[−][src]Macro nom::cond_reduce
cond_reduce!(bool, I -> IResult<I,O>) => I -> IResult<I, O>
Conditional combinator with error
Wraps another parser and calls it if the condition is met. This combinator returns an error if the condition is false
This is especially useful if a parser depends
on the value returned by a preceding parser in
a do_parse!
.
let b = true; let f = closure!(&'static[u8], cond_reduce!( b, tag!("abcd") ) ); let a = b"abcdef"; assert_eq!(f(&a[..]), Done(&b"ef"[..], &b"abcd"[..])); let b2 = false; let f2 = closure!(&'static[u8], cond_reduce!( b2, tag!("abcd") ) ); assert_eq!(f2(&a[..]), Error(error_position!(ErrorKind::CondReduce, &a[..])));