Webrexp.GraphWalker

This module store the interface between the evaluator and the manipulated graph.

Classes

class (GraphPath rezPath, Eq a) => GraphWalker a rezPath | a -> rezPath where

The aim of this typeclass is to permit the use of different html/xml parser if if the first one is found to be bad. All the logic should use this interface.

Minimal implementation : everything.

Methods

attribOf :: String -> a -> Maybe String

Get back an attribute of the node if it exists

nameOf :: a -> Maybe String

If the current node is named, return it's name, otherwise return Nothing.

childrenOf :: MonadIO m => a -> m [a]

Get all the children of the current node.

valueOf :: a -> String

Retrieve the value of the tag (textual)

indirectLinks :: a -> [rezPath]

Retrieve all the indirectly linked content of a node, can be used for element like an HTML link or an linked image/obj

accessGraph :: MonadIO m => Loggers -> rezPath -> m (AccessResult a rezPath)

The idea behind link following. The graph engine may have another name for the resource, so an updated name can be given. The given function is there to log information, the second is to log errors

isHistoryMutable :: a -> Bool

Tell if the history associated is fixed or not. If the history is not fixed and can change (if you are querying the filesystem for example, it should return False)

Instances

GraphWalker DirectoryNode ResourcePath

GraphWalker JsonNode ResourcePath

GraphWalker HaXmLNode ResourcePath

(PartialGraph a ResourcePath, PartialGraph b ResourcePath) => GraphWalker (UnionNode a b) ResourcePath

class Show a => GraphPath a where

Represent indirect links or links which necessitate the use of the IO monad to walk around the graph.

Methods

(<//>) :: a -> a -> a

Combine two path togethers, you can think of the / operator for an equivalence.

importPath :: String -> Maybe a

conversion to be used to import path from attributes/document (not really well specified).

dumpDataAtPath :: (Monad m, MonadIO m) => Loggers -> a -> m ()

Move semantic, try to dump the pointed resource to the current folder.

localizePath :: a -> FilePath

Given a graphpath, transform it to a filepath which can be used to store a node.

Instances

GraphPath ResourcePath

Commodity types

data AccessResult a rezPath

Result of indirect access demand.

Constructors

Result rezPath a

We got a result and parsed it, maybe it has changed of location, so we give back the location

DataBlob rezPath ByteString

We got something, but we can't interpret it, so we return a binary blob.

AccessError

Cannot access the resource.

type Logger = String -> IO ()

Type used to propagate different logging level across the software.

type Loggers = (Logger, Logger, Logger)

NormalErrverbose loggers.

type NodePath a = [(a, Int)]

Represent the path used to find the node from the starting point of the graph.

Helper functions.

descendants :: (MonadIO m, GraphWalker a r) => a -> m [(a, [(a, Int)])]

Return a list of all the children/linked node of a given node. The given node is not included in the list. A list of node with the taken path is returned.

findNamed :: (Functor m, MonadIO m, GraphWalker a r) => String -> a -> m [(a, [(a, Int)])]

Given a tag and a name, retrieve the first matching tags in the hierarchy. It must return the list of ancestors permitting the acess to the path used to find children

the returned list must contain : the node itself if it match the name, and all the children containing the good name.

findFirstNamed :: (Functor m, MonadIO m, GraphWalker a r) => String -> [a] -> m (Maybe (a, [(a, Int)]))

Return the first found node if any.