/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.byteCode.control;
import com.facebook.presto.byteCode.Block;
import com.facebook.presto.byteCode.ByteCodeNode;
import com.facebook.presto.byteCode.ByteCodeNodeFactory;
import com.facebook.presto.byteCode.ByteCodeVisitor;
import com.facebook.presto.byteCode.CompilerContext;
import com.facebook.presto.byteCode.instruction.LabelNode;
import com.google.common.collect.ImmutableList;
import org.objectweb.asm.MethodVisitor;
import java.util.List;
import static com.facebook.presto.byteCode.ByteCodeNodes.buildBlock;
import static com.facebook.presto.byteCode.ExpectedType.BOOLEAN;
import static com.facebook.presto.byteCode.ExpectedType.VOID;
public class WhileLoop
implements FlowControl
{
public static WhileLoopBuilder whileLoopBuilder(CompilerContext context)
{
return new WhileLoopBuilder(context);
}
public static class WhileLoopBuilder
{
private final CompilerContext context;
private final LabelNode beginLabel = new LabelNode("begin");
private final LabelNode endLabel = new LabelNode("end");
private String comment;
private ByteCodeNode condition;
private ByteCodeNode body;
public WhileLoopBuilder(CompilerContext context)
{
this.context = context;
context.pushIterationScope(beginLabel, endLabel);
}
public WhileLoopBuilder comment(String format, Object... args)
{
this.comment = String.format(format, args);
return this;
}
public WhileLoopBuilder condition(ByteCodeNode condition)
{
this.condition = buildBlock(context, condition, "condition");
return this;
}
public WhileLoopBuilder condition(ByteCodeNodeFactory condition)
{
this.condition = buildBlock(context, condition, BOOLEAN, "condition");
return this;
}
public WhileLoopBuilder body(ByteCodeNode body)
{
this.body = buildBlock(context, body, "body");
return this;
}
public WhileLoopBuilder body(ByteCodeNodeFactory body)
{
this.body = buildBlock(context, body, VOID, "body");
return this;
}
public WhileLoop build()
{
WhileLoop whileLoop = new WhileLoop(context, comment, condition, body, beginLabel, endLabel);
context.popIterationScope();
return whileLoop;
}
}
private final CompilerContext context;
private final String comment;
private final ByteCodeNode condition;
private final ByteCodeNode body;
private final LabelNode beginLabel;
private final LabelNode endLabel;
private WhileLoop(CompilerContext context, String comment, ByteCodeNode condition, ByteCodeNode body, LabelNode beginLabel, LabelNode endLabel)
{
this.context = context;
this.comment = comment;
this.condition = condition;
this.body = body;
this.beginLabel = beginLabel;
this.endLabel = endLabel;
}
@Override
public String getComment()
{
return comment;
}
public ByteCodeNode getCondition()
{
return condition;
}
public ByteCodeNode getBody()
{
return body;
}
@Override
public void accept(MethodVisitor visitor)
{
Block block = new Block(context)
.visitLabel(beginLabel)
.append(condition)
.ifZeroGoto(endLabel)
.append(body)
.gotoLabel(beginLabel)
.visitLabel(endLabel);
block.accept(visitor);
}
@Override
public List<ByteCodeNode> getChildNodes()
{
return ImmutableList.of(condition, body);
}
@Override
public <T> T accept(ByteCodeNode parent, ByteCodeVisitor<T> visitor)
{
return visitor.visitWhile(parent, this);
}
}