1 /*
2 * Copyright (c) 1997, 2010, 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.
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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_OOPS_SYMBOLOOP_HPP
26 #define SHARE_VM_OOPS_SYMBOLOOP_HPP
27
28 #include "oops/typeArrayOop.hpp"
29 #include "utilities/utf8.hpp"
30
31 // A symbolOop is a canonicalized string.
32 // All symbolOops reside in global symbolTable.
33 // See oopFactory::new_symbol for how to allocate a symbolOop
34
35 class symbolOopDesc : public oopDesc {
36 friend class VMStructs;
37 private:
38 unsigned short _length; // number of UTF8 characters in the symbol
39 jbyte _body[1];
40
41 enum {
42 // max_symbol_length is constrained by type of _length
43 max_symbol_length = (1 << 16) -1
44 };
45 public:
46
47 // Low-level access (used with care, since not GC-safe)
48 jbyte* base() { return &_body[0]; }
49
50
51 // Returns the largest size symbol we can safely hold.
52 static int max_length() {
53 return max_symbol_length;
54 }
55
56 static int object_size(int length) {
57 int size = header_size() + (sizeof(unsigned short) + length + HeapWordSize - 1) / HeapWordSize;
58 return align_object_size(size);
59 }
60
61 int object_size() { return object_size(utf8_length()); }
62
63 int byte_at(int index) const {
64 assert(index >=0 && index < _length, "symbol index overflow");
65 return ((symbolOopDesc*)this)->base()[index];
66 }
67
68 void byte_at_put(int index, int value) {
69 assert(index >=0 && index < _length, "symbol index overflow");
70 ((symbolOopDesc*)this)->base()[index] = value;
71 }
72
73 jbyte* bytes() { return base(); }
74
75 int utf8_length() const { return _length; }
76
77 void set_utf8_length(int len) { _length = len; }
78
79 // Compares the symbol with a string.
80 bool equals(const char* str, int len) const;
81 bool equals(const char* str) const { return equals(str, (int) strlen(str)); }
82
83 // Tests if the symbol starts with the given prefix.
84 bool starts_with(const char* prefix, int len) const;
85 bool starts_with(const char* prefix) const {
86 return starts_with(prefix, (int) strlen(prefix));
87 }
88
89 // Tests if the symbol starts with the given prefix.
90 int index_of_at(int i, const char* str, int len) const;
91 int index_of_at(int i, const char* str) const {
92 return index_of_at(i, str, (int) strlen(str));
93 }
94
95 // Three-way compare for sorting; returns -1/0/1 if receiver is </==/> than arg
96 // note that the ordering is not alfabetical
97 inline int fast_compare(symbolOop other) const;
98
99 // Returns receiver converted to null-terminated UTF-8 string; string is
100 // allocated in resource area, or in the char buffer provided by caller.
101 char* as_C_string() const;
102 char* as_C_string(char* buf, int size) const;
103 // Use buf if needed buffer length is <= size.
104 char* as_C_string_flexible_buffer(Thread* t, char* buf, int size) const;
105
106
107 // Returns a null terminated utf8 string in a resource array
108 char* as_utf8() const { return as_C_string(); }
109 char* as_utf8_flexible_buffer(Thread* t, char* buf, int size) const {
110 return as_C_string_flexible_buffer(t, buf, size);
111 }
112
113 jchar* as_unicode(int& length) const;
114
115 // Treating this symbol as a class name, returns the Java name for the class.
116 // String is allocated in resource area if buffer is not provided.
117 // See Klass::external_name()
118 const char* as_klass_external_name() const;
119 const char* as_klass_external_name(char* buf, int size) const;
120
121 bool object_is_parsable() const {
122 return (utf8_length() > 0 || (oop)this == Universe::emptySymbol());
123 }
124
125 // Printing
126 void print_symbol_on(outputStream* st = NULL);
127 };
128
129
130 // Note: this comparison is used for vtable sorting only; it doesn't matter
131 // what order it defines, as long as it is a total, time-invariant order
132 // Since symbolOops are in permSpace, their relative order in memory never changes,
133 // so use address comparison for speed
134 int symbolOopDesc::fast_compare(symbolOop other) const {
135 return (((uintptr_t)this < (uintptr_t)other) ? -1
136 : ((uintptr_t)this == (uintptr_t) other) ? 0 : 1);
137 }
138
139 #endif // SHARE_VM_OOPS_SYMBOLOOP_HPP