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Add support for +, - in num literals

This commit is contained in:
greg 2017-01-19 19:44:43 -08:00
parent eb6354e55a
commit eaf86ea908
1 changed files with 31 additions and 5 deletions
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36
src/parser.rs
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@ -15,8 +15,9 @@ use std::convert::From;
// exprlist := Expression (Comma Expression)* | e
//
// expression := primary_expression (op primary_expression)*
// primary_expression := Number | String | identifier_expr | paren_expr | conditional_expr |
// primary_expression := number_expr | String | identifier_expr | paren_expr | conditional_expr |
// while_expr | lambda_expr
// number_expr := (PLUS | MINUS ) number_expr | Number
// identifier_expr := call_expression | Variable
// call_expr := Identifier LParen exprlist RParen
// while_expr := WHILE primary_expression LCurlyBrace (expression delimiter)* RCurlyBrace
@ -391,10 +392,8 @@ impl Parser {
self.next();
Expression::Null
}
Some(NumLiteral(n)) => {
self.next();
Expression::Number(n)
}
Some(NumLiteral(_)) => try!(self.number_expression()),
Some(Operator(OpTok(ref a))) if **a == "+" || **a == "-" => try!(self.number_expression()),
Some(StrLiteral(s)) => {
self.next();
Expression::StringLiteral(s)
@ -413,6 +412,33 @@ impl Parser {
})
}
fn number_expression(&mut self) -> ParseResult<Expression> {
let mut multiplier = 1;
loop {
match self.peek() {
Some(NumLiteral(n)) => {
self.next();
return Ok(Expression::Number(n * multiplier as f64));
}
Some(Operator(OpTok(ref a))) if **a == "+" => {
self.next();
}
Some(Operator(OpTok(ref a))) if **a == "-" => {
multiplier *= -1;
self.next();
}
Some(e) => {
return ParseError::result_from_str(
&format!("Expected +, - or number, got {:?}", e));
}
None => {
return ParseError::result_from_str(
&format!("Expected +, - or number, got EoI"));
}
}
}
}
fn lambda_expr(&mut self) -> ParseResult<Expression> {
use self::Expression::*;
expect!(self, Keyword(Kw::Fn));