Add support for Lua 5.2 and cjson.new

Update all Lua scripts to use new module init style everywhere:
	local json = require "cjson"

Lua CJSON does not register a global table under Lua 5.2. The global
table can be disabled under Lua 5.1 with DISABLE_CJSON_GLOBAL.

Other changes:
- Store CJSON configuration as an upvalue for each function.
- Add "cjson.new" function to create another module table with a
  separate configuration.
- Add _NAME and _VERSION variables.

8 files changed, 122 insertions, 47 deletions

diff --git a/Makefile b/Makefile
index fb63d99..c9343f9 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,8 @@ LUA_VERSION =   5.1
 
 ## Available defines for CJSON_CFLAGS
 #
-# USE_INTERNAL_ISINF: Workaround for Solaris platforms missing isinf().
+# USE_INTERNAL_ISINF:   Workaround for Solaris platforms missing isinf().
+# DISABLE_CJSON_GLOBAL: Do not store module is "cjson" global
 
 ## Build defaults
 PREFIX =            /usr/local
diff --git a/lua_cjson.c b/lua_cjson.c
index 8e9b237..be5cdc2 100644
--- a/lua_cjson.c
+++ b/lua_cjson.c
@@ -45,6 +45,10 @@
 #include "strbuf.h"
 #include "fpconv.h"
 
+#ifndef CJSON_MODNAME
+#define CJSON_MODNAME   "cjson"
+#endif
+
 #ifndef CJSON_VERSION
 #define CJSON_VERSION   "1.0devel"
 #endif
@@ -175,22 +179,16 @@ static const char *char2escape[256] = {
     NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
 };
 
-static int json_config_key;
-
 /* ===== CONFIGURATION ===== */
 
 static json_config_t *json_fetch_config(lua_State *l)
 {
     json_config_t *cfg;
 
-    lua_pushlightuserdata(l, &json_config_key);
-    lua_gettable(l, LUA_REGISTRYINDEX);
-    cfg = lua_touserdata(l, -1);
+    cfg = lua_touserdata(l, lua_upvalueindex(1));
     if (!cfg)
         luaL_error(l, "BUG: Unable to fetch CJSON configuration");
 
-    lua_pop(l, 1);
-
     return cfg;
 }
 
@@ -1246,7 +1244,27 @@ static int json_decode(lua_State *l)
 
 /* ===== INITIALISATION ===== */
 
-int luaopen_cjson(lua_State *l)
+#if !defined(LUA_VERSION_NUM) || LUA_VERSION_NUM < 502
+/* Compatibility for Lua 5.1.
+ *
+ * luaL_setfuncs() is used to create a module table where the functions have
+ * json_config_t as their first upvalue. Code borrowed from Lua 5.2 source. */
+static void luaL_setfuncs (lua_State *l, const luaL_Reg *reg, int nup)
+{
+    int i;
+
+    luaL_checkstack(l, nup, "too many upvalues");
+    for (; reg->name != NULL; reg++) {  /* fill the table with given functions */
+        for (i = 0; i < nup; i++)  /* copy upvalues to the top */
+            lua_pushvalue(l, -nup);
+        lua_pushcclosure(l, reg->func, nup);  /* closure with those upvalues */
+        lua_setfield(l, -(nup + 2), reg->name);
+    }
+    lua_pop(l, nup);  /* remove upvalues */
+}
+#endif
+
+static int lua_cjson_new(lua_State *l)
 {
     luaL_Reg reg[] = {
         { "encode", json_encode },
@@ -1257,28 +1275,51 @@ int luaopen_cjson(lua_State *l)
         { "encode_keep_buffer", json_cfg_encode_keep_buffer },
         { "refuse_invalid_numbers", json_cfg_refuse_invalid_numbers },
         { "update_locale", json_update_locale },
+        { "new", lua_cjson_new },
         { NULL, NULL }
     };
 
-    /* Update the current locale for g_fmt/strtod */
+    /* Update the current locale for g_fmt/strtod.
+     * Using different locales per-thread is not supported. */
     fpconv_update_locale();
 
-    /* Use json_config_key as a pointer.
-     * It's faster than using a config string, and more unique */
-    lua_pushlightuserdata(l, &json_config_key);
-    json_create_config(l);
-    lua_settable(l, LUA_REGISTRYINDEX);
+    /* cjson module table */
+    lua_newtable(l);
 
-    luaL_register(l, "cjson", reg);
+    /* Register functions with config data as upvalue */
+    json_create_config(l);
+    luaL_setfuncs(l, reg, 1);
 
     /* Set cjson.null */
     lua_pushlightuserdata(l, NULL);
     lua_setfield(l, -2, "null");
 
-    /* Set cjson.version */
+    /* Set module name / version fields */
+    lua_pushliteral(l, CJSON_MODNAME);
+    lua_setfield(l, -2, "_NAME");
+    lua_pushliteral(l, CJSON_VERSION);
+    lua_setfield(l, -2, "_VERSION");
     lua_pushliteral(l, CJSON_VERSION);
     lua_setfield(l, -2, "version");
 
+    return 1;
+}
+
+int luaopen_cjson(lua_State *l)
+{
+    lua_cjson_new(l);
+
+#if !defined(DISABLE_CJSON_GLOBAL) && (!defined(LUA_VERSION_NUM) || LUA_VERSION_NUM < 502)
+    /* Register a global "cjson" table to maintain compatibility with earlier
+     * versions of Lua CJSON which used luaL_register() under Lua 5.1.
+     *
+     * From Lua 5.2 onwards, Lua CJSON does not automatically register a global
+     * table.
+     */
+    lua_pushvalue(l, -1);
+    lua_setglobal(l, CJSON_MODNAME);
+#endif
+
     /* Return cjson table */
     return 1;
 }
diff --git a/manual.txt b/manual.txt
index a3e12cf..810d3d1 100644
--- a/manual.txt
+++ b/manual.txt
@@ -16,8 +16,6 @@ Lua CJSON provides fast JSON parsing and encoding support for Lua.
 
 .Caveats
 - UTF-16 and UTF-32 are not supported.
-- Multi-threading within a single Lua state is not supported
-  (+lua_lock+ / +lua_unlock+).
 
 Lua CJSON is covered by the MIT license. Review the file +LICENSE+ for
 details.
@@ -32,7 +30,7 @@ comments.
 Installation Methods
 --------------------
 
-Lua CJSON requires either http://www.lua.org[Lua] or
+Lua CJSON requires either http://www.lua.org[Lua] 5.1, Lua 5.2, or
 http://www.luajit.org[LuaJIT] to build.
 
 There are 4 build methods available:
@@ -44,11 +42,13 @@ RPM:: Linux
 LuaRocks:: Unix, Windows
 
 
-Build options (#define)
+Build Options (#define)
 ~~~~~~~~~~~~~~~~~~~~~~~
 
 [horizontal]
 USE_INTERNAL_ISINF:: Workaround for Solaris platforms missing isinf().
+DISABLE_CJSON_GLOBAL:: Do not store module table in global "cjson"
+  variable.
 
 
 Make
@@ -125,9 +125,9 @@ Synopsis
 
 [source,lua]
 ------------
-require "cjson"
--- Or:
+-- Module initalisation methods
 local cjson = require "cjson"
+local cjson2 = cjson.new()
  
 -- Translate Lua value to/from JSON
 text = cjson.encode(value)
@@ -141,6 +141,34 @@ keep = cjson.encode_keep_buffer([keep])
 ------------
 
 
+Module Instantiation
+~~~~~~~~~~~~~~~~~~~~
+
+[source,lua]
+------------
+local cjson = require "cjson"
+local cjson2 = cjson.new()
+------------
+
+Lua CJSON can be loaded via +require+. A global +cjson+ table is
+registered under Lua 5.1 to maintain backward compatibility. Lua CJSON
+does not register a global table under Lua 5.2 since this practice is
+discouraged.
+
++cjson.new+ can be used to instantiate an independent copy of the Lua
+CJSON module. The new module has a separate persistent encoding
+buffer, and default settings.
+
+Lua CJSON can support Lua implementations using multiple pre-emptive
+threads within a single Lua state provided the persistent encoding
+buffer is not shared. This can be achieved by one of the following
+methods:
+
+- Disabling the persistent encoding buffer with +encode_keep_buffer+.
+- Ensuring only a single thread calls +encode+ at a time.
+- Using a separate +cjson+ instantiation per pre-emptive thread.
+
+
 decode
 ~~~~~~
 
@@ -423,6 +451,18 @@ Disabled for decoding:: All numbers supported by +strtod+(3) will be parsed.
 API (Variables)
 ---------------
 
+_NAME
+~~~~~
+
+The name of the Lua CJSON module (+"cjson"+).
+
+
+_VERSION
+~~~~~~~~
+
+The version number of the Lua CJSON module (Eg, +"1.0devel"+).
+
+
 null
 ~~~~
 
@@ -430,13 +470,6 @@ Lua CJSON decodes JSON +null+ as a Lua +lightuserdata+ NULL pointer.
 +cjson.null+ is provided for comparison.
 
 
-version
-~~~~~~~
-
-The version number of the Lua CJSON module in use can be found in
-+cjson.version+.
-
-
 [sect1]
 References
 ----------
@@ -445,4 +478,4 @@ References
 - http://www.json.org/[JSON website]
 
 
-// vi:tw=70:
+// vi:ft=asciidoc tw=70:
diff --git a/tests/bench.lua b/tests/bench.lua
index fdd0bb0..c81213d 100755
--- a/tests/bench.lua
+++ b/tests/bench.lua
@@ -72,7 +72,7 @@ function bench_file(filename)
     return benchmark(tests, 0.1, 5)
 end
 
-cjson.encode_keep_buffer(true)
+json.encode_keep_buffer(true)
 
 for i = 1, #arg do
     local results = bench_file(arg[i])
diff --git a/tests/common.lua b/tests/common.lua
index f3dc6f7..7472a10 100644
--- a/tests/common.lua
+++ b/tests/common.lua
@@ -1,4 +1,4 @@
-require "cjson"
+local json = require "cjson"
 
 -- Misc routines to assist with CJSON testing
 --
@@ -77,8 +77,8 @@ function serialise_value(value, indent, depth)
     if indent == nil then indent = "" end
     if depth == nil then depth = 0 end
 
-    if value == cjson.null then
-        return "cjson.null"
+    if value == json.null then
+        return "json.null"
     elseif type(value) == "string" then
         return string.format("%q", value)
     elseif type(value) == "nil" or type(value) == "number" or
diff --git a/tests/decode.lua b/tests/decode.lua
index cac29e6..89354cd 100755
--- a/tests/decode.lua
+++ b/tests/decode.lua
@@ -7,8 +7,8 @@
 -- ./decode.lua test.json
 
 require "common"
-require "cjson"
+local json = require "cjson"
 
 local json_text = file_load(arg[1])
-local t = cjson.decode(json_text)
+local t = json.decode(json_text)
 print(serialise_value(t))
diff --git a/tests/encode.lua b/tests/encode.lua
index f13787c..a8d749a 100755
--- a/tests/encode.lua
+++ b/tests/encode.lua
@@ -7,7 +7,7 @@
 -- ./encode.lua lua_data.lua
 
 require "common"
-require "cjson"
+local json = require "cjson"
 
 function get_lua_table(file)
         local func = loadstring("data = " .. file_load(file))
@@ -23,6 +23,6 @@ function get_lua_table(file)
 end
 
 local t = get_lua_table(arg[1])
-print(cjson.encode(t))
+print(json.encode(t))
 
 -- vi:ai et sw=4 ts=4:
diff --git a/tests/test.lua b/tests/test.lua
index bdae6ea..99ac73a 100755
--- a/tests/test.lua
+++ b/tests/test.lua
@@ -112,8 +112,8 @@ local decode_numeric_tests = {
 
 local encode_table_tests = {
     function()
-        cjson.encode_sparse_array(true, 2, 3)
-        cjson.encode_max_depth(5)
+        json.encode_sparse_array(true, 2, 3)
+        json.encode_max_depth(5)
         return "Setting sparse array (true, 2, 3) / max depth (5)"
     end,
     { json.encode, { { [3] = "sparse test" } },
@@ -211,19 +211,19 @@ local escape_tests = {
 local locale_tests = {
     function ()
         os.setlocale("cs_CZ")
-        cjson.update_locale()
+        json.update_locale()
         return "Setting locale to cs_CZ (comma separator)"
     end,
     { json.encode, { 1.5 }, true, { '1.5' } },
     { json.decode, { "[ 10, \"test\" ]" }, true, { { 10, "test" } } },
     function ()
         os.setlocale("C")
-        cjson.update_locale()
+        json.update_locale()
         return "Reverting locale to POSIX"
     end
 }
 
-print(string.format("Testing Lua CJSON version %s\n", cjson.version))
+print(string.format("Testing Lua CJSON version %s\n", json.version))
 
 run_test_group("decode simple value", decode_simple_tests)
 run_test_group("encode simple value", encode_simple_tests)
@@ -232,7 +232,7 @@ run_test_group("decode numeric", decode_numeric_tests)
 -- INCLUDE:
 -- - Sparse array exception..
 -- - ..
--- cjson.encode_sparse_array(true, 2, 3)
+-- json.encode_sparse_array(true, 2, 3)
 
 run_test_group("encode table", encode_table_tests)
 run_test_group("decode error", decode_error_tests)
@@ -240,8 +240,8 @@ run_test_group("encode error", encode_error_tests)
 run_test_group("escape", escape_tests)
 run_test_group("locale", locale_tests)
 
-cjson.refuse_invalid_numbers(false)
-cjson.encode_max_depth(20)
+json.refuse_invalid_numbers(false)
+json.encode_max_depth(20)
 for i = 1, #arg do
     run_test("decode cycle " .. arg[i], test_decode_cycle, { arg[i] },
              true, { true })