table.concat

1 files changed, 92 insertions, 0 deletions

diff --git a/src/ltablib.js b/src/ltablib.js
new file mode 100644
index 0000000..8e1f758
--- /dev/null
+++ b/src/ltablib.js
@@ -0,0 +1,92 @@
+/* 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 ldebug  = require('./ldebug.js');
+const CT      = lua.constant_types;
+const TS      = lua.thread_status;
+
+
+/*
+** Operations that an object must define to mimic a table
+** (some functions only need some of them)
+*/
+const TAB_R  = 1;               /* read */
+const TAB_W  = 2;               /* write */
+const TAB_L  = 4;               /* length */
+const TAB_RW = (TAB_R | TAB_W); /* read/write */
+
+const checkfield = function(L, key, n) {
+    lapi.lua_pushstring(L, key);
+    return lapi.lua_rawget(L, -n) !== CT.LUA_TNIL;
+};
+
+/*
+** Check that 'arg' either is a table or can behave like one (that is,
+** has a metatable with the required metamethods)
+*/
+const checktab = function(L, arg, what) {
+    if (lapi.lua_type(L, arg) !== CT.LUA_TTABLE) {  /* is it not a table? */
+        let n = 1;
+        if (lapi.lua_getmetatable(L, arg) &&  /* must have metatable */
+            (!(what & TAB_R) || checkfield(L, "__index", ++n)) &&
+            (!(what & TAB_W) || checkfield(L, "__newindex", ++n)) &&
+            (!(what & TAB_L) || checkfield(L, "__len", ++n))) {
+            lapi.lua_pop(L, n);  /* pop metatable and tested metamethods */
+        }
+        else
+            lauxlib.luaL_checktype(L, arg, CT.LUA_TTABLE);  /* force an error */
+    }
+};
+
+const aux_getn = function(L, n, w) {
+    checktab(L, n, w | TAB_L);
+    lauxlib.luaL_len(L, n);
+};
+
+const addfield = function(L, b, i) {
+    lapi.lua_geti(L, 1, i);
+    if (!lapi.lua_isstring(L, -1))
+        lauxlib.luaL_error(L, `invalid value (${lauxlib.luaL_typename(L, -1)}) at index ${i} in table for 'concat'`);
+
+    lauxlib.luaL_addvalue(b);
+};
+
+const tconcat = function(L) {
+    let last = aux_getn(L, 1, TAB_R);
+    let sep = lauxlib.luaL_optlstring(L, 2, "");
+    let i = lauxlib.luaL_optinteger(L, 3, 1);
+    last = lauxlib.luaL_optinteger(L, 4, last);
+
+    let b = new lauxlib.luaL_Buffer();
+    lauxlib.luaL_buffinit(L, b);
+
+    for (; i < last; i++) {
+        addfield(L, b, i);
+        lauxlib.luaL_addlstring(b, sep);
+    }
+
+    if (i === last)
+        addfield(L, b, i);
+
+    lauxlib.luaL_pushresult(b);
+
+    return 1;
+};
+
+const tab_funcs = {
+    "concat": tconcat
+};
+
+const luaopen_table = function(L) {
+    lauxlib.luaL_newlib(L, tab_funcs);
+    return 1;
+};
+
+module.exports.luaopen_table = luaopen_table;
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