feat(require('tomlua.env')): add a useful utility for the cli command

Makefile

@@ -76,6 +76,7 @@ TESTDIR         := $(SRC)/tests
 SRCS            := $(SRC)/src/tomlua.c \
                   $(SRC)/src/decode.c \
                   $(SRC)/src/encode.c \
+                  $(SRC)/src/env.c \
                   $(SRC)/src/dates.c
 
 CLI_SRCS        := $(SRC)/src/tomlua_cli.c \

src/env.c

@@ -0,0 +1,54 @@
+#include <stdlib.h>
+#include <lua.h>
+#include <lauxlib.h>
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+static int env__newindex(lua_State *L) {
+    const char *key = luaL_checkstring(L, 2);
+#ifdef _WIN32
+    if (lua_isnil(L, 3)) {
+        if (SetEnvironmentVariable(key, NULL) == 0) {
+            return luaL_error(L, "failed to unset env var");
+        }
+    } else if (lua_type(L, 3) == LUA_TSTRING) {
+        if (SetEnvironmentVariable(key, lua_tostring(L, 3)) == 0) {
+            return luaL_error(L, "failed to set env var");
+        }
+#else
+    if (lua_isnil(L, 3)) {
+        if (unsetenv(key) != 0) {
+            return luaL_error(L, "failed to unset env var");
+        }
+    } else if (lua_type(L, 3) == LUA_TSTRING) {
+        if (setenv(key, lua_tostring(L, 3), 1) != 0) {
+            return luaL_error(L, "failed to set env var");
+        }
+#endif
+    } else {
+        return luaL_error(L, "env values must be strings or nil");
+    }
+    return 0;
+}
+
+static int env__index(lua_State *L) {
+    const char *key = luaL_checkstring(L, 2);
+    const char *val = getenv(key);
+    if (val)
+        lua_pushstring(L, val);
+    else
+        lua_pushnil(L);
+    return 1;
+}
+
+int luaopen_tomlua_env(lua_State *L) {
+    lua_newtable(L); // module table
+    lua_newtable(L); // metatable
+    lua_pushcfunction(L, env__index);
+    lua_setfield(L, -2, "__index");
+    lua_pushcfunction(L, env__newindex);
+    lua_setfield(L, -2, "__newindex");
+    lua_setmetatable(L, -2); // setmetatable(t, mt)
+    return 1; // return env table
+}

src/tomlua_cli.c

@@ -8,6 +8,7 @@
 #include <string.h>
 
 extern int luaopen_tomlua(lua_State *L);
+extern int luaopen_tomlua_env(lua_State *L);
 
 static void inject_tomlua(lua_State *L) {
     lua_getglobal(L, "package");
@@ -16,6 +17,9 @@ static void inject_tomlua(lua_State *L) {
     lua_pushcfunction(L, luaopen_tomlua);
     lua_setfield(L, -2, "tomlua");
 
+    lua_pushcfunction(L, luaopen_tomlua_env);
+    lua_setfield(L, -2, "tomlua.env");
+
     lua_pop(L, 2);
 }
 

tests/opts_test.lua

@@ -42,3 +42,12 @@ define("opts({ int_keys = true }) doesn't copy", function()
     local opts = tomlua.opts()
     ok(type(opts) == "table", "opts when called with no args should return a table")
 end)
+
+define("require('tomlua.env') tests", function()
+    local env = require("tomlua.env")
+    ok(env ~= nil, "tomlua.env should be available")
+    env.TESTVARIABLE = "HELLO"
+    ok(env.TESTVARIABLE == os.getenv("TESTVARIABLE"), "tomlua.env should get the env var")
+    env.TESTVARIABLE = nil
+    ok(env.TESTVARIABLE == os.getenv("TESTVARIABLE"), "tomlua.env should be removed just like the env var")
+end)