Module XML

Library for processing XML data.

Warning: the structure of this library is not stable and might be changed in the future!

Author: Michael Hanus

Version: September 2017

Summary of exported operations:

tagOf
                  ::  XmlExp -> String

Returns the tag of an XML element (or empty for a textual element).

elemsOf
                  ::  XmlExp -> [XmlExp]

Returns the child elements an XML element.

textOf
                  ::  [XmlExp] -> String

Extracts the textual contents of a list of XML expressions.

textOfXml
                  ::  [XmlExp] -> String

Included for backward compatibility, better use textOf!

xtxt
                  ::  String -> XmlExp

Basic text (maybe containing special XML chars).

xml
                  ::  String -> [XmlExp] -> XmlExp

XML element without attributes.

writeXmlFile
                  ::  String -> XmlExp -> IO ()

Writes a file with a given XML document.

writeXmlFileWithParams
                  ::  String -> [XmlDocParams] -> XmlExp -> IO ()

Writes a file with a given XML document and XML parameters.

showXmlDoc
                  ::  XmlExp -> String

Show an XML document in indented format as a string.

showXmlDocWithParams
                  ::  [XmlDocParams] -> XmlExp -> String

readXmlFile
                  ::  String -> IO XmlExp

Reads a file with an XML document and returns the corresponding XML expression.

readUnsafeXmlFile
                  ::  String -> IO (Maybe XmlExp)

Tries to read a file with an XML document and returns the corresponding XML expression, if possible.

readFileWithXmlDocs
                  ::  String -> IO [XmlExp]

Reads a file with an arbitrary sequence of XML documents and returns the list of corresponding XML expressions.

parseXmlString
                  ::  String -> [XmlExp]

Transforms an XML string into a list of XML expressions.

updateXmlFile
                  ::  (XmlExp -> XmlExp) -> String -> IO ()

An action that updates the contents of an XML file by some transformation on the XML document.

Exported datatypes:

XmlExp

The data type for representing XML expressions.

Constructors:

XText :: String -> XmlExp : a text string (PCDATA)
XElem :: String -> [(String,String)] -> [XmlExp] -> XmlExp : an XML element with tag field, attributes, and a list of XML elements as contents

Encoding

The data type for encodings used in the XML document.

Constructors:

StandardEnc :: Encoding
Iso88591Enc :: Encoding

XmlDocParams

The data type for XML document parameters.

Constructors:

Enc :: Encoding -> XmlDocParams : the encoding for a document
DtdUrl :: String -> XmlDocParams : the url of the DTD for a document

Exported operations:

tagOf :: XmlExp -> String

Returns the tag of an XML element (or empty for a textual element).

Further infos:

solution complete, i.e., able to compute all solutions

elemsOf :: XmlExp -> [XmlExp]

Returns the child elements an XML element.

Further infos:

solution complete, i.e., able to compute all solutions

textOf :: [XmlExp] -> String

Extracts the textual contents of a list of XML expressions. Useful auxiliary function when transforming XML expressions into other data structures.

For instance, textOf [XText "xy", XElem "a" [] [], XText "bc"] == "xy bc"

textOfXml :: [XmlExp] -> String

Included for backward compatibility, better use textOf!

xtxt :: String -> XmlExp

Basic text (maybe containing special XML chars).

Further infos:

solution complete, i.e., able to compute all solutions

xml :: String -> [XmlExp] -> XmlExp

XML element without attributes.

Further infos:

solution complete, i.e., able to compute all solutions

writeXmlFile :: String -> XmlExp -> IO ()

Writes a file with a given XML document.

writeXmlFileWithParams :: String -> [XmlDocParams] -> XmlExp -> IO ()

Writes a file with a given XML document and XML parameters.

showXmlDoc :: XmlExp -> String

Show an XML document in indented format as a string.

showXmlDocWithParams :: [XmlDocParams] -> XmlExp -> String

readXmlFile :: String -> IO XmlExp

Reads a file with an XML document and returns the corresponding XML expression.

readUnsafeXmlFile :: String -> IO (Maybe XmlExp)

Tries to read a file with an XML document and returns the corresponding XML expression, if possible. If file or parse errors occur, Nothing is returned.

readFileWithXmlDocs :: String -> IO [XmlExp]

Reads a file with an arbitrary sequence of XML documents and returns the list of corresponding XML expressions.

parseXmlString :: String -> [XmlExp]

Transforms an XML string into a list of XML expressions. If the XML string is a well structured document, the list of XML expressions should contain exactly one element.

updateXmlFile :: (XmlExp -> XmlExp) -> String -> IO ()

An action that updates the contents of an XML file by some transformation on the XML document.

Example call:: (updateXmlFile f file)

Parameters:

f : the function to transform the XML document in the file
file : the name of the XML file