Added path views for abs and rel paths

include/tl/detail/path_view_base.h

@@ -0,0 +1,219 @@
+#pragma once
+
+#include "tl/detail/prologue.h"
+#include "tl/span.h"
+#include "tl/string.h"
+#include "tl/hash_and_combine.h"
+
+namespace tl
+{
+namespace detail
+{
+namespace path_system
+{
+
+class path_view_base;
+
+struct path_view_key_less
+{
+	bool operator()(const path_view_base& a1, const path_view_base& a2) const noexcept;
+};
+
+//////////////////////////////////////////////////////////////////////////
+
+// inner path_view_base definition
+class path_view_base
+{
+public:
+	path_view_base() noexcept;
+	path_view_base(tl::span<const string> elements) noexcept;
+	virtual ~path_view_base() noexcept = default;
+	using iterator = tl::span<const string>::iterator;
+	using const_iterator = tl::span<const string>::const_iterator;
+	using const_reverse_iterator = tl::span<const string>::const_reverse_iterator;
+	using key_less = path_view_key_less;
+	using value_type = std::string;
+
+	//both have checked indexing
+	const string&			at(size_t index) const noexcept;
+	const string&			operator[](size_t index) const noexcept;
+
+	void					shrink(size_t size) noexcept;
+
+	bool					empty() const noexcept;
+	size_t					size() const noexcept;
+
+	void					pop_back() noexcept;
+
+	iterator				begin() noexcept;
+	iterator				end() noexcept;
+	const_iterator			begin() const noexcept;
+	const_iterator			end() const noexcept;
+
+	const string&			front() const noexcept;
+	const string&			back() const noexcept;
+
+	uint32_t				hash() const noexcept;
+
+protected:
+	tl::span<const string>	m_elements;
+	mutable uint32_t		m_hash = 0;
+
+	friend bool path_view_key_less::operator()(const path_view_base& a1, const path_view_base& a2) const noexcept;
+};
+
+//////////////////////////////////////////////////////////////////////////
+
+
+
+}
+}
+}
+
+//////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////
+
+namespace tl
+{
+namespace detail
+{
+namespace path_system
+{
+
+//////////////////////////////////////////////////////////////////////////
+
+inline path_view_base::path_view_base() noexcept
+{
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline path_view_base::path_view_base(tl::span<const string> elements) noexcept
+	: m_elements(elements)
+{
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline const string& path_view_base::operator[](size_t index) const noexcept
+{
+	if (index >= m_elements.size())
+		TL_PLAIN_CRASH("Illegal access");
+	return m_elements[index];
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline const string& path_view_base::at(size_t index) const noexcept
+{
+	if (index >= m_elements.size())
+		TL_PLAIN_CRASH("Illegal access");
+	return m_elements[index];
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline void path_view_base::shrink(size_t size) noexcept
+{
+	if (size < this->size())
+	{
+		m_elements = tl::span<const string>(m_elements.data(), size);
+		m_hash = 0;
+	}
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline uint32_t path_view_base::hash() const noexcept
+{
+	if (m_hash == 0)
+	{
+		for (const string& e : *this)
+			hash_and_combine(m_hash, e);
+	}
+	return m_hash;
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline size_t path_view_base::size() const noexcept
+{
+	return m_elements.size();
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline bool path_view_base::empty() const noexcept
+{
+	return m_elements.empty();
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline void path_view_base::pop_back() noexcept
+{
+	if (empty())
+	{
+		TL_PLAIN_FAIL();
+		return;
+	}
+
+	m_hash = 0;
+	m_elements = tl::span<const string>(m_elements.data(), m_elements.size() - 1);
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline path_view_base::iterator path_view_base::begin() noexcept
+{
+	return m_elements.begin();
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline path_view_base::iterator path_view_base::end() noexcept
+{
+	return m_elements.end();
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline path_view_base::const_iterator path_view_base::begin() const noexcept
+{
+	return m_elements.cbegin();
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline path_view_base::const_iterator path_view_base::end() const noexcept
+{
+	return m_elements.cend();
+}
+
+inline const string& path_view_base::front() const noexcept
+{
+	return m_elements.front();
+}
+inline const string& path_view_base::back() const noexcept
+{
+	return m_elements.back();
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+inline bool path_view_key_less::operator()(const path_view_base& a1, const path_view_base& a2) const noexcept
+{
+	const size_t sz1 = a1.size();
+	const size_t sz2 = a2.size();
+	for (size_t i = 0; i < sz1 && i < sz2; ++i)
+	{
+		if (a1[i] != a2[i])
+			return a1[i].unique_key() < a2[i].unique_key();
+	}
+	return sz1 < sz2;
+}
+
+}
+}
+}