com.github.stokito.gag.instrument.util.StringBuilderVisitor.java Source code

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Here is the source code for com.github.stokito.gag.instrument.util.StringBuilderVisitor.java

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/**
 * Copyright 2010 Google Inc.
 *
 * 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.github.stokito.gag.instrument.util;

import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Type;

import static org.objectweb.asm.Opcodes.*;

public class StringBuilderVisitor {
    private static final Type SB = Type.getType(StringBuilder.class);
    private static final String SB_NAME = SB.getInternalName();
    private final MethodVisitor mv;

    public StringBuilderVisitor(MethodVisitor mv) {
        this.mv = mv;
        mv.visitTypeInsn(NEW, SB_NAME);
        mv.visitInsn(DUP);
        mv.visitMethodInsn(INVOKESPECIAL, SB_NAME, "<init>", "()V");
    }

    public void visitAppend(String s) {
        mv.visitLdcInsn(s);
        visitMethod("append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;");
    }

    public void visitAppend(Type paramType, int paramIndex) {
        mv.visitVarInsn(getLoad(paramType), paramIndex);
        visitMethod("append", "(" + getAppendType(paramType).getDescriptor() + ")Ljava/lang/StringBuilder;");
    }

    public void visitToString() {
        visitMethod("toString", "()Ljava/lang/String;");
    }

    private void visitMethod(String methodName, String desc) {
        mv.visitMethodInsn(INVOKEVIRTUAL, SB_NAME, methodName, desc);
    }

    private static int getLoad(Type paramType) {
        switch (paramType.getSort()) {
        case Type.INT:
        case Type.SHORT:
        case Type.BYTE:
        case Type.CHAR:
        case Type.BOOLEAN:
            return ILOAD;
        case Type.LONG:
            return LLOAD;
        case Type.DOUBLE:
            return DLOAD;
        case Type.FLOAT:
            return FLOAD;
        default:
            return ALOAD;
        }
    }

    private static Type getAppendType(Type paramType) {
        switch (paramType.getSort()) {
        case Type.INT:
        case Type.BYTE:
        case Type.CHAR:
        case Type.BOOLEAN:
        case Type.LONG:
        case Type.DOUBLE:
        case Type.FLOAT:
            return paramType;
        case Type.SHORT:
            return Type.INT_TYPE;
        default:
            return Type.getType(Object.class);
        }
    }
}