forked from KPGPMC/furlang
441 lines
17 KiB
C++
441 lines
17 KiB
C++
#include "furc/front/parser.hpp"
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#include "furc/ast/declaration.hpp" // IWYU pragma: keep
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#include "furc/ast/expression.hpp" // IWYU pragma: keep
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#include "furc/ast/literal.hpp" // IWYU pragma: keep
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#include "furc/ast/program.hpp" // IWYU pragma: keep
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#include "furc/ast/statement.hpp" // IWYU pragma: keep
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#include <fstream>
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#include <iostream>
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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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parser::parser(std::string_view filename, std::string_view content)
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: m_filename(filename), m_content(content), m_lexer(m_filename, m_content) {}
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parser::parser(std::string_view filename)
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: m_filename(filename) {
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std::ifstream file(m_filename, std::ios_base::binary | std::ios_base::ate);
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if (!file.is_open()) throw std::runtime_error("failed to open file "s.append(m_filename));
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std::streampos size = file.tellg();
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file.seekg(0);
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m_content.resize(size);
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file.read(m_content.data(), size);
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m_lexer = { filename, m_content };
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}
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ast::program_node_r parser::parse() & {
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auto program = m_arena.allocate_shared<ast::program_node>(location{ m_filename });
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while (peek_token().has_value()) {
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auto decl = parse_declaration();
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if (decl.has_error()) {
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program = nullptr;
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} else if (program != nullptr) {
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program->push(std::move(decl.value()));
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}
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}
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return program != nullptr ? std::move(program) : ast::program_node_r(ast::error{ location{ m_filename } });
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}
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ast::declaration_node_r parser::parse_declaration() {
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const auto& first = peek_token();
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switch (first->type) {
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case token_t::Keyword: {
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auto first = next_token();
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switch ((*first)->keyword) {
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case keyword_token::Func: {
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auto name = eat_token(token_t::Identifier);
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if (name.has_error()) return ast::declaration_node_r(ast::error{ name.error().location });
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auto tok = eat_token(token_t::LParen);
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if (tok.has_error()) return ast::declaration_node_r(ast::error{ tok.error().location });
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tok = eat_token(token_t::RParen);
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if (tok.has_error()) return ast::declaration_node_r(ast::error{ tok.error().location });
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const auto& peek = peek_token();
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if (peek.has_error()) return ast::declaration_node_r(ast::error{ peek.error().location });
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switch (peek->type) {
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case token_t::LBrace: {
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ast::body_r body = parse_body();
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if (body.has_error()) return ast::declaration_node_r(ast::error{ body.error().location });
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return m_arena.allocate_shared<ast::function_definition_node>(first->location,
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name->value.string,
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std::move(body.value()));
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}
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case token_t::Semicolon: {
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m_peekBuffer.clear();
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return m_arena.allocate_shared<ast::function_declaration_node>(first->location, name->value.string);
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}
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default: return ast::declaration_node_r(ast::error{ tok->location });
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}
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}
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default: return ast::declaration_node_r(ast::error{ first->location });
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}
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}
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case token_t::None:
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case token_t::Identifier:
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case token_t::Integer:
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case token_t::LParen:
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case token_t::RParen:
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case token_t::LBrace:
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case token_t::RBrace:
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case token_t::LBracket:
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case token_t::RBracket:
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case token_t::Semicolon:
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case token_t::Colon:
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default: {
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return ast::declaration_node_r(ast::error{ first->location });
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}
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}
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}
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ast::statement_node_r parser::parse_statement() {
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const auto& tok = peek_token();
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if (tok.has_error()) return ast::statement_node_r(ast::error{ tok.error().location });
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auto location = tok->location;
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switch (tok->type) {
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case token_t::Keyword: {
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switch (tok->value.keyword) {
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case keyword_token::Return: {
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auto tok = next_token();
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if (peek_token()->type == token_t::Semicolon) {
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next_token();
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return m_arena.allocate_shared<ast::return_statement_node>(location);
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}
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auto value = parse_expression();
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auto err = eat_token(token_t::Semicolon);
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if (err.has_error()) return ast::statement_node_r(ast::error{ err.error().location });
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return m_arena.allocate_shared<ast::return_statement_node>(location, std::move(value.value()));
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}
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case keyword_token::If: {
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auto tok = next_token();
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auto err = eat_token(token_t::LParen);
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if (err.has_error()) return ast::statement_node_r(ast::error{ err.error().location });
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auto cond = parse_expression();
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err = eat_token(token_t::RParen);
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if (err.has_error()) return ast::statement_node_r(ast::error{ err.error().location });
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auto then = parse_statement();
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if (then.has_error()) return ast::statement_node_r(ast::error{ then.error().location });
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if (peek_token().has_value() && peek_token()->type == token_t::Keyword &&
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peek_token()->value.keyword == keyword_token::Else) {
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next_token();
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auto elseBody = parse_statement();
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if (elseBody.has_error()) return ast::statement_node_r(ast::error{ elseBody.error().location });
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return m_arena.allocate_shared<ast::if_statement_node>(location,
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std::move(cond.value()),
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std::move(then.value()),
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std::move(elseBody.value()));
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}
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return m_arena.allocate_shared<ast::if_statement_node>(location,
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std::move(cond.value()),
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std::move(then.value()));
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}
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case keyword_token::None:
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case keyword_token::Func:
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default: break;
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}
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}
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case token_t::LBrace: {
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auto body = parse_body();
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if (body.has_error()) return ast::statement_node_r(ast::error{ body.error().location });
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return m_arena.allocate_shared<ast::compound_statement_node>(location, std::move(body.value()));
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}
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default: break;
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}
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auto declaration = parse_declaration();
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if (declaration.has_value()) return std::move(*declaration);
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auto expression = parse_expression();
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if (expression.has_value()) {
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auto semi = eat_token(token_t::Semicolon);
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if (semi.has_error()) return ast::statement_node_r(ast::error{ semi.error().location });
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return std::move(*expression);
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}
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auto token = next_token();
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return ast::statement_node_r(ast::error{ token->location });
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}
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ast::expression_node_r parser::parse_expression(std::uint32_t precedence) {
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auto expr = parse_expression_unary(precedence);
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if (expr.has_error()) {
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return ast::expression_node_r(ast::error{ expr.error().location });
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}
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return parse_expression_rhs(std::move(expr.value()), precedence);
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}
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ast::expression_node_r parser::parse_expression_primary() {
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const auto& tok = peek_token();
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switch (tok->type) {
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case token_t::Identifier: {
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auto tok = next_token();
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if (tok.has_error()) return ast::expression_node_r(ast::error{ tok.error().location });
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return m_arena.allocate_shared<ast::var_read_expression_node>(tok->location, (*tok)->string);
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}
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case token_t::LParen: {
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auto tok = next_token();
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auto node = parse_expression();
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auto err = eat_token(token_t::RParen);
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if (err.has_error()) return ast::expression_node_r(ast::error{ err.error().location });
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return node;
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}
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case token_t::String: {
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auto tok = next_token();
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if (tok.has_error()) return ast::expression_node_r(ast::error{ tok.error().location });
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return m_arena.allocate_shared<ast::string_literal_node>(tok->location, (*tok)->string);
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}
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case token_t::Integer: {
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auto tok = next_token();
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if (tok.has_error()) return ast::expression_node_r(ast::error{ tok.error().location });
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return m_arena.allocate_shared<ast::integer_literal_node>(tok->location, (*tok)->integer);
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}
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default: {
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return ast::expression_node_r(ast::error{ tok->location });
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}
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}
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}
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struct unaryop_info {
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ast::unaryop_expression_node_t type;
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std::uint32_t precedence;
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};
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ast::expression_node_r parser::parse_expression_unary(std::uint32_t precedence) {
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static std::unordered_map<token_t, unaryop_info> s_prefixes = {
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{ token_t::Plus, unaryop_info{ ast::unaryop_expression_node_t::Positive, 3 } },
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{ token_t::Minus, unaryop_info{ ast::unaryop_expression_node_t::Negative, 3 } },
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{ token_t::DPlus, unaryop_info{ ast::unaryop_expression_node_t::PrefixIncrement, 2 } },
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{ token_t::DMinus, unaryop_info{ ast::unaryop_expression_node_t::PrefixDecrement, 2 } },
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};
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std::shared_ptr<ast::unary_op_expression_node> result;
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while (true) {
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auto it = s_prefixes.find(peek_token()->type);
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if (it == s_prefixes.end()) break;
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auto current = it->second;
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if (current.precedence >= precedence) break;
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auto token = next_token();
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ast::expression_node_p expression;
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auto nextIt = s_prefixes.find(peek_token()->type);
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if (nextIt != s_prefixes.end()) {
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auto next = nextIt->second;
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auto expr = parse_expression_unary(current.precedence + 1);
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if (expr.has_error()) {
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return ast::expression_node_r(ast::error{ expr.error().location });
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}
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expression = std::move(std::move(expr.value()));
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}
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result = m_arena.allocate_shared<ast::unary_op_expression_node>(token->location,
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current.type,
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std::move(expression));
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}
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if (result == nullptr) return parse_expression_primary();
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if (result->get_node() == nullptr) {
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auto expr = parse_expression_primary();
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if (expr.has_error()) {
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return ast::expression_node_r(ast::error{ expr.error().location });
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}
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result->set_node(std::move(std::move(expr.value())));
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}
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return result;
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}
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enum class associativity {
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Left,
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Right,
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};
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enum class rhsop_info_t {
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Unaryop,
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Binop,
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Assignment,
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};
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struct rhsop_info {
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rhsop_info_t type;
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std::uint32_t precedence;
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associativity associativity;
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union {
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ast::unaryop_expression_node_t unary;
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ast::binop_expression_node_t binary;
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ast::binop_expression_node_t assignment;
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};
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static rhsop_info create(ast::unaryop_expression_node_t type, std::uint32_t precedence) {
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rhsop_info info{};
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info.type = rhsop_info_t::Unaryop;
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info.precedence = precedence;
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info.associativity = associativity::Left;
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info.unary = type;
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return info;
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}
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static rhsop_info create(ast::binop_expression_node_t type,
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std::uint32_t precedence,
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enum associativity associativity) {
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rhsop_info info{};
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info.type = rhsop_info_t::Binop;
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info.precedence = precedence;
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info.associativity = associativity;
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info.binary = type;
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return info;
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}
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static rhsop_info create(ast::binop_expression_node_t compound = ast::binop_expression_node_t::None) {
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rhsop_info info{};
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info.type = rhsop_info_t::Assignment;
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info.precedence = 14;
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info.associativity = associativity::Right;
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info.assignment = compound;
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return info;
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}
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};
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ast::expression_node_r parser::parse_expression_rhs(ast::expression_node_p&& init, std::uint32_t precedence) {
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static std::unordered_map<token_t, rhsop_info> s_rhsops = {
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{ token_t::Plus, rhsop_info::create(ast::binop_expression_node_t::Add, 5, associativity::Left) },
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{ token_t::Minus, rhsop_info::create(ast::binop_expression_node_t::Sub, 5, associativity::Left) },
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{ token_t::Star, rhsop_info::create(ast::binop_expression_node_t::Mul, 4, associativity::Left) },
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{ token_t::Slash, rhsop_info::create(ast::binop_expression_node_t::Div, 4, associativity::Left) },
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{ token_t::Percent, rhsop_info::create(ast::binop_expression_node_t::Mod, 5, associativity::Left) },
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{ token_t::DPlus, rhsop_info::create(ast::unaryop_expression_node_t::PostfixIncrement, 1) },
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{ token_t::DMinus, rhsop_info::create(ast::unaryop_expression_node_t::PostfixDecrement, 1) },
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{ token_t::DMinus, rhsop_info::create(ast::unaryop_expression_node_t::PostfixDecrement, 1) },
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{ token_t::Eq, rhsop_info::create() },
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{ token_t::PlusEq, rhsop_info::create(ast::binop_expression_node_t::Add) },
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{ token_t::MinusEq, rhsop_info::create(ast::binop_expression_node_t::Sub) },
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{ token_t::StarEq, rhsop_info::create(ast::binop_expression_node_t::Mul) },
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{ token_t::SlashEq, rhsop_info::create(ast::binop_expression_node_t::Div) },
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{ token_t::PercentEq, rhsop_info::create(ast::binop_expression_node_t::Mod) },
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{ token_t::DEq, rhsop_info::create(ast::binop_expression_node_t::Equal, 10, associativity::Left) },
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{ token_t::NotEq, rhsop_info::create(ast::binop_expression_node_t::NotEqual, 10, associativity::Left) },
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{ token_t::LessThan, rhsop_info::create(ast::binop_expression_node_t::LessThan, 9, associativity::Left) },
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{ token_t::GreaterThan, rhsop_info::create(ast::binop_expression_node_t::GreaterThan, 9, associativity::Left) },
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{ token_t::LessEq, rhsop_info::create(ast::binop_expression_node_t::LessEqual, 9, associativity::Left) },
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{ token_t::GreaterEq, rhsop_info::create(ast::binop_expression_node_t::GreaterEqual, 9, associativity::Left) },
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};
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ast::expression_node_p lhs = std::move(init);
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while (peek_token().has_value()) {
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auto it = s_rhsops.find(peek_token()->type);
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if (it == s_rhsops.end()) return lhs;
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rhsop_info current = it->second;
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if (current.precedence >= precedence) return lhs;
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auto opToken = next_token();
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ast::expression_node_p rhs;
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if (current.type != rhsop_info_t::Unaryop) {
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auto expr = parse_expression_unary(current.precedence + 1); // unary prefix is always right-associative
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if (expr.has_error()) {
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return ast::expression_node_r(ast::error{ expr.error().location });
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}
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rhs = std::move(expr.value());
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}
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auto nextIt = s_rhsops.find(peek_token()->type);
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if (nextIt != s_rhsops.end()) {
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rhsop_info next = nextIt->second;
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auto expr = std::move(parse_expression_rhs(std::move(rhs),
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current.precedence + static_cast<std::uint32_t>(current.associativity == associativity::Right)));
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if (expr.has_error()) {
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return ast::expression_node_r(ast::error{ expr.error().location });
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}
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if (current.type != rhsop_info_t::Unaryop) {
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rhs = std::move(expr.value());
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} else {
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lhs = std::move(expr.value());
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}
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}
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switch (current.type) {
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case rhsop_info_t::Unaryop:
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lhs = m_arena.allocate_shared<ast::unary_op_expression_node>(opToken->location,
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current.unary,
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std::move(lhs));
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break;
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case rhsop_info_t::Binop:
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lhs = m_arena.allocate_shared<ast::binary_op_expression_node>(opToken->location,
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current.binary,
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std::move(lhs),
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std::move(rhs));
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break;
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case rhsop_info_t::Assignment:
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lhs = m_arena.allocate_shared<ast::var_assign_expression_node>(opToken->location,
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current.assignment,
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std::move(lhs),
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std::move(rhs));
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break;
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}
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}
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return lhs;
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}
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ast::body_r parser::parse_body() {
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ast::body body;
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auto begin = eat_token(token_t::LBrace);
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if (begin.has_error()) return ast::body_r(ast::error{ begin.error().location });
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body.begin = begin->location;
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while (!peek_token().has_error() && peek_token()->type != token_t::None && peek_token()->type != token_t::RBrace) {
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body.statements.push_back(parse_statement());
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}
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auto end = eat_token(token_t::RBrace);
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if (end.has_error()) return ast::body_r(ast::error{ end.error().location });
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body.end = end->location;
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return body;
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}
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token_r parser::next_token() {
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if (!m_peekBuffer.empty()) {
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auto token = std::move(m_peekBuffer.back());
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m_peekBuffer.pop_back();
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return token;
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}
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return m_lexer.next_token();
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}
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const token_r& parser::peek_token() {
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if (m_peekBuffer.empty()) {
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auto token = m_lexer.next_token();
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return m_peekBuffer.emplace_back(std::move(token));
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}
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return m_peekBuffer.front();
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}
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token_r parser::eat_token(token_t type) {
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auto token = next_token();
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if (token.has_error()) return token;
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if (token->type != type) {
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if (token->type == token_t::None)
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return token_r(token_error{ token->location, token_error_t::UnexpectedToken, ", expected " + type });
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return token_r(
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token_error{ token->location, token_error_t::UnexpectedToken, ""s + token->type + ", expected " + type });
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}
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return token;
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}
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} // namespace furc::front
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