Text.XmlHtml

xmlhtml-0.2.3.3: XML parser and renderer with HTML 5 quirks mode

Safe Haskell | None
Language | Haskell98

Text.XmlHtml

Contents

- Types
- Manipulating documents
- Parsing
- Rendering

Description

Parsers and renderers for XML and HTML 5. Although the formats are treated differently, the data types used by each are the same, which makes it easy to write code that works with the element structure of either XML or HTML 5 documents.

Limitations:

- The XML parser does not parse internal DOCTYPE subsets. They are just stored as blocks of text, with minimal scanning done to match quotes and brackets to determine the end.
- Since DTDs are not parsed, the XML parser fails on entity references, except for those defined internally. You cannot use this library for parsing XML documents with entity references outside the predefined set.
- The HTML 5 parser is not a compliant HTML parser. Instead, it is a parser for valid HTML 5 content. It should only be used on content that you have reason to believe is probably correct, since the compatibility features of HTML 5 are missing. This is the wrong library on which to build a web spider.
- Both parsers accept fragments of documents, by which is meant that they do not enforce the top-level structure of the document. Files may contain more than one root element, for example.

Synopsis

- data Document
  - = XmlDocument {
    - docEncoding :: !Encoding
    - docType :: !(Maybe DocType)
    - docContent :: ![Node]
    }
  - | HtmlDocument {
    - docEncoding :: !Encoding
    - docType :: !(Maybe DocType)
    - docContent :: ![Node]
    }
- data Node
  - = TextNode !Text
  - | Comment !Text
  - | Element {
    - elementTag :: !Text
    - elementAttrs :: ![(Text, Text)]
    - elementChildren :: ![Node]
    }
- data DocType = DocType !Text !ExternalID !InternalSubset
- data ExternalID
  - = Public !Text !Text
  - | System !Text
  - | NoExternalID
- data InternalSubset
  - = InternalText !Text
  - | NoInternalSubset
- data Encoding
  - = UTF8
  - | UTF16BE
  - | UTF16LE
- isTextNode :: Node -> Bool
- isComment :: Node -> Bool
- isElement :: Node -> Bool
- tagName :: Node -> Maybe Text
- getAttribute :: Text -> Node -> Maybe Text
- hasAttribute :: Text -> Node -> Bool
- setAttribute :: Text -> Text -> Node -> Node
- nodeText :: Node -> Text
- childNodes :: Node -> [Node]
- childElements :: Node -> [Node]
- childElementsTag :: Text -> Node -> [Node]
- childElementTag :: Text -> Node -> Maybe Node
- descendantNodes :: Node -> [Node]
- descendantElements :: Node -> [Node]
- descendantElementsTag :: Text -> Node -> [Node]
- descendantElementTag :: Text -> Node -> Maybe Node
- parseXML :: String -> ByteString -> Either String Document
- parseHTML :: String -> ByteString -> Either String Document
- render :: Document -> Builder
- renderXmlFragment :: Encoding -> [Node] -> Builder
- renderHtmlFragment :: Encoding -> [Node] -> Builder
- renderDocType :: Encoding -> Maybe DocType -> Builder

# Types

data Document

Represents a document fragment, including the format, encoding, and document type declaration as well as its content.

Constructors

XmlDocument |
Fields docEncoding :: !Encoding docType :: !(Maybe DocType) docContent :: ![Node]
HtmlDocument |
Fields docEncoding :: !Encoding docType :: !(Maybe DocType) docContent :: ![Node]

Instances

Eq Document |
Show Document |

data Node

A node of a document structure. A node can be text, a comment, or an element. XML processing instructions are intentionally omitted as a simplification, and CDATA and plain text are both text nodes, since they ought to be semantically interchangeable.

Constructors

TextNode !Text |
Comment !Text |
Element |
Fields elementTag :: !Text elementAttrs :: ![(Text, Text)] elementChildren :: ![Node]

Instances

Eq Node |
Show Node |

data DocType

A document type declaration. Note that DTD internal subsets are currently unimplemented.

Constructors

DocType !Text !ExternalID !InternalSubset |

Instances

Eq DocType |
Show DocType |

data ExternalID

An external ID, as in a document type declaration. This can be a SYSTEM identifier, or a PUBLIC identifier, or can be omitted.

Constructors

Public !Text !Text |
System !Text |
NoExternalID |

Instances

Eq ExternalID |
Show ExternalID |

data InternalSubset

The internal subset is unparsed, but preserved in case it's actually wanted.

Constructors

InternalText !Text |
NoInternalSubset |

Instances

Eq InternalSubset |
Show InternalSubset |

data Encoding

The character encoding of a document. Currently only the required character encodings are implemented.

Constructors

UTF8 |
UTF16BE |
UTF16LE |

Instances

Eq Encoding |
Show Encoding |

# Manipulating documents

isTextNode :: Node -> Bool

Determines whether the node is text or not.

isComment :: Node -> Bool

Determines whether the node is a comment or not.

isElement :: Node -> Bool

Determines whether the node is an element or not.

tagName :: Node -> Maybe Text

Gives the tag name of an element, or `Nothing` if the node isn't an element.

getAttribute :: Text -> Node -> Maybe Text

Retrieves the attribute with the given name. If the `Node` is not an element, the result is always `Nothing`

hasAttribute :: Text -> Node -> Bool

Checks if a given attribute exists in a `Node`.

setAttribute :: Text -> Text -> Node -> Node

Sets the attribute name to the given value. If the `Node` is not an element, this is the identity.

nodeText :: Node -> Text

Gives the entire text content of a node, ignoring markup.

childNodes :: Node -> [Node]

Gives the child nodes of the given node. Only elements have child nodes.

childElements :: Node -> [Node]

Gives the child elements of the given node.

childElementsTag :: Text -> Node -> [Node]

Gives all of the child elements of the node with the given tag name.

childElementTag :: Text -> Node -> Maybe Node

Gives the first child element of the node with the given tag name, or `Nothing` if there is no such child element.

descendantNodes :: Node -> [Node]

Gives the descendants of the given node in the order that they begin in the document.

descendantElements :: Node -> [Node]

Gives the descendant elements of the given node, in the order that their start tags appear in the document.

descendantElementsTag :: Text -> Node -> [Node]

Gives the descendant elements with a given tag name.

descendantElementTag :: Text -> Node -> Maybe Node

Gives the first descendant element of the node with the given tag name, or `Nothing` if there is no such element.

# Parsing

parseXML

Arguments

:: String | Name of document source (perhaps a filename) for error messages
-> ByteString | Document contents
-> Either String Document | The document or an error message

Parses the given XML fragment.

parseHTML

Arguments

:: String | Name of document source (perhaps a filename) for error messages
-> ByteString | Document contents
-> Either String Document | The document or an error message

Parses the given HTML fragment. This enables HTML quirks mode, which changes the parsing algorithm to parse valid HTML 5 documents correctly.

# Rendering

render :: Document -> Builder

Renders a `Document`.

renderXmlFragment :: Encoding -> [Node] -> Builder

Function for rendering XML nodes without the overhead of creating a Document structure.

renderHtmlFragment :: Encoding -> [Node] -> Builder

Function for rendering HTML nodes without the overhead of creating a Document structure.

renderDocType :: Encoding -> Maybe DocType -> Builder