// Parse a primary expression.
//
// primary-expr -> literal | identifier | '(' expr ')'
//
// literal -> integer-literal
// | boolean-literal
// | character-literal
// | string-literal
Expr*
Parser::primary_expr()
{
// identifier
if (Token tok = match_if(identifier_tok))
return on_id(tok);
// boolean-literal
if (Token tok = match_if(boolean_tok))
return on_bool(tok);
// integer-literal
if (Token tok = match_if(integer_tok))
return on_int(tok);
// character-literal
if (Token tok = match_if(character_tok))
return on_char(tok);
// string-literal
if (Token tok = match_if(string_tok))
return on_str(tok);
// paren-expr
if (match_if(lparen_tok)) {
Expr* e = expr();
match(rparen_tok);
return e;
}
// FIXME: Is this definitely an error? Or can we
// actually return nullptr and continue?
error("expected primary expression");
}
// Parse a postfix expression.
//
// postfix-expression -> postfix-expression '(' argument-list ')'
// | postfix-expression '[' expression ']'
// | postfix-expression . identifier
// | primary-expression
Expr*
Parser::postfix_expr()
{
Expr* e1 = primary_expr();
while (true) {
// dot-expr
if (match_if(dot_tok)) {
Token tok = match(identifier_tok);
Expr* e2 = on_id(tok);
e1 = on_dot(e1, e2);
}
// call-expr
else if (match_if(lparen_tok)) {
Expr_seq args;
while (lookahead() != rparen_tok) {
args.push_back(expr());
if (match_if(comma_tok))
continue;
else
break;
}
match(rparen_tok);
e1 = on_call(e1, args);
}
// index-expr
else if (match_if(lbrack_tok)) {
Expr* e2 = expr();
match(rbrack_tok);
e1 = on_index(e1, e2);
}
// anything else
else {
break;
}
}
return e1;
}
Expr const*
Parser::id()
{
Token tok = require(identifier_tok);
return on_id(tok);
}
