forked from KPGPMC/furlang
CHatingPython
115 lines
4.0 KiB
C++
115 lines
4.0 KiB
C++
#include "furc/front/lexer.hpp"
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#include <cctype>
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#include <string>
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#include <unordered_map>
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namespace furc::front {
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using namespace std::string_literals;
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lexer::lexer(std::string_view filename, std::string_view content)
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: m_filename(filename), m_content(content) {}
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token_handle<> lexer::next_token() {
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skip_spaces();
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while (m_cursor + 2 <= m_content.size() && m_content[m_cursor] == '/') {
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if (m_content[m_cursor + 1] == '/') {
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m_cursor += 2;
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while (m_content[m_cursor] != '\n') {
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next();
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}
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} else if (m_content[m_cursor + 1] == '*') {
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m_cursor += 2;
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while (m_cursor + 2 < m_content.size()) {
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if (m_content[m_cursor + 1] == '*') {
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next();
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} else if (m_content[m_cursor + 0] != '*' || m_content[m_cursor + 1] != '/') {
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next();
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next();
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} else {
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break;
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}
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}
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if (m_cursor + 2 >= m_content.size()) {
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next();
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return { current_location(), "unexpected end of file before enclosing `*/`" };
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}
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m_cursor += 2;
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}
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skip_spaces();
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}
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location location = current_location();
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char ch = get();
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switch (ch) {
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case '(': return { location, token_t::Lparen, m_content.substr(m_cursor++, 1) };
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case ')': return { location, token_t::Rparen, m_content.substr(m_cursor++, 1) };
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case '{': return { location, token_t::Lbrace, m_content.substr(m_cursor++, 1) };
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case '}': return { location, token_t::Rbrace, m_content.substr(m_cursor++, 1) };
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case '[': return { location, token_t::Lbracket, m_content.substr(m_cursor++, 1) };
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case ']': return { location, token_t::Rbracket, m_content.substr(m_cursor++, 1) };
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case ';': return { location, token_t::Semicolon, m_content.substr(m_cursor++, 1) };
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case ':': return { location, token_t::Colon, m_content.substr(m_cursor++, 1) };
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case ',': return { location, token_t::Comma, m_content.substr(m_cursor++, 1) };
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case '.': return { location, token_t::Dot, m_content.substr(m_cursor++, 1) };
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case '"': {
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std::size_t begin = ++m_cursor;
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while (m_cursor < m_content.size() && m_content[m_cursor] != '"')
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++m_cursor;
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if (m_cursor >= m_content.size()) return { current_location(), "unexpected end of file before enclosing '\"'" };
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++m_cursor;
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return { location, token_t::String, m_content.substr(begin, m_cursor - begin - 1) };
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}
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case std::char_traits<char>::eof(): return { location, token_t::None };
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default: {
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if (std::isdigit(ch) != 0) {}
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if (std::isalnum(ch) != 0 || ch == '_') {
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std::size_t start = m_cursor++;
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while (std::isalnum(get()) != 0 || get() == '_')
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next();
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std::string_view value = m_content.substr(start, m_cursor - start);
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static std::unordered_map<std::string_view, keyword_token> s_keywords = {
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{ "func", keyword_token::Func },
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{ "return", keyword_token::Return },
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};
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if (auto it = s_keywords.find(value); it != s_keywords.end()) return { location, it->second, value };
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return { location, token_t::Identifier, value };
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}
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return { location, "unexpected character '"s.append(m_content.substr(m_cursor, 1)) + "'" };
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}
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}
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}
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void lexer::next() {
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if (m_cursor >= m_content.size()) return;
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char ch = get();
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++m_cursor;
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if (ch == '\n') {
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++m_row;
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m_lineStart = m_cursor;
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}
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}
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char lexer::get(std::size_t offset) const {
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if (m_cursor + offset < m_content.size()) return m_content[m_cursor + offset];
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return std::char_traits<char>::eof();
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}
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void lexer::skip_spaces() {
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while (std::isspace(get()) != 0)
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next();
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}
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location lexer::current_location() {
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return { m_filename, m_row, m_cursor - m_lineStart };
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}
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} // namespace furc::front
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