Add capability to read table flag fields from Lua API

doc/lua_api.txt

@@ -410,6 +410,7 @@ All default ores are of the uniformly-distributed scatter type.
 
 Ore attributes
 -------------------
+See section Flag Specifier Format.
 Currently supported flags:  absheight
  - absheight
     Also produce this same ore between the height range of -height_max and -height_min.
@@ -451,6 +452,7 @@ Important note: Node aliases cannot be used for a raw schematic provided when re
 
 Schematic attributes
 ---------------------
+See section Flag Specifier Format.
 Currently supported flags:  place_center_x, place_center_y, place_center_z
  - place_center_x
     Placement of this decoration is centered along the X axis.
@@ -525,6 +527,26 @@ pointed_thing:
   {type="node", under=pos, above=pos}
   {type="object", ref=ObjectRef}
 
+Flag Specifier Format
+-----------------------
+Flags using the standardized flag specifier format can be specified in either of two ways, by string or table.
+The string format is a comma-delimited set of flag names; whitespace and unrecognized flag fields are ignored.
+Specifying a flag in the string sets the flag, and specifying a flag prefixed by the string "no" explicitly
+clears the flag from whatever the default may be.
+In addition to the standard string flag format, the schematic flags field can also be a table of flag names
+to boolean values representing whether or not the flag is set.  Additionally, if a field with the flag name
+prefixed with "no" is present, mapped to a boolean of any value, the specified flag is unset.
+
+e.g. A flag field of value
+  {place_center_x = true, place_center_y=false, place_center_z=true}
+is equivalent to
+  {place_center_x = true, noplace_center_y=true, place_center_z=true}
+which is equivalent to
+  "place_center_x, noplace_center_y, place_center_z"
+or even
+  "place_center_x, place_center_z"
+since, by default, no schematic attributes are set.
+
 Items
 ------
 Node (register_node):

src/porting.h

@@ -88,6 +88,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 	#define strtoull(x, y, z) _strtoui64(x, y, z)
 	#define strcasecmp(x, y) stricmp(x, y)
 	#define strncasecmp(x, y, n) strnicmp(x, y, n)
+
+	// We can't simply alias strlcpy() to MSVC's strcpy_s(), since strcpy_s
+	// by default raises an assertion error and aborts the program if the
+	// buffer is too small.  So we need to define our own.
+	#define strlcpy(x, y, n) mystrlcpy(x, y, n)
 #else
 	#define ALIGNOF(x) __alignof__(x)
 #endif

src/script/common/c_content.cpp

@@ -842,8 +842,45 @@ void push_hit_params(lua_State *L,const HitParams &params)
 u32 getflagsfield(lua_State *L, int table, const char *fieldname,
 	FlagDesc *flagdesc, u32 *flagmask)
 {
-	std::string flagstring = getstringfield_default(L, table, fieldname, "");
+	u32 flags = 0;
-	return readFlagString(flagstring, flagdesc, flagmask);
+	
+	lua_getfield(L, table, fieldname);
+
+	if (lua_isstring(L, -1)) {
+		std::string flagstr = lua_tostring(L, -1);
+		flags = readFlagString(flagstr, flagdesc, flagmask);
+	} else if (lua_istable(L, -1)) {
+		flags = read_flags_table(L, -1, flagdesc, flagmask);
+	}
+
+	lua_pop(L, 1);
+
+	return flags;
+}
+
+u32 read_flags_table(lua_State *L, int table, FlagDesc *flagdesc, u32 *flagmask)
+{
+	u32 flags = 0, mask = 0;
+	char fnamebuf[64] = "no";
+
+	for (int i = 0; flagdesc[i].name; i++) {
+		bool result;
+
+		if (getboolfield(L, table, flagdesc[i].name, result)) {
+			mask |= flagdesc[i].flag;
+			if (result)
+				flags |= flagdesc[i].flag;
+		}
+
+		strlcpy(fnamebuf + 2, flagdesc[i].name, sizeof(fnamebuf) - 2);
+		if (getboolfield(L, table, fnamebuf, result))
+			mask |= flagdesc[i].flag;
+	}
+
+	if (flagmask)
+		*flagmask = mask;
+
+	return flags;
 }
 
 /******************************************************************************/

src/script/common/c_content.h

@@ -123,6 +123,9 @@ u32                getflagsfield             (lua_State *L, int table,
                                               const char *fieldname,
                                               FlagDesc *flagdesc, u32 *flagmask);
 
+u32                read_flags_table          (lua_State *L, int table,
+                                              FlagDesc *flagdesc, u32 *flagmask);
+
 void               push_items                (lua_State *L,
                                               const std::vector<ItemStack> &items);
 

src/script/lua_api/l_mapgen.cpp

@@ -456,7 +456,6 @@ int ModApiMapgen::l_register_ore(lua_State *L)
 	ore->height_max     = getintfield_default(L, index, "height_max", 0);
 	ore->flags          = getflagsfield(L, index, "flags", flagdesc_ore, NULL);
 	ore->nthresh        = getfloatfield_default(L, index, "noise_threshhold", 0.);
-
 	lua_getfield(L, index, "wherein");
 	if (lua_istable(L, -1)) {
 		int  i = lua_gettop(L);

src/util/string.cpp

@@ -163,6 +163,19 @@ std::string writeFlagString(u32 flags, FlagDesc *flagdesc, u32 flagmask)
 	return result;
 }
 
+size_t mystrlcpy(char *dst, const char *src, size_t size)
+{
+	size_t srclen  = strlen(src) + 1;
+	size_t copylen = MYMIN(srclen, size);
+
+	if (copylen > 0) {
+		memcpy(dst, src, copylen);
+		dst[copylen - 1] = '\0';
+	}
+
+	return srclen;
+}
+
 char *mystrtok_r(char *s, const char *sep, char **lasts)
 {
 	char *t;

src/util/string.h

@@ -321,6 +321,7 @@ std::string urlencode(std::string str);
 std::string urldecode(std::string str);
 u32 readFlagString(std::string str, FlagDesc *flagdesc, u32 *flagmask);
 std::string writeFlagString(u32 flags, FlagDesc *flagdesc, u32 flagmask);
+size_t mystrlcpy(char *dst, const char *src, size_t size);
 char *mystrtok_r(char *s, const char *sep, char **lasts);
 u64 read_seed(const char *str);