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Make convenience macro for parse errors

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This commit is contained in:
greg 2015-12-31 21:43:44 -08:00
parent 8c0ac19fa8
commit 51745fd800
1 changed files with 13 additions and 13 deletions
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26
src/parser.rs
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@ -40,6 +40,12 @@ struct Parser {
tokens: Peekable<IntoIter<Token>> tokens: Peekable<IntoIter<Token>>
} }
macro_rules! parse_error {
($($text:tt)*) => {
Err(ParseError { err: format!($($text)*) })
}
}
impl Parser { impl Parser {
fn next(&mut self) -> Option<Token> { fn next(&mut self) -> Option<Token> {
self.tokens.next() self.tokens.next()
@ -57,12 +63,10 @@ impl Parser {
match self.next() { match self.next() {
Some(ref next) if *next == expected => Ok(()), Some(ref next) if *next == expected => Ok(()),
Some(next) => { Some(next) => {
let err = format!("Expected {:?} but got {:?}", expected, next); return parse_error!("Expected {:?} but got {:?}", expected, next);
return Err(ParseError { err: err });
}, },
None => { None => {
let err = format!("Expected {:?} but got end of input", expected); return parse_error!("Expected {:?} but got end of input", expected);
return Err(ParseError { err: err });
} }
} }
} }
@ -72,12 +76,10 @@ impl Parser {
match self.next() { match self.next() {
Some(Identifier(ref s)) if s == identifier_str => Ok(()), Some(Identifier(ref s)) if s == identifier_str => Ok(()),
Some(next) => { Some(next) => {
let err = format!("Expected identifier `{}` but got {:?}", identifier_str, next); return parse_error!("Expected identifier `{}` but got {:?}", identifier_str, next);
Err(ParseError { err: err })
} }
None => { None => {
let err = format!("Expected identifier `{}` but got end of input", identifier_str); return parse_error!("Expected identifier `{}` but got end of input", identifier_str);
Err(ParseError { err: err })
} }
} }
} }
@ -87,12 +89,10 @@ impl Parser {
match self.next() { match self.next() {
Some(NumLiteral(f)) => Ok(f), Some(NumLiteral(f)) => Ok(f),
Some(t) => { Some(t) => {
let err = format!("Expected NumLiteral, but got {:?}", t); return parse_error!("Expected NumLiteral, but got {:?}", t);
Err(ParseError { err: err })
}, },
None => { None => {
let err = format!("Expected NumLiteral but got end of input"); return parse_error!("Expected NumLiteral but got end of input");
Err(ParseError { err: err })
} }
} }
} }
@ -157,7 +157,7 @@ impl Parser {
self.next(); self.next();
Ok(AST::Number(n)) Ok(AST::Number(n))
}, },
_ => Err(ParseError { err: format!("Expected LParen or NumLiteral") }) _ => parse_error!("Expected LParen or NumLiteral")
} }
} }
} }