preparing compile time url parsing

1 files changed, 52 insertions, 0 deletions

diff --git a/utility.h b/utility.h
new file mode 100644
index 0000000..c8575d3
--- /dev/null
+++ b/utility.h
@@ -0,0 +1,52 @@
+#pragma once
+
+namespace flask
+{
+	namespace black_magic
+	{
+		struct OutOfRange
+		{
+			OutOfRange(unsigned pos, unsigned length) {}
+		};
+		constexpr unsigned requires_in_range( unsigned i, unsigned len )
+		{
+			return i >= len ? throw OutOfRange(i, len) : i;
+		}
+
+		// from http://akrzemi1.wordpress.com/2011/05/11/parsing-strings-at-compile-time-part-i/
+		class StrWrap
+		{
+			const char * const begin_;
+			unsigned size_;
+
+			public:
+			template< unsigned N >
+				constexpr StrWrap( const char(&arr)[N] ) : begin_(arr), size_(N - 1) {
+					static_assert( N >= 1, "not a string literal");
+				}
+
+			constexpr char operator[]( unsigned i ) { 
+				return requires_in_range(i, size_), begin_[i]; 
+			}
+
+			constexpr operator const char *() { 
+				return begin_; 
+			}
+
+			constexpr unsigned size() { 
+				return size_; 
+			}
+		};
+
+
+		constexpr int find_closing_tag(StrWrap s, std::size_t p)
+		{
+			return s[p] == '>' ? p : find_closing_tag(s, p+1);
+		}
+
+		constexpr int count(StrWrap s, int i=0)
+		{
+			return i == s.size() ? 0 : s[i] == '<' ? 1+count(s,i+1) : count(s,i+1);
+		}
+	}
+}