# HG changeset patch
# User jbe
# Date 1406827649 -7200
# Node ID 581878c613d664ad7ee31056362d18226c311427
# Parent  3b8c1e2aef9cb257db28262f9cd5e21d6ae3fcad
Always sort keys in JSON objects when exporting

diff -r 3b8c1e2aef9c -r 581878c613d6 libraries/json/json.c
--- a/libraries/json/json.c	Thu Jul 31 16:24:39 2014 +0200
+++ b/libraries/json/json.c	Thu Jul 31 19:27:29 2014 +0200
@@ -678,6 +678,35 @@
   return 3;
 }
 
+typedef struct {
+  size_t length;
+  const char *data;
+} json_key_t;
+
+static int json_key_cmp(json_key_t *key1, json_key_t *key2) {
+  size_t pos = 0;
+  unsigned char c1, c2;
+  while (1) {
+    if (key1->length > pos) {
+      if (key2->length > pos) {
+        c1 = key1->data[pos];
+        c2 = key2->data[pos];
+        if (c1 < c2) return -1;
+        else if (c1 > c2) return 1;
+      } else {
+        return 1;
+      }
+    } else {
+      if (key2->length > pos) {
+        return -1;
+      } else {
+        return 0;
+      }
+    }
+    pos++;
+  }
+}
+
 #define JSON_TABLETYPE_UNKNOWN 0
 #define JSON_TABLETYPE_OBJECT 1
 #define JSON_TABLETYPE_ARRAY 2
@@ -693,6 +722,9 @@
   int luatype;
   int tabletype = JSON_TABLETYPE_UNKNOWN;
   int needsep = 0;
+  size_t keycount = 0;
+  size_t keypos = 0;
+  json_key_t *keybuf;
   lua_Integer idx;
   lua_settop(L, 1);
   if (json_isnullmark(L, 1)) {
@@ -768,33 +800,43 @@
     }
     switch (tabletype) {
     case JSON_TABLETYPE_OBJECT:
-      lua_settop(L, 3);
+      for (lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
+        if (lua_type(L, -2) == LUA_TSTRING) keycount++;
+      }
+      if (keycount) {
+        keybuf = calloc(keycount, sizeof(json_key_t));
+        if (!keybuf) return luaL_error(L, "Memory allocation failed in JSON library");
+        for (lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
+          if (lua_type(L, -2) == LUA_TSTRING) {
+            json_key_t *key = keybuf + (keypos++);
+            key->data = lua_tolstring(L, -2, &key->length);
+          }
+        }
+        qsort(keybuf, keycount, sizeof(json_key_t), (void *)json_key_cmp);
+      }
       luaL_buffinit(L, &buf);
       luaL_addchar(&buf, '{');
-      for (lua_pushnil(L); lua_next(L, 1); ) {
-        if (lua_type(L, -2) == LUA_TSTRING) {
-          lua_replace(L, 3);
-          lua_replace(L, 2);
-          if (needsep) luaL_addchar(&buf, ',');
-          else needsep = 1;
-          lua_pushcfunction(L, json_export);
-          lua_pushvalue(L, 2);
-          lua_call(L, 1, 1);
-          luaL_addvalue(&buf);
-          luaL_addchar(&buf, ':');
-          if (json_isnullmark(L, 3)) {
-            luaL_addstring(&buf, "null");
-          } else {
-            lua_pushcfunction(L, json_export);
-            lua_pushvalue(L, 3);
-            lua_call(L, 1, 1);
-            luaL_addvalue(&buf);
-          }
-          lua_pushvalue(L, 2);
-        } else {
-          lua_pop(L, 1);
+      for (keypos=0; keypos<keycount; keypos++) {
+        json_key_t *key = keybuf + keypos;
+        if (keypos) luaL_addchar(&buf, ',');
+        lua_pushcfunction(L, json_export);
+        lua_pushlstring(L, key->data, key->length);
+        if (lua_pcall(L, 1, 1, 0)) {
+          if (keybuf) free(keybuf);
+          return lua_error(L);
         }
+        luaL_addvalue(&buf);
+        luaL_addchar(&buf, ':');
+        lua_pushcfunction(L, json_export);
+        lua_pushlstring(L, key->data, key->length);
+        lua_rawget(L, 1);
+        if (lua_pcall(L, 1, 1, 0)) {
+          if (keybuf) free(keybuf);
+          return lua_error(L);
+        }
+        luaL_addvalue(&buf);
       }
+      if (keybuf) free(keybuf);
       luaL_addchar(&buf, '}');
       luaL_pushresult(&buf);
       return 1;