Add a feature to the schema validator to limit the constrain number of subtags

data/schema/core/themes.cfg

@@ -124,7 +124,7 @@
 			name="add"
 			max=infinite
 			super="theme/~content~"
-			#max_children=1
+			max_tags=1
 		[/tag]
 	[/tag]
 	[tag]

data/schema/schema.cfg

@@ -146,6 +146,8 @@
 				{SIMPLE_KEY super path_list}
 				{DEFAULT_KEY any_tag bool no}
 				{DEFAULT_KEY deprecated bool no}
+				{DEFAULT_KEY min_tags int 0}
+				{DEFAULT_KEY max_tags int,inf infinite}
 				[tag]
 					name="key"
 					max=infinite

src/serialization/schema/tag.cpp

@@ -30,6 +30,8 @@ wml_tag::wml_tag(const config& cfg)
 	: name_(cfg["name"].str())
 	, min_(cfg["min"].to_int())
 	, max_(cfg["max"].str() == "infinite" ? -1 : cfg["max"].to_int(1))
+	, min_children_(cfg["min_tags"].to_int())
+	, max_children_(cfg["max_tags"].str() == "infinite" ? -1 : cfg["max_tags"].to_int(-1))
 	, super_("")
 	, tags_()
 	, keys_()
@@ -42,6 +44,9 @@ wml_tag::wml_tag(const config& cfg)
 	if(max_ < 0) {
 		max_ = INT_MAX;
 	}
+	if(max_children_ < 0) {
+		max_children_ = INT_MAX;
+	}
 
 	if(cfg.has_attribute("super")) {
 		super_ = cfg["super"].str();

src/serialization/schema/tag.hpp

@@ -126,6 +126,8 @@ public:
 		: name_(name)
 		, min_(min)
 		, max_(max)
+		, min_children_(0)
+		, max_children_(INT_MAX)
 		, super_(super)
 		, tags_()
 		, keys_()
@@ -169,6 +171,16 @@ public:
 		return max_;
 	}
 
+	int get_min_children() const
+	{
+		return min_children_;
+	}
+
+	int get_max_children() const
+	{
+		return max_children_;
+	}
+
 	const std::string& get_super() const
 	{
 		return super_;
@@ -202,9 +214,22 @@ public:
 		max_ = o;
 	}
 
+	void set_min_children(int o)
+	{
+		min_children_ = o;
+	}
+
+	void set_max_children(int o)
+	{
+		max_children_ = o;
+	}
+
 	void set_min(const std::string& s);
 	void set_max(const std::string& s);
 
+	void set_min_children(const std::string& s);
+	void set_max_children(const std::string& s);
+
 	void set_super(const std::string& s)
 	{
 		super_ = s;
@@ -302,12 +327,18 @@ private:
 	/** name of tag. */
 	std::string name_;
 
-	/** number of minimum occasions. */
+	/** minimum number of occurrences. */
 	int min_;
 
-	/** number of maximum occasions. */
+	/** maximum number of occurrences. */
 	int max_;
 
+	/** minimum number of children. */
+	int min_children_;
+
+	/** maximum number of children. */
+	int max_children_;
+
 	/**
 	 * name of tag to extend "super-tag"
 	 * Extension is smth like inheritance and is used in case

src/serialization/schema_validator.cpp

@@ -231,6 +231,8 @@ void schema_validator::open_tag(const std::string& name, const config& parent, i
 				if(!addittion) {
 					counter& cnt = counter_.top()[name];
 					++cnt.cnt;
+					counter& total_cnt = counter_.top()[""];
+					++total_cnt.cnt;
 				}
 			}
 		}
@@ -271,7 +273,8 @@ void schema_validator::validate(const config& cfg, const std::string& name, int
 	// Please note that validating unknown tag keys the result will be false
 	// Checking all elements counters.
 	if(have_active_tag() && is_valid()) {
-		for(const auto& tag : active_tag().tags(cfg)) {
+		const wml_tag& active = active_tag();
+		for(const auto& tag : active.tags(cfg)) {
 			int cnt = counter_.top()[tag.first].cnt;
 
 			if(tag.second.get_min() > cnt) {
@@ -283,9 +286,16 @@ void schema_validator::validate(const config& cfg, const std::string& name, int
 				queue_message(cfg, EXTRA_TAG, file, start_line, tag.second.get_max(), tag.first, "", name);
 			}
 		}
+		
+		int total_cnt = counter_.top()[""].cnt;
+		if(active.get_min_children() > total_cnt) {
+			queue_message(cfg, MISSING_TAG, file, start_line, active.get_min_children(), "*", "", active.get_name());
+		} else if(active_tag().get_max_children() < total_cnt) {
+			queue_message(cfg, EXTRA_TAG, file, start_line, active.get_max_children(), "*", "", active.get_name());
+		}
 
 		// Checking if all mandatory keys are present
-		for(const auto& key : active_tag().keys(cfg)) {
+		for(const auto& key : active.keys(cfg)) {
 			if(key.second.is_mandatory()) {
 				if(cfg.get(key.first) == nullptr) {
 					queue_message(cfg, MISSING_KEY, file, start_line, 0, name, key.first);