coroutines

1 files changed, 86 insertions, 0 deletions

diff --git a/src/lcorolib.js b/src/lcorolib.js
new file mode 100644
index 0000000..73699a7
--- /dev/null
+++ b/src/lcorolib.js
@@ -0,0 +1,86 @@
+/* jshint esversion: 6 */
+"use strict";
+
+const assert  = require('assert');
+
+const lua     = require('./lua.js');
+const lapi    = require('./lapi.js');
+const lauxlib = require('./lauxlib.js');
+const lstate  = require('./lstate.js');
+const ldo     = require('./ldo.js');
+const CT      = lua.constant_types;
+const TS      = lua.thread_status;
+
+const getco = function(L) {
+    let co = lapi.lua_tothread(L, 1);
+    lauxlib.luaL_argcheck(L, co, 1, "thread expected");
+    return co;
+};
+
+const auxresume = function(L, co, narg) {
+    if (!lapi.lua_checkstack(co, narg)) {
+        lapi.lua_pushliteral(L, "too many arguments to resume");
+        return -1;  /* error flag */
+    }
+
+    if (lapi.lua_status(co) === TS.LUA_OK && lapi.lua_gettop(co) === 0) {
+        lapi.lua_pushliteral(L, "cannot resume dead coroutine");
+        return -1;  /* error flag */
+    }
+
+    lapi.lua_xmove(L, co, narg);
+    let status = ldo.lua_resume(co, L, narg);
+    if (status === TS.LUA_OK || status === TS.LUA_YIELD) {
+        let nres = lapi.lua_gettop(L);
+        if (!lapi.lua_checkstack(L, nres + 1)) {
+            lapi.lua_pop(co, nres);  /* remove results anyway */
+            lapi.lua_pushliteral(L, "too many results to resume");
+            return -1;  /* error flag */
+        }
+
+        lapi.lua_xmove(co,  L, nres);  /* move yielded values */
+        return nres;
+    } else {
+        lapi.lua_xmove(co, L, 1);  /* move error message */
+        return -1;  /* error flag */
+    }
+};
+
+const luaB_resume = function(L) {
+    let co = getco(L);
+    let r = auxresume(L, co, lapi.lua_gettop(L) - 1);
+    if (r < 0) {
+        lapi.lua_pushboolean(L, 0);
+        lapi.lua_insert(L, -2);
+        return 2;  /* return false + error message */
+    } else {
+        lapi.lua_pushboolean(L, 1);
+        lapi.lua_insert(L, -(r + 1));
+        return r + 1;  /* return true + 'resume' returns */
+    }
+};
+
+const luaB_cocreate = function(L) {
+    lauxlib.luaL_checktype(L, 1, CT.LUA_TFUNCTION);
+    let NL = lstate.lua_newthread(L);
+    lapi.lua_pushvalue(L, 1);  /* move function to top */
+    lapi.lua_xmove(L, NL, 1);  /* move function from L to NL */
+    return 1;
+};
+
+const luaB_yield = function(L) {
+    return ldo.lua_yield(L, lapi.lua_gettop(L));
+};
+
+const co_funcs = {
+    "create":  luaB_cocreate,
+    "yield":   luaB_yield,
+    "resume":  luaB_resume
+};
+
+const luaopen_coroutine = function(L) {
+    lauxlib.luaL_newlib(L, co_funcs);
+    return 1;
+};
+
+module.exports.luaopen_coroutine = luaopen_coroutine;
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