Trait ContextExt

Source

pub trait ContextExt<'i, O>: Parser<Input<'i>, O, ErrMode<ParseStack<'i>>> + Sized {
    // Provided methods
    fn label(self, label: impl Into<String>) -> ContextParser<Self> { ... }
    fn expected_char(self, expected: char) -> ContextParser<Self> { ... }
    fn expected_chars(
        self,
        expected: impl IntoIterator<Item = char>,
    ) -> ContextParser<Self> { ... }
    fn expected_string(self, expected: &'static str) -> ContextParser<Self> { ... }
    fn expected_strings<I>(self, expected: I) -> ContextParser<Self>
       where I: IntoIterator,
             I::Item: Borrow<&'static str> { ... }
    fn expected_text(self, expected: impl Into<String>) -> ContextParser<Self> { ... }
    fn description(self, description: impl Into<String>) -> ContextParser<Self> { ... }
}

Expand description

The trait that adds context functions to all parsers over Input.

These functions are the String-capable counterparts to Parser::context.

§Note

Just like Parser::context calls, any attached context becomes part of the current layer, which is closed by the next LayerExt::layer.

§Example

use alpm_parsers::prelude::*;
use winnow::ascii::digit1;

// Context messages may be built at runtime.
let expected = format!("Hoped for exactly {} decimal digit", 1);
let mut parser = digit1
    .label("version number")
    .description(expected)
    .layer("version");

parser.parse(Input::new("42"))?;