msp430-repl/src/parser/parsable.rs

// © 2023 John Breaux
//! A [`Parsable`] struct (an AST node) can parse tokens from a [stream](TokenStream) into it[`self`](https://doc.rust-lang.org/stable/std/keyword.SelfTy.html)
use super::*;
/// Parses tokens from [stream](TokenStream) into Self node
pub trait Parsable {
    /// Parses tokens from [TokenStream](TokenStream) into Self nodes
    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
    where
        Self: Sized,
        T: TokenStream<'text>;

    /// Attempts to parse tokens from [stream](TokenStream) into Self nodes.
    ///
    /// Masks failed expectations.
    fn try_parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Option<Self>, Error>
    where
        Self: Sized,
        T: TokenStream<'text>,
    {
        match Self::parse(p, stream).map_err(|e| e.bare()) {
            Ok(tt) => Ok(Some(tt)),
            Err(Error::UnexpectedToken { .. }) | Err(Error::AllExpectationsFailed { .. }) => Ok(None),
            Err(e) => Err(e.context(stream.context())),
        }
    }

    fn parse_and<'text, T, R>(p: &Parser, stream: &mut T, f: fn(p: &Parser, &mut T) -> R) -> Result<(Self, R), Error>
    where
        Self: Sized,
        T: TokenStream<'text>,
    {
        Ok((Self::parse(p, stream)?, f(p, stream)))
    }

    /// Attempts to parse tokens from [stream](TokenStream) into Self nodes.
    ///
    /// Returns [`Self::default()`](Default::default()) on error
    fn parse_or_default<'text, T>(p: &Parser, stream: &mut T) -> Self
    where
        Self: Sized + Default,
        T: TokenStream<'text>,
    {
        Self::parse(p, stream).unwrap_or_default()
    }
}