HackStudio: Start building a C++ lexer to help with syntax highlighting

DevTools/HackStudio/CppLexer.h

@@ -0,0 +1,61 @@
+#pragma once
+
+#include <AK/StringView.h>
+#include <AK/Vector.h>
+
+#define FOR_EACH_TOKEN_TYPE        \
+    __TOKEN(Invalid)               \
+    __TOKEN(Whitespace)            \
+    __TOKEN(PreprocessorStatement) \
+    __TOKEN(LeftParen)             \
+    __TOKEN(RightParen)            \
+    __TOKEN(LeftCurly)             \
+    __TOKEN(RightCurly)            \
+    __TOKEN(LeftBracket)           \
+    __TOKEN(RightBracket)          \
+    __TOKEN(Comma)                 \
+    __TOKEN(Asterisk)              \
+    __TOKEN(Semicolon)             \
+    __TOKEN(DoubleQuotedString)    \
+    __TOKEN(SingleQuotedString)    \
+    __TOKEN(Comment)               \
+    __TOKEN(Number)                \
+    __TOKEN(Keyword)               \
+    __TOKEN(Identifier)
+
+struct CppToken {
+    enum class Type {
+#define __TOKEN(x) x,
+        FOR_EACH_TOKEN_TYPE
+#undef __TOKEN
+    };
+
+    const char* to_string() const
+    {
+        switch (m_type) {
+#define __TOKEN(x) \
+    case Type::x:  \
+        return #x;
+            FOR_EACH_TOKEN_TYPE
+#undef __TOKEN
+        }
+        ASSERT_NOT_REACHED();
+    }
+
+    Type m_type { Type::Invalid };
+    StringView m_view;
+};
+
+class CppLexer {
+public:
+    CppLexer(const StringView&);
+
+    Vector<CppToken> lex();
+
+private:
+    char peek(int offset = 0) const;
+    char consume();
+
+    StringView m_input;
+    int m_index { 0 };
+};