Text.XML.Expat.Annotated

A variant of Node in which Element nodes have an annotation of any type, and some concrete functions that annotate with the XML parse location.

The names conflict with those in Tree so you must use qualified import if you want to use both modules.

Tree structure

type Node a tag text = NodeG a [] tag text

A pure tree representation that uses a list as its container type, annotated variant.

In the hexpat package, a list of nodes has the type [Node tag text], but note that you can also use the more general type function ListOf to give a list of any node type, using that node's associated list type, e.g. ListOf (UNode Text).

data NodeG a c tag text

Annotated variant of the tree representation of the XML document, meaning that it has an extra piece of information of your choice attached to each Element.

c is the container type for the element's children, which would normally be [], but could potentially be a monadic list type to allow for chunked I/O.

tag is the tag type, which can either be one of several string types, or a special type from the Text.XML.Expat.Namespaced or Text.XML.Expat.Qualified modules.

text is the string type for text content.

a is the type of the annotation. One of the things this can be used for is to store the XML parse location, which is useful for error handling.

Note that some functions in the Text.XML.Expat.Cursor module need to create new nodes through the MkElementClass type class. Normally this can only be done if a is a Maybe type or () (so it can provide the Nothing value for the annotation on newly created nodes). Or, you can write your own MkElementClass instance. Apart from that, there is no requirement for a to be a Maybe type.

Constructors

Element

Fields

eName :: !tag

eAttributes :: ![(tag, text)]

eChildren :: c (NodeG a c tag text)

eAnn :: a

Text !text

Instances

(Functor c, List c) => MkElementClass (NodeG ()) c

(Functor c, List c) => MkElementClass (NodeG (Maybe a)) c

(Functor c, List c) => NodeClass (NodeG a) c

(Eq tag, Eq text, Eq a) => Eq (NodeG a [] tag text)

(Show tag, Show text, Show a) => Show (NodeG a [] tag text)

(NFData tag, NFData text, NFData a) => NFData (NodeG a [] tag text)

type UNode a text = Node a text text

Type alias for an annotated node with unqualified tag names where tag and text are the same string type

type LNode tag text = Node XMLParseLocation tag text

Type alias for an annotated node, annotated with parse location

type ULNode text = LNode text text

Type alias for an annotated node with unqualified tag names where tag and text are the same string type, annotated with parse location

Generic node manipulation

module Text.XML.Expat.Internal.NodeClass

Annotation-specific

modifyAnnotation :: (a -> a) -> Node a tag text -> Node a tag text

Modify this node's annotation (non-recursively) if it's an element, otherwise no-op.

mapAnnotation :: (a -> b) -> Node a tag text -> Node b tag text

Modify this node's annotation and all its children recursively if it's an element, otherwise no-op.

Qualified nodes

type QNode a text = Node a (QName text) text

Type alias for an annotated node where qualified names are used for tags

type QLNode text = LNode (QName text) text

Type alias for an annotated node where qualified names are used for tags, annotated with parse location

module Text.XML.Expat.Internal.Qualified

Namespaced nodes

type NNode a text = Node a (NName text) text

Type alias for an annotated node where namespaced names are used for tags

type NLNode text = LNode (NName text) text

Type alias for an annotated node where namespaced names are used for tags, annotated with parse location

module Text.XML.Expat.Internal.Namespaced

Parse to tree

data ParseOptions tag text

Constructors

ParseOptions

Fields

overrideEncoding :: Maybe Encoding

The encoding parameter, if provided, overrides the document's encoding declaration.

entityDecoder :: Maybe (tag -> Maybe text)

If provided, entity references (i.e.   and friends) will be decoded into text using the supplied lookup function

defaultParseOptions :: ParseOptions tag text

data Encoding

Constructors

ASCII

UTF8

UTF16

ISO88591

parse

Arguments

:: (GenericXMLString tag, GenericXMLString text)

=> ParseOptions tag text

Parse options

-> ByteString

Input text (a lazy ByteString)

-> (LNode tag text, Maybe XMLParseError)

Lazily parse XML to tree. Note that forcing the XMLParseError return value will force the entire parse. Therefore, to ensure lazy operation, don't check the error status until you have processed the tree.

parse'

Arguments

:: (GenericXMLString tag, GenericXMLString text)

=> ParseOptions tag text

Parse options

-> ByteString

Input text (a strict ByteString)

-> Either XMLParseError (LNode tag text)

Strictly parse XML to tree. Returns error message or valid parsed tree.

parseG

Arguments

:: (GenericXMLString tag, GenericXMLString text, List l)

=> ParseOptions tag text

Parse options

-> l ByteString

Input text as a generalized list of blocks

-> ItemM l (NodeG XMLParseLocation l tag text)

Parse a generalized list to a tree, ignoring parse errors. This function allows for a parse from an enumerator/iteratee to a lazy tree structure using the List-enumerator package.

data XMLParseError

Parse error, consisting of message text and error location

Constructors

XMLParseError String XMLParseLocation

Instances

Eq XMLParseError

Show XMLParseError

NFData XMLParseError

data XMLParseLocation

Specifies a location of an event within the input text

Constructors

XMLParseLocation

Fields

xmlLineNumber :: Int64

Line number of the event

xmlColumnNumber :: Int64

Column number of the event

xmlByteIndex :: Int64

Byte index of event from start of document

xmlByteCount :: Int64

The number of bytes in the event

Instances

Eq XMLParseLocation

Show XMLParseLocation

NFData XMLParseLocation

Variant that throws exceptions

parseThrowing

Arguments

:: (GenericXMLString tag, GenericXMLString text)

=> ParseOptions tag text

Parse options

-> ByteString

Input text (a lazy ByteString)

-> LNode tag text

Lazily parse XML to tree. In the event of an error, throw XMLParseException.

parseThrowing can throw an exception from pure code, which is generally a bad way to handle errors, because Haskell's lazy evaluation means it's hard to predict where it will be thrown from. However, it may be acceptable in situations where it's not expected during normal operation, depending on the design of your program.

data XMLParseException

An exception indicating an XML parse error, used by the ..Throwing variants.

Constructors

XMLParseException XMLParseError

Instances

Eq XMLParseException

Show XMLParseException

Typeable XMLParseException

Exception XMLParseException

Convert from SAX

saxToTree :: GenericXMLString tag => [(SAXEvent tag text, a)] -> (Node a tag text, Maybe XMLParseError)

A lower level function that lazily converts a SAX stream into a tree structure. Variant that takes annotations for start tags.

saxToTreeG :: forall l a tag text. (GenericXMLString tag, List l, Monad (ItemM l)) => l (SAXEvent tag text, a) -> ItemM l (NodeG a l tag text)

A lower level function that converts a generalized SAX stream into a tree structure. Ignores parse errors.

Abstraction of string types

class (Monoid s, Eq s) => GenericXMLString s where

An abstraction for any string type you want to use as xml text (that is, attribute values or element text content). If you want to use a new string type with hexpat, you must make it an instance of GenericXMLString.

Methods

gxNullString :: s -> Bool

gxToString :: s -> String

gxFromString :: String -> s

gxFromChar :: Char -> s

gxHead :: s -> Char

gxTail :: s -> s

gxBreakOn :: Char -> s -> (s, s)

gxFromByteString :: ByteString -> s

gxToByteString :: s -> ByteString

Instances

GenericXMLString String

GenericXMLString ByteString

GenericXMLString Text