Support single char StringView

remove single char escape function overload, add unescape function

src/string.cc

@@ -62,18 +62,6 @@ std::vector<StringView> split(StringView str, char separator)
     return res;
 }
 
-String escape(StringView str, char character, char escape)
-{
-    String res;
-    for (auto& c : str)
-    {
-        if (c == character)
-            res += escape;
-        res += c;
-    }
-    return res;
-}
-
 String escape(StringView str, StringView characters, char escape)
 {
     String res;
@@ -86,6 +74,19 @@ String escape(StringView str, StringView characters, char escape)
     return res;
 }
 
+String unescape(StringView str, StringView characters, char escape)
+{
+    String res;
+    for (auto& c : str)
+    {
+        if (contains(characters, c) and not res.empty() and res.back() == escape)
+            res.back() = c;
+        else
+            res += c;
+    }
+    return res;
+}
+
 int str_to_int(StringView str)
 {
     int res = 0;

src/string.hh

@@ -66,6 +66,7 @@ public:
     StringView(const char* data) : m_data{data}, m_length{(int)strlen(data)} {}
     constexpr StringView(const char* begin, const char* end) : m_data{begin}, m_length{(int)(end - begin)} {}
     StringView(const std::string& str) : m_data{str.data()}, m_length{(int)str.length()} {}
+    StringView(const char& c) : m_data(&c), m_length(1) {}
 
     bool operator==(StringView other) const;
     bool operator!=(StringView other) const;
@@ -274,8 +275,8 @@ inline String operator+(StringView lhs, StringView rhs)
 std::vector<String> split(StringView str, char separator, char escape);
 std::vector<StringView> split(StringView str, char separator);
 
-String escape(StringView str, char character, char escape);
 String escape(StringView str, StringView characters, char escape);
+String unescape(StringView str, StringView characters, char escape);
 
 inline String operator"" _str(const char* str, size_t)
 {