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