1/*
2** $Id: lcorolib.c $
3** Coroutine Library
4** See Copyright Notice in lua.h
5*/
6
7#define lcorolib_c
8#define LUA_LIB
9
10#include "lprefix.h"
11
12
13#include <stdlib.h>
14
15#include "lua.h"
16
17#include "lauxlib.h"
18#include "lualib.h"
19
20
21static lua_State *getco (lua_State *L) {
22 lua_State *co = lua_tothread(L, 1);
23 luaL_argexpected(L, co, 1, "thread");
24 return co;
25}
26
27
28/*
29** Resumes a coroutine. Returns the number of results for non-error
30** cases or -1 for errors.
31*/
32static int auxresume (lua_State *L, lua_State *co, int narg) {
33 int status, nres;
34 if (l_unlikely(!lua_checkstack(co, narg))) {
35 lua_pushliteral(L, "too many arguments to resume");
36 return -1; /* error flag */
37 }
38 lua_xmove(L, co, narg);
39 status = lua_resume(co, L, narg, &nres);
40 if (l_likely(status == LUA_OK || status == LUA_YIELD)) {
41 if (l_unlikely(!lua_checkstack(L, nres + 1))) {
42 lua_pop(co, nres); /* remove results anyway */
43 lua_pushliteral(L, "too many results to resume");
44 return -1; /* error flag */
45 }
46 lua_xmove(co, L, nres); /* move yielded values */
47 return nres;
48 }
49 else {
50 lua_xmove(co, L, 1); /* move error message */
51 return -1; /* error flag */
52 }
53}
54
55
56static int luaB_coresume (lua_State *L) {
57 lua_State *co = getco(L);
58 int r;
59 r = auxresume(L, co, lua_gettop(L) - 1);
60 if (l_unlikely(r < 0)) {
61 lua_pushboolean(L, 0);
62 lua_insert(L, -2);
63 return 2; /* return false + error message */
64 }
65 else {
66 lua_pushboolean(L, 1);
67 lua_insert(L, -(r + 1));
68 return r + 1; /* return true + 'resume' returns */
69 }
70}
71
72
73static int luaB_auxwrap (lua_State *L) {
74 lua_State *co = lua_tothread(L, lua_upvalueindex(1));
75 int r = auxresume(L, co, lua_gettop(L));
76 if (l_unlikely(r < 0)) { /* error? */
77 int stat = lua_status(co);
78 if (stat != LUA_OK && stat != LUA_YIELD) { /* error in the coroutine? */
79 stat = lua_closethread(co, L); /* close its tbc variables */
80 lua_assert(stat != LUA_OK);
81 lua_xmove(co, L, 1); /* move error message to the caller */
82 }
83 if (stat != LUA_ERRMEM && /* not a memory error and ... */
84 lua_type(L, -1) == LUA_TSTRING) { /* ... error object is a string? */
85 luaL_where(L, 1); /* add extra info, if available */
86 lua_insert(L, -2);
87 lua_concat(L, 2);
88 }
89 return lua_error(L); /* propagate error */
90 }
91 return r;
92}
93
94
95static int luaB_cocreate (lua_State *L) {
96 lua_State *NL;
97 luaL_checktype(L, 1, LUA_TFUNCTION);
98 NL = lua_newthread(L);
99 lua_pushvalue(L, 1); /* move function to top */
100 lua_xmove(L, NL, 1); /* move function from L to NL */
101 return 1;
102}
103
104
105static int luaB_cowrap (lua_State *L) {
106 luaB_cocreate(L);
107 lua_pushcclosure(L, luaB_auxwrap, 1);
108 return 1;
109}
110
111
112static int luaB_yield (lua_State *L) {
113 return lua_yield(L, lua_gettop(L));
114}
115
116
117#define COS_RUN 0
118#define COS_DEAD 1
119#define COS_YIELD 2
120#define COS_NORM 3
121
122
123static const char *const statname[] =
124 {"running", "dead", "suspended", "normal"};
125
126
127static int auxstatus (lua_State *L, lua_State *co) {
128 if (L == co) return COS_RUN;
129 else {
130 switch (lua_status(co)) {
131 case LUA_YIELD:
132 return COS_YIELD;
133 case LUA_OK: {
134 lua_Debug ar;
135 if (lua_getstack(co, 0, &ar)) /* does it have frames? */
136 return COS_NORM; /* it is running */
137 else if (lua_gettop(co) == 0)
138 return COS_DEAD;
139 else
140 return COS_YIELD; /* initial state */
141 }
142 default: /* some error occurred */
143 return COS_DEAD;
144 }
145 }
146}
147
148
149static int luaB_costatus (lua_State *L) {
150 lua_State *co = getco(L);
151 lua_pushstring(L, statname[auxstatus(L, co)]);
152 return 1;
153}
154
155
156static int luaB_yieldable (lua_State *L) {
157 lua_State *co = lua_isnone(L, 1) ? L : getco(L);
158 lua_pushboolean(L, lua_isyieldable(co));
159 return 1;
160}
161
162
163static int luaB_corunning (lua_State *L) {
164 int ismain = lua_pushthread(L);
165 lua_pushboolean(L, ismain);
166 return 2;
167}
168
169
170static int luaB_close (lua_State *L) {
171 lua_State *co = getco(L);
172 int status = auxstatus(L, co);
173 switch (status) {
174 case COS_DEAD: case COS_YIELD: {
175 status = lua_closethread(co, L);
176 if (status == LUA_OK) {
177 lua_pushboolean(L, 1);
178 return 1;
179 }
180 else {
181 lua_pushboolean(L, 0);
182 lua_xmove(co, L, 1); /* move error message */
183 return 2;
184 }
185 }
186 default: /* normal or running coroutine */
187 return luaL_error(L, "cannot close a %s coroutine", statname[status]);
188 }
189}
190
191
192static const luaL_Reg co_funcs[] = {
193 {"create", luaB_cocreate},
194 {"resume", luaB_coresume},
195 {"running", luaB_corunning},
196 {"status", luaB_costatus},
197 {"wrap", luaB_cowrap},
198 {"yield", luaB_yield},
199 {"isyieldable", luaB_yieldable},
200 {"close", luaB_close},
201 {NULL, NULL}
202};
203
204
205
206LUAMOD_API int luaopen_coroutine (lua_State *L) {
207 luaL_newlib(L, co_funcs);
208 return 1;
209}
210