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comparison src/share/vm/oops/symbolOop.hpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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-1:000000000000 0:a61af66fc99e
1 /*
2 * Copyright 1997-2005 Sun Microsystems, Inc. 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // A symbolOop is a canonicalized string.
26 // All symbolOops reside in global symbolTable.
27 // See oopFactory::new_symbol for how to allocate a symbolOop
28
29 class symbolOopDesc : public oopDesc {
30 friend class VMStructs;
31 private:
32 unsigned short _length; // number of UTF8 characters in the symbol
33 jbyte _body[1];
34
35 enum {
36 // max_symbol_length is constrained by type of _length
37 max_symbol_length = (1 << 16) -1
38 };
39 public:
40
41 // Low-level access (used with care, since not GC-safe)
42 jbyte* base() { return &_body[0]; }
43
44
45 // Returns the largest size symbol we can safely hold.
46 static int max_length() {
47 return max_symbol_length;
48 }
49
50 static int object_size(int length) {
51 int size = header_size() + (sizeof(unsigned short) + length + HeapWordSize - 1) / HeapWordSize;
52 return align_object_size(size);
53 }
54
55 int object_size() { return object_size(utf8_length()); }
56
57 int byte_at(int index) const {
58 assert(index >=0 && index < _length, "symbol index overflow");
59 return ((symbolOopDesc*)this)->base()[index];
60 }
61
62 void byte_at_put(int index, int value) {
63 assert(index >=0 && index < _length, "symbol index overflow");
64 ((symbolOopDesc*)this)->base()[index] = value;
65 }
66
67 jbyte* bytes() { return base(); }
68
69 int utf8_length() const { return _length; }
70
71 void set_utf8_length(int len) { _length = len; }
72
73 // Compares the symbol with a string
74 bool equals(const char* str, int len) const;
75
76 // Three-way compare for sorting; returns -1/0/1 if receiver is </==/> than arg
77 // note that the ordering is not alfabetical
78 inline int fast_compare(symbolOop other) const;
79
80 // Returns receiver converted to null-terminated UTF-8 string; string is
81 // allocated in resource area, or in the char buffer provided by caller.
82 char* as_C_string() const;
83 char* as_C_string(char* buf, int size) const;
84 // Use buf if needed buffer length is <= size.
85 char* as_C_string_flexible_buffer(Thread* t, char* buf, int size) const;
86
87
88 // Returns a null terminated utf8 string in a resource array
89 char* as_utf8() const { return as_C_string(); }
90 char* as_utf8_flexible_buffer(Thread* t, char* buf, int size) const {
91 return as_C_string_flexible_buffer(t, buf, size);
92 }
93
94 jchar* as_unicode(int& length) const;
95
96 // Treating this symbol as a class name, returns the Java name for the class.
97 // String is allocated in resource area if buffer is not provided.
98 // See Klass::external_name()
99 const char* as_klass_external_name() const;
100 const char* as_klass_external_name(char* buf, int size) const;
101
102 bool object_is_parsable() const {
103 return (utf8_length() > 0 || (oop)this == Universe::emptySymbol());
104 }
105
106 // Printing
107 void print_symbol_on(outputStream* st = NULL);
108 };
109
110
111 // Note: this comparison is used for vtable sorting only; it doesn't matter
112 // what order it defines, as long as it is a total, time-invariant order
113 // Since symbolOops are in permSpace, their relative order in memory never changes,
114 // so use address comparison for speed
115 int symbolOopDesc::fast_compare(symbolOop other) const {
116 return (((uintptr_t)this < (uintptr_t)other) ? -1
117 : ((uintptr_t)this == (uintptr_t) other) ? 0 : 1);
118 }