/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.felix.gogo.runtime;
import java.lang.annotation.Annotation;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.apache.felix.service.command.CommandSession;
import org.apache.felix.service.command.Parameter;
public final class Reflective
{
public final static Object NO_MATCH = new Object();
public final static String MAIN = "_main";
public final static Set<String> KEYWORDS = new HashSet<String>(
Arrays.asList(new String[] { "abstract", "continue", "for", "new", "switch",
"assert", "default", "goto", "package", "synchronized", "boolean", "do",
"if", "private", "this", "break", "double", "implements", "protected",
"throw", "byte", "else", "import", "public", "throws", "case", "enum",
"instanceof", "return", "transient", "catch", "extends", "int", "short",
"try", "char", "final", "interface", "static", "void", "class",
"finally", "long", "strictfp", "volatile", "const", "float", "native",
"super", "while" }));
/**
* invokes the named method on the given target using the supplied args,
* which are converted if necessary.
* @param session
* @param target
* @param name
* @param args
* @return the result of the invoked method
* @throws Exception
*/
public static Object invoke(CommandSession session, Object target, String name,
List<Object> args) throws Exception
{
Method[] methods = target.getClass().getMethods();
name = name.toLowerCase();
String get = "get" + name;
String is = "is" + name;
String set = "set" + name;
if (KEYWORDS.contains(name))
{
name = "_" + name;
}
if (target instanceof Class<?>)
{
Method[] staticMethods = ((Class<?>) target).getMethods();
for (Method m : staticMethods)
{
String mname = m.getName().toLowerCase();
if (mname.equals(name) || mname.equals(get) || mname.equals(set)
|| mname.equals(is) || mname.equals(MAIN))
{
methods = staticMethods;
break;
}
}
}
Method bestMethod = null;
Object[] bestArgs = null;
int lowestMatch = Integer.MAX_VALUE;
ArrayList<Class<?>[]> possibleTypes = new ArrayList<Class<?>[]>();
for (Method m : methods)
{
String mname = m.getName().toLowerCase();
if (mname.equals(name) || mname.equals(get) || mname.equals(set)
|| mname.equals(is) || mname.equals(MAIN))
{
Class<?>[] types = m.getParameterTypes();
ArrayList<Object> xargs = new ArrayList<Object>(args);
// pass command name as argv[0] to main, so it can handle
// multiple commands
if (mname.equals(MAIN))
{
xargs.add(0, name);
}
Object[] parms = new Object[types.length];
int match = coerce(session, target, m, types, parms, xargs);
if (match < 0)
{
// coerce failed
possibleTypes.add(types);
}
else
{
if (match < lowestMatch)
{
lowestMatch = match;
bestMethod = m;
bestArgs = parms;
}
if (match == 0)
break; // can't get better score
}
}
}
if (bestMethod != null)
{
bestMethod.setAccessible(true);
try
{
return bestMethod.invoke(target, bestArgs);
}
catch (InvocationTargetException e)
{
Throwable cause = e.getCause();
if (cause instanceof Exception)
{
throw (Exception) cause;
}
throw e;
}
}
else
{
ArrayList<String> list = new ArrayList<String>();
for (Class<?>[] types : possibleTypes)
{
StringBuilder buf = new StringBuilder();
buf.append('(');
for (Class<?> type : types)
{
if (buf.length() > 1)
{
buf.append(", ");
}
buf.append(type.getSimpleName());
}
buf.append(')');
list.add(buf.toString());
}
StringBuilder params = new StringBuilder();
for (Object arg : args)
{
if (params.length() > 1)
{
params.append(", ");
}
params.append(arg == null ? "null" : arg.getClass().getSimpleName());
}
throw new IllegalArgumentException(String.format(
"Cannot coerce %s(%s) to any of %s", name, params, list));
}
}
/**
* transform name/value parameters into ordered argument list.
* params: --param2, value2, --flag1, arg3
* args: true, value2, arg3
* @param method
* @param params
* @return new ordered list of args.
*/
private static List<Object> transformParameters(Method method, List<Object> in)
{
Annotation[][] pas = method.getParameterAnnotations();
ArrayList<Object> out = new ArrayList<Object>();
ArrayList<Object> parms = new ArrayList<Object>(in);
for (Annotation as[] : pas)
{
for (Annotation a : as)
{
if (a instanceof Parameter)
{
int i = -1;
Parameter p = (Parameter) a;
for (String name : p.names())
{
i = parms.indexOf(name);
if (i >= 0)
break;
}
if (i >= 0)
{
// parameter present
parms.remove(i);
Object value = p.presentValue();
if (Parameter.UNSPECIFIED.equals(value))
{
if (i >= parms.size())
return null; // missing parameter, so try other methods
value = parms.remove(i);
}
out.add(value);
}
else
{
out.add(p.absentValue());
}
}
}
}
out.addAll(parms);
return out;
}
/**
* Complex routein to convert the arguments given from the command line to
* the arguments of the method call. First, an attempt is made to convert
* each argument. If this fails, a check is made to see if varargs can be
* applied. This happens when the last method argument is an array.
*
* @param session
* @param target
* @param m
* @param types
* @param out
* @param in
* @return -1 if arguments can't be coerced; 0 if no coercion was necessary; > 0 if coercion was needed.
*/
private static int coerce(CommandSession session, Object target, Method m,
Class<?> types[], Object out[], List<Object> in)
{
in = transformParameters(m, in);
if (in == null)
{
// missing parameter argument?
return -1;
}
int[] convert = { 0 };
// Check if the command takes a session
if ((types.length > 0) && types[0].isInterface()
&& types[0].isAssignableFrom(session.getClass()))
{
in.add(0, session);
}
int i = 0;
while (i < out.length)
{
out[i] = null;
// Try to convert one argument
if (in.size() == 0)
{
out[i] = NO_MATCH;
}
else
{
out[i] = coerce(session, types[i], in.get(0), convert);
if (out[i] == null && types[i].isArray() && in.size() > 0)
{
// don't coerce null to array FELIX-2432
out[i] = NO_MATCH;
}
if (out[i] != NO_MATCH)
{
in.remove(0);
}
}
if (out[i] == NO_MATCH)
{
// No match, check for varargs
if (types[i].isArray() && (i == types.length - 1))
{
// Try to parse the remaining arguments in an array
Class<?> ctype = types[i].getComponentType();
int asize = in.size();
Object array = Array.newInstance(ctype, asize);
int n = i;
while (in.size() > 0)
{
Object t = coerce(session, ctype, in.remove(0), convert);
if (t == NO_MATCH)
{
return -1;
}
Array.set(array, i - n, t);
i++;
}
out[n] = array;
/*
* 1. prefer f() to f(T[]) with empty array
* 2. prefer f(T) to f(T[1])
* 3. prefer f(T) to f(Object[1]) even if there is a conversion cost for T
*
* 1 & 2 require to add 1 to conversion cost, but 3 also needs to match
* the conversion cost for T.
*/
return convert[0] + 1 + (asize * 2);
}
return -1;
}
i++;
}
if (in.isEmpty())
return convert[0];
return -1;
}
/**
* converts given argument to specified type and increments convert[0] if any conversion was needed.
* @param session
* @param type
* @param arg
* @param convert convert[0] is incremented according to the conversion needed,
* to allow the "best" conversion to be determined.
* @return converted arg or NO_MATCH if no conversion possible.
*/
private static Object coerce(CommandSession session, Class<?> type, Object arg,
int[] convert)
{
if (arg == null)
{
return null;
}
if (type.isAssignableFrom(arg.getClass()))
{
return arg;
}
if (type.isArray())
{
return NO_MATCH;
}
if (type.isPrimitive() && arg instanceof Long)
{
// no-cost conversions between integer types
Number num = (Number) arg;
if (type == short.class)
{
return num.shortValue();
}
if (type == int.class)
{
return num.intValue();
}
if (type == long.class)
{
return num.longValue();
}
}
// all following conversions cost 2 points
convert[0] += 2;
Object converted = session.convert(type, arg);
if (converted != null)
{
return converted;
}
String string = arg.toString();
if (type.isAssignableFrom(String.class))
{
return string;
}
if (type.isPrimitive())
{
type = primitiveToObject(type);
}
try
{
return type.getConstructor(String.class).newInstance(string);
}
catch (Exception e)
{
}
if (type == Character.class && string.length() == 1)
{
return string.charAt(0);
}
return NO_MATCH;
}
private static Class<?> primitiveToObject(Class<?> type)
{
if (type == boolean.class)
{
return Boolean.class;
}
if (type == byte.class)
{
return Byte.class;
}
if (type == char.class)
{
return Character.class;
}
if (type == short.class)
{
return Short.class;
}
if (type == int.class)
{
return Integer.class;
}
if (type == float.class)
{
return Float.class;
}
if (type == double.class)
{
return Double.class;
}
if (type == long.class)
{
return Long.class;
}
return null;
}
}