -- | The document @colon@ contains a colon, \":\". colon :: Doc colon = char ':' -- | The document @comma@ contains a comma, \",\". comma :: Doc comma = char ',' -- | The document @space@ contains a single space, \" \". -- -- > x <+> y = x <> space <> y space :: Doc space = char ' ' -- | The document @dot@ contains a single dot, \".\". dot :: Doc dot = char '.' -- | The document @backslash@ contains a back slash, \"\\\". backslash :: Doc backslash = char '\\' -- | The document @equals@ contains an equal sign, \"=\". equals :: Doc equals = char '=' ----------------------------------------------------------- -- Combinators for prelude types ----------------------------------------------------------- -- string is like "text" but replaces '\n' by "line" -- | The document @(string s)@ concatenates all characters in @s@ -- using @line@ for newline characters and @char@ for all other -- characters. It is used instead of 'text' whenever the text contains -- newline characters. string :: String -> Doc string "" = empty string ('\n':s) = line <> string s string s = case (span (/='\n') s) of (xs,ys) -> text xs <> string ys bool :: Bool -> Doc bool b = text (show b) -- | The document @(int i)@ shows the literal integer @i@ using -- 'text'. int :: Int -> Doc int i = text (show i) -- | The document @(integer i)@ shows the literal integer @i@ using -- 'text'. integer :: Integer -> Doc integer i = text (show i) -- | The document @(float f)@ shows the literal float @f@ using -- 'text'. float :: Float -> Doc float f = text (show f) -- | The document @(double d)@ shows the literal double @d@ using -- 'text'. double :: Double -> Doc double d = text (show d) -- | The document @(rational r)@ shows the literal rational @r@ using -- 'text'. rational :: Rational -> Doc rational r = text (show r) ----------------------------------------------------------- -- overloading "pretty" ----------------------------------------------------------- -- | The member @prettyList@ is only used to define the @instance Pretty -- a => Pretty [a]@. In normal circumstances only the @pretty@ function -- is used. class Pretty a where pretty :: a -> Doc prettyList :: [a] -> Doc prettyList = list . map pretty instance Pretty a => Pretty [a] where pretty = prettyList instance Pretty Doc where pretty = id instance Pretty () where pretty () = text "()" instance Pretty Bool where pretty b = bool b instance Pretty Char where pretty c = char c prettyList s = string s instance Pretty Int where pretty i = int i instance Pretty Integer where pretty i = integer i instance Pretty Float where pretty f = float f instance Pretty Double where pretty d = double d --instance Pretty Rational where -- pretty r = rational r instance (Pretty a,Pretty b) => Pretty (a,b) where pretty (x,y) = tupled [pretty x, pretty y] instance (Pretty a,Pretty b,Pretty c) => Pretty (a,b,c) where pretty (x,y,z)= tupled [pretty x, pretty y, pretty z] instance Pretty a => Pretty (Maybe a) where pretty Nothing = empty pretty (Just x) = pretty x ----------------------------------------------------------- -- semi primitive: fill and fillBreak ----------------------------------------------------------- -- | The document @(fillBreak i x)@ first renders document @x@. It -- than appends @space@s until the width is equal to @i@. If the -- width of @x@ is already larger than @i@, the nesting level is -- increased by @i@ and a @line@ is appended. When we redefine @ptype@ -- in the previous example to use @fillBreak@, we get a useful -- variation of the previous output: -- -- > ptype (name,tp) -- > = fillBreak 6 (text name) <+> text "::" <+> text tp -- -- The output will now be: -- -- @ -- let empty :: Doc -- nest :: Int -> Doc -> Doc -- linebreak -- :: Doc -- @ fillBreak :: Int -> Doc -> Doc fillBreak f x = width x (\w -> if (w > f) then nest f linebreak else text (spaces (f - w))) -- | The document @(fill i x)@ renders document @x@. It than appends -- @space@s until the width is equal to @i@. If the width of @x@ is -- already larger, nothing is appended. This combinator is quite -- useful in practice to output a list of bindings. The following -- example demonstrates this. -- -- > types = [("empty","Doc") -- > ,("nest","Int -> Doc -> Doc") -- > ,("linebreak","Doc")] -- > -- > ptype (name,tp) -- > = fill 6 (text name) <+> text "::" <+> text tp -- > -- > test = text "let" <+> align (vcat (map ptype types)) -- -- Which is layed out as: -- -- @ -- let empty :: Doc -- nest :: Int -> Doc -> Doc -- linebreak :: Doc -- @ fill :: Int -> Doc -> Doc fill f d = width d (\w -> if (w >= f) then empty else text (spaces (f - w))) width :: Doc -> (Int -> Doc) -> Doc width d f = column (\k1 -> d <> column (\k2 -> f (k2 - k1))) ----------------------------------------------------------- -- semi primitive: Alignment and indentation ----------------------------------------------------------- -- | The document @(indent i x)@ indents document @x@ with @i@ spaces. -- -- > test = indent 4 (fillSep (map text -- > (words "the indent combinator indents these words !"))) -- -- Which lays out with a page width of 20 as: -- -- @ -- the indent -- combinator -- indents these -- words ! -- @ indent :: Int -> Doc -> Doc indent i d = hang i (text (spaces i) <> d) -- | The hang combinator implements hanging indentation. The document -- @(hang i x)@ renders document @x@ with a nesting level set to the -- current column plus @i@. The following example uses hanging -- indentation for some text: -- -- > test = hang 4 (fillSep (map text -- > (words "the hang combinator indents these words !"))) -- -- Which lays out on a page with a width of 20 characters as: -- -- @ -- the hang combinator -- indents these -- words ! -- @ -- -- The @hang@ combinator is implemented as: -- -- > hang i x = align (nest i x) hang :: Int -> Doc -> Doc hang i d = align (nest i d) -- | The document @(align x)@ renders document @x@ with the nesting -- level set to the current column. It is used for example to -- implement 'hang'. -- -- As an example, we will put a document right above another one, -- regardless of the current nesting level: -- -- > x $$ y = align (x <$> y) -- -- > test = text "hi" <+> (text "nice" $$ text "world") -- -- which will be layed out as: -- -- @ -- hi nice -- world -- @ align :: Doc -> Doc align d = column (\k -> nesting (\i -> nest (k - i) d)) --nesting might be negative :-) ----------------------------------------------------------- -- Primitives ----------------------------------------------------------- -- | The abstract data type @Doc@ represents pretty documents. -- -- @Doc@ is an instance of the 'Show' class. @(show doc)@ pretty -- prints document @doc@ with a page width of 100 characters and a -- ribbon width of 40 characters. -- -- > show (text "hello" <$> text "world") -- -- Which would return the string \"hello\\nworld\", i.e. -- -- @ -- hello -- world -- @ data Doc = Empty | Char Char -- invariant: char is not '\n' | Text !Int String -- invariant: text doesn't contain '\n' | Line !Bool -- True <=> when undone by group, do not insert a space | Cat Doc Doc | Nest !Int Doc | Union Doc Doc -- invariant: first lines of first doc longer than the first lines of the second doc | Column (Int -> Doc) | Nesting (Int -> Doc) | Color ConsoleLayer ColorIntensity -- Introduces coloring /around/ the embedded document Color Doc | EndColor (Maybe (ColorIntensity, Color)) -- Only used during the rendered phase, to signal a color end marker should be output before continuing (Maybe (ColorIntensity, Color)) -- These are the colors to revert the current forecolor/backcolor to (i.e. those from before the start of the Color block) -- | The data type @SimpleDoc@ represents rendered documents and is -- used by the display functions. -- -- The @Int@ in @SText@ contains the length of the string. The @Int@ -- in @SLine@ contains the indentation for that line. The library -- provides two default display functions 'displayS' and -- 'displayIO'. You can provide your own display function by writing a -- function from a @SimpleDoc@ to your own output format. data SimpleDoc = SEmpty | SChar Char SimpleDoc | SText !Int String SimpleDoc | SLine !Int SimpleDoc | SSGR [SGR] SimpleDoc -- | The empty document is, indeed, empty. Although @empty@ has no -- content, it does have a \'height\' of 1 and behaves exactly like -- @(text \"\")@ (and is therefore not a unit of @\<$\>@). empty :: Doc empty = Empty -- | The document @(char c)@ contains the literal character @c@. The -- character shouldn't be a newline (@'\n'@), the function 'line' -- should be used for line breaks. char :: Char -> Doc char '\n' = line char c = Char c -- | The document @(text s)@ contains the literal string @s@. The -- string shouldn't contain any newline (@'\n'@) characters. If the -- string contains newline characters, the function 'string' should be -- used. text :: String -> Doc text "" = Empty text s = Text (length s) s -- | The @line@ document advances to the next line and indents to the -- current nesting level. Document @line@ behaves like @(text \" \")@ -- if the line break is undone by 'group'. line :: Doc line = Line False -- | The @linebreak@ document advances to the next line and indents to -- the current nesting level. Document @linebreak@ behaves like -- 'empty' if the line break is undone by 'group'. linebreak :: Doc linebreak = Line True beside x y = Cat x y -- | The document @(nest i x)@ renders document @x@ with the current -- indentation level increased by i (See also 'hang', 'align' and -- 'indent'). -- -- > nest 2 (text "hello" <$> text "world") <$> text "!" -- -- outputs as: -- -- @ -- hello -- world -- ! -- @ nest :: Int -> Doc -> Doc nest i x = Nest i x column, nesting :: (Int -> Doc) -> Doc column f = Column f nesting f = Nesting f -- | The @group@ combinator is used to specify alternative -- layouts. The document @(group x)@ undoes all line breaks in -- document @x@. The resulting line is added to the current line if -- that fits the page. Otherwise, the document @x@ is rendered without -- any changes. group :: Doc -> Doc group x = Union (flatten x) x flatten :: Doc -> Doc flatten (Cat x y) = Cat (flatten x) (flatten y) flatten (Nest i x) = Nest i (flatten x) flatten (Line break) = if break then Empty else Text 1 " " flatten (Union x y) = flatten x flatten (Column f) = Column (flatten . f) flatten (Nesting f) = Nesting (flatten . f) flatten (Color l i c x) = Color l i c (flatten x) flatten other = other --Empty,Char,Text,EndColor -- | Displays a document with the given forecolor black, red, green, yellow, blue, magenta, cyan, white, dullblack, dullred, dullgreen, dullyellow, dullblue, dullmagenta, dullcyan, dullwhite :: Doc -> Doc (black, dullblack) = colorFunctions Black (red, dullred) = colorFunctions Red (green, dullgreen) = colorFunctions Green (yellow, dullyellow) = colorFunctions Yellow (blue, dullblue) = colorFunctions Blue (magenta, dullmagenta) = colorFunctions Magenta (cyan, dullcyan) = colorFunctions Cyan (white, dullwhite) = colorFunctions White -- | Displays a document with a forecolor given in the first parameter color, dullcolor :: Color -> Doc -> Doc color = Color Foreground Vivid dullcolor = Color Foreground Dull colorFunctions :: Color -> (Doc -> Doc, Doc -> Doc) colorFunctions what = (color what, dullcolor what) -- | Displays a document with the given backcolor onblack, onred, ongreen, onyellow, onblue, onmagenta, oncyan, onwhite, ondullblack, ondullred, ondullgreen, ondullyellow, ondullblue, ondullmagenta, ondullcyan, ondullwhite :: Doc -> Doc (onblack, ondullblack) = oncolorFunctions Black (onred, ondullred) = oncolorFunctions Red (ongreen, ondullgreen) = oncolorFunctions Green (onyellow, ondullyellow) = oncolorFunctions Yellow (onblue, ondullblue) = oncolorFunctions Blue (onmagenta, ondullmagenta) = oncolorFunctions Magenta (oncyan, ondullcyan) = oncolorFunctions Cyan (onwhite, ondullwhite) = oncolorFunctions White -- | Displays a document with a backcolor given in the first parameter oncolor, ondullcolor :: Color -> Doc -> Doc oncolor = Color Background Vivid ondullcolor = Color Background Dull oncolorFunctions :: Color -> (Doc -> Doc, Doc -> Doc) oncolorFunctions what = (oncolor what, ondullcolor what) ----------------------------------------------------------- -- Renderers ----------------------------------------------------------- ----------------------------------------------------------- -- renderPretty: the default pretty printing algorithm ----------------------------------------------------------- -- list of indentation/document pairs; saves an indirection over [(Int,Doc)] data Docs = Nil | Cons !Int Doc Docs -- | This is the default pretty printer which is used by 'show', -- 'putDoc' and 'hPutDoc'. @(renderPretty ribbonfrac width x)@ renders -- document @x@ with a page width of @width@ and a ribbon width of -- @(ribbonfrac * width)@ characters. The ribbon width is the maximal -- amount of non-indentation characters on a line. The parameter -- @ribbonfrac@ should be between @0.0@ and @1.0@. If it is lower or -- higher, the ribbon width will be 0 or @width@ respectively. renderPretty :: Float -> Int -> Doc -> SimpleDoc renderPretty rfrac w x -- I used to do a @SSGR [Reset]@ here, but if you do that it will result -- in any rendered @Doc@ containing at least some ANSI control codes. This -- may be undesirable if you want to render to non-ANSI devices by simply -- not making use of the ANSI color combinators I provide. -- -- What I "really" want to do here is do an initial Reset iff there is some -- ANSI color within the Doc, but that's a bit fiddly. I'll fix it if someone -- complains! = best 0 0 Nothing Nothing (Cons 0 x Nil) where -- r :: the ribbon width in characters r = max 0 (min w (round (fromIntegral w * rfrac))) -- best :: n = indentation of current line -- k = current column -- (ie. (k >= n) && (k - n == count of inserted characters) best n k mb_fc mb_bc Nil = SEmpty best n k mb_fc mb_bc (Cons i d ds) = case d of Empty -> best n k mb_fc mb_bc ds Char c -> let k' = k+1 in seq k' (SChar c (best n k' mb_fc mb_bc ds)) Text l s -> let k' = k+l in seq k' (SText l s (best n k' mb_fc mb_bc ds)) Line _ -> SLine i (best i i mb_fc mb_bc ds) Cat x y -> best n k mb_fc mb_bc (Cons i x (Cons i y ds)) Nest j x -> let i' = i+j in seq i' (best n k mb_fc mb_bc (Cons i' x ds)) Union x y -> nicest n k (best n k mb_fc mb_bc (Cons i x ds)) (best n k mb_fc mb_bc (Cons i y ds)) Column f -> best n k mb_fc mb_bc (Cons i (f k) ds) Nesting f -> best n k mb_fc mb_bc (Cons i (f i) ds) Color l t c x -> SSGR [toSGR l t c] (best n k mb_fc' mb_bc' (Cons i x (Cons i (EndColor mb_fc mb_bc) ds))) where mb_fc' = case l of { Background -> mb_fc; Foreground -> Just (t, c) } mb_bc' = case l of { Background -> Just (t, c); Foreground -> mb_bc } EndColor mb_fc' mb_bc' -> SSGR sgr3 (best n k mb_fc' mb_bc' ds) where sgr3 = Reset : sgr2 sgr2 = maybe id ((:) . uncurry (toSGR Foreground)) mb_fc' sgr1 sgr1 = maybe id ((:) . uncurry (toSGR Background)) mb_bc' [] --nicest :: r = ribbon width, w = page width, -- n = indentation of current line, k = current column -- x and y, the (simple) documents to chose from. -- precondition: first lines of x are longer than the first lines of y. nicest n k x y | fits width x = x | otherwise = y where width = min (w - k) (r - k + n) toSGR :: ConsoleLayer -> ColorIntensity -> Color -> SGR toSGR layer intensity color = SetColor layer intensity color fits w x | w < 0 = False fits w SEmpty = True fits w (SChar c x) = fits (w - 1) x fits w (SText l s x) = fits (w - l) x fits w (SLine i x) = True fits w (SSGR s x) = fits w x ----------------------------------------------------------- -- renderCompact: renders documents without indentation -- fast and fewer characters output, good for machines ----------------------------------------------------------- -- | @(renderCompact x)@ renders document @x@ without adding any -- indentation. Since no \'pretty\' printing is involved, this -- renderer is very fast. The resulting output contains fewer -- characters than a pretty printed version and can be used for output -- that is read by other programs. -- -- This rendering function does not add any colorisation information. renderCompact :: Doc -> SimpleDoc renderCompact x = scan 0 [x] where scan k [] = SEmpty scan k (d:ds) = case d of Empty -> scan k ds Char c -> let k' = k+1 in seq k' (SChar c (scan k' ds)) Text l s -> let k' = k+l in seq k' (SText l s (scan k' ds)) Line _ -> SLine 0 (scan 0 ds) Cat x y -> scan k (x:y:ds) Nest j x -> scan k (x:ds) Union x y -> scan k (y:ds) Column f -> scan k (f k:ds) Nesting f -> scan k (f 0:ds) Color _ _ _ x -> scan k (x:ds) EndColor _ _ -> scan k ds ----------------------------------------------------------- -- Displayers: displayS and displayIO ----------------------------------------------------------- -- | @(displayS simpleDoc)@ takes the output @simpleDoc@ from a -- rendering function and transforms it to a 'ShowS' type (for use in -- the 'Show' class). -- -- > showWidth :: Int -> Doc -> String -- > showWidth w x = displayS (renderPretty 0.4 w x) "" -- -- ANSI color information will be discarded by this function unless -- you are running on a Unix-like operating system. This is due to -- a technical limitation in Windows ANSI support. displayS :: SimpleDoc -> ShowS displayS SEmpty = id displayS (SChar c x) = showChar c . displayS x displayS (SText l s x) = showString s . displayS x displayS (SLine i x) = showString ('\n':indentation i) . displayS x displayS (SSGR s x) = showString (setSGRCode s) . displayS x -- | @(displayIO handle simpleDoc)@ writes @simpleDoc@ to the file -- handle @handle@. This function is used for example by 'hPutDoc': -- -- > hPutDoc handle doc = displayIO handle (renderPretty 0.4 100 doc) -- -- Any ANSI colorisation in @simpleDoc@ will be output. displayIO :: Handle -> SimpleDoc -> IO () displayIO handle simpleDoc = display simpleDoc where display SEmpty = return () display (SChar c x) = do{ hPutChar handle c; display x} display (SText l s x) = do{ hPutStr handle s; display x} display (SLine i x) = do{ hPutStr handle ('\n':indentation i); display x} display (SSGR s x) = do{ hSetSGR handle s; display x} ----------------------------------------------------------- -- default pretty printers: show, putDoc and hPutDoc ----------------------------------------------------------- instance Show Doc where showsPrec d doc = displayS (renderPretty 0.4 80 doc) -- | The action @(putDoc doc)@ pretty prints document @doc@ to the -- standard output, with a page width of 100 characters and a ribbon -- width of 40 characters. -- -- > main :: IO () -- > main = do{ putDoc (text "hello" <+> text "world") } -- -- Which would output -- -- @ -- hello world -- @ -- -- Any ANSI colorisation in @doc@ will be output. putDoc :: Doc -> IO () putDoc doc = hPutDoc stdout doc -- | @(hPutDoc handle doc)@ pretty prints document @doc@ to the file -- handle @handle@ with a page width of 100 characters and a ribbon -- width of 40 characters. -- -- > main = do{ handle <- openFile "MyFile" WriteMode -- > ; hPutDoc handle (vcat (map text -- > ["vertical","text"])) -- > ; hClose handle -- > } -- -- Any ANSI colorisation in @doc@ will be output. hPutDoc :: Handle -> Doc -> IO () hPutDoc handle doc = displayIO handle (renderPretty 0.4 80 doc) ----------------------------------------------------------- -- insert spaces -- "indentation" used to insert tabs but tabs seem to cause -- more trouble than they solve :-) ----------------------------------------------------------- spaces n | n <= 0 = "" | otherwise = replicate n ' ' indentation n = spaces n --indentation n | n >= 8 = '\t' : indentation (n-8) -- | otherwise = spaces n -- LocalWords: PPrint combinators Wadler Wadler's encloseSep