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+/* hashlib.h -- the data structures used in hashing in Bash. */
+
+/* Copyright (C) 1993-2020 Free Software Foundation, Inc.
+
+ This file is part of GNU Bash, the Bourne Again SHell.
+
+ Bash is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Bash is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with Bash. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#if !defined (_HASHLIB_H_)
+#define _HASHLIB_H_
+
+#include "stdc.h"
+
+#ifndef PTR_T
+# ifdef __STDC__
+# define PTR_T void *
+# else
+# define PTR_T char *
+# endif
+#endif
+
+typedef struct bucket_contents {
+ struct bucket_contents *next; /* Link to next hashed key in this bucket. */
+ char *key; /* What we look up. */
+ PTR_T data; /* What we really want. */
+ unsigned int khash; /* What key hashes to */
+ int times_found; /* Number of times this item has been found. */
+} BUCKET_CONTENTS;
+
+typedef struct hash_table {
+ BUCKET_CONTENTS **bucket_array; /* Where the data is kept. */
+ int nbuckets; /* How many buckets does this table have. */
+ int nentries; /* How many entries does this table have. */
+} HASH_TABLE;
+
+typedef int hash_wfunc PARAMS((BUCKET_CONTENTS *));
+
+/* Operations on tables as a whole */
+extern HASH_TABLE *hash_create PARAMS((int));
+extern HASH_TABLE *hash_copy PARAMS((HASH_TABLE *, sh_string_func_t *));
+extern void hash_flush PARAMS((HASH_TABLE *, sh_free_func_t *));
+extern void hash_dispose PARAMS((HASH_TABLE *));
+extern void hash_walk PARAMS((HASH_TABLE *, hash_wfunc *));
+
+/* Operations to extract information from or pieces of tables */
+extern int hash_bucket PARAMS((const char *, HASH_TABLE *));
+extern int hash_size PARAMS((HASH_TABLE *));
+
+/* Operations on hash table entries */
+extern BUCKET_CONTENTS *hash_search PARAMS((const char *, HASH_TABLE *, int));
+extern BUCKET_CONTENTS *hash_insert PARAMS((char *, HASH_TABLE *, int));
+extern BUCKET_CONTENTS *hash_remove PARAMS((const char *, HASH_TABLE *, int));
+
+/* Miscellaneous */
+extern unsigned int hash_string PARAMS((const char *));
+
+/* Redefine the function as a macro for speed. */
+#define hash_items(bucket, table) \
+ ((table && (bucket < table->nbuckets)) ? \
+ table->bucket_array[bucket] : \
+ (BUCKET_CONTENTS *)NULL)
+
+/* Default number of buckets in the hash table. */
+#define DEFAULT_HASH_BUCKETS 128 /* must be power of two */
+
+#define HASH_ENTRIES(ht) ((ht) ? (ht)->nentries : 0)
+
+/* flags for hash_search and hash_insert */
+#define HASH_NOSRCH 0x01
+#define HASH_CREATE 0x02
+
+#if !defined (NULL)
+# if defined (__STDC__)
+# define NULL ((void *) 0)
+# else
+# define NULL 0x0
+# endif /* !__STDC__ */
+#endif /* !NULL */
+
+#endif /* _HASHLIB_H */