Add 'is_subsequence_of' function to String

core/ustring.cpp

@@ -2752,6 +2752,50 @@ bool String::begins_with(const char* p_string) const {
 
 }
 
+bool String::is_subsequence_of(const String& p_string) const {
+
+	return _base_is_subsequence_of(p_string, false);
+}
+
+bool String::is_subsequence_ofi(const String& p_string) const {
+
+	return _base_is_subsequence_of(p_string, true);
+}
+
+bool String::_base_is_subsequence_of(const String& p_string, bool case_insensitive) const {
+
+	int len=length();
+	if (len == 0) {
+		// Technically an empty string is subsequence of any string
+		return true;
+	}
+
+	if (len > p_string.length()) {
+		return false;
+	}
+
+	const CharType *src = &operator[](0);
+	const CharType *tgt = &p_string[0];
+
+	for (;*src && *tgt;tgt++) {
+		bool match = false;
+		if (case_insensitive) {
+			CharType srcc = _find_lower(*src);
+			CharType tgtc = _find_lower(*tgt);
+			match = srcc == tgtc;
+		} else {
+			match = *src == *tgt;
+		}
+		if (match) {
+			src++;
+			if(!*src) {
+				return true;
+			}
+		}
+	}
+
+	return false;
+}
 
 static bool _wildcard_match(const CharType* p_pattern, const CharType* p_string,bool p_case_sensitive) {
 	switch (*p_pattern) {

core/ustring.h

@@ -66,6 +66,7 @@ class String : public Vector<CharType> {
 	void copy_from(const char *p_cstr);
 	void copy_from(const CharType* p_cstr, int p_clip_to=-1);
 	void copy_from(const CharType& p_char);
+	bool _base_is_subsequence_of(const String& p_string, bool case_insensitive) const;
 
 
 public:
@@ -122,6 +123,8 @@ public:
 	bool begins_with(const String& p_string) const;
 	bool begins_with(const char* p_string) const;
 	bool ends_with(const String& p_string) const;
+	bool is_subsequence_of(const String& p_string) const;
+	bool is_subsequence_ofi(const String& p_string) const;
 	String replace_first(String p_key,String p_with) const;
 	String replace(String p_key,String p_with) const;
 	String replacen(String p_key,String p_with) const;

core/variant_call.cpp

@@ -247,6 +247,8 @@ static void _call_##m_type##_##m_method(Variant& r_ret,Variant& p_self,const Var
 	VCALL_LOCALMEM1R(String,matchn);
 	VCALL_LOCALMEM1R(String,begins_with);
 	VCALL_LOCALMEM1R(String,ends_with);
+	VCALL_LOCALMEM1R(String,is_subsequence_of);
+	VCALL_LOCALMEM1R(String,is_subsequence_ofi);
 	VCALL_LOCALMEM2R(String,replace);
 	VCALL_LOCALMEM2R(String,replacen);
 	VCALL_LOCALMEM2R(String,insert);
@@ -1269,6 +1271,8 @@ _VariantCall::addfunc(Variant::m_vtype,Variant::m_ret,_SCS(#m_method),VCALL(m_cl
 	ADDFUNC1(STRING,BOOL,String,matchn,STRING,"expr",varray());
 	ADDFUNC1(STRING,BOOL,String,begins_with,STRING,"text",varray());
 	ADDFUNC1(STRING,BOOL,String,ends_with,STRING,"text",varray());
+	ADDFUNC1(STRING,BOOL,String,is_subsequence_of,STRING,"text",varray());
+	ADDFUNC1(STRING,BOOL,String,is_subsequence_ofi,STRING,"text",varray());
 
 	ADDFUNC2(STRING,STRING,String,replace,STRING,"what",STRING,"forwhat",varray());
 	ADDFUNC2(STRING,STRING,String,replacen,STRING,"what",STRING,"forwhat",varray());