Add java API for using with external types

community/cypher/expression-evaluator/src/main/java/org/neo4j/cypher/evaluator/EvaluationException.java → community/cypher/expression-evaluator/src/main/java/org/neo4j/cypher/internal/evaluator/EvaluationException.java

@@ -17,9 +17,9 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package org.neo4j.cypher.evaluator;
+package org.neo4j.cypher.internal.evaluator;
 
-public class EvaluationException extends RuntimeException
+public class EvaluationException extends Exception
 {
     public EvaluationException( String message )
     {

community/cypher/expression-evaluator/src/main/java/org/neo4j/cypher/internal/evaluator/EvaluationRuntimeException.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2002-2019 "Neo4j,"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.cypher.internal.evaluator;
+
+class EvaluationRuntimeException extends RuntimeException
+{
+    EvaluationRuntimeException( String message )
+    {
+        super( message );
+    }
+}

community/cypher/expression-evaluator/src/main/java/org/neo4j/cypher/internal/evaluator/Evaluator.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2002-2019 "Neo4j,"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.cypher.internal.evaluator;
+
+@SuppressWarnings( "WeakerAccess" )
+public final class Evaluator
+{
+    private Evaluator()
+    {
+        throw new UnsupportedOperationException( "Do not instantiate" );
+    }
+
+    public static ExpressionEvaluator expressionEvaluator()
+    {
+        return new SimpleExpressionEvaluator();
+    }
+}

community/cypher/expression-evaluator/src/main/java/org/neo4j/cypher/internal/evaluator/ExpressionEvaluator.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2002-2019 "Neo4j,"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.cypher.internal.evaluator;
+
+/**
+ * An ExpressionEvaluator takes an arbitrary Cypher expression and evaluates it to a java value.
+ */
+public interface ExpressionEvaluator
+{
+    /**
+     * Evaluates a Cypher expression
+     *
+     * @param expression The expression to evaluate.
+     * @param type The type that we expect the returned value to have
+     * @return The evaluated Cypher expression.
+     * @throws EvaluationException if the evaluation fails.
+     */
+    <T> T evaluate( String expression, Class<T> type ) throws EvaluationException;
+}

community/cypher/expression-evaluator/src/main/java/org/neo4j/cypher/internal/evaluator/SimpleExpressionEvaluator.java

@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2002-2019 "Neo4j,"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.cypher.internal.evaluator;
+
+import org.neo4j.values.AnyValue;
+import org.neo4j.values.ValueMapper;
+import org.neo4j.values.virtual.PathValue;
+import org.neo4j.values.virtual.VirtualNodeValue;
+import org.neo4j.values.virtual.VirtualRelationshipValue;
+
+class SimpleExpressionEvaluator implements ExpressionEvaluator
+{
+    private InternalExpressionEvaluator evaluator = new SimpleInternalExpressionEvaluator();
+
+    @Override
+    public <T> T evaluate( String expression, Class<T> type ) throws EvaluationException
+    {
+        if ( expression == null )
+        {
+            throw new EvaluationException( "Cannot evaluate null as an expression " );
+        }
+        if ( type == null )
+        {
+            throw new EvaluationException( "Cannot evaluate to type null" );
+        }
+
+        return cast( map( evaluator.evaluate( expression ) ), type );
+    }
+
+    private <T> T cast( Object value, Class<T> type ) throws EvaluationException
+    {
+        try
+        {
+            return type.cast( value );
+        }
+        catch ( ClassCastException e )
+        {
+            throw new EvaluationException( String.format( "Expected expression of be of type `%s` but it was `%s`",
+                    type.getCanonicalName(),
+                    value.getClass().getCanonicalName() ), e );
+        }
+    }
+
+    private Object map( AnyValue value ) throws EvaluationException
+    {
+        try
+        {
+            return value.map( MAPPER );
+        }
+        catch ( EvaluationRuntimeException e )
+        {
+            throw new EvaluationException( e.getMessage(), e );
+        }
+    }
+
+    private static ValueMapper<Object> MAPPER = new ValueMapper.JavaMapper()
+    {
+        @Override
+        public Object mapPath( PathValue value )
+        {
+            throw new EvaluationRuntimeException( "Unable to evaluate paths" );
+        }
+
+        @Override
+        public Object mapNode( VirtualNodeValue value )
+        {
+            throw new EvaluationRuntimeException( "Unable to evaluate nodes" );
+        }
+
+        @Override
+        public Object mapRelationship( VirtualRelationshipValue value )
+        {
+            throw new EvaluationRuntimeException( "Unable to evaluate relationships" );
+        }
+    };
+}

community/cypher/expression-evaluator/src/main/scala/org/neo4j/cypher/internal/evaluator/InternalExpressionEvaluator.scala

@@ -28,9 +28,12 @@ trait InternalExpressionEvaluator {
 
   /**
     * Evaluates a Cypher expression provided as a String to an instance of [[AnyValue]]
+    *
     * @param expression The cypher expression string
     * @return An instance of [[AnyValue]] corresponding to the provided expression string
+    * @throws EvaluationException if evaluation fails
     */
+  @throws(classOf[EvaluationException])
   def evaluate(expression: String): AnyValue
 }
 

community/cypher/expression-evaluator/src/main/scala/org/neo4j/cypher/internal/evaluator/SimpleInternalExpressionEvaluator.scala

@@ -19,7 +19,6 @@
  */
 package org.neo4j.cypher.internal.evaluator
 
-import org.neo4j.cypher.evaluator.EvaluationException
 import org.neo4j.cypher.internal.planner.v3_5.spi.TokenContext
 import org.neo4j.cypher.internal.runtime.interpreted.ExecutionContext
 import org.neo4j.cypher.internal.runtime.interpreted.commands.convert.{CommunityExpressionConverter, ExpressionConverters}

community/cypher/expression-evaluator/src/test/java/org/neo4j/cypher/internal/evaluator/SimpleExpressionEvaluatorTest.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2002-2019 "Neo4j,"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.cypher.internal.evaluator;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import org.neo4j.helpers.collection.MapUtil;
+
+import static java.util.Arrays.asList;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+class SimpleExpressionEvaluatorTest
+{
+    @Test
+    void shouldConvertToSpecificType() throws EvaluationException
+    {
+        // Given
+        ExpressionEvaluator evaluator = Evaluator.expressionEvaluator();
+
+        // When
+        List<?> list = evaluator.evaluate( "[1, 2, 3]", List.class );
+
+        // Then
+        assertEquals( asList( 1L, 2L, 3L ), list );
+    }
+
+    @Test
+    void shouldConvertToObject() throws EvaluationException
+    {
+        // Given
+        ExpressionEvaluator evaluator = Evaluator.expressionEvaluator();
+
+        // When
+        Object object = evaluator.evaluate( "{prop: 42}", Object.class );
+
+        // Then
+        assertEquals( MapUtil.map( "prop", 42L ), object );
+    }
+
+    @Test
+    void shouldThrowIfWrongType()
+    {
+        // Given
+        ExpressionEvaluator evaluator = Evaluator.expressionEvaluator();
+
+        // Expect
+        assertThrows( EvaluationException.class, () -> evaluator.evaluate( "{prop: 42}", List.class ) );
+    }
+}