Struct Acceptor

Source

pub struct Acceptor<'a, 'b, T, V> { /* private fields */ }

Expand description

A type that wraps a Scanner and holds a successfully accepted value.

When a value is successfully accepted, the Acceptor stores the value in its data field and returns itself. If a value is not accepted, the Acceptor rewinds the scanner to the previous position and returns itself.

§Type Parameters

T - The type of the data to scan.
V - The type of the value to accept.
'a - The lifetime of the data to scan.
'b - The lifetime of the acceptor.

Implementations§

Source §

impl<'a, 'b, T, V> Acceptor<'a, 'b, T, V>

Source

pub fn new(scanner: &'b mut Scanner<'a, T>) -> Acceptor<'a, 'b, T, V>

Create a new acceptor.

§Arguments

scanner - The scanner to use when consuming input.

§Returns

A new acceptor that uses the given scanner.

Examples found in repository ?

examples/colors.rs (line 102)

101    fn accept(scanner: &mut Scanner<u8>) -> ParseResult<Self> {
102        let color = Acceptor::new(scanner)
103            .try_or(ColorInternal::Hex)?
104            .try_or(ColorInternal::Rgb)?
105            .try_or(ColorInternal::Tuple)?
106            .finish()
107            .ok_or(UnexpectedToken)?;
108        Ok(color.into())
109    }

Source §

impl<'a, T, V> Acceptor<'a, '_, T, V>

Source

pub fn try_or<U: Visitor<'a, T>, F>(self, transformer: F) -> ParseResult<Self>
where F: Fn(U) -> V,

Attempt to accept a U using the given transformer, and rewind the scanner and return the current acceptor if it fails.

§Arguments

transformer - A function that takes a U and returns a ParseResult<V>.

§Returns

If the U is successfully accepted and the transformer returns Ok, returns the current acceptor with the resulting value in data. If the U is not successfully accepted, returns the current acceptor with the current position of the scanner rewound to the position at which the U was attempted, and data is left None.

Examples found in repository ?

examples/colors.rs (line 103)

101    fn accept(scanner: &mut Scanner<u8>) -> ParseResult<Self> {
102        let color = Acceptor::new(scanner)
103            .try_or(ColorInternal::Hex)?
104            .try_or(ColorInternal::Rgb)?
105            .try_or(ColorInternal::Tuple)?
106            .finish()
107            .ok_or(UnexpectedToken)?;
108        Ok(color.into())
109    }

Source

pub fn finish(self) -> Option<V>

Consume the acceptor and return the V that was accepted if the acceptor was successful.

§Returns

If the acceptor was successful (i.e., data is Some), returns the V that was accepted. Otherwise, returns None.

Examples found in repository ?

examples/colors.rs (line 106)

101    fn accept(scanner: &mut Scanner<u8>) -> ParseResult<Self> {
102        let color = Acceptor::new(scanner)
103            .try_or(ColorInternal::Hex)?
104            .try_or(ColorInternal::Rgb)?
105            .try_or(ColorInternal::Tuple)?
106            .finish()
107            .ok_or(UnexpectedToken)?;
108        Ok(color.into())
109    }