Struct PrintingTokenSink 

pub struct PrintingTokenSink<'a: 'b, 'b, S: TokenSink, W: Write> { /* private fields */ }

A token sink that prints a description of the tokens to a writer, and forwards them to another sink. For debugging.

Each token is output on one line. Start and end tokens adjust indentation.

Example

let mut got = TokenVec::new();
let mut output = Vec::new();
vec![42u32]
    .into_tokens(&mut PrintingTokenSink::new(&mut got, &mut output, "T: "))
    .unwrap();
assert_eq!(
    String::from_utf8(output).unwrap(),
    concat!(
        "T: Seq(SeqMeta { size_hint: Some(1) })\n",
        "T:   U32(42)\n",
        "T: EndSeq\n")
);

Implementations

impl<'a: 'b, 'b, S: TokenSink, W: Write> PrintingTokenSink<'a, 'b, S, W>

pub fn new(sink: &'b mut S, writer: W, prefix: &'a str) -> Self

Creates a new printing sink. The prefix is used for each output line, before the indentation.

Trait Implementations

impl<'a: 'b, 'b, S: TokenSink, W: Write> TokenSink for PrintingTokenSink<'a, 'b, S, W>

type Error = PrintError<<S as TokenSink>::Error>

fn yield_token(&mut self, token: Token<'_>) -> Result<bool, Self::Error>

Handles the next token from the stream. Returns true if the sink requires more tokens.

fn expect_tokens(&mut self) -> Option<TokenTypes>

Returns the set of token types expected next. The Self::yield_token function may accept or refuse any token; this is an optional type negotation mechanism. E.g. if String isn’t expected, but U32 is, then the source may choose to do a conversion. In general, sources should not expect sinks to do type conversions.

fn into_any(self: Box<Self>) -> Box<dyn Any>

Converts the boxed sink into a boxed Any. This is used in the FromTokens derive macro to support dynamic dispatch for fields and variants. It only needs to be overridden for types where Self::yield_token returns true.