src/tools/rustfmt/config_proc_macro/src/utils.rs

   1 use proc_macro2::TokenStream;
   2 use quote::{quote, ToTokens};
   3
   4 pub fn fold_quote<F, I, T>(input: impl Iterator<Item = I>, f: F) -> TokenStream
   5 where
   6     F: Fn(I) -> T,
   7     T: ToTokens,
   8 {
   9     input.fold(quote! {}, |acc, x| {
  10         let y = f(x);
  11         quote! { #acc #y }
  12     })
  13 }
  14
  15 pub fn is_unit(v: &syn::Variant) -> bool {
  16     match v.fields {
  17         syn::Fields::Unit => true,
  18         _ => false,
  19     }
  20 }
  21
  22 #[cfg(feature = "debug-with-rustfmt")]
  23 /// Pretty-print the output of proc macro using rustfmt.
  24 pub fn debug_with_rustfmt(input: &TokenStream) {
  25     use std::env;
  26     use std::ffi::OsStr;
  27     use std::io::Write;
  28     use std::process::{Command, Stdio};
  29
  30     let rustfmt_var = env::var_os("RUSTFMT");
  31     let rustfmt = match &rustfmt_var {
  32         Some(rustfmt) => rustfmt,
  33         None => OsStr::new("rustfmt"),
  34     };
  35     let mut child = Command::new(rustfmt)
  36         .stdin(Stdio::piped())
  37         .stdout(Stdio::piped())
  38         .spawn()
  39         .expect("Failed to spawn rustfmt in stdio mode");
  40     {
  41         let stdin = child.stdin.as_mut().expect("Failed to get stdin");
  42         stdin
  43             .write_all(format!("{}", input).as_bytes())
  44             .expect("Failed to write to stdin");
  45     }
  46     let rustfmt_output = child.wait_with_output().expect("rustfmt has failed");
  47
  48     eprintln!(
  49         "{}",
  50         String::from_utf8(rustfmt_output.stdout).expect("rustfmt returned non-UTF8 string")
  51     );
  52 }