lcorolib.c revision 344220 
1/*
2** $Id: lcorolib.c,v 1.10.1.1 2017/04/19 17:20:42 roberto Exp $
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_argcheck(L, co, 1, "thread expected");
24  return co;
25}
26
27
28static int auxresume (lua_State *L, lua_State *co, int narg) {
29  int status;
30  if (!lua_checkstack(co, narg)) {
31    lua_pushliteral(L, "too many arguments to resume");
32    return -1;  /* error flag */
33  }
34  if (lua_status(co) == LUA_OK && lua_gettop(co) == 0) {
35    lua_pushliteral(L, "cannot resume dead coroutine");
36    return -1;  /* error flag */
37  }
38  lua_xmove(L, co, narg);
39  status = lua_resume(co, L, narg);
40  if (status == LUA_OK || status == LUA_YIELD) {
41    int nres = lua_gettop(co);
42    if (!lua_checkstack(L, nres + 1)) {
43      lua_pop(co, nres);  /* remove results anyway */
44      lua_pushliteral(L, "too many results to resume");
45      return -1;  /* error flag */
46    }
47    lua_xmove(co, L, nres);  /* move yielded values */
48    return nres;
49  }
50  else {
51    lua_xmove(co, L, 1);  /* move error message */
52    return -1;  /* error flag */
53  }
54}
55
56
57static int luaB_coresume (lua_State *L) {
58  lua_State *co = getco(L);
59  int r;
60  r = auxresume(L, co, lua_gettop(L) - 1);
61  if (r < 0) {
62    lua_pushboolean(L, 0);
63    lua_insert(L, -2);
64    return 2;  /* return false + error message */
65  }
66  else {
67    lua_pushboolean(L, 1);
68    lua_insert(L, -(r + 1));
69    return r + 1;  /* return true + 'resume' returns */
70  }
71}
72
73
74static int luaB_auxwrap (lua_State *L) {
75  lua_State *co = lua_tothread(L, lua_upvalueindex(1));
76  int r = auxresume(L, co, lua_gettop(L));
77  if (r < 0) {
78    if (lua_type(L, -1) == LUA_TSTRING) {  /* error object is a string? */
79      luaL_where(L, 1);  /* add extra info */
80      lua_insert(L, -2);
81      lua_concat(L, 2);
82    }
83    return lua_error(L);  /* propagate error */
84  }
85  return r;
86}
87
88
89static int luaB_cocreate (lua_State *L) {
90  lua_State *NL;
91  luaL_checktype(L, 1, LUA_TFUNCTION);
92  NL = lua_newthread(L);
93  lua_pushvalue(L, 1);  /* move function to top */
94  lua_xmove(L, NL, 1);  /* move function from L to NL */
95  return 1;
96}
97
98
99static int luaB_cowrap (lua_State *L) {
100  luaB_cocreate(L);
101  lua_pushcclosure(L, luaB_auxwrap, 1);
102  return 1;
103}
104
105
106static int luaB_yield (lua_State *L) {
107  return lua_yield(L, lua_gettop(L));
108}
109
110
111static int luaB_costatus (lua_State *L) {
112  lua_State *co = getco(L);
113  if (L == co) lua_pushliteral(L, "running");
114  else {
115    switch (lua_status(co)) {
116      case LUA_YIELD:
117        lua_pushliteral(L, "suspended");
118        break;
119      case LUA_OK: {
120        lua_Debug ar;
121        if (lua_getstack(co, 0, &ar) > 0)  /* does it have frames? */
122          lua_pushliteral(L, "normal");  /* it is running */
123        else if (lua_gettop(co) == 0)
124            lua_pushliteral(L, "dead");
125        else
126          lua_pushliteral(L, "suspended");  /* initial state */
127        break;
128      }
129      default:  /* some error occurred */
130        lua_pushliteral(L, "dead");
131        break;
132    }
133  }
134  return 1;
135}
136
137
138static int luaB_yieldable (lua_State *L) {
139  lua_pushboolean(L, lua_isyieldable(L));
140  return 1;
141}
142
143
144static int luaB_corunning (lua_State *L) {
145  int ismain = lua_pushthread(L);
146  lua_pushboolean(L, ismain);
147  return 2;
148}
149
150
151static const luaL_Reg co_funcs[] = {
152  {"create", luaB_cocreate},
153  {"resume", luaB_coresume},
154  {"running", luaB_corunning},
155  {"status", luaB_costatus},
156  {"wrap", luaB_cowrap},
157  {"yield", luaB_yield},
158  {"isyieldable", luaB_yieldable},
159  {NULL, NULL}
160};
161
162
163
164LUAMOD_API int luaopen_coroutine (lua_State *L) {
165  luaL_newlib(L, co_funcs);
166  return 1;
167}
168
169