3 * $Id: sym.h,v 1.1 1997/07/21 13:47:43 mdw Exp $
5 * Symbol table management
10 /*----- Licencing notice --------------------------------------------------*
12 * This file is part of `become'
14 * `Become' 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.
19 * `Become' 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.
24 * You should have received a copy of the GNU General Public License
25 * along with `become'; if not, write to the Free Software
26 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
29 /*----- Revision history --------------------------------------------------*
32 * Revision 1.1 1997/07/21 13:47:43 mdw
44 /*----- Required headers --------------------------------------------------*/
48 /*----- Type definitions --------------------------------------------------*/
50 /* --- Symbol table --- *
52 * A @sym_table@ contains the information needed to manage a symbol table.
53 * Users shouldn't fiddle with this information directly, but it needs to be
54 * here so that objects of the correct type can be created.
57 typedef struct sym_table
{
58 unsigned long mask
; /* Bit mask for hashing purposes */
59 size_t c
; /* Down counter for growing table */
60 struct sym_base
**a
; /* Array of hash bins */
63 /* --- A symbol table entry --- *
65 * I don't care what actually gets stored in symbol entries because I don't
66 * create them: that's the responsibility of my client. All I care about
67 * here is that whatever gets passed to me is a structure whose first member
68 * is a @sym_base@. The ANSI guarantees about structure layout are
69 * sufficient to allow me to manipulate such objects.
72 typedef struct sym_base
{
73 struct sym_base
*next
; /* Next symbol in hash bin */
74 unsigned long hash
; /* Hash value for symbol's name */
75 char *name
; /* Name of this symbol */
76 size_t len
; /* Length of the symbol's name */
79 /* --- An iterator block --- */
81 typedef struct sym_iter
{
82 sym_table
*t
; /* Symbol table being iterated */
83 sym_base
*n
; /* Address of next item to return */
84 size_t i
; /* Index of next hash bin to use */
87 /*----- External functions ------------------------------------------------*/
89 /* --- @sym_createTable@ --- *
91 * Arguments: @sym_table *t@ = symbol table to initialise
95 * Use: Initialises the given symbol table.
98 extern void sym_createTable(sym_table */
*t*/
);
100 /* --- @sym_destroyTable@ --- *
102 * Arguments: @sym_table *t@ = pointer to symbol table in question
106 * Use: Destroys a symbol table, freeing all the memory it used to
110 extern void sym_destroyTable(sym_table */
*t*/
);
112 /* --- @sym_find@ --- *
114 * Arguments: @sym_table *t@ = pointer to symbol table in question
115 * @const char *n@ = pointer to symbol table to look up
116 * @long l@ = length of the name string or negative to measure
117 * @size_t sz@ = size of desired symbol object, or zero
118 * @unsigned *f@ = pointer to a flag, or null.
120 * Returns: The address of a @sym_base@ structure, or null if not found
123 * Use: Looks up a symbol in a given symbol table. The name is
124 * passed by the address of its first character. The length
125 * may be given, in which case the name may contain arbitrary
126 * binary data, or it may be given as a negative number, in
127 * which case the length of the name is calculated as
130 * The return value is the address of a pointer to a @sym_base@
131 * block (which may have other things on the end, as above). If
132 * the symbol could be found, the return value points to the
133 * symbol block. If the symbol wasn't there, then if @sz@ is
134 * nonzero, a new symbol is created and its address is returned;
135 * otherwise a null pointer is returned.
137 * The value of @*f@ indicates whether a new symbol entry was
138 * created: a nonzero value indicates that an old value was
142 extern void *sym_find(sym_table */
*t*/
, const char */
*n*/
, long /*l*/,
143 size_t /*sz*/, unsigned */
*f*/
);
145 /* --- @sym_remove@ --- *
147 * Arguments: @sym_table *i@ = pointer to a symbol table object
148 * @void *b@ = pointer to symbol table entry
152 * Use: Removes the object from the symbol table. The space occupied
153 * by the object and its name is freed; anything else attached
154 * to the entry should already be gone by this point.
157 extern void sym_remove(sym_table */
*t*/
, void */
*b*/
);
159 /* --- @sym_createIter@ --- *
161 * Arguments: @sym_iter *i@ = pointer to an iterator object
162 * @sym_table *t@ = pointer to a symbol table object
166 * Use: Creates a new symbol table iterator which may be used to
167 * iterate through a symbol table.
170 extern void sym_createIter(sym_iter */
*i*/
, sym_table */
*t*/
);
172 /* --- @sym_next@ --- *
174 * Arguments: @sym_iter *i@ = pointer to iterator object
176 * Returns: Pointer to the next symbol found, or null when finished.
178 * Use: Returns the next symbol from the table. Symbols are not
179 * returned in any particular order.
182 extern void *sym_next(sym_iter */
*i*/
);
184 /*----- That's all, folks -------------------------------------------------*/