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Basic parser

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Signed-off-by: CHatingPython <chatingpython@gmail.com>
This commit is contained in:
CHatingPython
2026-05-25 07:45:24 +02:00
committed by CHatingPython
parent 28f6deaba5
commit 7df35fc075
11 changed files with 687 additions and 36 deletions
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furc/src/back/lexer.cpp → furc/src/front/lexer.cpp
+15 -14
View File
@@ -8,22 +8,24 @@ namespace furc::front {
lexer::lexer(std::string_view filename, std::string_view content)
: m_filename(filename), m_content(content) {}
token lexer::next_token() {
token_handle<> lexer::next_token() {
skip_spaces();
location location = current_location();
char ch = get();
switch (ch) {
case '(': return create_token(location, token_t::Lparen, m_content.substr(m_cursor++, 1));
case ')': return create_token(location, token_t::Rparen, m_content.substr(m_cursor++, 1));
case '{': return create_token(location, token_t::Lbrace, m_content.substr(m_cursor++, 1));
case '}': return create_token(location, token_t::Rbrace, m_content.substr(m_cursor++, 1));
case '[': return create_token(location, token_t::Lbracket, m_content.substr(m_cursor++, 1));
case ']': return create_token(location, token_t::Rbracket, m_content.substr(m_cursor++, 1));
case ';': return create_token(location, token_t::Semicolon, m_content.substr(m_cursor++, 1));
case ':': return create_token(location, token_t::Colon, m_content.substr(m_cursor++, 1));
case std::char_traits<char>::eof(): return create_token(location, token_t::None);
case '(': return { location, token_t::Lparen, m_content.substr(m_cursor++, 1) };
case ')': return { location, token_t::Rparen, m_content.substr(m_cursor++, 1) };
case '{': return { location, token_t::Lbrace, m_content.substr(m_cursor++, 1) };
case '}': return { location, token_t::Rbrace, m_content.substr(m_cursor++, 1) };
case '[': return { location, token_t::Lbracket, m_content.substr(m_cursor++, 1) };
case ']': return { location, token_t::Rbracket, m_content.substr(m_cursor++, 1) };
case ';': return { location, token_t::Semicolon, m_content.substr(m_cursor++, 1) };
case ':': return { location, token_t::Colon, m_content.substr(m_cursor++, 1) };
case ',': return { location, token_t::Comma, m_content.substr(m_cursor++, 1) };
case '.': return { location, token_t::Dot, m_content.substr(m_cursor++, 1) };
case std::char_traits<char>::eof(): return { location, token_t::None };
default: {
if (std::isdigit(ch) != 0) {}
@@ -39,12 +41,11 @@ token lexer::next_token() {
{ "return", keyword_token::Return },
};
if (auto it = s_keywords.find(value); it != s_keywords.end())
return create_token(location, it->second, value);
return create_token(location, token_t::Identifier, value);
if (auto it = s_keywords.find(value); it != s_keywords.end()) return { location, it->second, value };
return { location, token_t::Identifier, value };
}
return create_token(location, error_token::UnexpectedCharacter, m_content.substr(m_cursor, 1));
return { location, error_token::UnexpectedCharacter, m_content.substr(m_cursor, 1) };
}
}
}
furc/src/front/parser.cpp
+166
View File
@@ -0,0 +1,166 @@
#include "furc/front/parser.hpp"
#include "furc/ast/declaration.hpp"
#include <fstream>
#include <iostream>
#include <string>
namespace furc::front {
using namespace std::string_literals;
parser::parser(std::string_view filename, std::string_view content)
: m_filename(filename), m_content(content), m_lexer(m_filename, m_content) {}
parser::parser(std::string_view filename)
: m_filename(filename) {
std::ifstream file(m_filename, std::ios_base::binary | std::ios_base::ate);
if (!file.is_open()) throw std::runtime_error("failed to open file "s.append(m_filename));
std::streampos size = file.tellg();
file.seekg(0);
m_content.resize(size);
file.read(m_content.data(), size);
m_lexer = { filename, m_content };
}
ast::node_handle<ast::program_node> parser::parse() {
auto program = std::make_shared<ast::program_node>();
while (!m_lexer.empty()) {
program->push(std::move(parse_declaration()));
}
return { location{ m_filename, 0, 0 }, program };
}
ast::node_handle<ast::declaration_node> parser::parse_declaration() {
token_handle<> first = next_token();
switch (first->type) {
case token_t::Keyword: {
switch (first->keyword) {
case keyword_token::Func: {
token_handle<> name = eat_token(token_t::Identifier);
if (name.error()) return { name.location(), name };
auto tok = eat_token(token_t::Lparen);
if (tok.error()) return tok;
tok = eat_token(token_t::Rparen);
if (tok.error()) return tok;
const auto& peek = peek_token();
if (peek.error()) return peek;
switch (peek->type) {
case token_t::Lbrace: {
ast::function_body_handle body = parse_body();
if (body.error()) return body;
return ast::node_handle<ast::function_declarartion_node>{ first.location(),
name,
std::move(body.move()) };
}
case token_t::Semicolon: {
m_peekBuffer.clear();
return ast::node_handle<ast::function_declarartion_node>{ first.location(), name };
}
case token_t::None:
case token_t::Error:
case token_t::Identifier:
case token_t::Keyword:
case token_t::Integer:
case token_t::Lparen:
case token_t::Rparen:
case token_t::Rbrace:
case token_t::Lbracket:
case token_t::Rbracket:
case token_t::Colon:
case token_t::Comma:
case token_t::Dot: return { tok.location(), "unexpected token "s + tok->type };
}
}
case keyword_token::Return:
case keyword_token::None:
default: return { first.location(), "unexpected keyword "s + first->keyword };
}
}
case token_t::None:
case token_t::Error:
case token_t::Identifier:
case token_t::Integer:
case token_t::Lparen:
case token_t::Rparen:
case token_t::Lbrace:
case token_t::Rbrace:
case token_t::Lbracket:
case token_t::Rbracket:
case token_t::Semicolon:
case token_t::Colon:
default: {
return { first.location(), "unexpected token "s + first->type };
}
}
}
ast::node_handle<ast::statement_node> parser::parse_statement() {
const auto& tok = peek_token();
if (tok.error()) return tok;
switch (tok->type) {
case token_t::Keyword: {
next_token();
auto err = eat_token(token_t::Semicolon);
if (err.error()) return err;
return ast::node_handle<ast::return_statement_node>{ tok.location() };
}
default: break;
}
auto declaration = parse_declaration();
if (declaration.error())
return { declaration.location(), "unexpected token "s + tok->type + ", expected statement" };
return ast::node_handle<ast::declaration_statement_node>{ declaration.location(), declaration };
}
ast::function_body_handle parser::parse_body() {
ast::function_body body;
token_handle<> begin = eat_token(token_t::Lbrace);
if (begin.error()) return begin;
body.begin = begin.location();
while (!peek_token().error() && peek_token()->type != token_t::Rbrace) {
body.statements.push_back(parse_statement());
}
token_handle<> end = eat_token(token_t::Rbrace);
if (end.error()) return end;
body.end = end.location();
return { begin.location(), body };
}
token_handle<> parser::next_token() {
if (!m_peekBuffer.empty()) {
token_handle<> token = std::move(m_peekBuffer.back());
m_peekBuffer.pop_back();
return token;
}
return m_lexer.next_token();
}
const token_handle<>& parser::peek_token() {
if (m_peekBuffer.empty()) {
token_handle<> token = m_lexer.next_token();
return m_peekBuffer.emplace_back(std::move(token));
}
return m_peekBuffer.front();
}
token_handle<> parser::eat_token(token_t type) {
token_handle<> token = next_token();
if (!token.present()) return token;
if (token->type != type) return { token.location(), "unexpected token "s + token->type + ", expected " + type };
return token;
}
} // namespace furc::front
furc/src/main.cpp
+3 -8
View File
@@ -1,15 +1,10 @@
#include "furc/front/lexer.hpp"
#include "furc/front/parser.hpp"
#include <iostream>
int main(void) {
furc::front::lexer lexer("<TEMP>", "func main() {\n return 0;\n}");
furc::front::token token = {};
while (!furc::front::is_token_type_empty((token = lexer.next_token()).type)) {
std::cout << token << '\n';
}
if (token.type == furc::front::token_t::Error) std::cout << token << '\n';
furc::front::parser parser("<TEMP>", "func main() {\n return;\n}");
std::cout << parser.parse() << '\n';
return 0;
}