1 files changed, 71 insertions, 0 deletions
diff --git a/server/lexer/token.cpp b/server/lexer/token.cpp
new file mode 100644
index 0000000..6ffb721
--- /dev/null
+++ b/server/lexer/token.cpp
@@ -0,0 +1,71 @@
+#include "error.hpp"
+#include "token.hpp"
+#include "token_type.hpp"
+
+#include <cmath>
+
+#include <limits>
+#include <variant>
+
+namespace math::server::lexer {
+namespace {
+
+static constexpr double nan() { return std::numeric_limits<double>::quiet_NaN(); }
+
+static bool is_nan(double x) { return std::isnan(x); }
+
+static bool numbers_equal(double x, double y) {
+    if (is_nan(x) && is_nan(y)) {
+        return true;
+    }
+    return x == y;
+}
+
+}
+
+Token::Token(Type type)
+    : m_type{type} {
+
+    if (token::token_has_value(type)) {
+        throw LexerError{"internal: must have a value: " + token::type_to_int_string(type)};
+    }
+}
+
+Token::Token(double value)
+    : m_type{Type::NUMBER}, m_value{value}
+{ }
+
+bool Token::operator==(const Token& other) const {
+    if (m_type != other.m_type) {
+        return false;
+    }
+    if (token::is_const_token(m_type)) {
+        return true;
+    }
+    if (m_type == Type::NUMBER) {
+        return numbers_equal(as_number(), other.as_number());
+    }
+    throw LexerError{"internal: can't compare tokens of type: " + token::type_to_int_string(m_type)};
+}
+
+double Token::as_number() const {
+    const auto type = get_type();
+    if (type != Type::NUMBER) {
+        throw LexerError{"internal: not a number: " + token::type_to_int_string(type)};
+    }
+    return std::get<double>(m_value);
+}
+
+std::ostream& operator<<(std::ostream& os, const Token& token) {
+    switch (token.m_type) {
+        case token::Type::NUMBER:
+            os << token.as_number();
+            break;
+        default:
+            os << token::type_to_string(token.m_type);
+            break;
+    }
+    return os;
+}
+
+}