s416496
/
musique
1
0
Fork 0
Code Issues 3 Pull Requests 1 Projects Releases Wiki Activity

Precedense aware parser

This commit is contained in:
Robert Bendun 2022-06-20 05:45:28 +02:00
parent 854b72cf35
commit ea1dddaf26
2 changed files with 69 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
src/musique.hh
View File

@ -575,6 +575,9 @@ struct Parser
/// Parse infix expression
Result<Ast> parse_infix_expression();
/// Parse right hand size of infix expression
Result<Ast> parse_rhs_of_infix_expression(Ast lhs);
/// Parse either index expression or atomic expression
Result<Ast> parse_index_expression();

70
src/parser.cc
View File

@ -3,6 +3,8 @@
static Ast wrap_if_several(std::vector<Ast> &&ast, Ast(*wrapper)(std::vector<Ast>));
static usize precedense(std::string_view op);
static inline bool is_identifier_looking(Token::Type type)
{
switch (type) {
@ -122,17 +124,61 @@ Result<Ast> Parser::parse_infix_expression()
auto atomics = Try(parse_many(*this, &Parser::parse_index_expression, std::nullopt, At_Least::One));
auto lhs = wrap_if_several(std::move(atomics), Ast::call);
if (expect(Token::Type::Operator) || expect(Token::Type::Keyword, "and") || expect(Token::Type::Keyword, "or")) {
bool const next_is_operator = expect(Token::Type::Operator)
|| expect(Token::Type::Keyword, "and")
|| expect(Token::Type::Keyword, "or");
if (next_is_operator) {
assert(not expect(Token::Type::Operator, "."), "This should be handled by parse_index_expression");
auto op = consume();
return parse_expression().map([&](Ast rhs) {
return Ast::binary(std::move(op), std::move(lhs), std::move(rhs));
});
Ast ast;
ast.location = op.location;
ast.type = Ast::Type::Binary;
ast.token = std::move(op);
ast.arguments.emplace_back(std::move(lhs));
return parse_rhs_of_infix_expression(std::move(ast));
}
return lhs;
}
Result<Ast> Parser::parse_rhs_of_infix_expression(Ast lhs)
{
auto atomics = Try(parse_many(*this, &Parser::parse_index_expression, std::nullopt, At_Least::One));
auto rhs = wrap_if_several(std::move(atomics), Ast::call);
bool const next_is_operator = expect(Token::Type::Operator)
|| expect(Token::Type::Keyword, "and")
|| expect(Token::Type::Keyword, "or");
if (!next_is_operator) {
lhs.arguments.emplace_back(std::move(rhs));
return lhs;
}
assert(not expect(Token::Type::Operator, "."), "This should be handled by parse_index_expression");
auto op = consume();
if (precedense(lhs.token.source) > precedense(op.source)) {
lhs.arguments.emplace_back(std::move(rhs));
Ast ast;
ast.location = op.location;
ast.type = Ast::Type::Binary;
ast.token = std::move(op);
ast.arguments.emplace_back(std::move(lhs));
return parse_rhs_of_infix_expression(std::move(ast));
}
Ast ast;
ast.location = op.location;
ast.type = Ast::Type::Binary;
ast.token = std::move(op);
ast.arguments.emplace_back(std::move(rhs));
lhs.arguments.emplace_back(Try(parse_rhs_of_infix_expression(std::move(ast))));
return lhs;
}
Result<Ast> Parser::parse_index_expression()
{
auto result = Try(parse_atomic_expression());
@ -433,6 +479,22 @@ Ast wrap_if_several(std::vector<Ast> &&ast, Ast(*wrapper)(std::vector<Ast>))
return wrapper(std::move(ast));
}
constexpr bool one_of(std::string_view id, auto const& ...args)
{
return ((id == args) || ...);
}
static usize precedense(std::string_view op)
{
if (one_of(op, "or")) return 100;
if (one_of(op, "and")) return 150;
if (one_of(op, "<", ">", "<=", ">=", "==", "!=")) return 200;
if (one_of(op, "+", "-")) return 300;
if (one_of(op, "*", "/")) return 400;
unreachable();
}
bool operator==(Ast const& lhs, Ast const& rhs)
{
if (lhs.type != rhs.type) {