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// Copyright (c) 2019 Egor Tensin <Egor.Tensin@gmail.com>
// This file is part of the "math-server" project.
// For details, see https://github.com/egor-tensin/math-server.
// Distributed under the MIT License.
#include "error.hpp"
#include "token_type.hpp"
#include <functional>
#include <map>
#include <ostream>
#include <stdexcept>
#include <string>
#include <unordered_map>
namespace math::server::lexer::token {
namespace {
using ToStringMap = std::unordered_map<Type, std::string>;
using FromStringMap = std::map<std::string, Type, std::greater<std::string>>;
class ToStringConverter {
public:
ToStringConverter() : m_map{to_string_map()} {
validate();
}
const ToStringMap& map() const { return m_map; }
private:
static const ToStringMap& to_string_map() {
static const ToStringMap map{
{Type::WHITESPACE, "whitespace"},
{Type::PLUS, "+"},
{Type::MINUS, "-"},
{Type::ASTERISK, "*"},
{Type::SLASH, "/"},
{Type::CARET, "^"},
{Type::LEFT_PAREN, "("},
{Type::RIGHT_PAREN, ")"},
{Type::NUMBER, "number"},
};
return map;
}
void validate() const {
check_for_duplicates();
}
void check_for_duplicates() const {
std::unordered_set<std::string> strings;
for (const auto& [type, str] : m_map) {
const auto [_, inserted] = strings.emplace(str);
if (!inserted) {
throw std::logic_error{"multiple tokens have the same string representation: " + str};
}
}
}
const ToStringMap& m_map;
};
const ToStringMap& to_string_map() {
static const ToStringConverter converter;
return converter.map();
}
class FromStringConverter {
public:
FromStringConverter(const ToStringMap& to_string)
: m_map{build_map(to_string)} {
}
const FromStringMap& map() const { return m_map; }
private:
static FromStringMap build_map(const ToStringMap& to_string) {
FromStringMap from_string;
for (const auto& [type, str] : to_string) {
const auto [_, inserted] = from_string.emplace(str, type);
if (!inserted) {
throw std::logic_error{"multiple tokens have the same string representation: " + str};
}
}
return from_string;
}
FromStringMap m_map;
};
const FromStringMap& from_string_map() {
static const FromStringConverter converter{to_string_map()};
return converter.map();
}
class ConstTokens {
public:
ConstTokens() {
const auto& map = to_string_map();
for (const auto& [type, _] : map) {
if (is_const_token(type)) {
m_set.emplace(type);
}
}
}
const TypeSet& set() const { return m_set; }
private:
TypeSet m_set;
};
}
TypeInt type_to_int(Type type) {
return static_cast<TypeInt>(type);
}
std::string type_to_int_string(Type type) {
return std::to_string(type_to_int(type));
}
bool is_const_token(Type type) {
switch (type) {
case Type::WHITESPACE:
case Type::NUMBER:
return false;
default:
return true;
}
}
const TypeSet& const_tokens() {
static const ConstTokens tokens;
return tokens.set();
}
bool token_has_value(Type type) {
switch (type) {
case Type::NUMBER:
return true;
default:
return false;
}
}
std::string type_to_string(Type type) {
const auto& map = to_string_map();
const auto it = map.find(type);
if (it == map.cend()) {
throw LexerError{"type_to_string: unsupported token type: " + type_to_int_string(type)};
}
return it->second;
}
Type type_from_string(const std::string& src) {
const auto& map = from_string_map();
const auto it = map.find(src);
if (it == map.cend()) {
throw LexerError{"type_from_string: unsupported token: " + std::string{src}};
}
return it->second;
}
std::ostream& operator<<(std::ostream& os, const Type& type) {
os << type_to_int(type);
return os;
}
}
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