net.hasor.dataql.compiler.cc.SwitchInstCompiler Maven / Gradle / Ivy
/*
* Copyright 2008-2009 the original author or authors.
*
* 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 net.hasor.dataql.compiler.cc;
import net.hasor.dataql.compiler.QueryCompilerException;
import net.hasor.dataql.compiler.qil.CompilerContext;
import net.hasor.dataql.compiler.qil.InstCompiler;
import net.hasor.dataql.compiler.qil.InstQueue;
import net.hasor.dataql.compiler.qil.Label;
import net.hasor.dataql.parser.ast.Expression;
import net.hasor.dataql.parser.ast.inst.InstSet;
import net.hasor.dataql.parser.ast.inst.SwitchInst;
import net.hasor.dataql.parser.ast.inst.SwitchInst.SwitchExpression;
import java.util.List;
/**
* if指令
* @author 赵永春 ([email protected])
* @version : 2017-03-23
*/
public class SwitchInstCompiler implements InstCompiler {
@Override
public void doCompiler(SwitchInst astInst, InstQueue queue, CompilerContext compilerContext) {
List testBlockSet = astInst.getTestBlockSet();
InstSet elseBlockSet = astInst.getElseBlockSet();
//
if (testBlockSet.isEmpty()) {
throw new QueryCompilerException("if testBlockSet is empty.");
}
/*
if (a == b)
var a = b
elseif (a == null)
var b = a
else
var c = a
end
----- // if (a == b)
LABEL "label_0"
LOAD 1
LOAD 2
DO "eq"
IF "label_1"
...
GOTO "label_4"
----- // elseif (a == null)
LABEL "label_1"
LOAD 1
LDC_N
DO "eq"
IF "label_2"
...
GOTO "label_4"
----- // else
GOTO "label_2"
...
-----
GOTO "label_4"
*/
//
// .if 和 elseif
//
Label finalLabel = queue.labelDef(); // if 的总出口 Label
for (SwitchExpression switchExp : testBlockSet) {
//
// .产生新的入口，流给下一个if分支使用
Label lastEnterIn = queue.labelDef();
//
// .条件判断
Expression testExpression = switchExp.testExpression;
compilerContext.findInstCompilerByInst(testExpression).doCompiler(queue);
instLocation(queue, switchExp.testExpression.expressCodeLocation());
queue.inst(IF, lastEnterIn);//如果判断失败，跳转到下一个Label
//
// .if的body
InstSet instBlockSet = switchExp.instBlockSet;
compilerContext.findInstCompilerByInst(instBlockSet).doCompiler(queue);
queue.inst(GOTO, finalLabel);//执行完毕，跳转到总出口
queue.inst(LABEL, lastEnterIn);
}
// .else
if (elseBlockSet != null) {
compilerContext.findInstCompilerByInst(elseBlockSet).doCompiler(queue);
queue.inst(GOTO, finalLabel);
}
// .if 的结束点
queue.inst(LABEL, finalLabel);
}
}