Scala example source code file (SignatureWriter.java)

This example Scala source code file (SignatureWriter.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

asm, override, signaturevisitor, signaturewriter, string, stringbuffer

The SignatureWriter.java Scala example source code

/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package scala.tools.asm.signature;

import scala.tools.asm.Opcodes;

/**
 * A signature visitor that generates signatures in string format.
 *
 * @author Thomas Hallgren
 * @author Eric Bruneton
 */
public class SignatureWriter extends SignatureVisitor {

    /**
     * Buffer used to construct the signature.
     */
    private final StringBuffer buf = new StringBuffer();

    /**
     * Indicates if the signature contains formal type parameters.
     */
    private boolean hasFormals;

    /**
     * Indicates if the signature contains method parameter types.
     */
    private boolean hasParameters;

    /**
     * Stack used to keep track of class types that have arguments. Each element
     * of this stack is a boolean encoded in one bit. The top of the stack is
     * the lowest order bit. Pushing false = *2, pushing true = *2+1, popping =
     * /2.
     */
    private int argumentStack;

    /**
     * Constructs a new {@link SignatureWriter} object.
     */
    public SignatureWriter() {
        super(Opcodes.ASM4);
    }

    // ------------------------------------------------------------------------
    // Implementation of the SignatureVisitor interface
    // ------------------------------------------------------------------------

    @Override
    public void visitFormalTypeParameter(final String name) {
        if (!hasFormals) {
            hasFormals = true;
            buf.append('<');
        }
        buf.append(name);
        buf.append(':');
    }

    @Override
    public SignatureVisitor visitClassBound() {
        return this;
    }

    @Override
    public SignatureVisitor visitInterfaceBound() {
        buf.append(':');
        return this;
    }

    @Override
    public SignatureVisitor visitSuperclass() {
        endFormals();
        return this;
    }

    @Override
    public SignatureVisitor visitInterface() {
        return this;
    }

    @Override
    public SignatureVisitor visitParameterType() {
        endFormals();
        if (!hasParameters) {
            hasParameters = true;
            buf.append('(');
        }
        return this;
    }

    @Override
    public SignatureVisitor visitReturnType() {
        endFormals();
        if (!hasParameters) {
            buf.append('(');
        }
        buf.append(')');
        return this;
    }

    @Override
    public SignatureVisitor visitExceptionType() {
        buf.append('^');
        return this;
    }

    @Override
    public void visitBaseType(final char descriptor) {
        buf.append(descriptor);
    }

    @Override
    public void visitTypeVariable(final String name) {
        buf.append('T');
        buf.append(name);
        buf.append(';');
    }

    @Override
    public SignatureVisitor visitArrayType() {
        buf.append('[');
        return this;
    }

    @Override
    public void visitClassType(final String name) {
        buf.append('L');
        buf.append(name);
        argumentStack *= 2;
    }

    @Override
    public void visitInnerClassType(final String name) {
        endArguments();
        buf.append('.');
        buf.append(name);
        argumentStack *= 2;
    }

    @Override
    public void visitTypeArgument() {
        if (argumentStack % 2 == 0) {
            ++argumentStack;
            buf.append('<');
        }
        buf.append('*');
    }

    @Override
    public SignatureVisitor visitTypeArgument(final char wildcard) {
        if (argumentStack % 2 == 0) {
            ++argumentStack;
            buf.append('<');
        }
        if (wildcard != '=') {
            buf.append(wildcard);
        }
        return this;
    }

    @Override
    public void visitEnd() {
        endArguments();
        buf.append(';');
    }

    /**
     * Returns the signature that was built by this signature writer.
     *
     * @return the signature that was built by this signature writer.
     */
    @Override
    public String toString() {
        return buf.toString();
    }

    // ------------------------------------------------------------------------
    // Utility methods
    // ------------------------------------------------------------------------

    /**
     * Ends the formal type parameters section of the signature.
     */
    private void endFormals() {
        if (hasFormals) {
            hasFormals = false;
            buf.append('>');
        }
    }

    /**
     * Ends the type arguments of a class or inner class type.
     */
    private void endArguments() {
        if (argumentStack % 2 != 0) {
            buf.append('>');
        }
        argumentStack /= 2;
    }
}