FinalScriptFunctionData.java revision 953:221a84ef44c0 
1/*
2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package jdk.nashorn.internal.runtime;
27
28import java.lang.invoke.MethodHandle;
29import java.lang.invoke.MethodType;
30
31/**
32 * This is a subclass that represents a script function that may not be regenerated.
33 * This is used for example for bound functions and builtins.
34 */
35final class FinalScriptFunctionData extends ScriptFunctionData {
36
37    private static final long serialVersionUID = -930632846167768864L;
38
39    /**
40     * Constructor - used for bind
41     *
42     * @param name      name
43     * @param arity     arity
44     * @param functions precompiled code
45     * @param flags     {@link ScriptFunctionData} flags
46     */
47    FinalScriptFunctionData(final String name, final int arity, final CompiledFunctions functions, final int flags) {
48        super(name, arity, flags);
49        assert !functions.needsCallee();
50        code.addAll(functions);
51    }
52
53    /**
54     * Constructor - used from ScriptFunction. This assumes that we have code already for the
55     * method (typically a native method) and possibly specializations.
56     *
57     * @param name  name
58     * @param mh    method handle for generic version of method
59     * @param specs specializations
60     * @param flags {@link ScriptFunctionData} flags
61     */
62    FinalScriptFunctionData(final String name, final MethodHandle mh, final MethodHandle[] specs, final int flags) {
63        super(name, methodHandleArity(mh), flags);
64
65        addInvoker(mh);
66        if (specs != null) {
67            for (final MethodHandle spec : specs) {
68                addInvoker(spec);
69            }
70        }
71    }
72
73    @Override
74    boolean isRecompilable() {
75        return false;
76    }
77
78    @Override
79    boolean needsCallee() {
80        return code.needsCallee();
81    }
82
83    @Override
84    MethodType getGenericType() {
85        // We need to ask the code for its generic type. We can't just rely on this function data's arity, as it's not
86        // actually correct for lots of built-ins. E.g. ECMAScript 5.1 section 15.5.3.2 prescribes that
87        // Script.fromCharCode([char0[, char1[, ...]]]) has a declared arity of 1 even though it's a variable arity
88        // method.
89        return code.getFinalGenericType();
90    }
91
92    private void addInvoker(final MethodHandle mh) {
93        assert !needsCallee(mh);
94        if (isConstructor(mh)) {
95            // only nasgen constructors: (boolean, self, args) are subject to binding a boolean newObj. isConstructor
96            // is too conservative a check. However, isConstructor(mh) always implies isConstructor param
97            assert isConstructor();
98            code.add(CompiledFunction.createBuiltInConstructor(mh));
99        } else {
100            code.add(new CompiledFunction(mh));
101        }
102    }
103
104    private static int methodHandleArity(final MethodHandle mh) {
105        if (isVarArg(mh)) {
106            return MAX_ARITY;
107        }
108
109        //drop self, callee and boolean constructor flag to get real arity
110        return mh.type().parameterCount() - 1 - (needsCallee(mh) ? 1 : 0) - (isConstructor(mh) ? 1 : 0);
111    }
112
113    private static boolean isConstructor(final MethodHandle mh) {
114        return mh.type().parameterCount() >= 1 && mh.type().parameterType(0) == boolean.class;
115    }
116
117}
118