Text.HTML.TagSoup.Tree

NOTE: This module is preliminary and may change at a future date.

This module is intended to help converting a list of tags into a tree of tags.

Documentation

data TagTree str

Constructors

TagBranch str [Attribute str] [TagTree str]

TagLeaf (Tag str)

Instances

Functor TagTree

Eq str => Eq (TagTree str)

Ord str => Ord (TagTree str)

Show str => Show (TagTree str)

tagTree :: Eq str => [Tag str] -> [TagTree str]

Convert a list of tags into a tree. This version is not lazy at all, that is saved for version 2.

flattenTree :: [TagTree str] -> [Tag str]

transformTree :: (TagTree str -> [TagTree str]) -> [TagTree str] -> [TagTree str]

This operation is based on the Uniplate transform function. Given a list of trees, it applies the function to every tree in a bottom-up manner. This operation is useful for manipulating a tree - for example to make all tag names upper case:

upperCase = transformTree f
  where f (TagBranch name atts inner) = [TagBranch (map toUpper name) atts inner]
        f x = [x]

universeTree :: [TagTree str] -> [TagTree str]

This operation is based on the Uniplate universe function. Given a list of trees, it returns those trees, and all the children trees at any level. For example:

universeTree
   [TagBranch "a" [("href","url")] [TagBranch "b" [] [TagLeaf (TagText "text")]]]
== [TagBranch "a" [("href","url")] [TagBranch "b" [] [TagLeaf (TagText "text")]]]
   ,TagBranch "b" [] [TagLeaf (TagText "text")]]

This operation is particularly useful for queries. To collect all "a" tags in a tree, simply do:

[x | x@(TagBranch "a" _ _) <- universeTree tree]