Java tutorial
// 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.objectweb.asm.util; import java.util.Collections; import java.util.HashMap; import java.util.Map; import org.objectweb.asm.Opcodes; import org.objectweb.asm.signature.SignatureVisitor; /** * A {@link SignatureVisitor} that builds the Java generic type declaration corresponding to the * signature it visits. * * @author Eugene Kuleshov * @author Eric Bruneton */ public final class TraceSignatureVisitor extends SignatureVisitor { private static final String COMMA_SEPARATOR = ", "; private static final String EXTENDS_SEPARATOR = " extends "; private static final String IMPLEMENTS_SEPARATOR = " implements "; private static final Map<Character, String> BASE_TYPES; static { HashMap<Character, String> baseTypes = new HashMap<>(); baseTypes.put('Z', "boolean"); baseTypes.put('B', "byte"); baseTypes.put('C', "char"); baseTypes.put('S', "short"); baseTypes.put('I', "int"); baseTypes.put('J', "long"); baseTypes.put('F', "float"); baseTypes.put('D', "double"); baseTypes.put('V', "void"); BASE_TYPES = Collections.unmodifiableMap(baseTypes); } /** Whether the visited signature is a class signature of a Java interface. */ private final boolean isInterface; /** The Java generic type declaration corresponding to the visited signature. */ private final StringBuilder declaration; /** The Java generic method return type declaration corresponding to the visited signature. */ private StringBuilder returnType; /** The Java generic exception types declaration corresponding to the visited signature. */ private StringBuilder exceptions; /** Whether {@link #visitFormalTypeParameter} has been called. */ private boolean formalTypeParameterVisited; /** Whether {@link #visitInterfaceBound} has been called. */ private boolean interfaceBoundVisited; /** Whether {@link #visitParameterType} has been called. */ private boolean parameterTypeVisited; /** Whether {@link #visitInterface} has been called. */ private boolean interfaceVisited; /** * 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. */ private int argumentStack; /** * The stack used to keep track of array class types. 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 arrayStack; /** The separator to append before the next visited class or inner class type. */ private String separator = ""; /** * Constructs a new {@link TraceSignatureVisitor}. * * @param accessFlags for class type signatures, the access flags of the class. */ public TraceSignatureVisitor(final int accessFlags) { super(/* latest api = */ Opcodes.ASM7); this.isInterface = (accessFlags & Opcodes.ACC_INTERFACE) != 0; this.declaration = new StringBuilder(); } private TraceSignatureVisitor(final StringBuilder stringBuilder) { super(/* latest api = */ Opcodes.ASM7); this.isInterface = false; this.declaration = stringBuilder; } @Override public void visitFormalTypeParameter(final String name) { declaration.append(formalTypeParameterVisited ? COMMA_SEPARATOR : "<").append(name); formalTypeParameterVisited = true; interfaceBoundVisited = false; } @Override public SignatureVisitor visitClassBound() { separator = EXTENDS_SEPARATOR; startType(); return this; } @Override public SignatureVisitor visitInterfaceBound() { separator = interfaceBoundVisited ? COMMA_SEPARATOR : EXTENDS_SEPARATOR; interfaceBoundVisited = true; startType(); return this; } @Override public SignatureVisitor visitSuperclass() { endFormals(); separator = EXTENDS_SEPARATOR; startType(); return this; } @Override public SignatureVisitor visitInterface() { if (interfaceVisited) { separator = COMMA_SEPARATOR; } else { separator = isInterface ? EXTENDS_SEPARATOR : IMPLEMENTS_SEPARATOR; interfaceVisited = true; } startType(); return this; } @Override public SignatureVisitor visitParameterType() { endFormals(); if (parameterTypeVisited) { declaration.append(COMMA_SEPARATOR); } else { declaration.append('('); parameterTypeVisited = true; } startType(); return this; } @Override public SignatureVisitor visitReturnType() { endFormals(); if (parameterTypeVisited) { parameterTypeVisited = false; } else { declaration.append('('); } declaration.append(')'); returnType = new StringBuilder(); return new TraceSignatureVisitor(returnType); } @Override public SignatureVisitor visitExceptionType() { if (exceptions == null) { exceptions = new StringBuilder(); } else { exceptions.append(COMMA_SEPARATOR); } return new TraceSignatureVisitor(exceptions); } @Override public void visitBaseType(final char descriptor) { String baseType = BASE_TYPES.get(descriptor); if (baseType == null) { throw new IllegalArgumentException(); } declaration.append(baseType); endType(); } @Override public void visitTypeVariable(final String name) { declaration.append(separator).append(name); separator = ""; endType(); } @Override public SignatureVisitor visitArrayType() { startType(); arrayStack |= 1; return this; } @Override public void visitClassType(final String name) { if ("java/lang/Object".equals(name)) { // 'Map<java.lang.Object,java.util.List>' or 'abstract public V get(Object key);' should have // Object 'but java.lang.String extends java.lang.Object' is unnecessary. boolean needObjectClass = argumentStack % 2 != 0 || parameterTypeVisited; if (needObjectClass) { declaration.append(separator).append(name.replace('/', '.')); } } else { declaration.append(separator).append(name.replace('/', '.')); } separator = ""; argumentStack *= 2; } @Override public void visitInnerClassType(final String name) { if (argumentStack % 2 != 0) { declaration.append('>'); } argumentStack /= 2; declaration.append('.'); declaration.append(separator).append(name.replace('/', '.')); separator = ""; argumentStack *= 2; } @Override public void visitTypeArgument() { if (argumentStack % 2 == 0) { ++argumentStack; declaration.append('<'); } else { declaration.append(COMMA_SEPARATOR); } declaration.append('?'); } @Override public SignatureVisitor visitTypeArgument(final char tag) { if (argumentStack % 2 == 0) { ++argumentStack; declaration.append('<'); } else { declaration.append(COMMA_SEPARATOR); } if (tag == EXTENDS) { declaration.append("? extends "); } else if (tag == SUPER) { declaration.append("? super "); } startType(); return this; } @Override public void visitEnd() { if (argumentStack % 2 != 0) { declaration.append('>'); } argumentStack /= 2; endType(); } // ----------------------------------------------------------------------------------------------- /** * Returns the Java generic type declaration corresponding to the visited signature. * * @return the Java generic type declaration corresponding to the visited signature. */ public String getDeclaration() { return declaration.toString(); } /** * Returns the Java generic method return type declaration corresponding to the visited signature. * * @return the Java generic method return type declaration corresponding to the visited signature. */ public String getReturnType() { return returnType == null ? null : returnType.toString(); } /** * Returns the Java generic exception types declaration corresponding to the visited signature. * * @return the Java generic exception types declaration corresponding to the visited signature. */ public String getExceptions() { return exceptions == null ? null : exceptions.toString(); } // ----------------------------------------------------------------------------------------------- private void endFormals() { if (formalTypeParameterVisited) { declaration.append('>'); formalTypeParameterVisited = false; } } private void startType() { arrayStack *= 2; } private void endType() { if (arrayStack % 2 == 0) { arrayStack /= 2; } else { while (arrayStack % 2 != 0) { arrayStack /= 2; declaration.append("[]"); } } } }