Package graphql.schema.diffing

Class PossibleMappingsCalculator

java.lang.Object

graphql.schema.diffing.PossibleMappingsCalculator

public class PossibleMappingsCalculator
extends java.lang.Object

We don't want to allow arbitrary schema changes. For example changing an Object type into a Scalar is not something we want to consider.

We do this to make SchemaDiffings better understandable, but also to improve the overall runtime of the algorithm. By restricting the possible mappings the Schema diffing algo is actually able to finish in a reasonable time for real life inputs.

We restrict the algo by calculating which mappings are possible for given vertex. This is later used in DiffImpl.calcLowerBoundMappingCost(graphql.schema.diffing.Vertex, graphql.schema.diffing.Vertex, java.util.List<graphql.schema.diffing.Vertex>, java.util.Set<graphql.schema.diffing.Vertex>, java.util.List<graphql.schema.diffing.Vertex>, java.util.Set<graphql.schema.diffing.Vertex>). While doing this we need to also ensure that there are the same amount of vertices in the same "context": for example if the source graph has 3 Objects, the target graph needs to have 3 Objects. We achieve this by adding "isolated vertices" as needed.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	PossibleMappingsCalculator.PossibleMappings
static class	PossibleMappingsCalculator.VertexContextSegment

Constructor Summary

Constructors

Constructor	Description
PossibleMappingsCalculator(SchemaGraph sourceGraph, SchemaGraph targetGraph, graphql.schema.diffing.SchemaDiffingRunningCheck runningCheck)

Method Summary

Modifier and Type	Method	Description
void	calcPossibleMappings(java.util.List<PossibleMappingsCalculator.VertexContextSegment> contexts, java.lang.String typeNameForDebug)
PossibleMappingsCalculator.PossibleMappings	calculate()
PossibleMappingsCalculator.PossibleMappings	getIsolatedVertices()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PossibleMappingsCalculator

public PossibleMappingsCalculator(SchemaGraph sourceGraph,
                                  SchemaGraph targetGraph,
                                  graphql.schema.diffing.SchemaDiffingRunningCheck runningCheck)

Method Detail

calculate

public PossibleMappingsCalculator.PossibleMappings calculate()

calcPossibleMappings

public void calcPossibleMappings(java.util.List<PossibleMappingsCalculator.VertexContextSegment> contexts,
                                 java.lang.String typeNameForDebug)

getIsolatedVertices

public PossibleMappingsCalculator.PossibleMappings getIsolatedVertices()