1 files changed, 0 insertions, 168 deletions
diff --git a/server/parser.hpp b/server/parser.hpp
deleted file mode 100644
index a9e5f54..0000000
--- a/server/parser.hpp
+++ /dev/null
@@ -1,168 +0,0 @@
-#pragma once
-
-#include "error.hpp"
-#include "lexer.hpp"
-
-#include <optional>
-#include <string>
-#include <string_view>
-
-namespace math::server {
-namespace parser {
-
-class Error : public server::Error {
-public:
-    explicit Error(const std::string& what)
-        : server::Error{"parser error: " + what}
-    { }
-};
-
-class BinaryOp {
-public:
-    static bool is(const lexer::Token& token) {
-        using Type = lexer::Token::Type;
-        switch (token.get_type()) {
-            case Type::PLUS:
-            case Type::MINUS:
-            case Type::ASTERISK:
-            case Type::SLASH:
-                return true;
-
-            default:
-                return false;
-        }
-    }
-
-    static BinaryOp from_token(const lexer::Token& token) {
-        if (!is(token)) {
-            throw Error{"internal: token is not a binary operator"};
-        }
-        return BinaryOp{token};
-    }
-
-    static constexpr unsigned min_precedence() { return 0; }
-
-    unsigned get_precedence() const {
-        using Type = lexer::Token::Type;
-        switch (m_type) {
-            case Type::PLUS:
-            case Type::MINUS:
-                return min_precedence();
-
-            case Type::ASTERISK:
-            case Type::SLASH:
-                return min_precedence() + 1;
-
-            default:
-                throw Error{"internal: undefined operator precedence"};
-        }
-    }
-
-    double exec(double lhs, double rhs) const {
-        using Type = lexer::Token::Type;
-        switch (m_type) {
-            case Type::PLUS:
-                return lhs + rhs;
-            case Type::MINUS:
-                return lhs - rhs;
-            case Type::ASTERISK:
-                return lhs * rhs;
-            case Type::SLASH:
-                // Trapping the CPU would be better?
-                if (rhs == 0.) {
-                    throw Error{"division by zero"};
-                }
-                return lhs / rhs;
-            default:
-                throw Error{"internal: unsupported operator"};
-        }
-    }
-
-private:
-    explicit BinaryOp(const lexer::Token& token)
-        : m_type{token.get_type()}
-    { }
-
-    lexer::Token::Type m_type;
-};
-
-}
-
-class Parser {
-public:
-    // I did simple recursive descent parsing a long time ago (see
-    // https://github.com/egor-tensin/simple-interpreter), this appears to be
-    // a finer algorithm for parsing arithmetic expressions.
-    // Reference: https://en.wikipedia.org/wiki/Operator-precedence_parser
-
-    explicit Parser(const std::string_view& input)
-        : m_lexer{input}
-    { }
-
-    double exec() {
-        m_lexer.parse_token();
-        const auto result = exec_expr();
-        if (m_lexer.has_token()) {
-            throw parser::Error{"expected a binary operator"};
-        }
-        return result;
-    }
-
-private:
-    double exec_expr() {
-        return exec_expr(exec_primary(), parser::BinaryOp::min_precedence());
-    }
-
-    double exec_expr(double lhs, unsigned min_prec) {
-        for (auto op = peek_operator(); op.has_value() && op->get_precedence() >= min_prec;) {
-            const auto lhs_op = *op;
-            m_lexer.drop_token();
-            auto rhs = exec_primary();
-
-            for (op = peek_operator(); op.has_value() && op->get_precedence() > lhs_op.get_precedence(); op = peek_operator()) {
-                rhs = exec_expr(rhs, op->get_precedence());
-            }
-
-            lhs = lhs_op.exec(lhs, rhs);
-        }
-        return lhs;
-    }
-
-    std::optional<parser::BinaryOp> peek_operator() {
-        const auto token = m_lexer.peek_token();
-        if (!token.has_value() || !parser::BinaryOp::is(*token)) {
-            return {};
-        }
-        return parser::BinaryOp::from_token(*token);
-    }
-
-    double exec_primary() {
-        if (!m_lexer.has_token()) {
-            throw parser::Error{"expected '-', '(' or a number"};
-        }
-
-        using Type = lexer::Token::Type;
-
-        if (m_lexer.drop_token_if(Type::MINUS).has_value()) {
-            return -exec_primary();
-        }
-
-        if (m_lexer.drop_token_if(Type::LEFT_PAREN).has_value()) {
-            const auto inner = exec_expr();
-            if (!m_lexer.has_token() || !m_lexer.drop_token_if(Type::RIGHT_PAREN).has_value()) {
-                throw parser::Error{"missing closing ')'"};
-            }
-            return inner;
-        }
-
-        if (const auto token = m_lexer.drop_token_if(Type::NUMBER); token.has_value()) {
-            return token.value().get_number_value();
-        }
-
-        throw parser::Error{"expected '-', '(' or a number"};
-    }
-
-    Lexer m_lexer;
-};
-
-}