working AST

simulator_SIC_XE/include/lexer.h

@@ -0,0 +1,55 @@
+#ifndef LEXER_H
+#define LEXER_H
+
+#include <string>
+#include <stdexcept>
+#include <cstddef>
+
+class SyntaxError : public std::runtime_error {
+public:
+    int row;
+    int col;
+
+    SyntaxError(const std::string& msg, int row_, int col_)
+        : std::runtime_error(msg), row(row_), col(col_) {}
+};
+
+
+class Lexer {
+public:
+    int row;
+    int col;
+
+    explicit Lexer(std::string input);
+
+    Lexer& mark();
+
+    std::string extract(int ofs);
+    std::string extract();
+
+    char peek(int ahead) const;
+    char peek() const;
+
+    char advance();
+
+    bool advanceIf(char ch);
+    void advance(char ch);  
+
+
+    bool skipWhitespace();
+
+    std::string readTo(char delimiter);
+
+    std::string readAlphanumeric();
+
+    std::string readDigits(int radix);
+
+private:
+    std::string input_;
+    std::size_t pos_;
+    std::size_t start_;
+
+    static int digitValue(char c, int radix);
+};
+
+#endif // LEXER_H