Enum pw_format::macros::PrintfFormatStringFragment

pub enum PrintfFormatStringFragment {
    String(String),
    Expr {
        arg: Arg,
        format_trait: Ident,
    },
}

A fragment of a printf format string.

Printf format strings are built of multiple fragments. These fragments can be either a string (PrintfFormatStringFragment::String) or an expression that evaluates to a const &str (PrintfFormatStringFragment::Expr). These fragments can then be used to create a single const &str for use by code generation.

Example

use pw_bytes::concat_static_strs;
use pw_format::macros::{PrintfFormatStringFragment, Result};
use quote::quote;

fn handle_fragments(format_string_fragments: &[PrintfFormatStringFragment]) -> Result<()> {
  let format_string_pieces: Vec<_> = format_string_fragments
    .iter()
    .map(|fragment| fragment.as_token_stream("__pw_log_backend_crate"))
    .collect::<Result<Vec<_>>>()?;

  quote! {
    let format_string = concat_static_strs!("prefix: ", #(#format_string_pieces),*, "\n");
  };
  Ok(())
}

Variants

String(String)

A fragment that is a string.

Expr

Fields

arg: Arg

Argument to convert.

format_trait: Ident

Trait to used for getting the format specifier for the argument.

One of PrintfFormatter, PrintfHexFormatter, `PrintfUpperHexFormatter

An expressions that can be converted to a const &str.

Implementations

impl PrintfFormatStringFragment

pub fn as_token_stream( &self, printf_formatter_trait_location: &str ) -> Result<TokenStream>

Returns a proc_macro2::TokenStream representing this fragment.