From 4ce026ec7811094be3e93eeb17c3eb0e742a6bd3 Mon Sep 17 00:00:00 2001
From: Riyyi <riyyi3@gmail.com>
Date: Wed, 20 Jul 2022 22:04:16 +0200
Subject: [PATCH] Util: Add GenericLexer class

---
 src/util/genericlexer.cpp | 55 +++++++++++++++++++++++++++++++++++++++
 src/util/genericlexer.h   | 43 ++++++++++++++++++++++++++++++
 2 files changed, 98 insertions(+)
 create mode 100644 src/util/genericlexer.cpp
 create mode 100644 src/util/genericlexer.h

diff --git a/src/util/genericlexer.cpp b/src/util/genericlexer.cpp
new file mode 100644
index 0000000..f34b2a8
--- /dev/null
+++ b/src/util/genericlexer.cpp
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2022 Riyyi
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <algorithm> // max, min
+
+#include "util/genericlexer.h"
+
+namespace Util {
+
+GenericLexer::GenericLexer(std::string_view input)
+	: m_input(input)
+{
+}
+
+GenericLexer::~GenericLexer()
+{
+}
+
+// -----------------------------------------
+
+size_t GenericLexer::tell() const
+{
+	return m_index;
+}
+
+bool GenericLexer::isEOF() const
+{
+	return m_index >= m_input.length();
+}
+
+char GenericLexer::peek(size_t offset) const
+{
+	return m_input[std::max(std::min(m_index + offset, m_input.length()), (size_t)0)];
+}
+
+void GenericLexer::ignore(size_t count)
+{
+	m_index += std::min(count, m_input.length() - m_index);
+}
+
+void GenericLexer::retreat(size_t count)
+{
+	m_index -= std::min(count, m_index);
+}
+
+char GenericLexer::consume()
+{
+	assert(!isEOF());
+	return m_input[m_index++];
+}
+
+} // namespace Util
diff --git a/src/util/genericlexer.h b/src/util/genericlexer.h
new file mode 100644
index 0000000..1ee3864
--- /dev/null
+++ b/src/util/genericlexer.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2022 Riyyi
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#ifndef UTIL_GENERIC_LEXER_H
+#define UTIL_GENERIC_LEXER_H
+
+#include <cassert> // assert
+#include <cstddef> // size_t
+#include <string_view>
+
+namespace Util {
+
+class GenericLexer {
+public:
+	GenericLexer(std::string_view input);
+	virtual ~GenericLexer();
+
+	// Position
+
+	size_t tell() const;
+	bool isEOF() const;
+
+	// Access
+
+	char peek(size_t offset = 0) const;
+
+	// Modifiers
+
+	void ignore(size_t count = 1);
+	void retreat(size_t count = 1);
+	char consume();
+
+protected:
+	size_t m_index { 0 };
+	std::string_view m_input;
+};
+
+} // namespace Util
+
+#endif // UTIL_GENERIC_LEXER_H