com.khubla.jvmbasic.jvmbasicc.function.impl.rule.ifstmtRule.java Source code

Introduction

Here is the source code for com.khubla.jvmbasic.jvmbasicc.function.impl.rule.ifstmtRule.java

Source

package com.khubla.jvmbasic.jvmbasicc.function.impl.rule;

/*
 * jvmBasic Copyright 2012, khubla.com
 *
 *   This program 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/>.
 */
import org.objectweb.asm.Label;
import org.objectweb.asm.Opcodes;

import com.khubla.jvmbasic.jvmbasicc.compiler.Dispatcher;
import com.khubla.jvmbasic.jvmbasicc.compiler.GenerationContext;
import com.khubla.jvmbasic.jvmbasicc.compiler.RTLHelper;
import com.khubla.jvmbasic.jvmbasicc.function.BaseFunction;

/**
 * @author tome
 *         <p>
 *         <code>
 *  if (true == executionContext.pop().getBoolean()) {
 * </code>
 *         </p>
 *         <p>
 *         ifstmt : IF expression THEN? (statement | linenumber);
 *         </p>
 */
public class ifstmtRule extends BaseFunction {
    @Override
    public boolean execute(GenerationContext generationContext) throws Exception {
        try {
            if (generationContext.getParseTree().getChildCount() == 4) {
                /*
                 * dispatch into the test
                 */
                final GenerationContext testGenerationContext = new GenerationContext(generationContext,
                        generationContext.getParseTree().getChild(1));
                Dispatcher.dispatchChildren(testGenerationContext);
                /*
                 * check the result
                 */
                generationContext.getMethodVisitor().visitVarInsn(Opcodes.ALOAD, 0);
                generationContext.getMethodVisitor().visitFieldInsn(Opcodes.GETFIELD,
                        generationContext.getClassName(), RTLHelper.EXECUTIONCONTEXT_NAME,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT_TYPE);
                generationContext.getMethodVisitor().visitMethodInsn(Opcodes.INVOKEVIRTUAL,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT, "pop",
                        "()Lcom/khubla/jvmbasic/jvmbasicrt/Value;");
                generationContext.getMethodVisitor().visitMethodInsn(Opcodes.INVOKEVIRTUAL,
                        "com/khubla/jvmbasic/jvmbasicrt/Value", "getBoolean", "()Ljava/lang/Boolean;");
                generationContext.getMethodVisitor().visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Boolean",
                        "booleanValue", "()Z");
                /*
                 * check result
                 */
                final Label l1 = new Label();
                generationContext.getMethodVisitor().visitJumpInsn(Opcodes.IFEQ, l1);
                /*
                 * process the contained tree
                 */
                final GenerationContext statementGenerationContext = new GenerationContext(generationContext,
                        generationContext.getParseTree().getChild(3));
                Dispatcher.dispatch(statementGenerationContext);
                /*
                 * label to skip to
                 */
                generationContext.getMethodVisitor().visitLabel(l1);
                generationContext.getMethodVisitor().visitFrame(Opcodes.F_SAME, 0, null, 0, null);
                return true;
            } else if (generationContext.getParseTree().getChildCount() == 3) {
                /*
                 * dispatch into the test
                 */
                final GenerationContext testGenerationContext = new GenerationContext(generationContext,
                        generationContext.getParseTree().getChild(1));
                Dispatcher.dispatchChildren(testGenerationContext);
                /*
                 * check the result
                 */
                generationContext.getMethodVisitor().visitVarInsn(Opcodes.ALOAD, 0);
                generationContext.getMethodVisitor().visitFieldInsn(Opcodes.GETFIELD,
                        generationContext.getClassName(), RTLHelper.EXECUTIONCONTEXT_NAME,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT_TYPE);
                generationContext.getMethodVisitor().visitMethodInsn(Opcodes.INVOKEVIRTUAL,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT, "pop",
                        "()Lcom/khubla/jvmbasic/jvmbasicrt/Value;");
                generationContext.getMethodVisitor().visitMethodInsn(Opcodes.INVOKEVIRTUAL,
                        "com/khubla/jvmbasic/jvmbasicrt/Value", "getBoolean", "()Ljava/lang/Boolean;");
                generationContext.getMethodVisitor().visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Boolean",
                        "booleanValue", "()Z");
                /*
                 * check result
                 */
                final Label l1 = new Label();
                generationContext.getMethodVisitor().visitJumpInsn(Opcodes.IFEQ, l1);
                /*
                 * process the contained tree
                 */
                final GenerationContext statementGenerationContext = new GenerationContext(generationContext,
                        generationContext.getParseTree().getChild(2));
                Dispatcher.dispatch(statementGenerationContext);
                /*
                 * label to skip to
                 */
                generationContext.getMethodVisitor().visitLabel(l1);
                generationContext.getMethodVisitor().visitFrame(Opcodes.F_SAME, 0, null, 0, null);
                return true;
            } else {
                throw new Exception(
                        "Invalid number of tokens in subtree '" + generationContext.getParseTree().getChildCount()
                                + "' expected 3 on line number: " + generationContext.getLineNumber());
            }
        } catch (final Exception e) {
            throw new Exception("Exception in execute", e);
        }
    }
}