103 lines
2.5 KiB
C++
103 lines
2.5 KiB
C++
#include "parser.hpp"
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#include "ast/errors/error.hpp"
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#include "token/type.hpp"
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#include <sstream>
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namespace parser {
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parser::parser(lexer::lexer& lexer)
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: lexer(lexer),
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current(token::type::ILLEGAL, ""),
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next(token::type::ILLEGAL, "") {
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next_token();
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next_token();
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}
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void parser::next_token() {
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current = next;
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next = lexer.next_token();
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}
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ast::program* parser::parse_program() {
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ast::program* p = new ast::program();
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for (; current.type != token::type::END_OF_FILE; next_token()) {
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ast::statement* stmt = parse_statement();
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if (stmt != nullptr)
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p->statements.push_back(stmt);
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}
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return p;
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}
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ast::statement* parser::parse_statement() {
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switch (current.type) {
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case token::type::LET:
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return parse_let();
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case token::type::RETURN:
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return parse_return();
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default:
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return nullptr;
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}
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}
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bool parser::expect_next(token::type t) {
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if (next.type == t) {
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next_token();
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return true;
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}
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next_error(t);
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return false;
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}
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ast::expression* parser::parse_expression() {
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// TODO: we are currently skipping expressions until we encounter a
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// semicolon
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for (; current.type != token::type::SEMICOLON; next_token()) {}
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return nullptr;
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};
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ast::return_stmt* parser::parse_return() {
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ast::return_stmt* stmt = new ast::return_stmt(current);
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next_token();
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stmt->value = parse_expression();
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return stmt;
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}
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ast::let_stmt* parser::parse_let() {
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ast::let_stmt* stmt = new ast::let_stmt(current);
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if (!expect_next(token::type::IDENTIFIER)) {
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delete stmt;
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return nullptr;
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}
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stmt->name = new ast::identifier{current, current.literal};
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if (!expect_next(token::type::ASSIGN)) {
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delete stmt;
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return nullptr;
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}
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stmt->value = parse_expression();
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return stmt;
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}
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return stmt;
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}
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void parser::next_error(token::type t) {
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std::stringstream ss;
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ss << "Expected next token to be " << t << " but instead got "
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<< next.type;
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errors.push_back(new ast::error::expected_next(t, ss.str()));
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}
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parser::~parser() {
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for (const auto& e : errors)
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delete e;
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}
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} // namespace parser
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