Package org.aksw.jenax.io.json.accumulator

Interface AccJson

All Known Subinterfaces:

AccJsonEdge, AccJsonNode, AccJsonObjectLike

All Known Implementing Classes:

AccJsonBase, AccJsonFragmentBody, AccJsonFragmentHead, AccJsonLiteral, AccJsonObject, AccJsonObjectLikeBase, AccJsonProperty

public interface AccJson

Interface for accumulating a JSON object from a stream of triples (edges in a graph). The accumulator is like a (stateful) state in a state automaton: An accumulator receives an individual edge in order to decide whether it can transition to a child state. If it can't then it returns null. AccJsonDriver drives the lookup. If a state (=accumulator) cannot handle the edge, it searches whether any of that state's ancestors accepts it. It is an error if no suitable accumulator is found for an edge - because that means that it is unclear which accumulator should match the subsequent edges.

Method Summary

Modifier and Type	Method	Description
void	acceptContribution(RdfElement value, AccContextRdf context)	For materialization: Whenever end() is called on a state with materialization enabled, then it passes its accumulated value to the parent using this method.
void	begin(org.apache.jena.graph.Node node, AccContextRdf context, boolean skipOutput)	Start accumulation based on a given node in the underlying graph.
void	end(AccContextRdf cxt)	End the accumulator's current node
RdfElement	getInternalValue()	Internal method, mainly for processing fragments.
AccJson	getParent()	Get the parent of this accumulator.
org.aksw.commons.path.json.PathJson	getPath()
RdfElement	getValue()	If cxt.isMaterialize is enabled then this method returns the json data assembled for the current node.
boolean	hasBegun()	True after begin() and before end()
void	setParent(AccJson parent)	Sets the parent of this accumulator.
AccJson	transition(org.apache.jena.graph.Triple edge, AccContextRdf cxt)	Process an edge.

Method Details

getPath

org.aksw.commons.path.json.PathJson getPath()

setParent

void setParent(AccJson parent)

Sets the parent of this accumulator. Can only be called once. This method should never be called by application code.

getParent

AccJson getParent()

Get the parent of this accumulator. Null if there is none.

begin

void begin(org.apache.jena.graph.Node node,
 AccContextRdf context,
 boolean skipOutput)
    throws IOException

Start accumulation based on a given node in the underlying graph. Calls cannot be nested.

Parameters:

node - The source node to which the next incoming edge(s) will connect to

context - The context which holds the JSON serializers

skipOutput - When output should be disabled (used e.g. to skip over lists of items where just one was expected)

Throws:

IllegalStateException - if there was a prior call to begin() without corresponding end()

IOException

transition

AccJson transition(org.apache.jena.graph.Triple edge,
 AccContextRdf cxt)
            throws IOException

Process an edge. Based on the given edge, this accumulator attempts to transition to another AccJson instance and return it. If there is no valid transition then this method returns null.

Throws:

IOException

end

void end(AccContextRdf cxt)
  throws IOException

End the accumulator's current node

Throws:

IllegalStateException - if there was no prior call to begin()

IOException

hasBegun

boolean hasBegun()

True after begin() and before end()

getValue

RdfElement getValue()

If cxt.isMaterialize is enabled then this method returns the json data assembled for the current node. It is only valid to call this method after end().

getInternalValue

RdfElement getInternalValue()

Internal method, mainly for processing fragments. Unchecked access to the current value under construction. Should hardly be used.

acceptContribution

void acceptContribution(RdfElement value,
 AccContextRdf context)

For materialization: Whenever end() is called on a state with materialization enabled, then it passes its accumulated value to the parent using this method.