Add `String.to_{camel,pascal,snake}_case` methods

3 files changed, 54 insertions, 39 deletions

diff --git a/core/string/ustring.cpp b/core/string/ustring.cpp
index ed3d4b0b54..d8b93998af 100644
--- a/core/string/ustring.cpp
+++ b/core/string/ustring.cpp
@@ -970,62 +970,71 @@ const char32_t *String::get_data() const {
 	return size() ? &operator[](0) : &zero;
 }
 
-String String::capitalize() const {
-	String aux = this->camelcase_to_underscore(true).replace("_", " ").strip_edges();
-	String cap;
-	for (int i = 0; i < aux.get_slice_count(" "); i++) {
-		String slice = aux.get_slicec(' ', i);
-		if (slice.length() > 0) {
-			slice[0] = _find_upper(slice[0]);
-			if (i > 0) {
-				cap += " ";
-			}
-			cap += slice;
-		}
-	}
-
-	return cap;
-}
-
-String String::camelcase_to_underscore(bool lowercase) const {
+String String::_camelcase_to_underscore() const {
 	const char32_t *cstr = get_data();
 	String new_string;
 	int start_index = 0;
 
 	for (int i = 1; i < this->size(); i++) {
-		bool is_upper = is_ascii_upper_case(cstr[i]);
-		bool is_number = is_digit(cstr[i]);
+		bool is_prev_upper = is_ascii_upper_case(cstr[i - 1]);
+		bool is_prev_lower = is_ascii_lower_case(cstr[i - 1]);
+		bool is_prev_digit = is_digit(cstr[i - 1]);
 
-		bool are_next_2_lower = false;
-		bool is_next_lower = false;
-		bool is_next_number = false;
-		bool was_precedent_upper = is_ascii_upper_case(cstr[i - 1]);
-		bool was_precedent_number = is_digit(cstr[i - 1]);
-
-		if (i + 2 < this->size()) {
-			are_next_2_lower = is_ascii_lower_case(cstr[i + 1]) && is_ascii_lower_case(cstr[i + 2]);
-		}
+		bool is_curr_upper = is_ascii_upper_case(cstr[i]);
+		bool is_curr_lower = is_ascii_lower_case(cstr[i]);
+		bool is_curr_digit = is_digit(cstr[i]);
 
+		bool is_next_lower = false;
 		if (i + 1 < this->size()) {
 			is_next_lower = is_ascii_lower_case(cstr[i + 1]);
-			is_next_number = is_digit(cstr[i + 1]);
 		}
 
-		const bool cond_a = is_upper && !was_precedent_upper && !was_precedent_number;
-		const bool cond_b = was_precedent_upper && is_upper && are_next_2_lower;
-		const bool cond_c = is_number && !was_precedent_number;
-		const bool can_break_number_letter = is_number && !was_precedent_number && is_next_lower;
-		const bool can_break_letter_number = !is_number && was_precedent_number && (is_next_lower || is_next_number);
+		const bool cond_a = is_prev_lower && is_curr_upper; // aA
+		const bool cond_b = (is_prev_upper || is_prev_digit) && is_curr_upper && is_next_lower; // AAa, 2Aa
+		const bool cond_c = is_prev_digit && is_curr_lower && is_next_lower; // 2aa
+		const bool cond_d = (is_prev_upper || is_prev_lower) && is_curr_digit; // A2, a2
 
-		bool should_split = cond_a || cond_b || cond_c || can_break_number_letter || can_break_letter_number;
-		if (should_split) {
+		if (cond_a || cond_b || cond_c || cond_d) {
 			new_string += this->substr(start_index, i - start_index) + "_";
 			start_index = i;
 		}
 	}
 
 	new_string += this->substr(start_index, this->size() - start_index);
-	return lowercase ? new_string.to_lower() : new_string;
+	return new_string.to_lower();
+}
+
+String String::capitalize() const {
+	String aux = this->_camelcase_to_underscore().replace("_", " ").strip_edges();
+	String cap;
+	for (int i = 0; i < aux.get_slice_count(" "); i++) {
+		String slice = aux.get_slicec(' ', i);
+		if (slice.length() > 0) {
+			slice[0] = _find_upper(slice[0]);
+			if (i > 0) {
+				cap += " ";
+			}
+			cap += slice;
+		}
+	}
+
+	return cap;
+}
+
+String String::to_camel_case() const {
+	String s = this->to_pascal_case();
+	if (!s.is_empty()) {
+		s[0] = _find_lower(s[0]);
+	}
+	return s;
+}
+
+String String::to_pascal_case() const {
+	return this->capitalize().replace(" ", "");
+}
+
+String String::to_snake_case() const {
+	return this->_camelcase_to_underscore().replace(" ", "_").strip_edges();
 }
 
 String String::get_with_code_lines() const {
diff --git a/core/string/ustring.h b/core/string/ustring.h
index 2463fc35f7..31de7cc464 100644
--- a/core/string/ustring.h
+++ b/core/string/ustring.h
@@ -196,6 +196,7 @@ class String {
 
 	bool _base_is_subsequence_of(const String &p_string, bool case_insensitive) const;
 	int _count(const String &p_string, int p_from, int p_to, bool p_case_insensitive) const;
+	String _camelcase_to_underscore() const;
 
 public:
 	enum {
@@ -335,7 +336,9 @@ public:
 	static double to_float(const char32_t *p_str, const char32_t **r_end = nullptr);
 
 	String capitalize() const;
-	String camelcase_to_underscore(bool lowercase = true) const;
+	String to_camel_case() const;
+	String to_pascal_case() const;
+	String to_snake_case() const;
 
 	String get_with_code_lines() const;
 	int get_slice_count(String p_splitter) const;
diff --git a/core/variant/variant_call.cpp b/core/variant/variant_call.cpp
index 8e73c8dfc0..8af2a09111 100644
--- a/core/variant/variant_call.cpp
+++ b/core/variant/variant_call.cpp
@@ -1506,6 +1506,9 @@ static void _register_variant_builtin_methods() {
 	bind_method(String, repeat, sarray("count"), varray());
 	bind_method(String, insert, sarray("position", "what"), varray());
 	bind_method(String, capitalize, sarray(), varray());
+	bind_method(String, to_camel_case, sarray(), varray());
+	bind_method(String, to_pascal_case, sarray(), varray());
+	bind_method(String, to_snake_case, sarray(), varray());
 	bind_method(String, split, sarray("delimiter", "allow_empty", "maxsplit"), varray(true, 0));
 	bind_method(String, rsplit, sarray("delimiter", "allow_empty", "maxsplit"), varray(true, 0));
 	bind_method(String, split_floats, sarray("delimiter", "allow_empty"), varray(true));