Add 'minetest.write_json'

2 files changed, 52 insertions, 0 deletions

diff --git a/src/script/common/c_content.cpp b/src/script/common/c_content.cpp
index cf9f28d30..8eb57ba41 100644
--- a/src/script/common/c_content.cpp
+++ b/src/script/common/c_content.cpp
@@ -1081,3 +1081,52 @@ bool push_json_value(lua_State *L, const Json::Value &value, int nullindex)
 	else
 		return false;
 }
+
+// Converts Lua table --> JSON
+void get_json_value(lua_State *L, Json::Value &root, int index)
+{
+	int type = lua_type(L, index);
+	if (type == LUA_TBOOLEAN) {
+		root = (bool) lua_toboolean(L, index);
+	} else if (type == LUA_TNUMBER) {
+		root = lua_tonumber(L, index);
+	} else if (type == LUA_TSTRING) {
+		size_t len;
+		const char *str = lua_tolstring(L, index, &len);
+		root = std::string(str, len);
+	} else if (type == LUA_TTABLE) {
+		lua_pushnil(L);
+		while (lua_next(L, index)) {
+			// Key is at -2 and value is at -1
+			Json::Value value;
+			get_json_value(L, value, lua_gettop(L));
+
+			Json::ValueType roottype = root.type();
+			int keytype = lua_type(L, -1);
+			if (keytype == LUA_TNUMBER) {
+				lua_Number key = lua_tonumber(L, -1);
+				if (roottype != Json::nullValue && roottype != Json::arrayValue) {
+					throw LuaError(NULL, "Can't mix array and object values in JSON");
+				} else if (key < 1) {
+					throw LuaError(NULL, "Can't use zero-based or negative indexes in JSON");
+				} else if (floor(key) != key) {
+					throw LuaError(NULL, "Can't use indexes with a fractional part in JSON");
+				}
+				root[(Json::ArrayIndex) key - 1] = value;
+			} else if (keytype == LUA_TSTRING) {
+				if (roottype != Json::nullValue && roottype != Json::objectValue) {
+					throw LuaError(NULL, "Can't mix array and object values in JSON");
+				}
+				root[lua_tostring(L, -1)] = value;
+			} else {
+				throw LuaError(NULL, "Lua key to convert to JSON is not a string or number");
+			}
+		}
+	} else if (type == LUA_TNIL) {
+		root = Json::nullValue;
+	} else {
+		throw LuaError(NULL, "Can only store booleans, numbers, strings, objects, arrays, and null in JSON");
+	}
+	lua_pop(L, 1); // Pop value
+}
+
diff --git a/src/script/common/c_content.h b/src/script/common/c_content.h
index 27019e29e..3b85e5403 100644
--- a/src/script/common/c_content.h
+++ b/src/script/common/c_content.h
@@ -150,6 +150,9 @@ void               luaentity_get             (lua_State *L,u16 id);
 bool               push_json_value           (lua_State *L,
                                               const Json::Value &value,
                                               int nullindex);
+void               get_json_value            (lua_State *L,
+                                              Json::Value &root,
+                                              int index);
 
 extern struct EnumString es_TileAnimationType[];