1/***********************************************************************
2*                                                                      *
3*               This software is part of the ast package               *
4*          Copyright (c) 1985-2010 AT&T Intellectual Property          *
5*                      and is licensed under the                       *
6*                  Common Public License, Version 1.0                  *
7*                    by AT&T Intellectual Property                     *
8*                                                                      *
9*                A copy of the License is available at                 *
10*            http://www.opensource.org/licenses/cpl1.0.txt             *
11*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
12*                                                                      *
13*              Information and Software Systems Research               *
14*                            AT&T Research                             *
15*                           Florham Park NJ                            *
16*                                                                      *
17*                 Glenn Fowler <gsf@research.att.com>                  *
18*                  David Korn <dgk@research.att.com>                   *
19*                   Phong Vo <kpv@research.att.com>                    *
20*                                                                      *
21***********************************************************************/
22#pragma prototyped
23/*
24 * Glenn Fowler
25 * AT&T Bell Laboratories
26 *
27 * hash table library
28 */
29
30#include "hashlib.h"
31
32/*
33 * push/pop/query hash table scope
34 *
35 *	bot==0		pop top scope
36 *	bot==top	query
37 *	bot!=0		push top on bot
38 *
39 * scope table pointer returned
40 */
41
42Hash_table_t*
43hashview(Hash_table_t* top, Hash_table_t* bot)
44{
45	register Hash_bucket_t*		b;
46	register Hash_bucket_t*		p;
47	register Hash_bucket_t**	sp;
48	register Hash_bucket_t**	sx;
49
50	if (!top || top->frozen)
51		bot = 0;
52	else if (top == bot)
53		bot = top->scope;
54	else if (bot)
55	{
56		if (top->scope)
57			bot = 0;
58		else
59		{
60			sx = &top->table[top->size];
61			sp = &top->table[0];
62			while (sp < sx)
63				for (b = *sp++; b; b = b->next)
64					if (p = (Hash_bucket_t*)hashlook(bot, b->name, HASH_LOOKUP, NiL))
65					{
66						b->name = (p->hash & HASH_HIDES) ? p->name : (char*)b;
67						b->hash |= HASH_HIDES;
68					}
69			top->scope = bot;
70			bot->frozen++;
71		}
72	}
73	else if (bot = top->scope)
74	{
75		sx = &top->table[top->size];
76		sp = &top->table[0];
77		while (sp < sx)
78			for (b = *sp++; b; b = b->next)
79				if (b->hash & HASH_HIDES)
80				{
81					b->hash &= ~HASH_HIDES;
82					b->name = ((Hash_bucket_t*)b->name)->name;
83				}
84		top->scope = 0;
85		bot->frozen--;
86	}
87	return(bot);
88}
89