1 files changed, 74 insertions, 0 deletions

diff --git a/subprojects/viatra-runtime-matchers/src/main/java/tools/refinery/viatra/runtime/matchers/backend/ResultProviderRequestor.java b/subprojects/viatra-runtime-matchers/src/main/java/tools/refinery/viatra/runtime/matchers/backend/ResultProviderRequestor.java
new file mode 100644
index 00000000..6ec6d53e
--- /dev/null
+++ b/subprojects/viatra-runtime-matchers/src/main/java/tools/refinery/viatra/runtime/matchers/backend/ResultProviderRequestor.java
@@ -0,0 +1,74 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2018, Gabor Bergmann, IncQuery Labs Ltd.
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.matchers.backend;
+
+import tools.refinery.viatra.runtime.matchers.context.IQueryResultProviderAccess;
+import tools.refinery.viatra.runtime.matchers.psystem.IQueryReference;
+import tools.refinery.viatra.runtime.matchers.psystem.PConstraint;
+
+/**
+ * Uniform way of requesting result providers for pattern calls within queries.
+ * Intended users are query backends, for calling other backends to deliver results of dependee queries.
+ * 
+ * @author Gabor Bergmann
+ * @since 2.1
+ */
+public class ResultProviderRequestor {
+    IQueryBackend callerBackend;
+    IQueryResultProviderAccess resultProviderAccess;
+    IQueryBackendHintProvider hintProvider;
+    ICallDelegationStrategy delegationStrategy;
+    QueryEvaluationHint callerHint;
+    QueryEvaluationHint universalOverride;
+    
+    
+    /**
+     * @param callerBackend the actual backend evaluating the calling pattern.  
+     * @param resultProviderAccess
+     * @param hintProvider
+     * @param delegationStrategy
+     * @param callerHint  a hint under which the calling pattern is evaluated, 
+     * @param universalOverride if non-null, overrides the hint with extra options <i>after</i> the {@link ICallDelegationStrategy}
+     */
+    public ResultProviderRequestor(IQueryBackend callerBackend, IQueryResultProviderAccess resultProviderAccess,
+            IQueryBackendHintProvider hintProvider, ICallDelegationStrategy delegationStrategy,
+            QueryEvaluationHint callerHint, QueryEvaluationHint universalOverride) {
+        super();
+        this.callerBackend = callerBackend;
+        this.resultProviderAccess = resultProviderAccess;
+        this.hintProvider = hintProvider;
+        this.delegationStrategy = delegationStrategy;
+        this.callerHint = callerHint;
+        this.universalOverride = universalOverride;
+    }
+
+
+
+
+    /**
+     * 
+     * @param call a {@link PConstraint} in a query that calls another query.
+     * @param spotOverride if non-null, overrides the hint with extra options <i>after</i> the {@link ICallDelegationStrategy} 
+     * and the universal override specified in the constructor
+     * @return the obtained result provider
+     */
+    public IQueryResultProvider requestResultProvider(IQueryReference call, QueryEvaluationHint spotOverride) {
+        QueryEvaluationHint hints = 
+                delegationStrategy.transformHints(call, callerHint, callerBackend, hintProvider);
+        
+        if (universalOverride != null)
+            hints = hints.overrideBy(universalOverride);
+        
+        if (spotOverride != null)
+            hints = hints.overrideBy(spotOverride);
+        
+        return resultProviderAccess.getResultProvider(call.getReferredQuery(), hints);
+    }
+
+}