Source Code Cross Referenced for NativeJavaMethod.java in  » Scripting » rhino » org » mozilla » javascript » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Scripting » rhino » org.mozilla.javascript 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
002:         *
003:         * ***** BEGIN LICENSE BLOCK *****
004:         * Version: MPL 1.1/GPL 2.0
005:         *
006:         * The contents of this file are subject to the Mozilla Public License Version
007:         * 1.1 (the "License"); you may not use this file except in compliance with
008:         * the License. You may obtain a copy of the License at
009:         * http://www.mozilla.org/MPL/
010:         *
011:         * Software distributed under the License is distributed on an "AS IS" basis,
012:         * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
013:         * for the specific language governing rights and limitations under the
014:         * License.
015:         *
016:         * The Original Code is Rhino code, released
017:         * May 6, 1999.
018:         *
019:         * The Initial Developer of the Original Code is
020:         * Netscape Communications Corporation.
021:         * Portions created by the Initial Developer are Copyright (C) 1997-1999
022:         * the Initial Developer. All Rights Reserved.
023:         *
024:         * Contributor(s):
025:         *   Norris Boyd
026:         *   Frank Mitchell
027:         *   Mike Shaver
028:         *   Ulrike Mueller <umueller@demandware.com>
029:         *
030:         * Alternatively, the contents of this file may be used under the terms of
031:         * the GNU General Public License Version 2 or later (the "GPL"), in which
032:         * case the provisions of the GPL are applicable instead of those above. If
033:         * you wish to allow use of your version of this file only under the terms of
034:         * the GPL and not to allow others to use your version of this file under the
035:         * MPL, indicate your decision by deleting the provisions above and replacing
036:         * them with the notice and other provisions required by the GPL. If you do
037:         * not delete the provisions above, a recipient may use your version of this
038:         * file under either the MPL or the GPL.
039:         *
040:         * ***** END LICENSE BLOCK ***** */
041:
042:        package org.mozilla.javascript;
043:
044:        import java.lang.reflect.*;
045:
046:        /**
047:         * This class reflects Java methods into the JavaScript environment and
048:         * handles overloading of methods.
049:         *
050:         * @author Mike Shaver
051:         * @see NativeJavaArray
052:         * @see NativeJavaPackage
053:         * @see NativeJavaClass
054:         */
055:
056:        public class NativeJavaMethod extends BaseFunction {
057:            static final long serialVersionUID = -3440381785576412928L;
058:
059:            NativeJavaMethod(MemberBox[] methods) {
060:                this .functionName = methods[0].getName();
061:                this .methods = methods;
062:            }
063:
064:            NativeJavaMethod(MemberBox method, String name) {
065:                this .functionName = name;
066:                this .methods = new MemberBox[] { method };
067:            }
068:
069:            public NativeJavaMethod(Method method, String name) {
070:                this (new MemberBox(method), name);
071:            }
072:
073:            public String getFunctionName() {
074:                return functionName;
075:            }
076:
077:            static String scriptSignature(Object[] values) {
078:                StringBuffer sig = new StringBuffer();
079:                for (int i = 0; i != values.length; ++i) {
080:                    Object value = values[i];
081:
082:                    String s;
083:                    if (value == null) {
084:                        s = "null";
085:                    } else if (value instanceof  Boolean) {
086:                        s = "boolean";
087:                    } else if (value instanceof  String) {
088:                        s = "string";
089:                    } else if (value instanceof  Number) {
090:                        s = "number";
091:                    } else if (value instanceof  Scriptable) {
092:                        if (value instanceof  Undefined) {
093:                            s = "undefined";
094:                        } else if (value instanceof  Wrapper) {
095:                            Object wrapped = ((Wrapper) value).unwrap();
096:                            s = wrapped.getClass().getName();
097:                        } else if (value instanceof  Function) {
098:                            s = "function";
099:                        } else {
100:                            s = "object";
101:                        }
102:                    } else {
103:                        s = JavaMembers.javaSignature(value.getClass());
104:                    }
105:
106:                    if (i != 0) {
107:                        sig.append(',');
108:                    }
109:                    sig.append(s);
110:                }
111:                return sig.toString();
112:            }
113:
114:            String decompile(int indent, int flags) {
115:                StringBuffer sb = new StringBuffer();
116:                boolean justbody = (0 != (flags & Decompiler.ONLY_BODY_FLAG));
117:                if (!justbody) {
118:                    sb.append("function ");
119:                    sb.append(getFunctionName());
120:                    sb.append("() {");
121:                }
122:                sb.append("/*\n");
123:                sb.append(toString());
124:                sb.append(justbody ? "*/\n" : "*/}\n");
125:                return sb.toString();
126:            }
127:
128:            public String toString() {
129:                StringBuffer sb = new StringBuffer();
130:                for (int i = 0, N = methods.length; i != N; ++i) {
131:                    Method method = methods[i].method();
132:                    sb
133:                            .append(JavaMembers.javaSignature(method
134:                                    .getReturnType()));
135:                    sb.append(' ');
136:                    sb.append(method.getName());
137:                    sb.append(JavaMembers
138:                            .liveConnectSignature(methods[i].argTypes));
139:                    sb.append('\n');
140:                }
141:                return sb.toString();
142:            }
143:
144:            public Object call(Context cx, Scriptable scope,
145:                    Scriptable this Obj, Object[] args) {
146:                // Find a method that matches the types given.
147:                if (methods.length == 0) {
148:                    throw new RuntimeException("No methods defined for call");
149:                }
150:
151:                int index = findFunction(cx, methods, args);
152:                if (index < 0) {
153:                    Class c = methods[0].method().getDeclaringClass();
154:                    String sig = c.getName() + '.' + getFunctionName() + '('
155:                            + scriptSignature(args) + ')';
156:                    throw Context.reportRuntimeError1(
157:                            "msg.java.no_such_method", sig);
158:                }
159:
160:                MemberBox meth = methods[index];
161:                Class[] argTypes = meth.argTypes;
162:
163:                if (meth.vararg) {
164:                    // marshall the explicit parameters
165:                    Object[] newArgs = new Object[argTypes.length];
166:                    for (int i = 0; i < argTypes.length - 1; i++) {
167:                        newArgs[i] = Context.jsToJava(args[i], argTypes[i]);
168:                    }
169:
170:                    Object varArgs;
171:
172:                    // Handle special situation where a single variable parameter
173:                    // is given and it is a Java or ECMA array or is null.
174:                    if (args.length == argTypes.length
175:                            && (args[args.length - 1] == null
176:                                    || args[args.length - 1] instanceof  NativeArray || args[args.length - 1] instanceof  NativeJavaArray)) {
177:                        // convert the ECMA array into a native array
178:                        varArgs = Context.jsToJava(args[args.length - 1],
179:                                argTypes[argTypes.length - 1]);
180:                    } else {
181:                        // marshall the variable parameters
182:                        Class componentType = argTypes[argTypes.length - 1]
183:                                .getComponentType();
184:                        varArgs = Array.newInstance(componentType, args.length
185:                                - argTypes.length + 1);
186:                        for (int i = 0; i < Array.getLength(varArgs); i++) {
187:                            Object value = Context.jsToJava(
188:                                    args[argTypes.length - 1 + i],
189:                                    componentType);
190:                            Array.set(varArgs, i, value);
191:                        }
192:                    }
193:
194:                    // add varargs
195:                    newArgs[argTypes.length - 1] = varArgs;
196:                    // replace the original args with the new one
197:                    args = newArgs;
198:                } else {
199:                    // First, we marshall the args.
200:                    Object[] origArgs = args;
201:                    for (int i = 0; i < args.length; i++) {
202:                        Object arg = args[i];
203:                        Object coerced = Context.jsToJava(arg, argTypes[i]);
204:                        if (coerced != arg) {
205:                            if (origArgs == args) {
206:                                args = args.clone();
207:                            }
208:                            args[i] = coerced;
209:                        }
210:                    }
211:                }
212:                Object javaObject;
213:                if (meth.isStatic()) {
214:                    javaObject = null; // don't need an object
215:                } else {
216:                    Scriptable o = this Obj;
217:                    Class c = meth.getDeclaringClass();
218:                    for (;;) {
219:                        if (o == null) {
220:                            throw Context.reportRuntimeError3(
221:                                    "msg.nonjava.method", getFunctionName(),
222:                                    ScriptRuntime.toString(this Obj), c
223:                                            .getName());
224:                        }
225:                        if (o instanceof  Wrapper) {
226:                            javaObject = ((Wrapper) o).unwrap();
227:                            if (c.isInstance(javaObject)) {
228:                                break;
229:                            }
230:                        }
231:                        o = o.getPrototype();
232:                    }
233:                }
234:                if (debug) {
235:                    printDebug("Calling ", meth, args);
236:                }
237:
238:                Object retval = meth.invoke(javaObject, args);
239:                Class staticType = meth.method().getReturnType();
240:
241:                if (debug) {
242:                    Class actualType = (retval == null) ? null : retval
243:                            .getClass();
244:                    System.err.println(" ----- Returned " + retval
245:                            + " actual = " + actualType + " expect = "
246:                            + staticType);
247:                }
248:
249:                Object wrapped = cx.getWrapFactory().wrap(cx, scope, retval,
250:                        staticType);
251:                if (debug) {
252:                    Class actualType = (wrapped == null) ? null : wrapped
253:                            .getClass();
254:                    System.err.println(" ----- Wrapped as " + wrapped
255:                            + " class = " + actualType);
256:                }
257:
258:                if (wrapped == null && staticType == Void.TYPE) {
259:                    wrapped = Undefined.instance;
260:                }
261:                return wrapped;
262:            }
263:
264:            /**
265:             * Find the index of the correct function to call given the set of methods
266:             * or constructors and the arguments.
267:             * If no function can be found to call, return -1.
268:             */
269:            static int findFunction(Context cx, MemberBox[] methodsOrCtors,
270:                    Object[] args) {
271:                if (methodsOrCtors.length == 0) {
272:                    return -1;
273:                } else if (methodsOrCtors.length == 1) {
274:                    MemberBox member = methodsOrCtors[0];
275:                    Class[] argTypes = member.argTypes;
276:                    int alength = argTypes.length;
277:
278:                    if (member.vararg) {
279:                        alength--;
280:                        if (alength > args.length) {
281:                            return -1;
282:                        }
283:                    } else {
284:                        if (alength != args.length) {
285:                            return -1;
286:                        }
287:                    }
288:                    for (int j = 0; j != alength; ++j) {
289:                        if (!NativeJavaObject.canConvert(args[j], argTypes[j])) {
290:                            if (debug)
291:                                printDebug("Rejecting (args can't convert) ",
292:                                        member, args);
293:                            return -1;
294:                        }
295:                    }
296:                    if (debug)
297:                        printDebug("Found ", member, args);
298:                    return 0;
299:                }
300:
301:                int firstBestFit = -1;
302:                int[] extraBestFits = null;
303:                int extraBestFitsCount = 0;
304:
305:                search: for (int i = 0; i < methodsOrCtors.length; i++) {
306:                    MemberBox member = methodsOrCtors[i];
307:                    Class[] argTypes = member.argTypes;
308:                    int alength = argTypes.length;
309:                    if (member.vararg) {
310:                        alength--;
311:                        if (alength > args.length) {
312:                            continue search;
313:                        }
314:                    } else {
315:                        if (alength != args.length) {
316:                            continue search;
317:                        }
318:                    }
319:                    for (int j = 0; j < alength; j++) {
320:                        if (!NativeJavaObject.canConvert(args[j], argTypes[j])) {
321:                            if (debug)
322:                                printDebug("Rejecting (args can't convert) ",
323:                                        member, args);
324:                            continue search;
325:                        }
326:                    }
327:                    if (firstBestFit < 0) {
328:                        if (debug)
329:                            printDebug("Found first applicable ", member, args);
330:                        firstBestFit = i;
331:                    } else {
332:                        // Compare with all currently fit methods.
333:                        // The loop starts from -1 denoting firstBestFit and proceed
334:                        // until extraBestFitsCount to avoid extraBestFits allocation
335:                        // in the most common case of no ambiguity
336:                        int betterCount = 0; // number of times member was prefered over
337:                        // best fits
338:                        int worseCount = 0; // number of times best fits were prefered
339:                        // over member
340:                        for (int j = -1; j != extraBestFitsCount; ++j) {
341:                            int bestFitIndex;
342:                            if (j == -1) {
343:                                bestFitIndex = firstBestFit;
344:                            } else {
345:                                bestFitIndex = extraBestFits[j];
346:                            }
347:                            MemberBox bestFit = methodsOrCtors[bestFitIndex];
348:                            if (cx
349:                                    .hasFeature(Context.FEATURE_ENHANCED_JAVA_ACCESS)
350:                                    && (bestFit.member().getModifiers() & Modifier.PUBLIC) != (member
351:                                            .member().getModifiers() & Modifier.PUBLIC)) {
352:                                // When FEATURE_ENHANCED_JAVA_ACCESS gives us access
353:                                // to non-public members, continue to prefer public
354:                                // methods in overloading
355:                                if ((bestFit.member().getModifiers() & Modifier.PUBLIC) == 0)
356:                                    ++betterCount;
357:                                else
358:                                    ++worseCount;
359:                            } else {
360:                                int preference = preferSignature(args,
361:                                        argTypes, member.vararg,
362:                                        bestFit.argTypes, bestFit.vararg);
363:                                if (preference == PREFERENCE_AMBIGUOUS) {
364:                                    break;
365:                                } else if (preference == PREFERENCE_FIRST_ARG) {
366:                                    ++betterCount;
367:                                } else if (preference == PREFERENCE_SECOND_ARG) {
368:                                    ++worseCount;
369:                                } else {
370:                                    if (preference != PREFERENCE_EQUAL)
371:                                        Kit.codeBug();
372:                                    // This should not happen in theory
373:                                    // but on some JVMs, Class.getMethods will return all
374:                                    // static methods of the class heirarchy, even if
375:                                    // a derived class's parameters match exactly.
376:                                    // We want to call the dervied class's method.
377:                                    if (bestFit.isStatic()
378:                                            && bestFit
379:                                                    .getDeclaringClass()
380:                                                    .isAssignableFrom(
381:                                                            member
382:                                                                    .getDeclaringClass())) {
383:                                        // On some JVMs, Class.getMethods will return all
384:                                        // static methods of the class heirarchy, even if
385:                                        // a derived class's parameters match exactly.
386:                                        // We want to call the dervied class's method.
387:                                        if (debug)
388:                                            printDebug(
389:                                                    "Substituting (overridden static)",
390:                                                    member, args);
391:                                        if (j == -1) {
392:                                            firstBestFit = i;
393:                                        } else {
394:                                            extraBestFits[j] = i;
395:                                        }
396:                                    } else {
397:                                        if (debug)
398:                                            printDebug(
399:                                                    "Ignoring same signature member ",
400:                                                    member, args);
401:                                    }
402:                                    continue search;
403:                                }
404:                            }
405:                        }
406:                        if (betterCount == 1 + extraBestFitsCount) {
407:                            // member was prefered over all best fits
408:                            if (debug)
409:                                printDebug("New first applicable ", member,
410:                                        args);
411:                            firstBestFit = i;
412:                            extraBestFitsCount = 0;
413:                        } else if (worseCount == 1 + extraBestFitsCount) {
414:                            // all best fits were prefered over member, ignore it
415:                            if (debug)
416:                                printDebug(
417:                                        "Rejecting (all current bests better) ",
418:                                        member, args);
419:                        } else {
420:                            // some ambiguity was present, add member to best fit set
421:                            if (debug)
422:                                printDebug("Added to best fit set ", member,
423:                                        args);
424:                            if (extraBestFits == null) {
425:                                // Allocate maximum possible array
426:                                extraBestFits = new int[methodsOrCtors.length - 1];
427:                            }
428:                            extraBestFits[extraBestFitsCount] = i;
429:                            ++extraBestFitsCount;
430:                        }
431:                    }
432:                }
433:
434:                if (firstBestFit < 0) {
435:                    // Nothing was found
436:                    return -1;
437:                } else if (extraBestFitsCount == 0) {
438:                    // single best fit
439:                    return firstBestFit;
440:                }
441:
442:                // report remaining ambiguity
443:                StringBuffer buf = new StringBuffer();
444:                for (int j = -1; j != extraBestFitsCount; ++j) {
445:                    int bestFitIndex;
446:                    if (j == -1) {
447:                        bestFitIndex = firstBestFit;
448:                    } else {
449:                        bestFitIndex = extraBestFits[j];
450:                    }
451:                    buf.append("\n    ");
452:                    buf
453:                            .append(methodsOrCtors[bestFitIndex]
454:                                    .toJavaDeclaration());
455:                }
456:
457:                MemberBox firstFitMember = methodsOrCtors[firstBestFit];
458:                String memberName = firstFitMember.getName();
459:                String memberClass = firstFitMember.getDeclaringClass()
460:                        .getName();
461:
462:                if (methodsOrCtors[0].isMethod()) {
463:                    throw Context.reportRuntimeError3(
464:                            "msg.constructor.ambiguous", memberName,
465:                            scriptSignature(args), buf.toString());
466:                } else {
467:                    throw Context.reportRuntimeError4("msg.method.ambiguous",
468:                            memberClass, memberName, scriptSignature(args), buf
469:                                    .toString());
470:                }
471:            }
472:
473:            /** Types are equal */
474:            private static final int PREFERENCE_EQUAL = 0;
475:            private static final int PREFERENCE_FIRST_ARG = 1;
476:            private static final int PREFERENCE_SECOND_ARG = 2;
477:            /** No clear "easy" conversion */
478:            private static final int PREFERENCE_AMBIGUOUS = 3;
479:
480:            /**
481:             * Determine which of two signatures is the closer fit.
482:             * Returns one of PREFERENCE_EQUAL, PREFERENCE_FIRST_ARG,
483:             * PREFERENCE_SECOND_ARG, or PREFERENCE_AMBIGUOUS.
484:             */
485:            private static int preferSignature(Object[] args, Class[] sig1,
486:                    boolean vararg1, Class[] sig2, boolean vararg2) {
487:                // TODO: This test is pretty primitive. It bascially prefers
488:                // a matching no vararg method over a vararg method independent
489:                // of the type conversion cost. This can lead to unexpected results.
490:                int alength = args.length;
491:                if (!vararg1 && vararg2) {
492:                    // prefer the no vararg signature
493:                    return PREFERENCE_FIRST_ARG;
494:                } else if (vararg1 && !vararg2) {
495:                    // prefer the no vararg signature
496:                    return PREFERENCE_SECOND_ARG;
497:                } else if (vararg1 && vararg2) {
498:                    if (sig1.length < sig2.length) {
499:                        // prefer the signature with more explicit types
500:                        return PREFERENCE_SECOND_ARG;
501:                    } else if (sig1.length > sig2.length) {
502:                        // prefer the signature with more explicit types
503:                        return PREFERENCE_FIRST_ARG;
504:                    } else {
505:                        // Both are varargs and have the same length, so make the
506:                        // decision with the explicit args. 
507:                        alength = Math.min(args.length, sig1.length - 1);
508:                    }
509:                }
510:
511:                int totalPreference = 0;
512:                for (int j = 0; j < alength; j++) {
513:                    Class type1 = sig1[j];
514:                    Class type2 = sig2[j];
515:                    if (type1 == type2) {
516:                        continue;
517:                    }
518:                    Object arg = args[j];
519:
520:                    // Determine which of type1, type2 is easier to convert from arg.
521:
522:                    int rank1 = NativeJavaObject
523:                            .getConversionWeight(arg, type1);
524:                    int rank2 = NativeJavaObject
525:                            .getConversionWeight(arg, type2);
526:
527:                    int preference;
528:                    if (rank1 < rank2) {
529:                        preference = PREFERENCE_FIRST_ARG;
530:                    } else if (rank1 > rank2) {
531:                        preference = PREFERENCE_SECOND_ARG;
532:                    } else {
533:                        // Equal ranks
534:                        if (rank1 == NativeJavaObject.CONVERSION_NONTRIVIAL) {
535:                            if (type1.isAssignableFrom(type2)) {
536:                                preference = PREFERENCE_SECOND_ARG;
537:                            } else if (type2.isAssignableFrom(type1)) {
538:                                preference = PREFERENCE_FIRST_ARG;
539:                            } else {
540:                                preference = PREFERENCE_AMBIGUOUS;
541:                            }
542:                        } else {
543:                            preference = PREFERENCE_AMBIGUOUS;
544:                        }
545:                    }
546:
547:                    totalPreference |= preference;
548:
549:                    if (totalPreference == PREFERENCE_AMBIGUOUS) {
550:                        break;
551:                    }
552:                }
553:                return totalPreference;
554:            }
555:
556:            private static final boolean debug = false;
557:
558:            private static void printDebug(String msg, MemberBox member,
559:                    Object[] args) {
560:                if (debug) {
561:                    StringBuffer sb = new StringBuffer();
562:                    sb.append(" ----- ");
563:                    sb.append(msg);
564:                    sb.append(member.getDeclaringClass().getName());
565:                    sb.append('.');
566:                    if (member.isMethod()) {
567:                        sb.append(member.getName());
568:                    }
569:                    sb
570:                            .append(JavaMembers
571:                                    .liveConnectSignature(member.argTypes));
572:                    sb.append(" for arguments (");
573:                    sb.append(scriptSignature(args));
574:                    sb.append(')');
575:                    System.out.println(sb);
576:                }
577:            }
578:
579:            MemberBox[] methods;
580:            private String functionName;
581:        }
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