# HG changeset patch
# User jbe
# Date 1406832556 -7200
# Node ID 8e969519f7c722e4d9689f5ea015df49bb6707ee
# Parent  581878c613d664ad7ee31056362d18226c311427
JSON pretty printer

diff -r 581878c613d6 -r 8e969519f7c7 libraries/json/json.c
--- a/libraries/json/json.c	Thu Jul 31 19:27:29 2014 +0200
+++ b/libraries/json/json.c	Thu Jul 31 20:49:16 2014 +0200
@@ -212,7 +212,7 @@
     // limit nested levels:
     if (level >= JSON_MAXDEPTH) {
       lua_pushnil(L);
-      lua_pushliteral(L, "Too many nested JSON levels");
+      lua_pushfstring(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
       return 2;
     }
     // additional buffer overflow protection:
@@ -711,7 +711,15 @@
 #define JSON_TABLETYPE_OBJECT 1
 #define JSON_TABLETYPE_ARRAY 2
 
-static int json_export(lua_State *L) {
+#define json_export_internal_indentstring_idx 1
+#define json_export_internal_level_idx 2
+#define json_export_internal_value_idx 3
+#define json_export_internal_tmp_idx 4
+
+static int json_export_internal(lua_State *L) {
+  int level;
+  int pretty;
+  int i;
   lua_Number num;
   const char *str;
   unsigned char c;
@@ -719,34 +727,36 @@
   size_t pos = 0;
   luaL_Buffer buf;
   char hexcode[7];  // backslash, character 'u', 4 hex digits, and terminating NULL byte
-  int luatype;
   int tabletype = JSON_TABLETYPE_UNKNOWN;
-  int needsep = 0;
+  int anyelement = 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)) {
+  lua_settop(L, json_export_internal_value_idx);
+  if (json_isnullmark(L, json_export_internal_value_idx)) {
+    lua_pop(L, 1);
     lua_pushnil(L);
-    lua_replace(L, 1);
   }
-  switch (lua_type(L, 1)) {
+  switch (lua_type(L, json_export_internal_value_idx)) {
   case LUA_TNIL:
     lua_pushliteral(L, "null");
     return 1;
   case LUA_TNUMBER:
-    num = lua_tonumber(L, 1);
+    num = lua_tonumber(L, json_export_internal_value_idx);
     if (isnan(num)) return luaL_error(L, "JSON export not possible for NaN value");
     if (isinf(num)) return luaL_error(L, "JSON export not possible for infinite numbers");
-    lua_tostring(L, 1);
+    lua_tostring(L, json_export_internal_value_idx);
     return 1;
   case LUA_TBOOLEAN:
-    if (lua_toboolean(L, 1)) lua_pushliteral(L, "true");
-    else lua_pushliteral(L, "false");
+    if (lua_toboolean(L, json_export_internal_value_idx)) {
+      lua_pushliteral(L, "true");
+    } else {
+      lua_pushliteral(L, "false");
+    }
     return 1;
   case LUA_TSTRING:
-    str = lua_tolstring(L, 1, &strlen);
+    str = lua_tolstring(L, 3, &strlen);
     luaL_buffinit(L, &buf);
     luaL_addchar(&buf, '"');
     while (pos < strlen) {
@@ -770,43 +780,55 @@
     luaL_pushresult(&buf);
     return 1;
   case LUA_TTABLE:
-    if (lua_getmetatable(L, 1)) {
+    if (lua_getmetatable(L, json_export_internal_value_idx)) {
       json_regfetch(L, objectmt);
       if (lua_rawequal(L, -2, -1)) {
         tabletype = JSON_TABLETYPE_OBJECT;
       } else {
         json_regfetch(L, arraymt);
-        if (lua_rawequal(L, -3, -1)) tabletype = JSON_TABLETYPE_ARRAY;
+        if (lua_rawequal(L, -3, -1)) {
+          tabletype = JSON_TABLETYPE_ARRAY;
+        } else {
+          return luaL_error(L, "JSON export not possible for tables with nonsupported metatable");
+        }
       }
     }
     json_regfetch(L, shadowtbl);
-    lua_pushvalue(L, 1);
+    lua_pushvalue(L, json_export_internal_value_idx);
     lua_rawget(L, -2);
-    if (!lua_isnil(L, -1)) lua_replace(L, 1);
-    lua_settop(L, 1);
+    if (!lua_isnil(L, -1)) lua_replace(L, json_export_internal_value_idx);
+    lua_settop(L, json_export_internal_value_idx);
     if (tabletype == JSON_TABLETYPE_UNKNOWN) {
-      for (lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
-        luatype = lua_type(L, -2);
-        if (tabletype == JSON_TABLETYPE_UNKNOWN) {
-          if (luatype == LUA_TSTRING) tabletype = JSON_TABLETYPE_OBJECT;
-          else if (luatype == LUA_TNUMBER) tabletype = JSON_TABLETYPE_ARRAY;
-        } else if (
-          (tabletype == JSON_TABLETYPE_OBJECT && luatype == LUA_TNUMBER) ||
-          (tabletype == JSON_TABLETYPE_ARRAY && luatype == LUA_TSTRING)
-        ) {
-          goto json_export_tabletype_error;
+      for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
+        switch (lua_type(L, -2)) {
+        case LUA_TSTRING:
+          keycount++;
+          if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_OBJECT;
+          else if (tabletype == JSON_TABLETYPE_ARRAY) goto json_export_tabletype_error;
+          break;
+        case LUA_TNUMBER:
+          if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_ARRAY;
+          else if (tabletype == JSON_TABLETYPE_OBJECT) goto json_export_tabletype_error;
+          break;
         }
       }
     }
+    pretty = lua_toboolean(L, json_export_internal_indentstring_idx);
+    level = lua_tointeger(L, json_export_internal_level_idx) + 1;
+    if (level > JSON_MAXDEPTH) {
+      return luaL_error(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
+    }
     switch (tabletype) {
     case JSON_TABLETYPE_OBJECT:
-      for (lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
-        if (lua_type(L, -2) == LUA_TSTRING) keycount++;
+      if (!keycount) {
+        for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); 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)) {
+        for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); 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);
@@ -819,46 +841,83 @@
       for (keypos=0; keypos<keycount; keypos++) {
         json_key_t *key = keybuf + keypos;
         if (keypos) luaL_addchar(&buf, ',');
-        lua_pushcfunction(L, json_export);
+        if (pretty) {
+          luaL_addchar(&buf, '\n');
+          for (i=0; i<level; i++) {
+            lua_pushvalue(L, json_export_internal_indentstring_idx);
+            luaL_addvalue(&buf);
+          }
+        }
+        lua_pushcfunction(L, json_export_internal);
+        lua_pushvalue(L, json_export_internal_indentstring_idx);
+        lua_pushinteger(L, level);
         lua_pushlstring(L, key->data, key->length);
-        if (lua_pcall(L, 1, 1, 0)) {
+        if (lua_pcall(L, 3, 1, 0)) {
           if (keybuf) free(keybuf);
           return lua_error(L);
         }
         luaL_addvalue(&buf);
         luaL_addchar(&buf, ':');
-        lua_pushcfunction(L, json_export);
+        if (pretty) luaL_addchar(&buf, ' ');
+        lua_pushcfunction(L, json_export_internal);
+        lua_pushvalue(L, json_export_internal_indentstring_idx);
+        lua_pushinteger(L, level);
         lua_pushlstring(L, key->data, key->length);
-        lua_rawget(L, 1);
-        if (lua_pcall(L, 1, 1, 0)) {
+        lua_rawget(L, json_export_internal_value_idx);
+        if (lua_pcall(L, 3, 1, 0)) {
           if (keybuf) free(keybuf);
           return lua_error(L);
         }
         luaL_addvalue(&buf);
       }
       if (keybuf) free(keybuf);
+      if (pretty && keycount != 0) {
+        luaL_addchar(&buf, '\n');
+        for (i=0; i<level-1; i++) {
+          lua_pushvalue(L, json_export_internal_indentstring_idx);
+          luaL_addvalue(&buf);
+        }
+      }
       luaL_addchar(&buf, '}');
+      if (pretty && level == 1) luaL_addchar(&buf, '\n');
       luaL_pushresult(&buf);
       return 1;
     case JSON_TABLETYPE_ARRAY:
-      lua_settop(L, 2);
+      lua_settop(L, json_export_internal_tmp_idx);
       luaL_buffinit(L, &buf);
       luaL_addchar(&buf, '[');
       for (idx = 1; ; idx++) {
-        lua_rawgeti(L, 1, idx);
+        lua_rawgeti(L, json_export_internal_value_idx, idx);
         if (lua_isnil(L, -1)) {
           lua_pop(L, 1);
           break;
         }
-        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);
+        lua_replace(L, json_export_internal_tmp_idx);
+        if (anyelement) luaL_addchar(&buf, ',');
+        anyelement = 1;
+        if (pretty) {
+          luaL_addchar(&buf, '\n');
+          for (i=0; i<level; i++) {
+            lua_pushvalue(L, json_export_internal_indentstring_idx);
+            luaL_addvalue(&buf);
+          }
+        }
+        lua_pushcfunction(L, json_export_internal);
+        lua_pushvalue(L, json_export_internal_indentstring_idx);
+        lua_pushinteger(L, level);
+        lua_pushvalue(L, json_export_internal_tmp_idx);
+        lua_call(L, 3, 1);
         luaL_addvalue(&buf);
       }
+      if (pretty && anyelement) {
+        luaL_addchar(&buf, '\n');
+        for (i=0; i<level-1; i++) {
+          lua_pushvalue(L, json_export_internal_indentstring_idx);
+          luaL_addvalue(&buf);
+        }
+      }
       luaL_addchar(&buf, ']');
+      if (pretty && level == 1) luaL_addchar(&buf, '\n');
       luaL_pushresult(&buf);
       return 1;
     }
@@ -868,12 +927,34 @@
   return luaL_error(L, "JSON export not possible for values of type \"%s\"", lua_typename(L, lua_type(L, 1)));
 }
 
+static int json_export(lua_State *L) {
+  lua_settop(L, 1);
+  lua_pushcfunction(L, json_export_internal);
+  lua_pushnil(L);
+  lua_pushinteger(L, 0);
+  lua_pushvalue(L, 1);
+  lua_call(L, 3, 1);
+  return 1;
+}
+
+static int json_pretty(lua_State *L) {
+  lua_settop(L, 2);
+  lua_pushcfunction(L, json_export_internal);
+  if (lua_isnil(L, 2)) lua_pushliteral(L, "  ");
+  else lua_pushvalue(L, 2);
+  lua_pushinteger(L, 0);
+  lua_pushvalue(L, 1);
+  lua_call(L, 3, 1);
+  return 1;
+}
+
 // functions in library module:
 static const struct luaL_Reg json_module_functions[] = {
   {"object", json_object},
   {"array", json_array},
   {"import", json_import},
   {"export", json_export},
+  {"pretty", json_pretty},
   {"get", json_get},
   {"type", json_type},
   {NULL, NULL}