Added CharTools functionality

Src/CMakeLists.txt

@@ -3,4 +3,7 @@ project(StringTools)
 
 set(CMAKE_CXX_STANDARD 17)
 
-add_library(StringTools StringTools.cpp)
+add_library(StringTools
+        StringTools.cpp
+        CharTools.cpp
+)

Src/CharTools.cpp

@@ -0,0 +1,64 @@
+#include "CharTools.h"
+#include <algorithm>
+
+bool CharTools::IsVowel(const char c, const std::string &vowels) {
+    return std::any_of(
+            vowels.cbegin(),
+            vowels.cend(),
+            [c](const char vowel) {
+                return c == vowel;
+            }
+    );
+}
+
+bool CharTools::IsLetter(const char c) {
+    // Re-implementing IsUpper and MakeLower to prevent stack-overflow by endless recursion
+    const char lowercase_c = !(c & (1<<5)) ? (c | (1<<5)) : c;
+
+    return (lowercase_c >= 'a') && (lowercase_c <= 'z');
+}
+
+bool CharTools::IsGeneric(const char c) {
+    return (c == UPPERCASE) || (c == LOWERCASE);
+}
+
+bool CharTools::IsUpper(const char c) {
+    if ((!IsLetter(c)) && (!IsGeneric(c)))
+        return false;
+    else
+        return !(c & (1<<5));
+}
+
+char CharTools::MakeUpper(char c) {
+    if ((!IsLetter(c)) && (!IsGeneric(c)))
+        return c;
+    else if (IsUpper(c))
+        return c;
+    else
+        return c & ~(1<<5);
+}
+
+char CharTools::MakeLower(char c) {
+    if ((!IsLetter(c)) && (!IsGeneric(c)))
+        return c;
+    else if (!IsUpper(c))
+        return c;
+    else
+        return c | (1<<5);
+}
+
+char CharTools::GetSign(char c) {
+    if (IsUpper(c))
+        return UPPERCASE;
+    else
+        return LOWERCASE;
+}
+
+char CharTools::CopySign(char sign, char c) {
+    if ((!IsLetter(c)) && (!IsGeneric(c)))
+        return c;
+    if (IsUpper(sign))
+        return MakeUpper(c);
+    else
+        return MakeLower(c);
+}

Src/CharTools.h

@@ -0,0 +1,41 @@
+#ifndef STRINGTOOLS_CHARTOOLS_H
+#define STRINGTOOLS_CHARTOOLS_H
+
+#include <string>
+
+/* Handy utensils to manipulate characters */
+
+class CharTools {
+public:
+    //! Checks whether or not `c` is a vowel. You can define custom vowel characters.
+    static bool IsVowel(const char c, const std::string& vowels = "euioay");
+
+    //! Returns whether or not `c` is a letter.
+    static bool IsLetter(const char c);
+
+    //! Returns whether or not `c` is a generic character (that contains JUST the sign)
+    static bool IsGeneric(const char c);
+
+    //! Checks whether or not `c` is an uppercase character.
+    static bool IsUpper(const char c);
+
+    //! Will return `c` as an uppercase character.
+    static char MakeUpper(char c);
+
+    //! Will return `c` as a lowercase character.
+    static char MakeLower(char c);
+
+    //! Will return an empty character with the same sign/capitalization as `c`.
+    static char GetSign(char c);
+
+    //! Will return `c` with the same capitalization as `sign`.
+    static char CopySign(char sign, char c);
+
+    //! Generic uppercase character.
+    static constexpr char UPPERCASE = 0;
+
+    //! Generic lowercase character.
+    static constexpr char LOWERCASE = (1<<5);
+};
+
+#endif //STRINGTOOLS_CHARTOOLS_H