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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: sym.h,v 1.2 1998/11/26 19:27:34 mdw Exp $ |
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4 | * |
5 | * Symbol table management |
6 | * |
7 | * (c) 1998 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * mLib is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with mLib; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: sym.h,v $ |
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32 | * Revision 1.2 1998/11/26 19:27:34 mdw |
33 | * Move SYM_NAME into the header file. Fix bugs. |
34 | * |
35 | * Revision 1.1.1.1 1998/06/17 23:44:42 mdw |
36 | * Initial version of mLib |
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37 | * |
38 | */ |
39 | |
40 | #ifndef SYM_H |
41 | #define SYM_H |
42 | |
43 | #ifdef __cplusplus |
44 | extern "C" { |
45 | #endif |
46 | |
47 | /*----- Required headers --------------------------------------------------*/ |
48 | |
49 | #include <stddef.h> |
50 | |
51 | /*----- Type definitions --------------------------------------------------*/ |
52 | |
53 | /* --- Symbol table --- * |
54 | * |
55 | * A @sym_table@ contains the information needed to manage a symbol table. |
56 | * Users shouldn't fiddle with this information directly, but it needs to be |
57 | * here so that objects of the correct type can be created. |
58 | */ |
59 | |
60 | typedef struct sym_table { |
61 | unsigned long mask; /* Bit mask for hashing purposes */ |
62 | size_t c; /* Down counter for growing table */ |
63 | struct sym_base **a; /* Array of hash bins */ |
64 | } sym_table; |
65 | |
66 | /* --- A symbol table entry --- * |
67 | * |
68 | * I don't care what actually gets stored in symbol entries because I don't |
69 | * create them: that's the responsibility of my client. All I care about |
70 | * here is that whatever gets passed to me is a structure whose first member |
71 | * is a @sym_base@. The ANSI guarantees about structure layout are |
72 | * sufficient to allow me to manipulate such objects. |
73 | */ |
74 | |
75 | #define SYM_BUFSZ 16 /* Size of local string buffer */ |
76 | |
77 | typedef struct sym_base { |
78 | struct sym_base *next; /* Next symbol in hash bin */ |
79 | unsigned long hash; /* Hash value for symbol's name */ |
80 | union { |
81 | char *p; /* Pointer to name string */ |
82 | char b[SYM_BUFSZ]; /* Buffer containing a short name */ |
83 | } name; /* Name of this symbol */ |
84 | size_t len; /* Length of the symbol's name */ |
85 | } sym_base; |
86 | |
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87 | /* --- A macro to pick a symbol's name out from the mess --- */ |
88 | |
89 | #define SYM_NAME(sy) \ |
90 | (((sym_base *)(sy))->len > SYM_BUFSZ ? \ |
91 | ((sym_base *)(sy))->name.p : \ |
92 | ((sym_base *)(sy))->name.b) |
93 | |
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94 | /* --- An iterator block --- */ |
95 | |
96 | typedef struct sym_iter { |
97 | sym_table *t; /* Symbol table being iterated */ |
98 | sym_base *n; /* Address of next item to return */ |
99 | size_t i; /* Index of next hash bin to use */ |
100 | } sym_iter; |
101 | |
102 | /*----- External functions ------------------------------------------------*/ |
103 | |
104 | /* --- @sym_createTable@ --- * |
105 | * |
106 | * Arguments: @sym_table *t@ = symbol table to initialise |
107 | * |
108 | * Returns: --- |
109 | * |
110 | * Use: Initialises the given symbol table. Raises @EXC_NOMEM@ if |
111 | * there isn't enough memory. |
112 | */ |
113 | |
114 | extern void sym_createTable(sym_table */*t*/); |
115 | |
116 | /* --- @sym_destroyTable@ --- * |
117 | * |
118 | * Arguments: @sym_table *t@ = pointer to symbol table in question |
119 | * |
120 | * Returns: --- |
121 | * |
122 | * Use: Destroys a symbol table, freeing all the memory it used to |
123 | * occupy. |
124 | */ |
125 | |
126 | extern void sym_destroyTable(sym_table */*t*/); |
127 | |
128 | /* --- @sym_find@ --- * |
129 | * |
130 | * Arguments: @sym_table *t@ = pointer to symbol table in question |
131 | * @const char *n@ = pointer to symbol table to look up |
132 | * @long l@ = length of the name string or negative to measure |
133 | * @size_t sz@ = size of desired symbol object, or zero |
134 | * @unsigned *f@ = pointer to a flag, or null. |
135 | * |
136 | * Returns: The address of a @sym_base@ structure, or null if not found |
137 | * and @sz@ is zero. |
138 | * |
139 | * Use: Looks up a symbol in a given symbol table. The name is |
140 | * passed by the address of its first character. The length |
141 | * may be given, in which case the name may contain arbitrary |
142 | * binary data, or it may be given as a negative number, in |
143 | * which case the length of the name is calculated as |
144 | * @strlen(n)@. |
145 | * |
146 | * The return value is the address of a pointer to a @sym_base@ |
147 | * block (which may have other things on the end, as above). If |
148 | * the symbol could be found, the return value points to the |
149 | * symbol block. If the symbol wasn't there, then if @sz@ is |
150 | * nonzero, a new symbol is created and its address is returned; |
151 | * otherwise a null pointer is returned. The exception |
152 | * @EXC_NOMEM@ is raised if the block can't be allocated. |
153 | * |
154 | * The value of @*f@ indicates whether a new symbol entry was |
155 | * created: a nonzero value indicates that an old value was |
156 | * found. |
157 | */ |
158 | |
159 | extern void *sym_find(sym_table */*t*/, const char */*n*/, long /*l*/, |
160 | size_t /*sz*/, unsigned */*f*/); |
161 | |
162 | /* --- @sym_remove@ --- * |
163 | * |
164 | * Arguments: @sym_table *i@ = pointer to a symbol table object |
165 | * @void *b@ = pointer to symbol table entry |
166 | * |
167 | * Returns: --- |
168 | * |
169 | * Use: Removes the object from the symbol table. The space occupied |
170 | * by the object and its name is freed; anything else attached |
171 | * to the entry should already be gone by this point. |
172 | */ |
173 | |
174 | extern void sym_remove(sym_table */*t*/, void */*b*/); |
175 | |
176 | /* --- @sym_createIter@ --- * |
177 | * |
178 | * Arguments: @sym_iter *i@ = pointer to an iterator object |
179 | * @sym_table *t@ = pointer to a symbol table object |
180 | * |
181 | * Returns: --- |
182 | * |
183 | * Use: Creates a new symbol table iterator which may be used to |
184 | * iterate through a symbol table. |
185 | */ |
186 | |
187 | extern void sym_createIter(sym_iter */*i*/, sym_table */*t*/); |
188 | |
189 | /* --- @sym_next@ --- * |
190 | * |
191 | * Arguments: @sym_iter *i@ = pointer to iterator object |
192 | * |
193 | * Returns: Pointer to the next symbol found, or null when finished. |
194 | * |
195 | * Use: Returns the next symbol from the table. Symbols are not |
196 | * returned in any particular order. |
197 | */ |
198 | |
199 | extern void *sym_next(sym_iter */*i*/); |
200 | |
201 | /*----- That's all, folks -------------------------------------------------*/ |
202 | |
203 | #ifdef __cplusplus |
204 | } |
205 | #endif |
206 | |
207 | #endif |