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

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

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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.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;

/**
 * <p>
 * <code>
 * executionContext.push(StringFunctions.LEFT(executionContext.resolveValue(executionContext.pop()), executionContext.resolveValue(executionContext.pop())));
 * </code>
 * </p>
 * 
 * @author tome
 */
public class leftfuncRule extends BaseFunction {
    @Override
    public boolean execute(GenerationContext generationContext) throws Exception {
        try {
            /*
             * get the operands
             */
            Dispatcher.dispatchChildren(generationContext);
            /*
             * there should be 6 values. grammar is "LEFT LPAREN expression COMMA expression RPAREN"
             */
            if (generationContext.getParseTree().getChildCount() == 6) {
                generationContext.getMethodVisitor().visitVarInsn(Opcodes.ALOAD, 0);
                generationContext.getMethodVisitor().visitFieldInsn(Opcodes.GETFIELD,
                        generationContext.getClassName(), RTLHelper.EXECUTIONCONTEXT_NAME,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT_TYPE);
                generationContext.getMethodVisitor().visitVarInsn(Opcodes.ALOAD, 0);
                generationContext.getMethodVisitor().visitFieldInsn(Opcodes.GETFIELD,
                        generationContext.getClassName(), RTLHelper.EXECUTIONCONTEXT_NAME,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT_TYPE);
                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,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT, "resolveValue",
                        "(Lcom/khubla/jvmbasic/jvmbasicrt/Value;)Lcom/khubla/jvmbasic/jvmbasicrt/Value;");
                generationContext.getMethodVisitor().visitVarInsn(Opcodes.ALOAD, 0);
                generationContext.getMethodVisitor().visitFieldInsn(Opcodes.GETFIELD,
                        generationContext.getClassName(), RTLHelper.EXECUTIONCONTEXT_NAME,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT_TYPE);
                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,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT, "resolveValue",
                        "(Lcom/khubla/jvmbasic/jvmbasicrt/Value;)Lcom/khubla/jvmbasic/jvmbasicrt/Value;");
                generationContext.getMethodVisitor().visitMethodInsn(Opcodes.INVOKESTATIC,
                        "com/khubla/jvmbasic/jvmbasicrt/StringFunctions", "LEFT",
                        "(Lcom/khubla/jvmbasic/jvmbasicrt/Value;Lcom/khubla/jvmbasic/jvmbasicrt/Value;)Ljava/lang/String;");
                generationContext.getMethodVisitor().visitMethodInsn(Opcodes.INVOKEVIRTUAL,
                        RTLHelper.JASIC_RUNTIME_EXECUTIONCONTEXT, "push", "(Ljava/lang/String;)V");
                return true;
            } else {
                throw new Exception("Invalid number of values passed to leftfuncRule");
            }
        } catch (final Exception e) {
            throw new Exception("Exception in execute", e);
        }
    }
}