turbocharger-impl 0.4.0

//! This crate provides Turbocharger's procedural macros.
//!
//! Please refer to the `turbocharger` crate for details.

#![forbid(unsafe_code)]

#[cfg(test)]
todo_or_die::crates_io!("bincode", ">=2");

mod extract;
use proc_macro_error::{abort, proc_macro_error};
use quote::{format_ident, quote, quote_spanned};
use syn::{parse_macro_input, parse_quote, spanned::Spanned};

#[proc_macro]
pub fn remote_addr(_: proc_macro::TokenStream) -> proc_macro::TokenStream {
 quote!(_turbocharger_connection_info.as_ref().and_then(|ref i| i.remote_addr)).into()
}

#[proc_macro]
pub fn user_agent(_: proc_macro::TokenStream) -> proc_macro::TokenStream {
 quote!(_turbocharger_connection_info.as_ref().and_then(|ref i| i.user_agent.as_ref())).into()
}

struct ConnectionLocal {
 pub ident: syn::Ident,
 pub ty: syn::Type,
}

impl syn::parse::Parse for ConnectionLocal {
 fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
  let ident = input.parse()?;

  let _: syn::Token![:] = input.parse()?;
  let _: syn::Token![&] = input.parse()?;
  let _: syn::Token![mut] = input.parse()?;

  let ty = input.parse()?;
  Ok(Self { ident, ty })
 }
}

#[proc_macro]
pub fn connection_local(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
 let ConnectionLocal { ident, ty } = parse_macro_input!(input as ConnectionLocal);
 let ident_str = ident.to_string();

 quote! {
  let mut _turbocharger_connection_local_map = match _turbocharger_connection_info.as_ref() {
   Some(c) => Some(c.connection_local.lock().await),
   None => None,
  };

  let #ident = {
   _turbocharger_connection_local_map
    .as_mut()
    .unwrap()
    .entry(( #ident_str , std::any::TypeId::of::< #ty >()))
    .or_insert_with(|| Box::new( #ty ::default()))
    .downcast_mut::< #ty >()
    .unwrap()
  };
 }
 .into()
}

/// Apply this to an item to make it available on the server target only.
///
/// Only adds `#[cfg(not(target_arch = "wasm32"))]`
#[proc_macro_attribute]
pub fn server_only(
 _args: proc_macro::TokenStream,
 input: proc_macro::TokenStream,
) -> proc_macro::TokenStream {
 let orig_item = parse_macro_input!(input as syn::Item);
 proc_macro::TokenStream::from(quote! {
  #[cfg(not(target_arch = "wasm32"))]
  #orig_item
 })
}

/// Apply this to an item to make it available on the wasm target only.
///
/// Only adds `#[cfg(target_arch = "wasm32")]` and ensures `wasm_bindgen::prelude::*` is available.
#[proc_macro_attribute]
pub fn wasm_only(
 _args: proc_macro::TokenStream,
 input: proc_macro::TokenStream,
) -> proc_macro::TokenStream {
 let orig_item = parse_macro_input!(input as syn::Item);
 proc_macro::TokenStream::from(quote! {
  #[cfg(any(feature = "wasm", target_arch = "wasm32"))]
  #[allow(unused_imports)]
  use wasm_bindgen::prelude::*;

  #[cfg(any(feature = "wasm", target_arch = "wasm32"))]
  #orig_item
 })
}

/// Apply this to a `pub async fn` to make it available (over the network) to the JS frontend. Also apply to any `struct`s used in backend function signatures.
#[proc_macro_attribute]
#[proc_macro_error]
pub fn backend(
 args: proc_macro::TokenStream,
 input: proc_macro::TokenStream,
) -> proc_macro::TokenStream {
 backend_item(args, syn::parse_macro_input!(input as syn::Item)).into()
}

fn backend_item(args: proc_macro::TokenStream, orig_item: syn::Item) -> proc_macro2::TokenStream {
 match orig_item {
  syn::Item::Fn(orig) => backend_fn(args, orig),
  syn::Item::Struct(orig) => backend_struct(orig),
  // syn::Item::Mod(orig) => backend_mod(orig),
  _ => abort!(orig_item, "Apply #[backend] to `fn` or `struct`."),
 }
}

// fn backend_mod_item(orig_item: syn::Item) -> proc_macro2::TokenStream {
//  match orig_item {
//   syn::Item::Fn(orig) => backend_fn(orig),
//   syn::Item::Struct(orig) => backend_struct(orig),
//   orig => quote! { #orig },
//  }
// }

// fn backend_mod(orig_mod: syn::ItemMod) -> proc_macro2::TokenStream {
//  let content = orig_mod.content.clone();

//  let items: Vec<_> = content
//   .unwrap_or_else(|| abort!(orig_mod, "Apply #[backend] to a `mod` with a body."))
//   .1
//   .into_iter()
//   .map(backend_mod_item)
//   .collect();

//  quote! { #(#items)* }
// }

fn backend_struct(orig_struct: syn::ItemStruct) -> proc_macro2::TokenStream {
 if std::env::current_exe().unwrap().file_stem().unwrap() != "rust-analyzer" {
  let mut api_struct = orig_struct.clone();
  api_struct.vis = parse_quote!();
  api_struct.attrs.retain(|attr| attr.path.is_ident("doc"));
  for field in &mut api_struct.fields {
   field.vis = parse_quote!();
   field.attrs.retain(|attr| attr.path.is_ident("doc"));
  }

  let lockfile = std::fs::File::create(std::env::temp_dir().join("turbocharger.lock")).unwrap();
  fs2::FileExt::lock_exclusive(&lockfile).unwrap();

  // add api_struct to file if it doesn't already exist, or replace it if it does
  let mut file = read_backend_api_rs();

  let mut found = false;
  for item in &mut file.items {
   if let syn::Item::Struct(ref mut item) = item {
    if item.ident == api_struct.ident {
     found = true;
     *item = api_struct.clone();
     break;
    }
   }
  }
  if !found {
   file.items.push(syn::Item::Struct(api_struct));
  }

  write_backend_api_rs(file);
 }

 #[allow(clippy::redundant_clone)]
 let syn::ItemStruct { attrs, ident, fields, .. } = orig_struct.clone();

 let output = quote! {
  #[cfg(target_arch = "wasm32")]
  #[allow(unused_imports)]
  use wasm_bindgen::prelude::*;

  #[cfg_attr(target_arch = "wasm32", wasm_bindgen(getter_with_clone, inspectable))]
  #[derive(::turbocharger::serde::Serialize, ::turbocharger::serde::Deserialize, Clone)]
  #(#attrs)*
  #[serde(crate = "::turbocharger::serde")]
  pub struct #ident #fields

  #[cfg(target_arch = "wasm32")]
  #[wasm_bindgen]
  impl #ident {
   #[wasm_bindgen(constructor)]
   pub fn new() -> #ident {
    #ident::default()
   }
  }
 };

 #[cfg(feature = "debug_expansions")]
 {
  std::fs::create_dir_all("debug_expansions").ok();
  std::fs::write(
   project_root_path_with(format!("debug_expansions/{}.rs", orig_struct.ident)),
   prettyplease::unparse(&parse_quote!( #output )),
  )
  .unwrap();

  std::process::Command::new("rustfmt")
   .current_dir(project_root_path_with("debug_expansions"))
   .arg("--edition")
   .arg("2021")
   .arg("--config")
   .arg("tab_spaces=1")
   .arg(format!("{}.rs", orig_struct.ident))
   .output()
   .unwrap();
 }

 output
}

fn backend_fn(args: proc_macro::TokenStream, orig_fn: syn::ItemFn) -> proc_macro2::TokenStream {
 let is_js = args.to_string() == "js";

 if std::env::current_exe().unwrap().file_stem().unwrap() != "rust-analyzer" {
  let mut api_fn = orig_fn.clone();
  api_fn.vis = parse_quote!();
  api_fn.attrs.retain(|attr| attr.path.is_ident("doc"));
  api_fn.block = parse_quote!({});

  let lockfile = std::fs::File::create(std::env::temp_dir().join("turbocharger.lock")).unwrap();
  fs2::FileExt::lock_exclusive(&lockfile).unwrap();

  // add api_fn to file if it doesn't already exist, or replace it if it does
  let mut file = read_backend_api_rs();

  let mut found = false;
  for item in &mut file.items {
   if let syn::Item::Fn(ref mut item) = item {
    if item.sig.ident == api_fn.sig.ident {
     found = true;
     *item = api_fn.clone();
     break;
    }
   }
  }
  if !found {
   file.items.push(syn::Item::Fn(api_fn));
  }

  write_backend_api_rs(file);
 }

 let orig_fn_ident = orig_fn.sig.ident.clone();
 let orig_fn_string = orig_fn_ident.to_string();
 let orig_fn_params = orig_fn.sig.inputs.clone();
 let orig_fn_stmts = &orig_fn.block.stmts;
 let orig_fn_stmts = quote!(#( #orig_fn_stmts )*);

 let store_name = format_ident!("_TURBOCHARGER_STORE_{}", orig_fn_ident);
 let dispatch = format_ident!("_TURBOCHARGER_DISPATCH_{}", orig_fn_ident);
 let req = format_ident!("_TURBOCHARGER_REQ_{}", orig_fn_ident);
 let resp = format_ident!("_TURBOCHARGER_RESP_{}", orig_fn_ident);
 let js_fn_ident = format_ident!("_TURBOCHARGER_JS_{}", orig_fn_ident);
 let remote_fn_ident = format_ident!("remote_{}", orig_fn_ident);
 let remote_impl_ident = format_ident!("_TURBOCHARGER_REMOTEIMPL_{}", orig_fn_ident);
 let subscriber_fn_ident = format_ident!("_TURBOCHARGER_SUBSCRIBERFN_{}", orig_fn_ident);

 let orig_fn_ret_ty = match orig_fn.sig.output.clone() {
  syn::ReturnType::Type(_, path) => *path,
  syn::ReturnType::Default => parse_quote! { () },
 };
 let stream_inner_ty = extract::extract_stream(&orig_fn_ret_ty);
 let result_inner_ty = extract::extract_result(stream_inner_ty.unwrap_or(&orig_fn_ret_ty));
 let store_value_ty = if result_inner_ty.is_some() {
  quote! { Result<#result_inner_ty, JsValue> }
 } else {
  quote! { #stream_inner_ty }
 };

 let maybe_map_err_jsvalue = match result_inner_ty {
  Some(_) => quote! { .map_err(|e| ::turbocharger::js_sys::Error::new(&e.to_string()).into()) },
  None => quote! {},
 };

 let send_value_to_subscription = if result_inner_ty.is_some() {
  quote! {
   if let Some(value) = self.value.lock().unwrap().clone() {
    let promise: ::turbocharger::js_sys::Promise = match value.clone() {
     Ok(t) => ::turbocharger::js_sys::Promise::resolve(&t.into()).into(),
     Err(e) => ::turbocharger::js_sys::Promise::reject(&e.into()).into(),
    };
    subscription.call1(&JsValue::null(), &promise).ok();
   }
  }
 } else {
  quote! {
   if let Some(value) = self.value.lock().unwrap().clone() {
    subscription.call1(&JsValue::null(), &value.into()).ok();
   }
  }
 };

 let send_value_to_subscriptions = if result_inner_ty.is_some() {
  quote! {
   if let Some(value) = value.lock().unwrap().clone() {
    let promise: ::turbocharger::js_sys::Promise = match value.clone() {
     Ok(t) => ::turbocharger::js_sys::Promise::resolve(&t.into()).into(),
     Err(e) => ::turbocharger::js_sys::Promise::reject(&e.into()).into(),
    };
    for subscription in subscriptions.lock().unwrap().iter() {
     if let Some(subscription) = subscription.lock().unwrap().as_ref() {
      subscription.call1(&JsValue::null(), &promise).ok();
     }
    }
   }
  }
 } else {
  quote! {
   if let Some(value) = value.lock().unwrap().clone() {
    for subscription in subscriptions.lock().unwrap().iter() {
     if let Some(subscription) = subscription.lock().unwrap().as_ref() {
      subscription.call1(&JsValue::null(), &value.clone().into()).ok();
     }
    }
   }
  }
 };

 let bindgen_ret_ty = match (stream_inner_ty, result_inner_ty) {
  (None, Some(ty)) => quote! { Result<#ty, JsValue> },
  (Some(_ty), _) => quote! { #store_name },
  (None, None) => quote! { #orig_fn_ret_ty },
 };
 let serialize_ret_ty = match &stream_inner_ty {
  Some(ty) => quote! { #ty },
  None => quote! { #orig_fn_ret_ty },
 };

 let orig_fn_ret_ty = if let Some(ty) = stream_inner_ty {
  quote_spanned! {ty.span()=> impl ::turbocharger::futures_util::stream::Stream<Item = #ty > }
 } else {
  quote_spanned! {orig_fn_ret_ty.span()=> #orig_fn_ret_ty }
 };

 let tuple_indexes = (0..orig_fn_params.len()).map(syn::Index::from);
 let orig_fn_param_names: Vec<_> = orig_fn_params
  .iter()
  .map(|p| match p {
   syn::FnArg::Receiver(_) => abort!(p, "I don't know what to do with `self` here."),
   syn::FnArg::Typed(pattype) => match *pattype.pat.clone() {
    syn::Pat::Ident(i) => i.ident,
    _ => abort!(pattype, "Parameter name is not Ident"),
   },
  })
  .collect();

 let orig_fn_param_tys: Vec<_> = orig_fn_params
  .iter()
  .map(|p| match p {
   syn::FnArg::Receiver(_) => abort!(p, "I don't know what to do with `self` here."),
   syn::FnArg::Typed(pattype) => &pattype.ty,
  })
  .collect();

 let orig_fn_params_maybe_comma = if orig_fn_params.is_empty() { quote!() } else { quote!( , ) };

 let mut orig_fn = orig_fn;
 orig_fn.sig.output = parse_quote! { -> #orig_fn_ret_ty };
 orig_fn.block = parse_quote!({
  let _turbocharger_connection_info: Option<::turbocharger::ConnectionInfo> = None;
  #orig_fn_stmts
 });

 let mut remote_impl_fn = orig_fn.clone();
 remote_impl_fn.sig.ident = remote_impl_ident.clone();
 remote_impl_fn.sig.inputs = parse_quote!(
  _turbocharger_connection_info: Option<::turbocharger::ConnectionInfo>
  #orig_fn_params_maybe_comma
  #orig_fn_params
 );
 remote_impl_fn.block = parse_quote!({ #orig_fn_stmts });

 let executebody = match &stream_inner_ty {
  Some(_ty) => quote! {
   use ::turbocharger::futures_util::stream::StreamExt as _;
   use ::turbocharger::stream_cancel::StreamExt as _;
   let stream = #remote_impl_ident(_turbocharger_connection_info #orig_fn_params_maybe_comma #( self.params. #tuple_indexes .clone() ),*);
   ::turbocharger::futures_util::pin_mut!(stream);

   if let Some(tripwire) = tripwire {
    let mut incoming = stream.take_until_if(tripwire);
    while let Some(result) = incoming.next().await {
     let response = #resp {
      txid: self.txid,
      result: result.clone()
     };
     sender(::turbocharger::bincode::serialize(&response).unwrap());
    }
   }
   else {
    while let Some(result) = stream.next().await {
     let response = #resp {
      txid: self.txid,
      result: result.clone()
     };
     sender(::turbocharger::bincode::serialize(&response).unwrap());
    }
   }
  },
  None => quote! {
   let result = #remote_impl_ident(_turbocharger_connection_info #orig_fn_params_maybe_comma #( self.params. #tuple_indexes .clone() ),*).await;
   let response = #resp {
    txid: self.txid,
    result
   };
   sender(::turbocharger::bincode::serialize(&response).unwrap());
  },
 };

 let maybe_svelte_typescript_type = if cfg!(feature = "svelte") {
  quote! {
   #[cfg(target_arch = "wasm32")]
   #[wasm_bindgen]
   extern "C" {
    #[wasm_bindgen(typescript_type = "Subscriber<any>")]
    #[allow(non_camel_case_types)]
    pub type #subscriber_fn_ident;
   }
  }
 } else {
  quote!()
 };

 let wasm_side = match &stream_inner_ty {
  Some(_ty) => quote! {
   #[cfg(target_arch = "wasm32")]
   pub fn #orig_fn_ident(#orig_fn_params) -> #orig_fn_ret_ty {
    let tx = ::turbocharger::_Transaction::new();
    let req = ::turbocharger::bincode::serialize(&#req {
     typetag_const_one: 1,
     dispatch_name: #orig_fn_string,
     txid: tx.txid,
     params: (#( #orig_fn_param_names ),* #orig_fn_params_maybe_comma),
    })
    .unwrap();
    tx.send_ws(req);

    let (resp_tx, resp_rx) = ::turbocharger::futures_channel::mpsc::unbounded();

    tx.set_sender(Box::new(move |response| {
     use ::turbocharger::futures_util::SinkExt as _;
     let #resp { result, .. } =
      ::turbocharger::bincode::deserialize(&response).unwrap();
     let mut resp_tx = resp_tx.clone();
     wasm_bindgen_futures::spawn_local(async move {
      resp_tx.send(result).await.unwrap();
     });
    }));

    resp_rx
   }
  },
  None => quote! {
   #[cfg(target_arch = "wasm32")]
   pub async fn #orig_fn_ident(#orig_fn_params) -> #orig_fn_ret_ty {
    let tx = ::turbocharger::_Transaction::new();
    let req = ::turbocharger::bincode::serialize(&#req {
     typetag_const_one: 1,
     dispatch_name: #orig_fn_string,
     txid: tx.txid,
     params: (#( #orig_fn_param_names ),* #orig_fn_params_maybe_comma),
    })
    .unwrap();
    tx.send_ws(req);
    let response = tx.resp().await;
    let #resp { result, .. } =
     ::turbocharger::bincode::deserialize(&response).unwrap();
    result
   }
  },
 };

 let js_side = if !is_js {
  quote!()
 } else {
  match &stream_inner_ty {
   Some(_ty) => quote! {
    #[cfg(target_arch = "wasm32")]
    #[allow(non_camel_case_types)]
    #[wasm_bindgen]
    pub struct #store_name {
     req: std::sync::Arc<std::sync::Mutex<#req>>,
     value: std::sync::Arc<std::sync::Mutex<Option< #store_value_ty >>>,
     subscriptions: std::sync::Arc<std::sync::Mutex<Vec<std::sync::Arc<std::sync::Mutex<Option<::turbocharger::js_sys::Function>>>>>>,
    }

    #maybe_svelte_typescript_type

    #[cfg(target_arch = "wasm32")]
    #[wasm_bindgen]
    impl #store_name {
     #[wasm_bindgen]
     pub fn subscribe(&mut self, subscription: #subscriber_fn_ident) -> JsValue {
      let subscription: ::turbocharger::js_sys::Function = JsValue::from(subscription).into();
      if self.subscriptions.lock().unwrap().is_empty() {
       let tx = ::turbocharger::_Transaction::new();
       self.req.lock().unwrap().txid = tx.txid;
       tx.send_ws(::turbocharger::bincode::serialize(&*self.req.lock().unwrap()).unwrap());
       let subscriptions = self.subscriptions.clone();
       let value = self.value.clone();
       tx.set_sender(Box::new(move |response| {
        let #resp { result, .. } =
         ::turbocharger::bincode::deserialize(&response).unwrap();
        value.lock().unwrap().replace(result.clone() #maybe_map_err_jsvalue );
        #send_value_to_subscriptions
       }));
      }

      #send_value_to_subscription
      let subscription_handle = std::sync::Arc::new(std::sync::Mutex::new(Some(subscription)));
      self.subscriptions.lock().unwrap().push(subscription_handle.clone());
      let subscriptions = self.subscriptions.clone();
      let req_clone = self.req.clone();

      Closure::wrap(Box::new(move || {
       subscription_handle.lock().unwrap().take();
       subscriptions.lock().unwrap().retain(|s| { s.lock().unwrap().is_some() });
       if subscriptions.lock().unwrap().is_empty() {
        let tx = ::turbocharger::_Transaction::new();
        tx.send_ws(::turbocharger::bincode::serialize(&*req_clone.lock().unwrap()).unwrap());
       }
      }) as Box<dyn Fn()>)
      .into_js_value()
     }
    }

    #[cfg(target_arch = "wasm32")]
    #[allow(non_snake_case)]
    #[wasm_bindgen(js_name = #orig_fn_ident)]
    pub fn #js_fn_ident(#orig_fn_params) -> #bindgen_ret_ty {
     let req = #req {
      typetag_const_one: 1,
      dispatch_name: #orig_fn_string,
      txid: 1,
      params: (#( #orig_fn_param_names ),* #orig_fn_params_maybe_comma),
     };
     #store_name {
      req: std::sync::Arc::new(std::sync::Mutex::new(req)),
      value: Default::default(),
      subscriptions: Default::default()
     }
    }
   },
   None => quote! {
    #[cfg(target_arch = "wasm32")]
    #[allow(non_snake_case)]
    #[wasm_bindgen(js_name = #orig_fn_ident)]
    pub async fn #js_fn_ident(#orig_fn_params) -> #bindgen_ret_ty {
     #orig_fn_ident(#( #orig_fn_param_names ),*) .await #maybe_map_err_jsvalue
    }
   },
  }
 };

 let output = quote! {
  #[cfg(target_arch = "wasm32")]
  #[allow(unused_imports)]
  use wasm_bindgen::prelude::*;

  #[cfg(not(target_arch = "wasm32"))]
  #[allow(unused_imports)]
  use turbocharger::prelude::*;

  #[cfg(not(target_arch = "wasm32"))]
  #[tracked]
  #orig_fn

  #[cfg(not(target_arch = "wasm32"))]
  #[allow(non_snake_case)]
  #[tracked]
  #remote_impl_fn

  #[cfg(not(target_arch = "wasm32"))]
  #[allow(non_snake_case)]
  #[::turbocharger::typetag::serde(name = #orig_fn_string)]
  #[::turbocharger::async_trait]
  impl ::turbocharger::RPC for #dispatch {
   async fn execute(
    &self,
    sender: Box<dyn Fn(Vec<u8>) + Send>,
    tripwire: Option<::turbocharger::stream_cancel::Tripwire>,
    _turbocharger_connection_info: Option<::turbocharger::ConnectionInfo>
   ) {
    #executebody
   }
   fn txid(&self) -> i64 {
    self.txid
   }
  }

  #wasm_side
  #js_side

  #[cfg(not(target_arch = "wasm32"))]
  #[allow(non_snake_case)]
  async fn #remote_fn_ident(peer: &str, #orig_fn_params) -> #serialize_ret_ty {
   let tx = ::turbocharger::_Transaction::new();
   let req = ::turbocharger::bincode::serialize(&#req {
    typetag_const_one: 1,
    dispatch_name: #orig_fn_string,
    txid: tx.txid,
    params: (#( #orig_fn_param_names ),* #orig_fn_params_maybe_comma),
   })
   .unwrap();
   tx.send_udp(peer, req).await;
   let response = tx.resp().await;
   let #resp { result, .. } =
    ::turbocharger::bincode::deserialize(&response).unwrap();
   result
  }

  #[allow(non_camel_case_types)]
  #[derive(::turbocharger::serde::Serialize, ::turbocharger::serde::Deserialize)]
  #[serde(crate = "::turbocharger::serde")]
  struct #req {
   typetag_const_one: i64,
   dispatch_name: &'static str,
   txid: i64,
   params: (#( #orig_fn_param_tys ),* #orig_fn_params_maybe_comma),
  }

  #[allow(non_camel_case_types)]
  #[derive(::turbocharger::serde::Serialize, ::turbocharger::serde::Deserialize)]
  #[serde(crate = "::turbocharger::serde")]
  struct #dispatch {
   txid: i64,
   params: (#( #orig_fn_param_tys ),* #orig_fn_params_maybe_comma),
  }

  #[allow(non_camel_case_types)]
  #[derive(::turbocharger::serde::Serialize, ::turbocharger::serde::Deserialize)]
  #[serde(crate = "::turbocharger::serde")]
  struct #resp {
   txid: i64,
   result: #serialize_ret_ty,
  }
 };

 #[cfg(feature = "debug_expansions")]
 {
  std::fs::create_dir_all("debug_expansions").ok();
  std::fs::write(
   project_root_path_with(format!("debug_expansions/{}.rs", orig_fn_string)),
   prettyplease::unparse(&parse_quote!( #output )),
  )
  .unwrap();

  std::process::Command::new("rustfmt")
   .current_dir(project_root_path_with("debug_expansions"))
   .arg("--edition")
   .arg("2021")
   .arg("--config")
   .arg("tab_spaces=1")
   .arg(format!("{}.rs", orig_fn_string))
   .output()
   .unwrap();
 }

 output
}

fn read_backend_api_rs() -> syn::File {
 syn::parse_file(&std::fs::read_to_string(backend_api_rs_path()).unwrap_or_default()).unwrap()
}

fn write_backend_api_rs(file: syn::File) {
 let mut output = "// This file is auto-generated by Turbocharger.\n// Check it into version control to track API changes over time.\n// To regenerate: \"cargo clean && rm backend_api.rs && cargo check\"\n".to_string();
 let mut items = file.items;
 items.sort_by_key(|item| match item {
  syn::Item::Struct(s) => s.ident.to_string().to_lowercase(),
  syn::Item::Fn(f) => f.sig.ident.to_string().to_lowercase(),
  _ => unreachable!(),
 });
 for item in items {
  output.push('\n');
  output.push_str(&prettyplease::unparse(&parse_quote!( #item )));
 }
 if output != std::fs::read_to_string(backend_api_rs_path()).unwrap_or_default() {
  std::fs::write(backend_api_rs_path(), output).unwrap();
 }
}

fn backend_api_rs_path() -> std::path::PathBuf {
 project_root_path_with("backend_api.rs")
}

fn project_root_path_with<P: AsRef<std::path::Path>>(pushpath: P) -> std::path::PathBuf {
 let mut path = std::path::PathBuf::from(env!("OUT_DIR"));
 while path.file_name() != Some(std::ffi::OsStr::new("target")) {
  path.pop();
 }
 path.pop();
 path.push(pushpath);
 path
}