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use crate::*;
pub fn parse_constant_expression(string: &str, parent: &Tokeniser) -> ConstantExpression {
use ConstantExpressionTokenVariant as TokenVar;
use ConstantExpressionParseError as ParseError;
let mut tokens = Vec::new();
let mut t = Tokeniser::new_child(string, parent);
t.position.to_next_char(); // skip opening delimiter
loop {
t.drop_whitespace();
t.mark_start_position();
let token = t.eat_token();
if token.is_empty() {
break;
}
let variant = match token.as_str() {
"=" => TokenVar::Operator(Operator::Equal),
"!" => TokenVar::Operator(Operator::NotEqual),
"<" => TokenVar::Operator(Operator::LessThan),
">" => TokenVar::Operator(Operator::GreaterThan),
"+" => TokenVar::Operator(Operator::Add),
"-" => TokenVar::Operator(Operator::Subtract),
"<<" => TokenVar::Operator(Operator::LeftShift),
">>" => TokenVar::Operator(Operator::RightShift),
"&" => TokenVar::Operator(Operator::And),
"|" => TokenVar::Operator(Operator::Or),
"^" => TokenVar::Operator(Operator::Xor),
"~" => TokenVar::Operator(Operator::Not),
_ => if let Some(stripped) = token.strip_prefix("0x") {
match usize::from_str_radix(stripped, 16) {
Ok(value) => TokenVar::IntegerLiteral(value),
Err(_) => TokenVar::Error(
ParseError::InvalidHexadecimalLiteral(stripped.to_string())),
}
} else {
match usize::from_str_radix(&token, 10) {
Ok(value) => TokenVar::IntegerLiteral(value),
Err(_) => TokenVar::SymbolReference(token.to_string()),
}
}
};
let source = t.mark_end_position();
tokens.push(ConstantExpressionToken { source, variant });
}
return ConstantExpression { tokens };
}
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