src/include/ptable.h

   1 // -*- C++ -*-
   2 /* Copyright (C) 1989, 1990, 1991, 1992, 2003, 2004, 2006
   3    Free Software Foundation, Inc.
   4      Written by James Clark (jjc@jclark.com)
   5
   6 This file is part of groff.
   7
   8 groff is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 groff is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License along
  19 with groff; see the file COPYING.  If not, write to the Free Software
  20 Foundation, 51 Franklin St - Fifth Floor, Boston, MA 02110-1301, USA. */
  21
  22 #include <assert.h>
  23 #include <string.h>
  24
  25 // name2(a,b) concatenates two C identifiers.
  26 #ifdef TRADITIONAL_CPP
  27 # define name2(a,b) a/**/b
  28 #else /* not TRADITIONAL_CPP */
  29 # define name2(a,b) name2x(a,b)
  30 # define name2x(a,b) a ## b
  31 #endif /* not TRADITIONAL_CPP */
  32
  33 // `class PTABLE(T)' is the type of a hash table mapping a string
  34 // (const char *) to an object of type T.
  35 //
  36 // `struct PASSOC(T)' is the type of a association (pair) between a
  37 // string (const char *) and an object of type T.
  38 //
  39 // `class PTABLE_ITERATOR(T)' is the type of an iterator iterating through a
  40 // `class PTABLE(T)'.
  41 //
  42 // Nowadays one would use templates for this; this code predates the addition
  43 // of templates to C++.
  44 #define PTABLE(T) name2(T,_ptable)
  45 #define PASSOC(T) name2(T,_passoc)
  46 #define PTABLE_ITERATOR(T) name2(T,_ptable_iterator)
  47
  48 // itable.h declares this too
  49 #ifndef NEXT_PTABLE_SIZE_DEFINED
  50 # define NEXT_PTABLE_SIZE_DEFINED
  51 extern unsigned next_ptable_size(unsigned);     // Return the first suitable
  52                                 // hash table size greater than the given
  53                                 // value.
  54 #endif
  55
  56 extern unsigned long hash_string(const char *); // Return a hash code of the
  57                                 // given string.  The hash function is
  58                                 // platform dependent.  */
  59
  60 // Declare the types `class PTABLE(T)', `struct PASSOC(T)', and `class
  61 // PTABLE_ITERATOR(T)' for the type `T'.
  62 #define declare_ptable(T)                                                     \
  63                                                                               \
  64 struct PASSOC(T) {                                                            \
  65   char *key;                                                                  \
  66   T *val;                                                                     \
  67   PASSOC(T)();                                                                \
  68 };                                                                            \
  69                                                                               \
  70 class PTABLE(T);                                                              \
  71                                                                               \
  72 class PTABLE_ITERATOR(T) {                                                    \
  73   PTABLE(T) *p;                                                               \
  74   unsigned i;                                                                 \
  75 public:                                                                       \
  76   PTABLE_ITERATOR(T)(PTABLE(T) *);      /* Initialize an iterator running     \
  77                                            through the given table.  */       \
  78   int next(const char **, T **);        /* Fetch the next pair, store the key \
  79                                            and value in arg1 and arg2,        \
  80                                            respectively, and return 1.  If    \
  81                                            there is no more pair in the       \
  82                                            table, return 0.  */               \
  83 };                                                                            \
  84                                                                               \
  85 class PTABLE(T) {                                                             \
  86   PASSOC(T) *v;                                                               \
  87   unsigned size;                                                              \
  88   unsigned used;                                                              \
  89   enum {                                                                      \
  90     FULL_NUM = 2,                                                             \
  91     FULL_DEN = 3,                                                             \
  92     INITIAL_SIZE = 17                                                         \
  93   };                                                                          \
  94 public:                                                                       \
  95   PTABLE(T)();                          /* Create an empty table.  */         \
  96   ~PTABLE(T)();                         /* Delete a table, including its      \
  97                                            values.  */                        \
  98   const char *define(const char *, T *);/* Define the value (arg2) for a key  \
  99                                            (arg1).  Return the copy in the    \
 100                                            table of the key (arg1), or        \
 101                                            possibly NULL if the value (arg2)  \
 102                                            is NULL.  */                       \
 103   T *lookup(const char *);              /* Return a pointer to the value of   \
 104                                            the given key, if found in the     \
 105                                            table, or NULL otherwise.  */      \
 106   T *lookupassoc(const char **);        /* Return a pointer to the value of   \
 107                                            the given key, passed by reference,\
 108                                            and replace the key argument with  \
 109                                            the copy found in the table, if    \
 110                                            the key is found in the table.     \
 111                                            Return NULL otherwise.  */         \
 112   friend class PTABLE_ITERATOR(T);                                            \
 113 };
 114
 115
 116 // Keys (which are strings) are allocated and freed by PTABLE.
 117 // Values must be allocated by the caller (always using new[], not new)
 118 // and are freed by PTABLE.
 119
 120 // Define the implementations of the members of the types `class PTABLE(T)',
 121 // `struct PASSOC(T)', `class PTABLE_ITERATOR(T)' for the type `T'.
 122 #define implement_ptable(T)                                                   \
 123                                                                               \
 124 PASSOC(T)::PASSOC(T)()                                                        \
 125 : key(0), val(0)                                                              \
 126 {                                                                             \
 127 }                                                                             \
 128                                                                               \
 129 PTABLE(T)::PTABLE(T)()                                                        \
 130 {                                                                             \
 131   v = new PASSOC(T)[size = INITIAL_SIZE];                                     \
 132   used = 0;                                                                   \
 133 }                                                                             \
 134                                                                               \
 135 PTABLE(T)::~PTABLE(T)()                                                       \
 136 {                                                                             \
 137   for (unsigned i = 0; i < size; i++) {                                       \
 138     a_delete v[i].key;                                                        \
 139     a_delete v[i].val;                                                        \
 140   }                                                                           \
 141   a_delete v;                                                                 \
 142 }                                                                             \
 143                                                                               \
 144 const char *PTABLE(T)::define(const char *key, T *val)                        \
 145 {                                                                             \
 146   assert(key != 0);                                                           \
 147   unsigned long h = hash_string(key);                                         \
 148   unsigned n;                                                                 \
 149   for (n = unsigned(h % size);                                                \
 150        v[n].key != 0;                                                         \
 151        n = (n == 0 ? size - 1 : n - 1))                                       \
 152     if (strcmp(v[n].key, key) == 0) {                                         \
 153       a_delete v[n].val;                                                      \
 154       v[n].val = val;                                                         \
 155       return v[n].key;                                                        \
 156     }                                                                         \
 157   if (val == 0)                                                               \
 158     return 0;                                                                 \
 159   if (used*FULL_DEN >= size*FULL_NUM) {                                       \
 160     PASSOC(T) *oldv = v;                                                      \
 161     unsigned old_size = size;                                                 \
 162     size = next_ptable_size(size);                                            \
 163     v = new PASSOC(T)[size];                                                  \
 164     for (unsigned i = 0; i < old_size; i++)                                   \
 165       if (oldv[i].key != 0) {                                                 \
 166         if (oldv[i].val == 0)                                                 \
 167           a_delete oldv[i].key;                                               \
 168         else {                                                                \
 169           unsigned j;                                                         \
 170           for (j = unsigned(hash_string(oldv[i].key) % size);                 \
 171                v[j].key != 0;                                                 \
 172                j = (j == 0 ? size - 1 : j - 1))                               \
 173                  ;                                                            \
 174           v[j].key = oldv[i].key;                                             \
 175           v[j].val = oldv[i].val;                                             \
 176         }                                                                     \
 177       }                                                                       \
 178     for (n = unsigned(h % size);                                              \
 179          v[n].key != 0;                                                       \
 180          n = (n == 0 ? size - 1 : n - 1))                                     \
 181       ;                                                                       \
 182     a_delete oldv;                                                            \
 183   }                                                                           \
 184   char *temp = new char[strlen(key)+1];                                       \
 185   strcpy(temp, key);                                                          \
 186   v[n].key = temp;                                                            \
 187   v[n].val = val;                                                             \
 188   used++;                                                                     \
 189   return temp;                                                                \
 190 }                                                                             \
 191                                                                               \
 192 T *PTABLE(T)::lookup(const char *key)                                         \
 193 {                                                                             \
 194   assert(key != 0);                                                           \
 195   for (unsigned n = unsigned(hash_string(key) % size);                        \
 196        v[n].key != 0;                                                         \
 197        n = (n == 0 ? size - 1 : n - 1))                                       \
 198     if (strcmp(v[n].key, key) == 0)                                           \
 199       return v[n].val;                                                        \
 200   return 0;                                                                   \
 201 }                                                                             \
 202                                                                               \
 203 T *PTABLE(T)::lookupassoc(const char **keyptr)                                \
 204 {                                                                             \
 205   const char *key = *keyptr;                                                  \
 206   assert(key != 0);                                                           \
 207   for (unsigned n = unsigned(hash_string(key) % size);                        \
 208        v[n].key != 0;                                                         \
 209        n = (n == 0 ? size - 1 : n - 1))                                       \
 210     if (strcmp(v[n].key, key) == 0) {                                         \
 211       *keyptr = v[n].key;                                                     \
 212       return v[n].val;                                                        \
 213     }                                                                         \
 214   return 0;                                                                   \
 215 }                                                                             \
 216                                                                               \
 217 PTABLE_ITERATOR(T)::PTABLE_ITERATOR(T)(PTABLE(T) *t)                          \
 218 : p(t), i(0)                                                                  \
 219 {                                                                             \
 220 }                                                                             \
 221                                                                               \
 222 int PTABLE_ITERATOR(T)::next(const char **keyp, T **valp)                     \
 223 {                                                                             \
 224   unsigned size = p->size;                                                    \
 225   PASSOC(T) *v = p->v;                                                        \
 226   for (; i < size; i++)                                                       \
 227     if (v[i].key != 0) {                                                      \
 228       *keyp = v[i].key;                                                       \
 229       *valp = v[i].val;                                                       \
 230       i++;                                                                    \
 231       return 1;                                                               \
 232     }                                                                         \
 233   return 0;                                                                   \
 234 }
 235
 236 // end of ptable.h