tagsoup-0.7: Parsing and extracting information from (possibly malformed) HTML documentsContentsIndex
Text.HTML.TagSoup
Portabilityportable
Stabilityunstable
Maintainerhttp://www.cs.york.ac.uk/~ndm/
Contents
Data structures and parsing
Tag identification
Extraction
Utility
Combinators
Description

This module is for extracting information out of unstructured HTML code, sometimes known as tag-soup. This is for situations where the author of the HTML is not cooperating with the person trying to extract the information, but is also not trying to hide the information.

The standard practice is to parse a String to Tags using parseTags, then operate upon it to extract the necessary information.

Synopsis
data Tag
= TagOpen String [Attribute]
| TagClose String
| TagText String
| TagComment String
| TagWarning String
| TagPosition !Row !Column
type Attribute = (String, String)
module Text.HTML.TagSoup.Parser
canonicalizeTags :: [Tag] -> [Tag]
isTagOpen :: Tag -> Bool
isTagClose :: Tag -> Bool
isTagText :: Tag -> Bool
isTagWarning :: Tag -> Bool
isTagOpenName :: String -> Tag -> Bool
isTagCloseName :: String -> Tag -> Bool
fromTagText :: Tag -> String
fromAttrib :: String -> Tag -> String
maybeTagText :: Tag -> Maybe String
maybeTagWarning :: Tag -> Maybe String
innerText :: [Tag] -> String
sections :: (a -> Bool) -> [a] -> [[a]]
partitions :: (a -> Bool) -> [a] -> [[a]]
class TagRep a
class IsChar a
(~==) :: TagRep t => Tag -> t -> Bool
(~/=) :: TagRep t => Tag -> t -> Bool
Data structures and parsing
data Tag
An HTML element, a document is [Tag]. There is no requirement for TagOpen and TagClose to match
Constructors
TagOpen String [Attribute]An open tag with Attributes in their original order.
TagClose StringA closing tag
TagText StringA text node, guaranteed not to be the empty string
TagComment StringA comment
TagWarning StringMeta: Mark a syntax error in the input file
TagPosition !Row !ColumnMeta: The position of a parsed element
show/hide Instances
type Attribute = (String, String)
An HTML attribute id="name" generates ("id","name")
module Text.HTML.TagSoup.Parser
canonicalizeTags :: [Tag] -> [Tag]
Turns all tag names and attributes to lower case and converts DOCTYPE to upper case.
Tag identification
isTagOpen :: Tag -> Bool
Test if a Tag is a TagOpen
isTagClose :: Tag -> Bool
Test if a Tag is a TagClose
isTagText :: Tag -> Bool
Test if a Tag is a TagText
isTagWarning :: Tag -> Bool
Test if a Tag is a TagWarning
isTagOpenName :: String -> Tag -> Bool
Returns True if the Tag is TagOpen and matches the given name
isTagCloseName :: String -> Tag -> Bool
Returns True if the Tag is TagClose and matches the given name
Extraction
fromTagText :: Tag -> String
Extract the string from within TagText, crashes if not a TagText
fromAttrib :: String -> Tag -> String
Extract an attribute, crashes if not a TagOpen. Returns "" if no attribute present.
maybeTagText :: Tag -> Maybe String
Extract the string from within TagText, otherwise Nothing
maybeTagWarning :: Tag -> Maybe String
Extract the string from within TagWarning, otherwise Nothing
innerText :: [Tag] -> String
Extract all text content from tags (similar to Verbatim found in HaXml)
Utility
sections :: (a -> Bool) -> [a] -> [[a]]
This function takes a list, and returns all suffixes whose first item matches the predicate.
partitions :: (a -> Bool) -> [a] -> [[a]]
This function is similar to sections, but splits the list so no element appears in any two partitions.
Combinators
class TagRep a
Define a class to allow String's or Tag's to be used as matches
show/hide Instances
class IsChar a
show/hide Instances
(~==) :: TagRep t => Tag -> t -> Bool

Performs an inexact match, the first item should be the thing to match. If the second item is a blank string, that is considered to match anything. For example: 

 (TagText "test" ~== TagText ""    ) == True
 (TagText "test" ~== TagText "test") == True
 (TagText "test" ~== TagText "soup") == False

For TagOpen missing attributes on the right are allowed.

(~/=) :: TagRep t => Tag -> t -> Bool
Negation of ~==
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