Support try-catch-finally

This more or less rewrites how we do try-catch-finally. From an API point-of-view it looks
the same but behind the scenes we actually create the entire try-catch-finally in one go.

community/codegen/src/main/java/org/neo4j/codegen/CatchClause.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2002-2016 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.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.codegen;
+
+import java.util.List;
+import java.util.function.Consumer;
+
+public class CatchClause
+{
+    private final Parameter exception;
+    private final List<Consumer<MethodEmitter>> actions;
+
+    public CatchClause( Parameter exception, List<Consumer<MethodEmitter>> actions )
+    {
+        this.exception = exception;
+        this.actions = actions;
+    }
+
+    public Parameter exception()
+    {
+        return exception;
+    }
+
+    public List<Consumer<MethodEmitter>> actions()
+    {
+        return actions;
+    }
+
+}

community/codegen/src/main/java/org/neo4j/codegen/CodeBlock.java

@@ -19,39 +19,41 @@
  */
 package org.neo4j.codegen;
 
-import java.util.HashMap;
-import java.util.Map;
+import java.util.function.Consumer;
 
+import static org.neo4j.codegen.LocalVariables.copy;
 import static org.neo4j.codegen.Resource.withResource;
 import static org.neo4j.codegen.TypeReference.typeReference;
 
 public class CodeBlock implements AutoCloseable
 {
+
     final ClassGenerator clazz;
     private MethodEmitter emitter;
     private final CodeBlock parent;
     private boolean done;
-    private Map<String, LocalVariable> localVariables = new HashMap<>(  );
-    private int varCount = 0;
+
+    protected LocalVariables localVariables = new LocalVariables();
 
     CodeBlock( CodeBlock parent )
     {
         this.clazz = parent.clazz;
         this.emitter = parent.emitter;
         parent.emitter = InvalidState.IN_SUB_BLOCK;
         this.parent = parent;
-        this.localVariables = parent.localVariables;
+        //copy over local variables from parent
+        this.localVariables = copy(parent.localVariables);
     }
 
     CodeBlock( ClassGenerator clazz, MethodEmitter emitter, Parameter...parameters )
     {
         this.clazz = clazz;
         this.emitter = emitter;
         this.parent = null;
-        localVariables.put("this", localVariable( clazz.handle(), "this" ) );
+        localVariables.createNew( clazz.handle(), "this" );
         for ( Parameter parameter : parameters )
         {
-            localVariables.put( parameter.name(), localVariable( parameter.type(), parameter.name() ) );
+            localVariables.createNew( parameter.type(), parameter.name() );
         }
     }
 
@@ -75,7 +77,7 @@ public void close()
         this.emitter = InvalidState.BLOCK_CLOSED;
     }
 
-    private void endBlock()
+    protected void endBlock()
     {
         if ( !done )
         {
@@ -84,9 +86,14 @@ private void endBlock()
         }
     }
 
+    protected void emit( Consumer<MethodEmitter> emitFunction )
+    {
+        emitFunction.accept( emitter );
+    }
+
     public void expression( Expression expression )
     {
-        emitter.expression( expression );
+        emit( ( e ) -> e.expression( expression ) );
     }
 
     LocalVariable local( String name )
@@ -96,15 +103,14 @@ LocalVariable local( String name )
 
     public LocalVariable declare( TypeReference type, String name )
     {
-        LocalVariable local = localVariable( type, name );
-        localVariables.put(name, local);
-        emitter.declare( local );
+        LocalVariable local = localVariables.createNew( type, name );
+        emit( e -> e.declare( local ) );
         return local;
     }
 
     public void assign( LocalVariable local, Expression value )
     {
-        emitter.assignVariableInScope( local, value );
+        emit( e -> e.assignVariableInScope( local, value ) );
     }
 
     public void assign( Class<?> type, String name, Expression value )
@@ -114,14 +120,13 @@ public void assign( Class<?> type, String name, Expression value )
 
     public void assign( TypeReference type, String name, Expression value )
     {
-        LocalVariable variable = localVariable( type, name );
-        localVariables.put(name, variable );
-        emitter.assign( variable, value );
+        LocalVariable variable = localVariables.createNew( type, name );
+        emit( e -> e.assign( variable, value ) );
     }
 
     public void put( Expression target, FieldReference field, Expression value )
     {
-        emitter.put( target, field, value );
+        emit( e -> e.put( target, field, value ) );
     }
 
     public Expression self()
@@ -136,74 +141,55 @@ public Expression load( String name )
 
     public CodeBlock forEach( Parameter local, Expression iterable )
     {
-        emitter.beginForEach( local, iterable );
+        emit( e -> e.beginForEach( local, iterable ) );
         return new CodeBlock( this );
     }
 
     public CodeBlock whileLoop( Expression test )
     {
-        emitter.beginWhile( test );
+        emit( e -> e.beginWhile( test ) );
         return new CodeBlock( this );
     }
 
     public CodeBlock ifStatement( Expression test )
     {
-        emitter.beginIf( test );
+        emit( e -> e.beginIf( test ) );
         return new CodeBlock( this );
     }
 
-    CodeBlock emitCatch( Parameter exception )
-    {
-        endBlock();
-        emitter.beginCatch( exception );
-        return new CodeBlock( this );
-    }
-
-    CodeBlock emitFinally()
-    {
-        endBlock();
-        emitter.beginFinally();
-        return new CodeBlock( this );
-    }
-
-    public CodeBlock tryBlock( Class<?> resourceType, String resourceName, Expression resource )
+    public TryBlock tryBlock( Class<?> resourceType, String resourceName, Expression resource )
     {
         return tryBlock( withResource( resourceType, resourceName, resource ) );
     }
 
-    public CodeBlock tryBlock( TypeReference resourceType, String resourceName, Expression resource )
+    public TryBlock tryBlock( TypeReference resourceType, String resourceName, Expression resource )
     {
         return tryBlock( withResource( resourceType, resourceName, resource ) );
     }
 
     public TryBlock tryBlock( Resource... resources )
     {
-        emitter.beginTry( resources );
-        return new TryBlock( this );
+        return new TryBlock( this, resources );
     }
 
     public void returns()
     {
-        emitter.returns();
+        emit( MethodEmitter::returns );
     }
 
     public void returns( Expression value )
     {
-        emitter.returns( value );
+        emit( e -> e.returns( value ) );
     }
 
     public void throwException( Expression exception )
     {
-        emitter.throwException( exception );
+        emit( e -> e.throwException( exception ) );
     }
 
     public TypeReference owner()
     {
         return clazz.handle();
     }
 
-    private LocalVariable localVariable( TypeReference type, String name )
-    {
-        return new LocalVariable( type, name, varCount++ );
-    }
 }

community/codegen/src/main/java/org/neo4j/codegen/Expression.java

@@ -70,7 +70,7 @@ public void accept( ExpressionVisitor visitor )
         };
     }
 
-    static Expression load( final LocalVariable variable)
+    public static Expression load( final LocalVariable variable)
     {
         return new Expression()
         {

community/codegen/src/main/java/org/neo4j/codegen/InvalidState.java

@@ -19,6 +19,9 @@
  */
 package org.neo4j.codegen;
 
+import java.util.List;
+import java.util.function.Consumer;
+
 class InvalidState implements MethodEmitter
 {
     public static final ClassEmitter CLASS_DONE = new ClassEmitter()
@@ -98,20 +101,15 @@ public void beginIf( Expression test )
         throw new IllegalStateException( reason );
     }
 
-    @Override
-    public void beginFinally()
-    {
-        throw new IllegalStateException( reason );
-    }
-
     @Override
     public void endBlock()
     {
         throw new IllegalStateException( reason );
     }
 
     @Override
-    public void beginTry( Resource... resources )
+    public void tryCatchBlock( List<Consumer<MethodEmitter>> body, List<CatchClause> catchClauses,
+            List<Consumer<MethodEmitter>> finalClauses, LocalVariables localVariables, Resource... resources )
     {
         throw new IllegalStateException( reason );
     }
@@ -122,12 +120,6 @@ public void throwException( Expression exception )
         throw new IllegalStateException( reason );
     }
 
-    @Override
-    public void beginCatch( Parameter exception )
-    {
-        throw new IllegalStateException( reason );
-    }
-
     @Override
     public void declare( LocalVariable local )
     {

community/codegen/src/main/java/org/neo4j/codegen/LocalVariables.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2002-2016 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.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.codegen;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Repository of local variables.
+ */
+public class LocalVariables
+{
+    private final AtomicInteger counter = new AtomicInteger( 0 );
+    private final Map<String,LocalVariable> localVariables = new HashMap<>();
+
+    public LocalVariable createNew( TypeReference type, String name )
+    {
+        LocalVariable localVariable = new LocalVariable( type, name, counter.getAndIncrement() );
+        localVariables.put( name, localVariable );
+        return localVariable;
+    }
+
+    public LocalVariable get( String name )
+    {
+        return localVariables.get( name );
+    }
+
+    public static LocalVariables copy( LocalVariables original )
+    {
+        LocalVariables variables = new LocalVariables();
+        variables.counter.set( original.counter.get() );
+        original.localVariables.forEach( variables.localVariables::put );
+        return variables;
+    }
+
+    public int nextIndex()
+    {
+        return counter.getAndIncrement();
+    }
+}

community/codegen/src/main/java/org/neo4j/codegen/MethodEmitter.java

@@ -19,6 +19,9 @@
  */
 package org.neo4j.codegen;
 
+import java.util.List;
+import java.util.function.Consumer;
+
 public interface MethodEmitter
 {
     void done();
@@ -37,16 +40,15 @@ public interface MethodEmitter
 
     void beginIf( Expression test );
 
-    void beginFinally();
-
     void endBlock();
 
-    void beginTry( Resource... resources );
+    void tryCatchBlock( List<Consumer<MethodEmitter>> body,
+            List<CatchClause> catchClauses,
+            List<Consumer<MethodEmitter>> finalClauses,
+            LocalVariables localVariables, Resource... resources );
 
     void throwException( Expression exception );
 
-    void beginCatch( Parameter exception );
-
     void declare( LocalVariable local );
 
     void assignVariableInScope( LocalVariable local, Expression value );

community/codegen/src/main/java/org/neo4j/codegen/MethodReference.java

@@ -46,6 +46,12 @@ private static MethodReference methodReference( Class<?> owner, TypeReference re
         return methodReference( typeReference( owner ), returns, name, modifiers, parameters );
     }
 
+    public static MethodReference methodReference( TypeReference owner, TypeReference returns, String name,
+            TypeReference... parameters )
+    {
+        return new MethodReference( owner, name, returns, Modifier.PUBLIC, parameters );
+    }
+
     public static MethodReference methodReference( TypeReference owner, TypeReference returns, String name,
             int modifiers, TypeReference... parameters )
     {