src/include/ptable.h

   1 // -*- C++ -*-
   2 /* Copyright (C) 1989-2014  Free Software Foundation, Inc.
   3      Written by James Clark (jjc@jclark.com)
   4
   5 This file is part of groff.
   6
   7 groff is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation, either version 3 of the License, or
  10 (at your option) any later version.
  11
  12 groff is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
  19
  20 #include <assert.h>
  21 #include <string.h>
  22
  23 // name2(a,b) concatenates two C identifiers.
  24 #ifdef TRADITIONAL_CPP
  25 # define name2(a,b) a/**/b
  26 #else /* not TRADITIONAL_CPP */
  27 # define name2(a,b) name2x(a,b)
  28 # define name2x(a,b) a ## b
  29 #endif /* not TRADITIONAL_CPP */
  30
  31 // `class PTABLE(T)' is the type of a hash table mapping a string
  32 // (const char *) to an object of type T.
  33 //
  34 // `struct PASSOC(T)' is the type of a association (pair) between a
  35 // string (const char *) and an object of type T.
  36 //
  37 // `class PTABLE_ITERATOR(T)' is the type of an iterator iterating through a
  38 // `class PTABLE(T)'.
  39 //
  40 // Nowadays one would use templates for this; this code predates the addition
  41 // of templates to C++.
  42 #define PTABLE(T) name2(T,_ptable)
  43 #define PASSOC(T) name2(T,_passoc)
  44 #define PTABLE_ITERATOR(T) name2(T,_ptable_iterator)
  45
  46 // itable.h declares this too
  47 #ifndef NEXT_PTABLE_SIZE_DEFINED
  48 # define NEXT_PTABLE_SIZE_DEFINED
  49 extern unsigned next_ptable_size(unsigned);     // Return the first suitable
  50                                 // hash table size greater than the given
  51                                 // value.
  52 #endif
  53
  54 extern unsigned long hash_string(const char *); // Return a hash code of the
  55                                 // given string.  The hash function is
  56                                 // platform dependent.  */
  57
  58 // Declare the types `class PTABLE(T)', `struct PASSOC(T)', and `class
  59 // PTABLE_ITERATOR(T)' for the type `T'.
  60 #define declare_ptable(T)                                                     \
  61                                                                               \
  62 struct PASSOC(T) {                                                            \
  63   char *key;                                                                  \
  64   T *val;                                                                     \
  65   PASSOC(T)();                                                                \
  66 };                                                                            \
  67                                                                               \
  68 class PTABLE(T);                                                              \
  69                                                                               \
  70 class PTABLE_ITERATOR(T) {                                                    \
  71   PTABLE(T) *p;                                                               \
  72   unsigned i;                                                                 \
  73 public:                                                                       \
  74   PTABLE_ITERATOR(T)(PTABLE(T) *);      /* Initialize an iterator running     \
  75                                            through the given table.  */       \
  76   int next(const char **, T **);        /* Fetch the next pair, store the key \
  77                                            and value in arg1 and arg2,        \
  78                                            respectively, and return 1.  If    \
  79                                            there is no more pair in the       \
  80                                            table, return 0.  */               \
  81 };                                                                            \
  82                                                                               \
  83 class PTABLE(T) {                                                             \
  84   PASSOC(T) *v;                                                               \
  85   unsigned size;                                                              \
  86   unsigned used;                                                              \
  87   enum {                                                                      \
  88     FULL_NUM = 1,                                                             \
  89     FULL_DEN = 4,                                                             \
  90     INITIAL_SIZE = 17                                                         \
  91   };                                                                          \
  92 public:                                                                       \
  93   PTABLE(T)();                          /* Create an empty table.  */         \
  94   ~PTABLE(T)();                         /* Delete a table, including its      \
  95                                            values.  */                        \
  96   const char *define(const char *, T *);/* Define the value (arg2) for a key  \
  97                                            (arg1).  Return the copy in the    \
  98                                            table of the key (arg1), or        \
  99                                            possibly NULL if the value (arg2)  \
 100                                            is NULL.  */                       \
 101   T *lookup(const char *);              /* Return a pointer to the value of   \
 102                                            the given key, if found in the     \
 103                                            table, or NULL otherwise.  */      \
 104   T *lookupassoc(const char **);        /* Return a pointer to the value of   \
 105                                            the given key, passed by reference,\
 106                                            and replace the key argument with  \
 107                                            the copy found in the table, if    \
 108                                            the key is found in the table.     \
 109                                            Return NULL otherwise.  */         \
 110   friend class PTABLE_ITERATOR(T);                                            \
 111 };
 112
 113
 114 // Keys (which are strings) are allocated and freed by PTABLE.
 115 // Values must be allocated by the caller (always using new[], not new)
 116 // and are freed by PTABLE.
 117
 118 // Define the implementations of the members of the types `class PTABLE(T)',
 119 // `struct PASSOC(T)', `class PTABLE_ITERATOR(T)' for the type `T'.
 120 #define implement_ptable(T)                                                   \
 121                                                                               \
 122 PASSOC(T)::PASSOC(T)()                                                        \
 123 : key(0), val(0)                                                              \
 124 {                                                                             \
 125 }                                                                             \
 126                                                                               \
 127 PTABLE(T)::PTABLE(T)()                                                        \
 128 {                                                                             \
 129   v = new PASSOC(T)[size = INITIAL_SIZE];                                     \
 130   used = 0;                                                                   \
 131 }                                                                             \
 132                                                                               \
 133 PTABLE(T)::~PTABLE(T)()                                                       \
 134 {                                                                             \
 135   for (unsigned i = 0; i < size; i++) {                                       \
 136     a_delete v[i].key;                                                        \
 137     a_delete v[i].val;                                                        \
 138   }                                                                           \
 139   a_delete v;                                                                 \
 140 }                                                                             \
 141                                                                               \
 142 const char *PTABLE(T)::define(const char *key, T *val)                        \
 143 {                                                                             \
 144   assert(key != 0);                                                           \
 145   unsigned long h = hash_string(key);                                         \
 146   unsigned n;                                                                 \
 147   for (n = unsigned(h % size);                                                \
 148        v[n].key != 0;                                                         \
 149        n = (n == 0 ? size - 1 : n - 1))                                       \
 150     if (strcmp(v[n].key, key) == 0) {                                         \
 151       a_delete v[n].val;                                                      \
 152       v[n].val = val;                                                         \
 153       return v[n].key;                                                        \
 154     }                                                                         \
 155   if (val == 0)                                                               \
 156     return 0;                                                                 \
 157   if (used*FULL_DEN >= size*FULL_NUM) {                                       \
 158     PASSOC(T) *oldv = v;                                                      \
 159     unsigned old_size = size;                                                 \
 160     size = next_ptable_size(size);                                            \
 161     v = new PASSOC(T)[size];                                                  \
 162     for (unsigned i = 0; i < old_size; i++)                                   \
 163       if (oldv[i].key != 0) {                                                 \
 164         if (oldv[i].val == 0)                                                 \
 165           a_delete oldv[i].key;                                               \
 166         else {                                                                \
 167           unsigned j;                                                         \
 168           for (j = unsigned(hash_string(oldv[i].key) % size);                 \
 169                v[j].key != 0;                                                 \
 170                j = (j == 0 ? size - 1 : j - 1))                               \
 171                  ;                                                            \
 172           v[j].key = oldv[i].key;                                             \
 173           v[j].val = oldv[i].val;                                             \
 174         }                                                                     \
 175       }                                                                       \
 176     for (n = unsigned(h % size);                                              \
 177          v[n].key != 0;                                                       \
 178          n = (n == 0 ? size - 1 : n - 1))                                     \
 179       ;                                                                       \
 180     a_delete oldv;                                                            \
 181   }                                                                           \
 182   char *temp = new char[strlen(key)+1];                                       \
 183   strcpy(temp, key);                                                          \
 184   v[n].key = temp;                                                            \
 185   v[n].val = val;                                                             \
 186   used++;                                                                     \
 187   return temp;                                                                \
 188 }                                                                             \
 189                                                                               \
 190 T *PTABLE(T)::lookup(const char *key)                                         \
 191 {                                                                             \
 192   assert(key != 0);                                                           \
 193   for (unsigned n = unsigned(hash_string(key) % size);                        \
 194        v[n].key != 0;                                                         \
 195        n = (n == 0 ? size - 1 : n - 1))                                       \
 196     if (strcmp(v[n].key, key) == 0)                                           \
 197       return v[n].val;                                                        \
 198   return 0;                                                                   \
 199 }                                                                             \
 200                                                                               \
 201 T *PTABLE(T)::lookupassoc(const char **keyptr)                                \
 202 {                                                                             \
 203   const char *key = *keyptr;                                                  \
 204   assert(key != 0);                                                           \
 205   for (unsigned n = unsigned(hash_string(key) % size);                        \
 206        v[n].key != 0;                                                         \
 207        n = (n == 0 ? size - 1 : n - 1))                                       \
 208     if (strcmp(v[n].key, key) == 0) {                                         \
 209       *keyptr = v[n].key;                                                     \
 210       return v[n].val;                                                        \
 211     }                                                                         \
 212   return 0;                                                                   \
 213 }                                                                             \
 214                                                                               \
 215 PTABLE_ITERATOR(T)::PTABLE_ITERATOR(T)(PTABLE(T) *t)                          \
 216 : p(t), i(0)                                                                  \
 217 {                                                                             \
 218 }                                                                             \
 219                                                                               \
 220 int PTABLE_ITERATOR(T)::next(const char **keyp, T **valp)                     \
 221 {                                                                             \
 222   unsigned size = p->size;                                                    \
 223   PASSOC(T) *v = p->v;                                                        \
 224   for (; i < size; i++)                                                       \
 225     if (v[i].key != 0) {                                                      \
 226       *keyp = v[i].key;                                                       \
 227       *valp = v[i].val;                                                       \
 228       i++;                                                                    \
 229       return 1;                                                               \
 230     }                                                                         \
 231   return 0;                                                                   \
 232 }
 233
 234 // end of ptable.h