Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
tree: e5fbe6d21e
Fetching contributors…

Cannot retrieve contributors at this time

630 lines (533 sloc) 21.32 kb
{-# LANGUAGE FlexibleContexts, TypeSynonymInstances, FlexibleInstances, TypeFamilies, MultiParamTypeClasses, BangPatterns,
UndecidableInstances, OverlappingInstances #-}
-- | This module provides combinators for generating XML documents.
--
-- As an example, suppose you want to generate the following XML document:
--
-- > <?xml version="1.0"?>
-- > <people>
-- > <person age="32">Stefan</person>
-- > <person age="4">Judith</person>
-- > </people>
--
-- Then you could use the following Haskell code:
--
--
-- @
-- let people = [(\"Stefan\", \"32\"), (\"Judith\", \"4\")]
-- in 'doc' 'defaultDocInfo' $
-- 'xelem' \"people\" $
-- 'xelems' $ map (\(name, age) -> 'xelem' \"person\" ('xattr' \"age\" age '<#>' 'xtext' name)) people
-- @
module Text.XML.Generator (
-- * General
Xml
-- * Documents
, Doc, DocInfo(..), doc, defaultDocInfo
-- * Namespaces
, Namespace, Prefix, Uri
, namespace, noNamespace, defaultNamespace
-- * Elements
, Elem, MkElem(xelem), MkEmptyElem(xelemEmpty), AddChildren
, xelems, noElems, xelemWithText, (<>), (<#>)
-- * Attributes
, Attr, MkAttr(xattr, xattrRaw)
, xattrs, noAttrs
-- * Text
, RawTextContent, TextContent
, xtext, xtextRaw, xentityRef
-- * Other
, xempty , Misc(xprocessingInstruction, xcomment)
-- * Rendering
, xrender
, XmlOutput(fromBuilder), Renderable
-- * XHTML documents
, xhtmlFramesetDocInfo, xhtmlStrictDocInfo, xhtmlTransitionalDocInfo
, xhtmlRootElem
) where
import Prelude hiding (elem)
import Control.Monad.Reader (Reader(..), ask, asks, runReader)
import qualified Data.Map as Map
import qualified Data.ByteString.Lazy as BSL
import Data.Monoid hiding (mconcat)
import qualified Data.Monoid as M
import Blaze.ByteString.Builder
import qualified Blaze.ByteString.Builder as Blaze
import Blaze.ByteString.Builder.Char.Utf8
import qualified Data.ByteString as BS
import qualified Data.ByteString.Lazy as BSL
import Data.Char (isPrint, ord)
import qualified Data.String as S
import qualified Data.Text as T
import qualified Data.Text.Lazy as TL
--
-- Basic definitions
--
-- | A piece of XML at the element level.
newtype Elem = Elem { unElem :: Builder }
-- | A piece of XML at the attribute level.
newtype Attr = Attr { unAttr :: Builder }
-- | A piece of XML at the document level.
newtype Doc = Doc { unDoc :: Builder }
-- | Namespace prefix.
type Prefix = String
-- | Namespace URI.
type Uri = String -- must not be empty
-- | Type for representing presence or absence of an XML namespace.
data Namespace
= NoNamespace
| DefaultNamespace
| QualifiedNamespace Prefix Uri
deriving (Show, Eq)
-- | Constructs a qualified XML namespace.
-- The given URI must not be the empty string.
namespace :: Prefix -> Uri -> Namespace
namespace p u = if null u
then error "Text.XML.Generator.ns: namespace URI must not be empty"
else QualifiedNamespace p u
-- | A 'Namespace' value denoting the absence of any XML namespace information.
noNamespace :: Namespace
noNamespace = NoNamespace
-- | A 'Namespace' value denoting the default namespace.
--
-- * For elements, this is the namespace currently mapped to the empty prefix.
--
-- * For attributes, the default namespace does not carry any namespace information.
defaultNamespace :: Namespace
defaultNamespace = DefaultNamespace
data NsEnv = NsEnv { ne_namespaceMap :: Map.Map Prefix Uri
, ne_noNamespaceInUse :: Bool }
emptyNsEnv :: NsEnv
emptyNsEnv = NsEnv Map.empty False
-- | The type @Xml t@ represent a piece of XML of type @t@, where @t@
-- is usually one of 'Elem', 'Attr', or 'Doc'.
newtype Xml t = Xml { unXml :: Reader NsEnv (t, NsEnv) }
runXml :: NsEnv -> Xml t -> (t, NsEnv)
runXml nsEnv (Xml x) = runReader x nsEnv
-- | An empty, polymorphic piece of XML.
xempty :: Renderable t => Xml t
xempty = Xml $
do env <- ask
return (mkRenderable mempty, env)
--
-- Document
--
-- | The 'DocInfo' type contains all information of an XML document except the root element.
data DocInfo
= DocInfo
{ docInfo_standalone :: Bool -- ^ Value of the @standalone@ attribute in the @\<?xml ... ?\>@ header
, docInfo_docType :: Maybe String -- ^ Document type (N.B.: rendering does not escape this value)
, docInfo_preMisc :: Xml Doc -- ^ Content before the root element
, docInfo_postMisc :: Xml Doc -- ^ Content after the root element
}
-- | The default document info (standalone, without document type, without content before/after the root element).
defaultDocInfo :: DocInfo
defaultDocInfo = DocInfo { docInfo_standalone = True
, docInfo_docType = Nothing
, docInfo_preMisc = xempty
, docInfo_postMisc = xempty }
-- | Constructs an XML document from a 'DocInfo' value and the root element.
doc :: DocInfo -> Xml Elem -> Xml Doc
doc di rootElem = Xml $
do let prologBuf = fromString "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"" <>
fromString (if standalone then "yes" else "no") <>
fromString "\"?>\n" <>
case mDocType of
Nothing -> mempty
Just s -> fromString s <> fromString "\n"
env <- ask
let Doc preBuf = fst $ runXml env preMisc
Elem elemBuf = fst $ runXml env rootElem
Doc postBuf = fst $ runXml env postMisc
return $ (Doc $ prologBuf `mappend` preBuf `mappend` elemBuf `mappend` postBuf, env)
where
standalone = docInfo_standalone di
mDocType = docInfo_docType di
preMisc = docInfo_preMisc di
postMisc = docInfo_postMisc di
--
-- Text content
--
-- | Construction of text content not subject to escaping.
class RawTextContent t where
rawTextBuilder :: t -> Builder
-- | Construction of text content subject to escaping.
class RawTextContent t => TextContent t where
escape :: t -> t
textBuilder :: TextContent t => t -> Builder
textBuilder = rawTextBuilder . escape
instance RawTextContent String where
rawTextBuilder = fromString
instance TextContent String where
escape = genericEscape foldr showString showChar
instance RawTextContent T.Text where
rawTextBuilder = fromText
instance TextContent T.Text where
escape = genericEscape T.foldr T.append T.cons
instance RawTextContent TL.Text where
rawTextBuilder = fromLazyText
instance TextContent TL.Text where
escape = genericEscape TL.foldr TL.append TL.cons
instance RawTextContent BS.ByteString where
rawTextBuilder = fromByteString
instance RawTextContent BSL.ByteString where
rawTextBuilder = fromLazyByteString
--
-- Attributes
--
-- | Class providing methods for constructing XML attributes.
--
-- The 'String' instance of this class constructs an attribute with a name
-- in the default namespace, the 'Namespace' instance allows customization
-- of namespaces.
class MkAttr n t where
type MkAttrRes n t
-- | Construct an attribute by escaping its value
xattr :: TextContent t => n -> MkAttrRes n t
-- | Construct an attribute without escaping its value.
-- /Note:/ attribute values are quoted with double quotes.
xattrRaw :: RawTextContent t => n -> MkAttrRes n t
instance MkAttr String t where
type MkAttrRes String t = t -> Xml Attr
xattr = xattrQ DefaultNamespace
xattrRaw = xattrQRaw DefaultNamespace
instance MkAttr Namespace t where
type MkAttrRes Namespace t = String -> t -> Xml Attr
xattr = xattrQ
xattrRaw = xattrQRaw
-- value is escaped
xattrQ :: TextContent t => Namespace -> String -> t -> Xml Attr
xattrQ ns key value = xattrQRaw' ns key (textBuilder value)
-- value is NOT escaped
xattrQRaw :: RawTextContent t => Namespace -> String -> t -> Xml Attr
xattrQRaw ns key value = xattrQRaw' ns key (rawTextBuilder value)
xattrQRaw' :: Namespace -> String -> Builder -> Xml Attr
xattrQRaw' ns' key valueBuilder = Xml $
do uriMap' <- ask
let (mDecl, prefix, uriMap) = extendNsEnv True uriMap' ns'
nsDeclBuilder =
case mDecl of
Nothing -> mempty
Just (p, u) ->
let uriBuilder = fromString u
prefixBuilder =
if null p then mempty else colonBuilder `mappend` fromString p
in spaceBuilder `mappend` nsDeclStartBuilder
`mappend` prefixBuilder `mappend` startBuilder `mappend` uriBuilder
`mappend` endBuilder
prefixBuilder =
if null prefix
then spaceBuilder
else spaceBuilder `mappend` fromString prefix `mappend` colonBuilder
builder = nsDeclBuilder `mappend` prefixBuilder `mappend`
keyBuilder `mappend` startBuilder `mappend`
valueBuilder `mappend` endBuilder
return $ (Attr builder, uriMap)
where
spaceBuilder = fromString " "
keyBuilder = fromString key
startBuilder = fromString "=\""
endBuilder = fromString "\""
nsDeclStartBuilder = fromString "xmlns"
colonBuilder = fromString ":"
-- | Merges a list of attributes into a single piece of XML at the attribute level.
xattrs :: [Xml Attr] -> Xml Attr
xattrs = M.mconcat
-- | The empty attribute list.
noAttrs :: Xml Attr
noAttrs = xempty
instance Monoid (Xml Attr) where
mempty = noAttrs
mappend x1 x2 = Xml $
do env <- ask
let (Attr b1, env') = runXml env x1
let (Attr b2, env'') = runXml env' x2
return $ (Attr $ b1 `mappend` b2, env'')
--
-- Elements
--
-- | Class for adding children to an element.
--
-- The various instances of this class allow the addition of different kinds
-- of children.
class AddChildren c where
addChildren :: c -> NsEnv -> Builder
instance AddChildren (Xml Attr) where
addChildren attrs uriMap =
let (Attr builder', _) = runXml uriMap attrs
in builder' <> fromString "\n>"
instance AddChildren (Xml Elem) where
addChildren elems uriMap =
let (Elem builder', _) = runXml uriMap elems
in fromString "\n>" `mappend` builder'
instance AddChildren (Xml Attr, Xml Elem) where
addChildren (attrs, elems) uriMap =
let (Attr builder, uriMap') = runXml uriMap attrs
(Elem builder', _) = runXml uriMap' elems
in builder `mappend` fromString "\n>" `mappend` builder'
instance TextContent t => AddChildren t where
addChildren t _ = fromChar '>' <> textBuilder t
instance AddChildren () where
addChildren _ _ = fromChar '>'
-- | Class providing methods for constructing XML elements.
--
-- The 'String' instance of this class constructs an element in the
-- default namespace, the 'Namespace' instance allows customization of
-- namespaces.
class AddChildren c => MkElem n c where
type MkElemRes n c
xelem :: n -> MkElemRes n c
instance AddChildren c => MkElem String c where
type MkElemRes String c = c -> Xml Elem
xelem = xelemQ DefaultNamespace
instance AddChildren c => MkElem Namespace c where
type MkElemRes Namespace c = String -> c -> Xml Elem
xelem = xelemQ
-- | Class providing a method for constructing XML elements without children.
--
-- The 'String' instance of this class constructs an element in the
-- default namespace, the 'Namespace' instance allows customization of
-- namespaces.
class MkEmptyElem n where
type MkEmptyElemRes n
xelemEmpty :: n -> MkEmptyElemRes n
instance MkEmptyElem String where
type MkEmptyElemRes String = Xml Elem
xelemEmpty name = xelemQ DefaultNamespace name (mempty :: Xml Elem)
instance MkEmptyElem Namespace where
type MkEmptyElemRes Namespace = String -> Xml Elem
xelemEmpty ns name = xelemQ ns name (mempty :: Xml Elem)
xelemQ :: AddChildren c => Namespace -> String -> c -> Xml Elem
xelemQ ns' name children = Xml $
do oldUriMap <- ask
let (mDecl, prefix,!uriMap) = oldUriMap `seq` extendNsEnv False oldUriMap ns'
let elemNameBuilder =
if null prefix
then fromString name
else fromString prefix `mappend` fromString ":" `mappend` fromString name
let nsDeclBuilder =
case mDecl of
Nothing -> mempty
Just (p, u) ->
let prefixBuilder =
if null p then mempty else fromChar ':' `mappend` fromString p
in fromString " xmlns" `mappend` prefixBuilder `mappend` fromString "=\""
`mappend` fromString u `mappend` fromString "\""
let b1 = fromString "<"
let b2 = b1 `mappend` elemNameBuilder `mappend` nsDeclBuilder
let b3 = b2 `mappend` addChildren children uriMap
let builderOut = Elem (b3 `mappend` fromString "</" `mappend` elemNameBuilder `mappend` fromString "\n>")
return (builderOut, oldUriMap)
-- | Merges a list of elements into a single piece of XML at the element level.
xelems :: [Xml Elem] -> Xml Elem
xelems = M.mconcat
-- | No elements at all.
noElems :: Xml Elem
noElems = xempty
-- | The expression @xelemWithText n t@ constructs an XML element with name @n@ and text content @t@.
xelemWithText :: (TextContent t) => String -> t -> Xml Elem
xelemWithText n t = xelem n (xtext t)
instance Monoid (Xml Elem) where
mempty = noElems
mappend x1 x2 = Xml $
do env <- ask
let (Elem b1, env') = runXml env x1
(Elem b2, env'') = runXml env' x2
return (Elem $ b1 `mappend` b2, env'')
--
-- Other XML constructs
--
-- | Constructs a text node by escaping the given argument.
xtext :: TextContent t => t -> Xml Elem
xtext content = Xml $
do env <- ask
return (Elem $ textBuilder content, env)
-- | Constructs a text node /without/ escaping the given argument.
xtextRaw :: RawTextContent t => t -> Xml Elem
xtextRaw content = Xml $
do env <- ask
return (Elem $ rawTextBuilder content, env)
-- | Constructs a reference to the named entity.
-- /Note:/ no escaping is performed on the name of the entity
xentityRef :: String -> Xml Elem
xentityRef name = Xml $
do env <- ask
return (Elem $ fromChar '&' <> fromString name <> fromChar ';', env)
-- | Class providing methods for adding processing instructions and comments.
class Renderable t => Misc t where
-- | Constructs a processing instruction with the given target and content.
-- /Note:/ Rendering does not perform escaping on the target and the content.
xprocessingInstruction :: String -> String -> Xml t
xprocessingInstruction target content = Xml $
do env <- ask
return (mkRenderable $
fromString "<?" <>
fromString target <>
fromChar ' ' <>
fromString content <>
fromString "?>",
env)
-- | Constructs an XML comment.
-- /Note:/ No escaping is performed on the text of the comment.
xcomment :: String -> Xml t
xcomment content = Xml $
do env <- ask
return (mkRenderable $
fromString "<!--" <>
fromString content <>
fromString "-->",
env)
instance Misc Elem
instance Misc Doc
--
-- Operators
--
infixl 6 <>
-- | Shortcut for the 'mappend' functions of monoids. Used to concatenate elements, attributes
-- and text nodes.
(<>) :: Monoid t => t -> t -> t
(<>) = mappend
infixl 5 <#>
-- | Shortcut for coonstructing pairs. Used in combination with 'xelem' for separating child-attributes
-- from child-elements.
(<#>) :: a -> b -> (a, b)
(<#>) x y = (x, y)
--
-- Rendering
--
-- | Instances of the @XmlOutput@ class may serve as target of serializing an XML document.
class XmlOutput t where
-- | Creates the target type from a 'Builder'.
fromBuilder :: Builder -> t
instance XmlOutput Builder where
fromBuilder b = b
instance XmlOutput BS.ByteString where
fromBuilder = toByteString
instance XmlOutput BSL.ByteString where
fromBuilder = toLazyByteString
-- | Any type subject to rendering must implement this type class.
class Renderable t where
builder :: t -> Builder
mkRenderable :: Builder -> t
instance Renderable Elem where
builder (Elem b) = b
mkRenderable = Elem
instance Renderable Attr where
builder (Attr b) = b
mkRenderable = Attr
instance Renderable Doc where
builder (Doc b) = b
mkRenderable = Doc
-- | Renders a given piece of XML.
xrender :: (Renderable r, XmlOutput t) => Xml r -> t
xrender r = fromBuilder $ builder r'
where
r' = fst $ runXml emptyNsEnv r
--
-- Utilities
--
extendNsEnv :: Bool -> NsEnv -> Namespace -> (Maybe (Prefix, Uri), Prefix, NsEnv)
extendNsEnv isAttr env ns =
case ns of
NoNamespace
| isAttr -> (Nothing, "", env)
| otherwise ->
case Map.lookup "" (ne_namespaceMap env) of
Nothing -> -- empty prefix not in use
(Nothing, "", env { ne_noNamespaceInUse = True })
Just uri -> -- empty prefix mapped to uri
(Just ("", ""), "", env { ne_namespaceMap = Map.delete "" (ne_namespaceMap env)
, ne_noNamespaceInUse = True })
DefaultNamespace ->
(Nothing, "", env)
QualifiedNamespace p' u ->
let p = if null p' && (isAttr || ne_noNamespaceInUse env) then "_" else p'
(mDecl, prefix, newMap) = genValidPrefix (ne_namespaceMap env) p u
in (mDecl, prefix, env { ne_namespaceMap = newMap })
where
genValidPrefix map prefix uri =
case Map.lookup prefix map of
Nothing -> (Just (prefix, uri), prefix, Map.insert prefix uri map)
Just foundUri ->
if foundUri == uri
then (Nothing, prefix, map)
else genValidPrefix map ('_':prefix) uri
{-# SPECIALIZE INLINE genericEscape ::
((Char -> String -> String) -> String -> String -> String)
-> (String -> String -> String)
-> (Char -> String -> String)
-> String
-> String #-}
{-# SPECIALIZE INLINE genericEscape ::
((Char -> T.Text -> T.Text) -> T.Text -> T.Text -> T.Text)
-> (T.Text -> T.Text -> T.Text)
-> (Char -> T.Text -> T.Text)
-> T.Text
-> T.Text #-}
{-# SPECIALIZE INLINE genericEscape ::
((Char -> TL.Text -> TL.Text) -> TL.Text -> TL.Text -> TL.Text)
-> (TL.Text -> TL.Text -> TL.Text)
-> (Char -> TL.Text -> TL.Text)
-> TL.Text
-> TL.Text #-}
genericEscape :: (S.IsString s)
=> ((Char -> s -> s) -> s -> s -> s)
-> (s -> s -> s)
-> (Char -> s -> s)
-> s
-> s
genericEscape foldr showString' showChar x = foldr escChar (S.fromString "") x
where
-- copied from xml-light
escChar c = case c of
'<' -> showString "&lt;"
'>' -> showString "&gt;"
'&' -> showString "&amp;"
'"' -> showString "&quot;"
-- we use &#39 instead of &apos; because IE apparently has difficulties
-- rendering &apos; in xhtml.
-- Reported by Rohan Drape <rohan.drape@gmail.com>.
'\'' -> showString "&#39;"
-- XXX: Is this really wortherd?
-- We could deal with these issues when we convert characters to bytes.
_ | (oc <= 0x7f && isPrint c) || c == '\n' || c == '\r' -> showChar c
| otherwise -> showString "&#" . showString (show oc) . showChar ';'
where oc = ord c
showString = showString' . S.fromString
--
-- XHTML
--
-- | Document type for XHTML 1.0 strict.
xhtmlDoctypeStrict :: String
xhtmlDoctypeStrict =
"<!DOCTYPE html\n" ++
" PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\"\n" ++
" \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd\">"
-- | Document info for XHTML 1.0 strict.
xhtmlStrictDocInfo :: DocInfo
xhtmlStrictDocInfo = defaultDocInfo { docInfo_docType = Just xhtmlDoctypeStrict }
-- | Document type for XHTML 1.0 transitional.
xhtmlDoctypeTransitional :: String
xhtmlDoctypeTransitional =
"<!DOCTYPE html\n" ++
" PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\"\n" ++
" \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">"
-- | Document info for XHTML 1.0 transitional.
xhtmlTransitionalDocInfo :: DocInfo
xhtmlTransitionalDocInfo = defaultDocInfo { docInfo_docType = Just xhtmlDoctypeTransitional }
-- | Document type for XHTML 1.0 frameset.
xhtmlDoctypeFrameset :: String
xhtmlDoctypeFrameset =
"<!DOCTYPE html\n" ++
" PUBLIC \"-//W3C//DTD XHTML 1.0 Frameset//EN\"\n" ++
" \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd\">"
-- | Document info for XHTML 1.0 frameset.
xhtmlFramesetDocInfo :: DocInfo
xhtmlFramesetDocInfo = defaultDocInfo { docInfo_docType = Just xhtmlDoctypeFrameset }
-- | Constructs the root element of an XHTML document.
xhtmlRootElem :: String -> Xml Elem -> Xml Elem
xhtmlRootElem lang children =
xelem (namespace "" "http://www.w3.org/1999/xhtml") "html"
(xattr "xml:lang" lang <>
xattr "lang" lang <#>
children)
Jump to Line
Something went wrong with that request. Please try again.