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Utilities for ASM, a very small and fast Java bytecode manipulation framework

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/***
 * 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.io.FileInputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.objectweb.asm.AnnotationVisitor;
import org.objectweb.asm.Attribute;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.FieldVisitor;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.TypePath;
import org.objectweb.asm.TypeReference;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.MethodNode;
import org.objectweb.asm.tree.analysis.Analyzer;
import org.objectweb.asm.tree.analysis.BasicValue;
import org.objectweb.asm.tree.analysis.Frame;
import org.objectweb.asm.tree.analysis.SimpleVerifier;

/**
 * A {@link ClassVisitor} that checks that its methods are properly used. More
 * precisely this class adapter checks each method call individually, based
 * only on its arguments, but does not check the sequence
 * of method calls. For example, the invalid sequence
 * visitField(ACC_PUBLIC, "i", "I", null) visitField(ACC_PUBLIC,
 * "i", "D", null) will not be detected by this class adapter.
 * 
 * 

* CheckClassAdapter can be also used to verify bytecode * transformations in order to make sure transformed bytecode is sane. For * example: * *

 *   InputStream is = ...; // get bytes for the source class
 *   ClassReader cr = new ClassReader(is);
 *   ClassWriter cw = new ClassWriter(cr, ClassWriter.COMPUTE_MAXS);
 *   ClassVisitor cv = new MyClassAdapter(new CheckClassAdapter(cw));
 *   cr.accept(cv, 0);
 * 
 *   StringWriter sw = new StringWriter();
 *   PrintWriter pw = new PrintWriter(sw);
 *   CheckClassAdapter.verify(new ClassReader(cw.toByteArray()), false, pw);
 *   assertTrue(sw.toString(), sw.toString().length()==0);
 * 
* * Above code runs transformed bytecode trough the * CheckClassAdapter. It won't be exactly the same verification as * JVM does, but it run data flow analysis for the code of each method and * checks that expectations are met for each method instruction. * *

* If method bytecode has errors, assertion text will show the erroneous * instruction number and dump of the failed method with information about * locals and stack slot for each instruction. For example (format is - * insnNumber locals : stack): * *

 * org.objectweb.asm.tree.analysis.AnalyzerException: Error at instruction 71: Expected I, but found .
 *   at org.objectweb.asm.tree.analysis.Analyzer.analyze(Analyzer.java:289)
 *   at org.objectweb.asm.util.CheckClassAdapter.verify(CheckClassAdapter.java:135)
 * ...
 * remove()V
 * 00000 LinkedBlockingQueue$Itr . . . . . . . .  :
 *   ICONST_0
 * 00001 LinkedBlockingQueue$Itr . . . . . . . .  : I
 *   ISTORE 2
 * 00001 LinkedBlockingQueue$Itr . I . . . . . .  :
 * ...
 * 
 * 00071 LinkedBlockingQueue$Itr . I . . . . . .  :
 *   ILOAD 1
 * 00072 ?
 *   INVOKESPECIAL java/lang/Integer.<init> (I)V
 * ...
 * 
* * In the above output you can see that variable 1 loaded by * ILOAD 1 instruction at position 00071 is not * initialized. You can also see that at the beginning of the method (code * inserted by the transformation) variable 2 is initialized. * *

* Note that when used like that, CheckClassAdapter.verify() can * trigger additional class loading, because it is using * SimpleVerifier. * * @author Eric Bruneton */ public class CheckClassAdapter extends ClassVisitor { /** * The class version number. */ private int version; /** * true if the visit method has been called. */ private boolean start; /** * true if the visitSource method has been called. */ private boolean source; /** * true if the visitOuterClass method has been called. */ private boolean outer; /** * true if the visitEnd method has been called. */ private boolean end; /** * The already visited labels. This map associate Integer values to Label * keys. */ private Map labels; /** * true if the method code must be checked with a BasicVerifier. */ private boolean checkDataFlow; /** * Checks a given class. *

* Usage: CheckClassAdapter <binary class name or class file name> * * @param args * the command line arguments. * * @throws Exception * if the class cannot be found, or if an IO exception occurs. */ public static void main(final String[] args) throws Exception { if (args.length != 1) { System.err.println("Verifies the given class."); System.err.println("Usage: CheckClassAdapter " + ""); return; } ClassReader cr; if (args[0].endsWith(".class")) { cr = new ClassReader(new FileInputStream(args[0])); } else { cr = new ClassReader(args[0]); } verify(cr, false, new PrintWriter(System.err)); } /** * Checks a given class. * * @param cr * a ClassReader that contains bytecode for the * analysis. * @param loader * a ClassLoader which will be used to load * referenced classes. This is useful if you are verifiying * multiple interdependent classes. * @param dump * true if bytecode should be printed out not only when errors * are found. * @param pw * write where results going to be printed */ public static void verify(final ClassReader cr, final ClassLoader loader, final boolean dump, final PrintWriter pw) { ClassNode cn = new ClassNode(); cr.accept(new CheckClassAdapter(cn, false), ClassReader.SKIP_DEBUG); Type syperType = cn.superName == null ? null : Type .getObjectType(cn.superName); List methods = cn.methods; List interfaces = new ArrayList(); for (Iterator i = cn.interfaces.iterator(); i.hasNext();) { interfaces.add(Type.getObjectType(i.next())); } for (int i = 0; i < methods.size(); ++i) { MethodNode method = methods.get(i); SimpleVerifier verifier = new SimpleVerifier( Type.getObjectType(cn.name), syperType, interfaces, (cn.access & Opcodes.ACC_INTERFACE) != 0); Analyzer a = new Analyzer(verifier); if (loader != null) { verifier.setClassLoader(loader); } try { a.analyze(cn.name, method); if (!dump) { continue; } } catch (Exception e) { e.printStackTrace(pw); } printAnalyzerResult(method, a, pw); } pw.flush(); } /** * Checks a given class * * @param cr * a ClassReader that contains bytecode for the * analysis. * @param dump * true if bytecode should be printed out not only when errors * are found. * @param pw * write where results going to be printed */ public static void verify(final ClassReader cr, final boolean dump, final PrintWriter pw) { verify(cr, null, dump, pw); } static void printAnalyzerResult(MethodNode method, Analyzer a, final PrintWriter pw) { Frame[] frames = a.getFrames(); Textifier t = new Textifier(); TraceMethodVisitor mv = new TraceMethodVisitor(t); pw.println(method.name + method.desc); for (int j = 0; j < method.instructions.size(); ++j) { method.instructions.get(j).accept(mv); StringBuilder sb = new StringBuilder(); Frame f = frames[j]; if (f == null) { sb.append('?'); } else { for (int k = 0; k < f.getLocals(); ++k) { sb.append(getShortName(f.getLocal(k).toString())) .append(' '); } sb.append(" : "); for (int k = 0; k < f.getStackSize(); ++k) { sb.append(getShortName(f.getStack(k).toString())) .append(' '); } } while (sb.length() < method.maxStack + method.maxLocals + 1) { sb.append(' '); } pw.print(Integer.toString(j + 100000).substring(1)); pw.print(" " + sb + " : " + t.text.get(t.text.size() - 1)); } for (int j = 0; j < method.tryCatchBlocks.size(); ++j) { method.tryCatchBlocks.get(j).accept(mv); pw.print(" " + t.text.get(t.text.size() - 1)); } pw.println(); } private static String getShortName(final String name) { int n = name.lastIndexOf('/'); int k = name.length(); if (name.charAt(k - 1) == ';') { k--; } return n == -1 ? name : name.substring(n + 1, k); } /** * Constructs a new {@link CheckClassAdapter}. Subclasses must not use * this constructor. Instead, they must use the * {@link #CheckClassAdapter(int, ClassVisitor, boolean)} version. * * @param cv * the class visitor to which this adapter must delegate calls. */ public CheckClassAdapter(final ClassVisitor cv) { this(cv, true); } /** * Constructs a new {@link CheckClassAdapter}. Subclasses must not use * this constructor. Instead, they must use the * {@link #CheckClassAdapter(int, ClassVisitor, boolean)} version. * * @param cv * the class visitor to which this adapter must delegate calls. * @param checkDataFlow * true to perform basic data flow checks, or * false to not perform any data flow check (see * {@link CheckMethodAdapter}). This option requires valid * maxLocals and maxStack values. * @throws IllegalStateException * If a subclass calls this constructor. */ public CheckClassAdapter(final ClassVisitor cv, final boolean checkDataFlow) { this(Opcodes.ASM5, cv, checkDataFlow); if (getClass() != CheckClassAdapter.class) { throw new IllegalStateException(); } } /** * Constructs a new {@link CheckClassAdapter}. * * @param api * the ASM API version implemented by this visitor. Must be one * of {@link Opcodes#ASM4} or {@link Opcodes#ASM5}. * @param cv * the class visitor to which this adapter must delegate calls. * @param checkDataFlow * true to perform basic data flow checks, or * false to not perform any data flow check (see * {@link CheckMethodAdapter}). This option requires valid * maxLocals and maxStack values. */ protected CheckClassAdapter(final int api, final ClassVisitor cv, final boolean checkDataFlow) { super(api, cv); this.labels = new HashMap(); this.checkDataFlow = checkDataFlow; } // ------------------------------------------------------------------------ // Implementation of the ClassVisitor interface // ------------------------------------------------------------------------ @Override public void visit(final int version, final int access, final String name, final String signature, final String superName, final String[] interfaces) { if (start) { throw new IllegalStateException("visit must be called only once"); } start = true; checkState(); checkAccess(access, Opcodes.ACC_PUBLIC + Opcodes.ACC_FINAL + Opcodes.ACC_SUPER + Opcodes.ACC_INTERFACE + Opcodes.ACC_ABSTRACT + Opcodes.ACC_SYNTHETIC + Opcodes.ACC_ANNOTATION + Opcodes.ACC_ENUM + Opcodes.ACC_DEPRECATED + 0x40000); // ClassWriter.ACC_SYNTHETIC_ATTRIBUTE if (name == null || !name.endsWith("package-info")) { CheckMethodAdapter.checkInternalName(name, "class name"); } if ("java/lang/Object".equals(name)) { if (superName != null) { throw new IllegalArgumentException( "The super class name of the Object class must be 'null'"); } } else { CheckMethodAdapter.checkInternalName(superName, "super class name"); } if (signature != null) { checkClassSignature(signature); } if ((access & Opcodes.ACC_INTERFACE) != 0) { if (!"java/lang/Object".equals(superName)) { throw new IllegalArgumentException( "The super class name of interfaces must be 'java/lang/Object'"); } } if (interfaces != null) { for (int i = 0; i < interfaces.length; ++i) { CheckMethodAdapter.checkInternalName(interfaces[i], "interface name at index " + i); } } this.version = version; super.visit(version, access, name, signature, superName, interfaces); } @Override public void visitSource(final String file, final String debug) { checkState(); if (source) { throw new IllegalStateException( "visitSource can be called only once."); } source = true; super.visitSource(file, debug); } @Override public void visitOuterClass(final String owner, final String name, final String desc) { checkState(); if (outer) { throw new IllegalStateException( "visitOuterClass can be called only once."); } outer = true; if (owner == null) { throw new IllegalArgumentException("Illegal outer class owner"); } if (desc != null) { CheckMethodAdapter.checkMethodDesc(desc); } super.visitOuterClass(owner, name, desc); } @Override public void visitInnerClass(final String name, final String outerName, final String innerName, final int access) { checkState(); CheckMethodAdapter.checkInternalName(name, "class name"); if (outerName != null) { CheckMethodAdapter.checkInternalName(outerName, "outer class name"); } if (innerName != null) { int start = 0; while (start < innerName.length() && Character.isDigit(innerName.charAt(start))) { start++; } if (start == 0 || start < innerName.length()) { CheckMethodAdapter.checkIdentifier(innerName, start, -1, "inner class name"); } } checkAccess(access, Opcodes.ACC_PUBLIC + Opcodes.ACC_PRIVATE + Opcodes.ACC_PROTECTED + Opcodes.ACC_STATIC + Opcodes.ACC_FINAL + Opcodes.ACC_INTERFACE + Opcodes.ACC_ABSTRACT + Opcodes.ACC_SYNTHETIC + Opcodes.ACC_ANNOTATION + Opcodes.ACC_ENUM); super.visitInnerClass(name, outerName, innerName, access); } @Override public FieldVisitor visitField(final int access, final String name, final String desc, final String signature, final Object value) { checkState(); checkAccess(access, Opcodes.ACC_PUBLIC + Opcodes.ACC_PRIVATE + Opcodes.ACC_PROTECTED + Opcodes.ACC_STATIC + Opcodes.ACC_FINAL + Opcodes.ACC_VOLATILE + Opcodes.ACC_TRANSIENT + Opcodes.ACC_SYNTHETIC + Opcodes.ACC_ENUM + Opcodes.ACC_DEPRECATED + 0x40000); // ClassWriter.ACC_SYNTHETIC_ATTRIBUTE CheckMethodAdapter.checkUnqualifiedName(version, name, "field name"); CheckMethodAdapter.checkDesc(desc, false); if (signature != null) { checkFieldSignature(signature); } if (value != null) { CheckMethodAdapter.checkConstant(value); } FieldVisitor av = super .visitField(access, name, desc, signature, value); return new CheckFieldAdapter(av); } @Override public MethodVisitor visitMethod(final int access, final String name, final String desc, final String signature, final String[] exceptions) { checkState(); checkAccess(access, Opcodes.ACC_PUBLIC + Opcodes.ACC_PRIVATE + Opcodes.ACC_PROTECTED + Opcodes.ACC_STATIC + Opcodes.ACC_FINAL + Opcodes.ACC_SYNCHRONIZED + Opcodes.ACC_BRIDGE + Opcodes.ACC_VARARGS + Opcodes.ACC_NATIVE + Opcodes.ACC_ABSTRACT + Opcodes.ACC_STRICT + Opcodes.ACC_SYNTHETIC + Opcodes.ACC_DEPRECATED + 0x40000); // ClassWriter.ACC_SYNTHETIC_ATTRIBUTE if (!"".equals(name) && !"".equals(name)) { CheckMethodAdapter.checkMethodIdentifier(version, name, "method name"); } CheckMethodAdapter.checkMethodDesc(desc); if (signature != null) { checkMethodSignature(signature); } if (exceptions != null) { for (int i = 0; i < exceptions.length; ++i) { CheckMethodAdapter.checkInternalName(exceptions[i], "exception name at index " + i); } } CheckMethodAdapter cma; if (checkDataFlow) { cma = new CheckMethodAdapter(access, name, desc, super.visitMethod( access, name, desc, signature, exceptions), labels); } else { cma = new CheckMethodAdapter(super.visitMethod(access, name, desc, signature, exceptions), labels); } cma.version = version; return cma; } @Override public AnnotationVisitor visitAnnotation(final String desc, final boolean visible) { checkState(); CheckMethodAdapter.checkDesc(desc, false); return new CheckAnnotationAdapter(super.visitAnnotation(desc, visible)); } @Override public AnnotationVisitor visitTypeAnnotation(final int typeRef, final TypePath typePath, final String desc, final boolean visible) { checkState(); int sort = typeRef >>> 24; if (sort != TypeReference.CLASS_TYPE_PARAMETER && sort != TypeReference.CLASS_TYPE_PARAMETER_BOUND && sort != TypeReference.CLASS_EXTENDS) { throw new IllegalArgumentException("Invalid type reference sort 0x" + Integer.toHexString(sort)); } checkTypeRefAndPath(typeRef, typePath); CheckMethodAdapter.checkDesc(desc, false); return new CheckAnnotationAdapter(super.visitTypeAnnotation(typeRef, typePath, desc, visible)); } @Override public void visitAttribute(final Attribute attr) { checkState(); if (attr == null) { throw new IllegalArgumentException( "Invalid attribute (must not be null)"); } super.visitAttribute(attr); } @Override public void visitEnd() { checkState(); end = true; super.visitEnd(); } // ------------------------------------------------------------------------ // Utility methods // ------------------------------------------------------------------------ /** * Checks that the visit method has been called and that visitEnd has not * been called. */ private void checkState() { if (!start) { throw new IllegalStateException( "Cannot visit member before visit has been called."); } if (end) { throw new IllegalStateException( "Cannot visit member after visitEnd has been called."); } } /** * Checks that the given access flags do not contain invalid flags. This * method also checks that mutually incompatible flags are not set * simultaneously. * * @param access * the access flags to be checked * @param possibleAccess * the valid access flags. */ static void checkAccess(final int access, final int possibleAccess) { if ((access & ~possibleAccess) != 0) { throw new IllegalArgumentException("Invalid access flags: " + access); } int pub = (access & Opcodes.ACC_PUBLIC) == 0 ? 0 : 1; int pri = (access & Opcodes.ACC_PRIVATE) == 0 ? 0 : 1; int pro = (access & Opcodes.ACC_PROTECTED) == 0 ? 0 : 1; if (pub + pri + pro > 1) { throw new IllegalArgumentException( "public private and protected are mutually exclusive: " + access); } int fin = (access & Opcodes.ACC_FINAL) == 0 ? 0 : 1; int abs = (access & Opcodes.ACC_ABSTRACT) == 0 ? 0 : 1; if (fin + abs > 1) { throw new IllegalArgumentException( "final and abstract are mutually exclusive: " + access); } } /** * Checks a class signature. * * @param signature * a string containing the signature that must be checked. */ public static void checkClassSignature(final String signature) { // ClassSignature: // FormalTypeParameters? ClassTypeSignature ClassTypeSignature* int pos = 0; if (getChar(signature, 0) == '<') { pos = checkFormalTypeParameters(signature, pos); } pos = checkClassTypeSignature(signature, pos); while (getChar(signature, pos) == 'L') { pos = checkClassTypeSignature(signature, pos); } if (pos != signature.length()) { throw new IllegalArgumentException(signature + ": error at index " + pos); } } /** * Checks a method signature. * * @param signature * a string containing the signature that must be checked. */ public static void checkMethodSignature(final String signature) { // MethodTypeSignature: // FormalTypeParameters? ( TypeSignature* ) ( TypeSignature | V ) ( // ^ClassTypeSignature | ^TypeVariableSignature )* int pos = 0; if (getChar(signature, 0) == '<') { pos = checkFormalTypeParameters(signature, pos); } pos = checkChar('(', signature, pos); while ("ZCBSIFJDL[T".indexOf(getChar(signature, pos)) != -1) { pos = checkTypeSignature(signature, pos); } pos = checkChar(')', signature, pos); if (getChar(signature, pos) == 'V') { ++pos; } else { pos = checkTypeSignature(signature, pos); } while (getChar(signature, pos) == '^') { ++pos; if (getChar(signature, pos) == 'L') { pos = checkClassTypeSignature(signature, pos); } else { pos = checkTypeVariableSignature(signature, pos); } } if (pos != signature.length()) { throw new IllegalArgumentException(signature + ": error at index " + pos); } } /** * Checks a field signature. * * @param signature * a string containing the signature that must be checked. */ public static void checkFieldSignature(final String signature) { int pos = checkFieldTypeSignature(signature, 0); if (pos != signature.length()) { throw new IllegalArgumentException(signature + ": error at index " + pos); } } /** * Checks the reference to a type in a type annotation. * * @param typeRef * a reference to an annotated type. * @param typePath * the path to the annotated type argument, wildcard bound, array * element type, or static inner type within 'typeRef'. May be * null if the annotation targets 'typeRef' as a whole. */ static void checkTypeRefAndPath(int typeRef, TypePath typePath) { int mask = 0; switch (typeRef >>> 24) { case TypeReference.CLASS_TYPE_PARAMETER: case TypeReference.METHOD_TYPE_PARAMETER: case TypeReference.METHOD_FORMAL_PARAMETER: mask = 0xFFFF0000; break; case TypeReference.FIELD: case TypeReference.METHOD_RETURN: case TypeReference.METHOD_RECEIVER: case TypeReference.LOCAL_VARIABLE: case TypeReference.RESOURCE_VARIABLE: case TypeReference.INSTANCEOF: case TypeReference.NEW: case TypeReference.CONSTRUCTOR_REFERENCE: case TypeReference.METHOD_REFERENCE: mask = 0xFF000000; break; case TypeReference.CLASS_EXTENDS: case TypeReference.CLASS_TYPE_PARAMETER_BOUND: case TypeReference.METHOD_TYPE_PARAMETER_BOUND: case TypeReference.THROWS: case TypeReference.EXCEPTION_PARAMETER: mask = 0xFFFFFF00; break; case TypeReference.CAST: case TypeReference.CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT: case TypeReference.METHOD_INVOCATION_TYPE_ARGUMENT: case TypeReference.CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT: case TypeReference.METHOD_REFERENCE_TYPE_ARGUMENT: mask = 0xFF0000FF; break; default: throw new IllegalArgumentException("Invalid type reference sort 0x" + Integer.toHexString(typeRef >>> 24)); } if ((typeRef & ~mask) != 0) { throw new IllegalArgumentException("Invalid type reference 0x" + Integer.toHexString(typeRef)); } if (typePath != null) { for (int i = 0; i < typePath.getLength(); ++i) { int step = typePath.getStep(i); if (step != TypePath.ARRAY_ELEMENT && step != TypePath.INNER_TYPE && step != TypePath.TYPE_ARGUMENT && step != TypePath.WILDCARD_BOUND) { throw new IllegalArgumentException( "Invalid type path step " + i + " in " + typePath); } if (step != TypePath.TYPE_ARGUMENT && typePath.getStepArgument(i) != 0) { throw new IllegalArgumentException( "Invalid type path step argument for step " + i + " in " + typePath); } } } } /** * Checks the formal type parameters of a class or method signature. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkFormalTypeParameters(final String signature, int pos) { // FormalTypeParameters: // < FormalTypeParameter+ > pos = checkChar('<', signature, pos); pos = checkFormalTypeParameter(signature, pos); while (getChar(signature, pos) != '>') { pos = checkFormalTypeParameter(signature, pos); } return pos + 1; } /** * Checks a formal type parameter of a class or method signature. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkFormalTypeParameter(final String signature, int pos) { // FormalTypeParameter: // Identifier : FieldTypeSignature? (: FieldTypeSignature)* pos = checkIdentifier(signature, pos); pos = checkChar(':', signature, pos); if ("L[T".indexOf(getChar(signature, pos)) != -1) { pos = checkFieldTypeSignature(signature, pos); } while (getChar(signature, pos) == ':') { pos = checkFieldTypeSignature(signature, pos + 1); } return pos; } /** * Checks a field type signature. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkFieldTypeSignature(final String signature, int pos) { // FieldTypeSignature: // ClassTypeSignature | ArrayTypeSignature | TypeVariableSignature // // ArrayTypeSignature: // [ TypeSignature switch (getChar(signature, pos)) { case 'L': return checkClassTypeSignature(signature, pos); case '[': return checkTypeSignature(signature, pos + 1); default: return checkTypeVariableSignature(signature, pos); } } /** * Checks a class type signature. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkClassTypeSignature(final String signature, int pos) { // ClassTypeSignature: // L Identifier ( / Identifier )* TypeArguments? ( . Identifier // TypeArguments? )* ; pos = checkChar('L', signature, pos); pos = checkIdentifier(signature, pos); while (getChar(signature, pos) == '/') { pos = checkIdentifier(signature, pos + 1); } if (getChar(signature, pos) == '<') { pos = checkTypeArguments(signature, pos); } while (getChar(signature, pos) == '.') { pos = checkIdentifier(signature, pos + 1); if (getChar(signature, pos) == '<') { pos = checkTypeArguments(signature, pos); } } return checkChar(';', signature, pos); } /** * Checks the type arguments in a class type signature. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkTypeArguments(final String signature, int pos) { // TypeArguments: // < TypeArgument+ > pos = checkChar('<', signature, pos); pos = checkTypeArgument(signature, pos); while (getChar(signature, pos) != '>') { pos = checkTypeArgument(signature, pos); } return pos + 1; } /** * Checks a type argument in a class type signature. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkTypeArgument(final String signature, int pos) { // TypeArgument: // * | ( ( + | - )? FieldTypeSignature ) char c = getChar(signature, pos); if (c == '*') { return pos + 1; } else if (c == '+' || c == '-') { pos++; } return checkFieldTypeSignature(signature, pos); } /** * Checks a type variable signature. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkTypeVariableSignature(final String signature, int pos) { // TypeVariableSignature: // T Identifier ; pos = checkChar('T', signature, pos); pos = checkIdentifier(signature, pos); return checkChar(';', signature, pos); } /** * Checks a type signature. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkTypeSignature(final String signature, int pos) { // TypeSignature: // Z | C | B | S | I | F | J | D | FieldTypeSignature switch (getChar(signature, pos)) { case 'Z': case 'C': case 'B': case 'S': case 'I': case 'F': case 'J': case 'D': return pos + 1; default: return checkFieldTypeSignature(signature, pos); } } /** * Checks an identifier. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkIdentifier(final String signature, int pos) { if (!Character.isJavaIdentifierStart(getChar(signature, pos))) { throw new IllegalArgumentException(signature + ": identifier expected at index " + pos); } ++pos; while (Character.isJavaIdentifierPart(getChar(signature, pos))) { ++pos; } return pos; } /** * Checks a single character. * * @param signature * a string containing the signature that must be checked. * @param pos * index of first character to be checked. * @return the index of the first character after the checked part. */ private static int checkChar(final char c, final String signature, int pos) { if (getChar(signature, pos) == c) { return pos + 1; } throw new IllegalArgumentException(signature + ": '" + c + "' expected at index " + pos); } /** * Returns the signature car at the given index. * * @param signature * a signature. * @param pos * an index in signature. * @return the character at the given index, or 0 if there is no such * character. */ private static char getChar(final String signature, int pos) { return pos < signature.length() ? signature.charAt(pos) : (char) 0; } }





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