| // 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 org.apache.tapestry5.internal.plastic.asm.signature; |
| |
| import org.apache.tapestry5.internal.plastic.asm.Opcodes; |
| |
| /** |
| * A SignatureVisitor that generates signature literals, as defined in the Java Virtual Machine |
| * Specification (JVMS). |
| * |
| * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.9.1">JVMS |
| * 4.7.9.1</a> |
| * @author Thomas Hallgren |
| * @author Eric Bruneton |
| */ |
| public class SignatureWriter extends SignatureVisitor { |
| |
| /** The builder used to construct the visited signature. */ |
| private final StringBuilder stringBuilder = new StringBuilder(); |
| |
| /** Whether the visited signature contains formal type parameters. */ |
| private boolean hasFormals; |
| |
| /** Whether the visited signature contains method parameter types. */ |
| private boolean hasParameters; |
| |
| /** |
| * The 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 least significant bit. Pushing false |
| * = *2, pushing true = *2+1, popping = /2. |
| * |
| * <p>Class type arguments must be surrounded with '<' and '>' and, because |
| * |
| * <ol> |
| * <li>class types can be nested (because type arguments can themselves be class types), |
| * <li>SignatureWriter always returns 'this' in each visit* method (to avoid allocating new |
| * SignatureWriter instances), |
| * </ol> |
| * |
| * <p>we need a stack to properly balance these 'parentheses'. A new element is pushed on this |
| * stack for each new visited type, and popped when the visit of this type ends (either is |
| * visitEnd, or because visitInnerClassType is called). |
| */ |
| private int argumentStack; |
| |
| /** Constructs a new {@link SignatureWriter}. */ |
| public SignatureWriter() { |
| super(Opcodes.ASM7); |
| } |
| |
| // ----------------------------------------------------------------------------------------------- |
| // Implementation of the SignatureVisitor interface |
| // ----------------------------------------------------------------------------------------------- |
| |
| @Override |
| public void visitFormalTypeParameter(final String name) { |
| if (!hasFormals) { |
| hasFormals = true; |
| stringBuilder.append('<'); |
| } |
| stringBuilder.append(name); |
| stringBuilder.append(':'); |
| } |
| |
| @Override |
| public SignatureVisitor visitClassBound() { |
| return this; |
| } |
| |
| @Override |
| public SignatureVisitor visitInterfaceBound() { |
| stringBuilder.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; |
| stringBuilder.append('('); |
| } |
| return this; |
| } |
| |
| @Override |
| public SignatureVisitor visitReturnType() { |
| endFormals(); |
| if (!hasParameters) { |
| stringBuilder.append('('); |
| } |
| stringBuilder.append(')'); |
| return this; |
| } |
| |
| @Override |
| public SignatureVisitor visitExceptionType() { |
| stringBuilder.append('^'); |
| return this; |
| } |
| |
| @Override |
| public void visitBaseType(final char descriptor) { |
| stringBuilder.append(descriptor); |
| } |
| |
| @Override |
| public void visitTypeVariable(final String name) { |
| stringBuilder.append('T'); |
| stringBuilder.append(name); |
| stringBuilder.append(';'); |
| } |
| |
| @Override |
| public SignatureVisitor visitArrayType() { |
| stringBuilder.append('['); |
| return this; |
| } |
| |
| @Override |
| public void visitClassType(final String name) { |
| stringBuilder.append('L'); |
| stringBuilder.append(name); |
| // Pushes 'false' on the stack, meaning that this type does not have type arguments (as far as |
| // we can tell at this point). |
| argumentStack *= 2; |
| } |
| |
| @Override |
| public void visitInnerClassType(final String name) { |
| endArguments(); |
| stringBuilder.append('.'); |
| stringBuilder.append(name); |
| // Pushes 'false' on the stack, meaning that this type does not have type arguments (as far as |
| // we can tell at this point). |
| argumentStack *= 2; |
| } |
| |
| @Override |
| public void visitTypeArgument() { |
| // If the top of the stack is 'false', this means we are visiting the first type argument of the |
| // currently visited type. We therefore need to append a '<', and to replace the top stack |
| // element with 'true' (meaning that the current type does have type arguments). |
| if (argumentStack % 2 == 0) { |
| argumentStack |= 1; |
| stringBuilder.append('<'); |
| } |
| stringBuilder.append('*'); |
| } |
| |
| @Override |
| public SignatureVisitor visitTypeArgument(final char wildcard) { |
| // If the top of the stack is 'false', this means we are visiting the first type argument of the |
| // currently visited type. We therefore need to append a '<', and to replace the top stack |
| // element with 'true' (meaning that the current type does have type arguments). |
| if (argumentStack % 2 == 0) { |
| argumentStack |= 1; |
| stringBuilder.append('<'); |
| } |
| if (wildcard != '=') { |
| stringBuilder.append(wildcard); |
| } |
| return this; |
| } |
| |
| @Override |
| public void visitEnd() { |
| endArguments(); |
| stringBuilder.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 stringBuilder.toString(); |
| } |
| |
| // ----------------------------------------------------------------------------------------------- |
| // Utility methods |
| // ----------------------------------------------------------------------------------------------- |
| |
| /** Ends the formal type parameters section of the signature. */ |
| private void endFormals() { |
| if (hasFormals) { |
| hasFormals = false; |
| stringBuilder.append('>'); |
| } |
| } |
| |
| /** Ends the type arguments of a class or inner class type. */ |
| private void endArguments() { |
| // If the top of the stack is 'true', this means that some type arguments have been visited for |
| // the type whose visit is now ending. We therefore need to append a '>', and to pop one element |
| // from the stack. |
| if (argumentStack % 2 == 1) { |
| stringBuilder.append('>'); |
| } |
| argumentStack /= 2; |
| } |
| } |