libs: introduce lmo - Lua Machine Objects, an implementation of binary hash tables
[project/luci.git] / libs / lmo / src / lmo_lualib.c
1 /*
2 * lmo - Lua Machine Objects - Lookup utility
3 *
4 * Copyright (C) 2009 Jo-Philipp Wich <xm@subsignal.org>
5 *
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19 #include "lmo_lualib.h"
20
21 extern char _lmo_error[1024];
22
23
24 static int lmo_L_open(lua_State *L) {
25 const char *filename = luaL_checklstring(L, 1, NULL);
26 lmo_archive_t *ar, **udata;
27
28 if( (ar = lmo_open(filename)) != NULL )
29 {
30 if( (udata = lua_newuserdata(L, sizeof(lmo_archive_t *))) != NULL )
31 {
32 *udata = ar;
33 luaL_getmetatable(L, LMO_ARCHIVE_META);
34 lua_setmetatable(L, -2);
35 return 1;
36 }
37
38 lua_pushnil(L);
39 lua_pushstring(L, "out of memory");
40 return 2;
41 }
42
43 lua_pushnil(L);
44 lua_pushstring(L, lmo_error());
45 return 2;
46 }
47
48 static int lmo_L_hash(lua_State *L) {
49 const char *data = luaL_checkstring(L, 1);
50 uint32_t hash = sfh_hash(data, strlen(data));
51 lua_pushnumber(L, hash);
52 return 1;
53 }
54
55 static int lmo_L_lookup(lua_State *L) {
56 lmo_archive_t **ar = luaL_checkudata(L, 1, LMO_ARCHIVE_META);
57 lmo_entry_t *e = (*ar)->index;
58 const char *key = luaL_checkstring(L, 2);
59 uint32_t hash = sfh_hash(key, strlen(key));
60
61 while( e != NULL )
62 {
63 if( e->key_id == hash )
64 {
65 lua_pushlstring(L, &(*ar)->mmap[e->offset], e->length);
66 return 1;
67 }
68
69 e = e->next;
70 }
71
72 lua_pushnil(L);
73 return 1;
74 }
75
76 static int lmo_L__gc(lua_State *L) {
77 lmo_archive_t **ar = luaL_checkudata(L, 1, LMO_ARCHIVE_META);
78
79 if( (*ar) != NULL )
80 lmo_close(*ar);
81
82 *ar = NULL;
83
84 return 0;
85 }
86
87 static int lmo_L__tostring(lua_State *L) {
88 lmo_archive_t **ar = luaL_checkudata(L, 1, LMO_ARCHIVE_META);
89 lua_pushfstring(L, "LMO Archive (%d bytes)", (*ar)->length);
90 return 1;
91 }
92
93
94 /* method table */
95 static const luaL_reg M[] = {
96 {"close", lmo_L__gc},
97 {"lookup", lmo_L_lookup},
98 {"__tostring", lmo_L__tostring},
99 {"__gc", lmo_L__gc},
100 {NULL, NULL}
101 };
102
103 /* module table */
104 static const luaL_reg R[] = {
105 {"open", lmo_L_open},
106 {"hash", lmo_L_hash},
107 {NULL, NULL}
108 };
109
110 LUALIB_API int luaopen_lmo(lua_State *L) {
111 luaL_newmetatable(L, LMO_LUALIB_META);
112 luaL_register(L, NULL, R);
113 lua_pushvalue(L, -1);
114 lua_setfield(L, -2, "__index");
115 lua_setglobal(L, LMO_LUALIB_META);
116
117 luaL_newmetatable(L, LMO_ARCHIVE_META);
118 luaL_register(L, NULL, M);
119 lua_pushvalue(L, -1);
120 lua_setfield(L, -2, "__index");
121 lua_setglobal(L, LMO_ARCHIVE_META);
122
123 return 1;
124 }