NetServices: Rewrite BHttpFields to use raw strings as underlying data storage

This change also drops the principle that fields with the same keys would be
grouped together. This was initially inspired by Boost::Beast, but it means a
lot of extra copying of data when adding/organizing the list, as well as
inefficient querying on each add. Now that the design choice is to fully go
for the raw string as underlying data storage, that choice is not necessary.
In the future it may be able to emulate the grouping or retrieving of lists
of values in the API, rather than as a fundamental principle of the data
storage.

Change-Id: I2667cfa38eb3b7b75393ee71fb038231a40b4193

headers/private/netservices2/HttpFields.h

@@ -7,6 +7,7 @@
 #define _B_HTTP_FIELDS_H_
 
 #include <list>
+#include <optional>
 #include <string_view>
 #include <variant>
 #include <vector>
@@ -42,19 +43,17 @@ public:
 				bool			operator==(const FieldName& other) const noexcept;
 
 		// Conversion
-								operator BString() const;
 								operator std::string_view() const;
 	private:
 		friend	class			BHttpFields;
-								FieldName(const std::string_view& name);
-								FieldName(BString name);
-								FieldName(const FieldName& other);
+								FieldName() noexcept;
+								FieldName(const std::string_view& name) noexcept;
+								FieldName(const FieldName& other) noexcept;
 								FieldName(FieldName&&) noexcept;
-		FieldName&				operator=(const FieldName& other);
+		FieldName&				operator=(const FieldName& other) noexcept;
 		FieldName&				operator=(FieldName&&) noexcept;
-		FieldName&				operator=(BString name);
 
-		std::variant<std::string_view, BString>	fName;
+		std::string_view		fName;
 	};
 
 	class Field {
@@ -62,6 +61,7 @@ public:
 		// Constructors
 								Field() noexcept;
 								Field(const std::string_view& name, const std::string_view& value);
+								Field(BString& field);
 								Field(const Field& other);
 								Field(Field&&) noexcept;
 
@@ -72,54 +72,56 @@ public:
 		// Access Operators
 		const FieldName&		Name() const noexcept;
 		std::string_view		Value() const noexcept;
+		std::string_view		RawField() const noexcept;
 		bool					IsEmpty() const noexcept;
 
 	private:
 		friend	class			BHttpFields;
 
-								Field(const std::string_view& name, const std::string_view& value, bool borrowed);
+								Field(BString&& rawField);
+
+		std::optional<BString>	fRawField;
 
 		FieldName				fName;
-		std::variant<std::string_view, BString>
-						fValue;
+		std::string_view		fValue;
 	};
 
 	// Type Aliases
 	using ConstIterator = std::list<Field>::const_iterator;
 
 	// Constructors & Destructor
-						BHttpFields();
-						BHttpFields(std::initializer_list<Field> fields);
-						BHttpFields(const BHttpFields& other);
-						BHttpFields(BHttpFields&& other);
-						~BHttpFields() noexcept;
+								BHttpFields();
+								BHttpFields(std::initializer_list<Field> fields);
+								BHttpFields(const BHttpFields& other);
+								BHttpFields(BHttpFields&& other);
+								~BHttpFields() noexcept;
 
 	// Assignment operators
-	BHttpFields&		operator=(const BHttpFields&);
-	BHttpFields&		operator=(BHttpFields&&) noexcept;
+			BHttpFields&		operator=(const BHttpFields&);
+			BHttpFields&		operator=(BHttpFields&&) noexcept;
 
 	// Access list
-	const	Field&		operator[](size_t index) const;
+	const	Field&				operator[](size_t index) const;
 
 	// Modifiers
-	void				AddField(const std::string_view& name, const std::string_view& value);
-	void				AddFields(std::initializer_list<Field> fields);
-	void				RemoveField(const std::string_view& name) noexcept; 
-	void				RemoveField(ConstIterator it) noexcept;
-	void				MakeEmpty() noexcept;
+			void				AddField(const std::string_view& name,
+									const std::string_view& value);
+			void				AddField(BString& field);
+			void				AddFields(std::initializer_list<Field> fields);
+			void				RemoveField(const std::string_view& name) noexcept; 
+			void				RemoveField(ConstIterator it) noexcept;
+			void				MakeEmpty() noexcept;
 
 	// Querying
-	ConstIterator		FindField(const std::string_view& name) const noexcept;
-	size_t				CountFields() const noexcept;
+			ConstIterator		FindField(const std::string_view& name) const noexcept;
+			size_t				CountFields() const noexcept;
 
 	// Range-based iteration
-	ConstIterator		begin() const noexcept;
-	ConstIterator		end() const noexcept;
+			ConstIterator		begin() const noexcept;
+			ConstIterator		end() const noexcept;
 
 private:
-	void				_AddField(Field&& field);
-
-	std::list<Field>	fFields;
+			std::list<Field>	fFields;
 };