| type signature | Java type |
|---|
* Z | boolean |
* B | byte |
* S | short |
* C | char |
* I | int |
* F | float |
* J | long |
* D | double |
* Ljava/lang/Object; |
* java.lang.Object |
* [[I | int[][] |
* (Ljava/lang/Object;I)V |
* method with argument types Object and
* int and void return type. |
* ()I |
* method without arguments
* and int return type. |
* <E:Ljava/lang/Object;>Ljava/lang/Object;Ljava/util/Collection<TE;>; |
*
|
* generic class over <E extends Object> extending
* Object and implementing Collections<E> |
* <T:Ljava/lang/Object;>([TT;)[TT; |
*
|
* generic method over <T extends Object> taking an
* array of T as parameters and returning an array of T. |
*
*
*
* @author Jochen Hoenicke
*/
public class TypeSignature {
/**
* This is a private method for generating the signature of a
* given type.
*/
private static final StringBuffer appendSignature(StringBuffer sb,
Class javaType) {
if (javaType.isPrimitive()) {
if (javaType == Boolean.TYPE)
return sb.append('Z');
else if (javaType == Byte.TYPE)
return sb.append('B');
else if (javaType == Character.TYPE)
return sb.append('C');
else if (javaType == Short.TYPE)
return sb.append('S');
else if (javaType == Integer.TYPE)
return sb.append('I');
else if (javaType == Long.TYPE)
return sb.append('J');
else if (javaType == Float.TYPE)
return sb.append('F');
else if (javaType == Double.TYPE)
return sb.append('D');
else if (javaType == Void.TYPE)
return sb.append('V');
else
throw new InternalError("Unknown primitive type: "+javaType);
} else if (javaType.isArray()) {
return appendSignature(sb.append('['),
javaType.getComponentType());
} else {
return sb.append('L')
.append(javaType.getName().replace('.','/')).append(';');
}
}
/**
* Generates the type signature of the given Class.
* @param clazz a java.lang.Class, this may also be a primitive or
* array type.
* @return the type signature.
*/
public static String getSignature(Class clazz) {
return appendSignature(new StringBuffer(), clazz).toString();
}
/**
* Generates a method signature.
* @param paramT the java.lang.Class of the parameter types of the method.
* @param returnT the java.lang.Class of the return type of the method.
* @return the method type signature
*/
public static String getSignature(Class paramT[], Class returnT) {
StringBuffer sig = new StringBuffer("(");
for (int i=0; i< paramT.length; i++)
appendSignature(sig, paramT[i]);
return appendSignature(sig.append(')'), returnT).toString();
}
/**
* Generates a Class object for a type signature. This is the
* inverse function of getSignature.
* @param typeSig a single type signature
* @return the Class object representing that type.
*/
public static Class getClass(String typeSig)
throws ClassNotFoundException
{
switch(typeSig.charAt(0)) {
case 'Z':
return Boolean.TYPE;
case 'B':
return Byte.TYPE;
case 'C':
return Character.TYPE;
case 'S':
return Short.TYPE;
case 'I':
return Integer.TYPE;
case 'F':
return Float.TYPE;
case 'J':
return Long.TYPE;
case 'D':
return Double.TYPE;
case 'V':
return Void.TYPE;
case 'L':
typeSig = typeSig.substring(1, typeSig.length()-1)
.replace('/','.');
/* fall through */
case '[':
return Class.forName(typeSig);
}
throw new IllegalArgumentException(typeSig);
}
/**
* Check if the given type is a two slot type. The only two slot
* types are long and double.
*/
private static boolean usingTwoSlots(char type) {
return "JD".indexOf(type) >= 0;
}
/**
* Returns the number of words, an object of the given simple type
* signature takes. For long and double this is two, for all other
* types it is one.
*/
public static int getTypeSize(String typeSig) {
return usingTwoSlots(typeSig.charAt(0)) ? 2 : 1;
}
/**
* Gets the element type of an array.
* @param typeSig type signature of the array.
* @return type signature for the element type.
* @exception IllegalArgumentException if typeSig is not an array
* type signature.
*/
public static String getElementType(String typeSig) {
if (typeSig.charAt(0) != '[')
throw new IllegalArgumentException();
return typeSig.substring(1);
}
/**
* Gets the ClassInfo for a class type.
* @param classpath the classpath in which the ClassInfo is searched.
* @param typeSig type signature of the class.
* @return the ClassInfo object for the class.
* @exception IllegalArgumentException if typeSig is not an class
* type signature.
*/
public static ClassInfo getClassInfo(ClassPath classpath, String typeSig) {
if (typeSig.charAt(0) != 'L')
throw new IllegalArgumentException();
return classpath.getClassInfo
(typeSig.substring(1, typeSig.length()-1).replace('/', '.'));
}
/**
* Skips the next entry of a method type signature
* @param methodTypeSig type signature of the method.
* @param position the index to the last entry.
* @return the index to the next entry.
*/
static int skipType(String methodTypeSig, int position) {
char c = methodTypeSig.charAt(position++);
while (c == '[')
c = methodTypeSig.charAt(position++);
if (c == 'L')
return methodTypeSig.indexOf(';', position) + 1;
return position;
}
/**
* Gets the number of words the parameters for the given method
* type signature takes. This is the sum of getTypeSize() for
* each parameter type.
* @param methodTypeSig the method type signature.
* @return the number of words the parameters take.
*/
public static int getParameterSize(String methodTypeSig) {
int nargs = 0;
int i = 1;
for (;;) {
char c = methodTypeSig.charAt(i);
if (c == ')')
return nargs;
i = skipType(methodTypeSig, i);
if (usingTwoSlots(c))
nargs += 2;
else
nargs++;
}
}
/**
* Gets the size of the return type of the given method in words.
* This is zero for void return type, two for double or long return
* type and one otherwise.
* @param methodTypeSig the method type signature.
* @return the size of the return type in words.
*/
public static int getReturnSize(String methodTypeSig) {
int length = methodTypeSig.length();
if (methodTypeSig.charAt(length - 2) == ')') {
// This is a single character return type.
char returnType = methodTypeSig.charAt(length - 1);
return returnType == 'V' ? 0
: usingTwoSlots(returnType) ? 2 : 1;
} else
// All multi character return types take one parameter
return 1;
}
/**
* Gets the parameter type signatures of the given method signature.
* @param methodTypeSig the method type signature.
* @return an array containing all parameter types in correct order.
*/
public static String[] getParameterTypes(String methodTypeSig) {
int pos = 1;
int count = 0;
while (methodTypeSig.charAt(pos) != ')') {
pos = skipType(methodTypeSig, pos);
count++;
}
String[] params = new String[count];
pos = 1;
for (int i = 0; i < count; i++) {
int start = pos;
pos = skipType(methodTypeSig, pos);
params[i] = methodTypeSig.substring(start, pos);
}
return params;
}
/**
* Gets the return type for a method signature
* @param methodTypeSig the method signature.
* @return the return type for a method signature, `V' for void methods.
*/
public static String getReturnType(String methodTypeSig) {
return methodTypeSig.substring(methodTypeSig.lastIndexOf(')')+1);
}
/**
* Gets the default value an object of the given type has. It is
* null for objects and arrays, Integer(0) for boolean and short
* integer types or Long(0L), Double(0.0), Float(0.0F) for long,
* double and float. This seems strange, but this way the type
* returned is the same as for FieldInfo.getConstant().
*
* @param typeSig the type signature.
* @return the default value.
* @exception IllegalArgumentException if this is a method type signature.
*/
public static Object getDefaultValue(String typeSig) {
switch(typeSig.charAt(0)) {
case 'Z':
case 'B':
case 'S':
case 'C':
case 'I':
return new Integer(0);
case 'J':
return new Long(0L);
case 'D':
return new Double(0.0);
case 'F':
return new Float(0.0F);
case 'L':
case '[':
return null;
default:
throw new IllegalArgumentException(typeSig);
}
}
/**
* Checks if there is a valid class name starting at index
* in string typesig and ending with a semicolon.
* @return the index at which the class name ends.
* @exception IllegalArgumentException if there was an illegal character.
* @exception StringIndexOutOfBoundsException if the typesig ended early.
*/
private static int checkClassName(String clName, int i)
throws IllegalArgumentException, StringIndexOutOfBoundsException
{
while (true) {
char c = clName.charAt(i++);
if (c == ';')
return i;
if (c != '/' && !Character.isJavaIdentifierPart(c))
throw new IllegalArgumentException("Illegal java class name: "
+ clName);
}
}
/**
* Checks if there is a valid simple type signature starting at index
* in string typesig.
* @return the index at which the type signature ends.
* @exception IllegalArgumentException if there was an illegal character.
* @exception StringIndexOutOfBoundsException if the typesig ended early.
*/
private static int checkTypeSig(String typesig, int index) {
char c = typesig.charAt(index++);
while (c == '[')
c = typesig.charAt(index++);
if (c == 'L') {
index = checkClassName(typesig, index);
} else {
if ("ZBSCIJFD".indexOf(c) == -1)
throw new IllegalArgumentException("Type sig error: "+typesig);
}
return index;
}
/**
* Checks whether a given type signature is a valid (not method)
* type signature. Throws an exception otherwise.
* @param typesig the type signature.
* @exception NullPointerException if typeSig is null.
* @exception IllegalArgumentException if typeSig is not a valid
* type signature or if it's a method type signature.
*/
public static void checkTypeSig(String typesig)
throws IllegalArgumentException
{
try {
if (checkTypeSig(typesig, 0) != typesig.length())
throw new IllegalArgumentException
("Type sig too long: "+typesig);
} catch (StringIndexOutOfBoundsException ex) {
throw new IllegalArgumentException
("Incomplete type sig: "+typesig);
}
}
/**
* Checks whether a given type signature is a valid method
* type signature. Throws an exception otherwise.
* @param typesig the type signature.
* @exception NullPointerException if typeSig is null.
* @exception IllegalArgumentException if typeSig is not a valid
* method type signature.
*/
public static void checkMethodTypeSig(String typesig)
throws IllegalArgumentException
{
try {
if (typesig.charAt(0) != '(')
throw new IllegalArgumentException
("No method signature: "+typesig);
int i = 1;
while (typesig.charAt(i) != ')')
i = checkTypeSig(typesig, i);
// skip closing parenthesis.
i++;
if (typesig.charAt(i) == 'V')
// accept void return type.
i++;
else
i = checkTypeSig(typesig, i);
if (i != typesig.length())
throw new IllegalArgumentException
("Type sig too long: "+typesig);
} catch (StringIndexOutOfBoundsException ex) {
throw new IllegalArgumentException
("Incomplete type sig: "+typesig);
}
}
}