My current config below
-- plugins-setup.lua
local status, packer = pcall(require, "packer")
if not status then
return
end
return packer.startup(function(use)
-- snip
use("williamboman/mason.nvim")
use("williamboman/mason-lspconfig.nvim")
use("simrat39/rust-tools.nvim")
use("rust-lang/rust.vim")
-- snip
-- rust-tools.lua
local rt = require("rust-tools")
rt.setup({
server = {
on_attach = function(_, bufnr)
-- Hover actions
vim.keymap.set("n", "<C-space>", rt.hover_actions.hover_actions, { buffer = bufnr })
-- Code action groups
vim.keymap.set("n", "<Leader>a", rt.code_action_group.code_action_group, { buffer = bufnr })
end,
},
})
And I have init.lua requires all of above.
I want:
struct Foo {}
impl Display for Foo {}
to be:
struct Foo {}
impl Display for Foo {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
todo!()
}
}
It is available in fleet like below:
Is it possible to do the same in neovim? If yes, I would like a setup instruction. If not, any explanation would be appreciated.
Related
I'm trying to use database connection from a Rocket's on_ignite fairing:
use sqlx::{ self, FromRow };
use rocket::fairing::{self, Fairing, Info, Kind};
use rocket::{Build, Rocket};
use crate::database::PostgresDb;
#[derive(FromRow)]
struct TableRow {
column_a: String,
column_b: String
}
#[rocket::async_trait]
impl Fairing for TableRow {
fn info(&self) -> Info {
Info {
name: "Cache table row",
kind: Kind::Ignite,
}
}
async fn on_ignite(&self, rocket: Rocket<Build>) -> fairing::Result {
let mut db = rocket
.state::<Connection<PostgresDb>>()
.expect("Unable to find db connection.");
let row = sqlx::query_as::<_, TableRow>("SELECT * FROM table WHERE id = 1;")
.fetch_one(&mut db)
.await
.unwrap();
fairing::Result::Ok(rocket.manage(row))
}
}
The problem is I get following rust error during .fetch_one(&mut db):
the trait bound `&mut rocket_db_pools::Connection<PostgresDb>: Executor<'_>` is not satisfied
the following other types implement trait `Executor<'c>`:
<&'c mut PgConnection as Executor<'c>>
<&'c mut PgListener as Executor<'c>>
<&'c mut PoolConnection<Postgres> as Executor<'c>>
<&'t mut Transaction<'c, Postgres> as Executor<'t>>
<&sqlx::Pool<DB> as Executor<'p>>rustcClick for full compiler diagnostic
cache_rbac_on_ignite.rs(56, 14): required by a bound introduced by this call
query_as.rs(132, 17): required by a bound in `QueryAs::<'q, DB, O, A>::fetch_all`
I tried solution suggested here: How to get the database Connection in rocket.rs Fairing. but it did not work out.
Here is the code:
use sqlx::{ self, FromRow, Database };
use rocket::fairing::{self, Fairing, Info, Kind};
use rocket::{Build, Rocket};
use crate::database::PostgresDb;
#[derive(FromRow)]
struct TableRow {
column_a: String,
column_b: String
}
#[rocket::async_trait]
impl Fairing for TableRow {
fn info(&self) -> Info {
Info {
name: "Cache table row",
kind: Kind::Ignite,
}
}
async fn on_ignite(&self, rocket: Rocket<Build>) -> fairing::Result {
let mut db = PostgresDb::get_one(rocket).await.unwrap();
let row = sqlx::query_as::<_, TableRow>("SELECT * FROM table WHERE id = 1;")
.fetch_one(&mut db)
.await
.unwrap();
fairing::Result::Ok(rocket.manage(row))
}
}
I get following rust error on line let mut db = PostgresDb::get_one(rocket).await.unwrap();:
no function or associated item named `get_one` found for struct `PostgresDb` in the current scope
function or associated item not found in `PostgresDb`rustcClick for full compiler diagnostic
mod.rs(8, 1): function or associated item `get_one` not found for this struct
What is the right way to use database connection inside of the fairing? Thank you!
Finally found an answer. Here is what worked for me:
use rocket::fairing::{self, Fairing, Info, Kind};
use rocket::{Build, Rocket};
use rocket_db_pools::{ sqlx::{ self, FromRow }, Database };
use crate::database::PostgresDb;
#[derive(FromRow)]
struct TableRow {
column_a: String,
column_b: String
}
#[rocket::async_trait]
impl Fairing for TableRow {
fn info(&self) -> Info {
Info {
name: "Cache table row",
kind: Kind::Ignite,
}
}
async fn on_ignite(&self, rocket: Rocket<Build>) -> fairing::Result {
let db = PostgresDb::fetch(&rocket).unwrap();
let mut conn = db.aquire().await.unwrap();
let row = sqlx::query_as::<_, TableRow>("SELECT * FROM table WHERE id = 1;")
.fetch_one(&mut conn)
.await
.unwrap();
fairing::Result::Ok(rocket.manage(row))
}
}
I'm trying to write a Udp Client Actor using Actix. I've followed this example, UDP-Echo, but I can't seem to send a message to the server using the UdpFramed tokio struct.
Here's what I have so far, this is the Udp Client Actor implementation
use std::collections::HashMap;
use std::net::{SocketAddr};
use actix_rt::net::UdpSocket;
use actix::{Actor, Addr, AsyncContext, Context, Handler, StreamHandler, Message};
use actix::io::SinkWrite;
use actix_web::web::{Bytes, BytesMut};
use futures_util::stream::{SplitSink};
use futures_util::StreamExt;
use log::info;
use serde_json::Value;
use tokio_util::codec::BytesCodec;
use tokio_util::udp::UdpFramed;
use crate::rosclient::messages::Subscribe;
use std::io::Result;
mod messages;
type SinkItem = (Bytes, SocketAddr);
type UdpSink = SplitSink<UdpFramed<BytesCodec, UdpSocket>, SinkItem>;
pub struct UdpClientActor {
pub address: SocketAddr,
pub sink: SinkWrite<SinkItem, UdpSink>,
}
impl UdpClientActor {
pub fn start(udp: UdpSocket, address: SocketAddr) -> Addr<UdpClientActor> {
let framed = UdpFramed::new(udp, BytesCodec::new());
let (split_sink, split_stream) = framed.split();
UdpClientActor::create(|ctx| {
ctx.add_stream(split_stream.filter_map(
|item: Result<(BytesMut, SocketAddr)>| async {
item.map(|(data, sender)| UdpPacket(data, sender)).ok()
},
));
UdpClientActor {
address,
sink: SinkWrite::new(split_sink, ctx),
}
})
}
}
impl Actor for UdpClientActor {
type Context = Context<Self>;
fn started(&mut self, ctx: &mut Self::Context) {
let mut hashmap = HashMap::new();
hashmap.insert(String::from("topic"), Value::String(String::from("/client_count")));
let subscription = Subscribe {
id: Default::default(),
op: "subscribe".to_string(),
extra: hashmap
};
ctx.notify(subscription);
}
}
#[derive(Message)]
#[rtype(result = "()")]
struct UdpPacket(BytesMut, SocketAddr);
impl StreamHandler<UdpPacket> for
UdpClientActor {
fn handle(&mut self, item: UdpPacket, _ctx: &mut Self::Context) {
println!("Received: ({:?}, {:?})", item.0, item.1);
self.sink.write((item.0.into(), item.1)).unwrap();
}
}
impl actix::io::WriteHandler<std::io::Error> for UdpClientActor {}
impl Handler<Subscribe> for UdpClientActor {
type Result = ();
fn handle(&mut self, msg: Subscribe, _ctx: &mut Self::Context) -> Self::Result {
let js = serde_json::json!(msg).to_string();
let _ = self.sink.write((Bytes::from(msg.to_string()), self.address));
info!("Subscribing to topic {}", js);
}
}
My main function creates the udp socket and spawns the actor.
fn main() {
////////////////////////////////////////////////////////////////////////////
let fut = async {
////////////////////////////////////////////////////////////////////////////
/////////// UDP_ACTOR
let sock = tokio::net::UdpSocket::bind("0.0.0.0:9091").await.unwrap();
let remote_addr = "172.30.89.169:9091".parse::<SocketAddr>().unwrap();
// let message = b"{ \"op\": \"subscribe\", \"topic\": \"/client_count\"}";
let _ = sock.connect(remote_addr).await;
// sock.send(message).await.unwrap();
let _udp_client = UdpClientActor::start(sock, remote_addr);
};
actix_rt::Arbiter::new().spawn(fut);
// system.block_on(fut);
system.run().unwrap();
}
If I remove the comments on
let message = b"{ \"op\": \"subscribe\", \"topic\": \"/client_count\"}";
and
sock.send(message).await.unwrap();
I can at least check that the server can actually receive messages. So I know that the problem must lie in my implementation of the actor. I do have another one which uses the LinesCodec instead of the BytesCodec, which follows the exact same implementation. Only difference is that SinkWrite becomes this:
SinkWrite<(String, SocketAddr), SplitSink<UdpFramed<codec::LinesCodec>,
(String, SocketAddr)>>
Here is my Cargo.toml for reference.
[package]
name = "local_websocket_client"
version = "0.1.0"
edition = "2018"
[dependencies]
actix="0.12"
actix-codec = "0.4"
actix-rt = "2.5"
bytestring = "1.0"
serde = {version="1.0", features=["serde_derive"]}
log = "0.4"
env_logger = "0.9.0"
chrono = "0.4"
dashmap = "4.0"
futures = "0.3"
openssl = "0.10"
tokio = { version = "1", features = ["full"] }
actix-web = "4.0.0-beta.15"
futures-util = "0.3"
tokio-util = { version="0.6", features=["net", "codec"] }
tokio-udp = "0.1.6"
bytes= { version="0.6", features=["serde"] }
[dependencies.awc]
features = ["openssl"]
version = "3.0.0-beta.9"
[dependencies.serde_json]
features = ["default"]
version = "1.0"
[dependencies.uuid]
features = ["v4", "serde", "v5"]
version = "0.8"
There are some extra crates there because I'm running 2 other websocket clients on the same application.
I would really appreciate some help on this matter.
Thank you
Solved it by wrapping the UdpSocket in an Arc and keeping the reference in the actor for later use. Using the socket to write messages works. The split stream used for the streamhandler needs no change, as it works as expected.
I am struggling getting the hash of the passed file name using the blake2 crate. From the documentation:
extern crate blake2;
use blake2::{Blake2b, Digest};
use std::env;
use std::fs;
use std::io::{self, Read};
const BUFFER_SIZE: usize = 1024;
fn print_result(sum: &[u8]) {
for byte in sum {
print!("{:02x}", byte);
}
}
fn process<D: Digest + Default, R: Read>(reader: &mut R) {
let mut sh = D::default();
let mut buffer = [0u8; BUFFER_SIZE];
loop {
let n = match reader.read(&mut buffer) {
Ok(n) => n,
Err(_) => return,
};
sh.input(&buffer[..n]);
if n == 0 || n < BUFFER_SIZE {
break;
}
}
print_result(&sh.result());
}
fn main() {
let args = env::args();
if args.len() > 1 {
for path in args.skip(1) {
if let Ok(mut file) = fs::File::open(&path) {
process::<Blake2b, _>(&mut file);
}
}
} else {
process::<Blake2b, _>(&mut io::stdin());
}
}
blake-test $ cargo run hoge.txt
Compiling blake-test v0.1.0 (/Users/hoge/blake-test)
Finished dev [unoptimized + debuginfo] target(s) in 0.61s
Running `target/debug/blake-test hoge.txt`
eefea9ae6b7fb678ed54e6d58d46aed9eae6d003f29419948cdb42a44a7016dee3eb566e7e95c68ac7587d5debd516a3b195eed0db84d72819e387d687fd06a6
It can successfully print the the &[u8] slice.
However, I want to receive/return the results instead of printing them.
When you're returning a newly-created object, you have to return it as an owned value.
Borrowed references, such as &[u8] are temporary and can't exist by themselves, they're merely a views of data that has storage in an owned form elsewhere.
You can for example, call .to_vec() on the slice and return Vec<u8>.
I want to create a macro that prints "Hello" a specified number of times. It's used like:
many_greetings!(3); // expands to three `println!("Hello");` statements
The naive way to create that macro is:
macro_rules! many_greetings {
($times:expr) => {{
println!("Hello");
many_greetings!($times - 1);
}};
(0) => ();
}
However, this doesn't work because the compiler does not evaluate expressions; $times - 1 isn't calculated, but fed as a new expression into the macro.
While the ordinary macro system does not enable you to repeat the macro expansion many times, there is no problem with using a for loop in the macro:
macro_rules! many_greetings {
($times:expr) => {{
for _ in 0..$times {
println!("Hello");
}
}};
}
If you really need to repeat the macro, you have to look into procedural macros/compiler plugins (which as of 1.4 are unstable, and a bit harder to write).
Edit: There are probably better ways of implementing this, but I've spent long enough on this for today, so here goes. repeat!, a macro that actually duplicates a block of code a number of times:
main.rs
#![feature(plugin)]
#![plugin(repeat)]
fn main() {
let mut n = 0;
repeat!{ 4 {
println!("hello {}", n);
n += 1;
}};
}
lib.rs
#![feature(plugin_registrar, rustc_private)]
extern crate syntax;
extern crate rustc;
use syntax::codemap::Span;
use syntax::ast::TokenTree;
use syntax::ext::base::{ExtCtxt, MacResult, MacEager, DummyResult};
use rustc::plugin::Registry;
use syntax::util::small_vector::SmallVector;
use syntax::ast::Lit_;
use std::error::Error;
fn expand_repeat(cx: &mut ExtCtxt, sp: Span, tts: &[TokenTree]) -> Box<MacResult + 'static> {
let mut parser = cx.new_parser_from_tts(tts);
let times = match parser.parse_lit() {
Ok(lit) => match lit.node {
Lit_::LitInt(n, _) => n,
_ => {
cx.span_err(lit.span, "Expected literal integer");
return DummyResult::any(sp);
}
},
Err(e) => {
cx.span_err(sp, e.description());
return DummyResult::any(sp);
}
};
let res = parser.parse_block();
match res {
Ok(block) => {
let mut stmts = SmallVector::many(block.stmts.clone());
for _ in 1..times {
let rep_stmts = SmallVector::many(block.stmts.clone());
stmts.push_all(rep_stmts);
}
MacEager::stmts(stmts)
}
Err(e) => {
cx.span_err(sp, e.description());
DummyResult::any(sp)
}
}
}
#[plugin_registrar]
pub fn plugin_registrar(reg: &mut Registry) {
reg.register_macro("repeat", expand_repeat);
}
added to Cargo.toml
[lib]
name = "repeat"
plugin = true
Note that if we really don't want to do looping, but expanding at compile-time, we have to do things like requiring literal numbers. After all, we are not able to evaluate variables and function calls that reference other parts of the program at compile time.
As the other answers already said: no, you can't count like this with declarative macros (macro_rules!).
But you can implement the many_greetings! example as a procedural macro. procedural macros were stabilized a while ago, so the definition works on stable. However, we can't yet expand macros into statements on stable -- that's what the #![feature(proc_macro_hygiene)] is for.
This looks like a lot of code, but most code is just error handling, so it's not that complicated!
examples/main.rs
#![feature(proc_macro_hygiene)]
use count_proc_macro::many_greetings;
fn main() {
many_greetings!(3);
}
Cargo.toml
[package]
name = "count-proc-macro"
version = "0.1.0"
authors = ["me"]
edition = "2018"
[lib]
proc-macro = true
[dependencies]
quote = "0.6"
src/lib.rs
extern crate proc_macro;
use std::iter;
use proc_macro::{Span, TokenStream, TokenTree};
use quote::{quote, quote_spanned};
/// Expands into multiple `println!("Hello");` statements. E.g.
/// `many_greetings!(3);` will expand into three `println`s.
#[proc_macro]
pub fn many_greetings(input: TokenStream) -> TokenStream {
let tokens = input.into_iter().collect::<Vec<_>>();
// Make sure at least one token is provided.
if tokens.is_empty() {
return err(Span::call_site(), "expected integer, found no input");
}
// Make sure we don't have too many tokens.
if tokens.len() > 1 {
return err(tokens[1].span(), "unexpected second token");
}
// Get the number from our token.
let count = match &tokens[0] {
TokenTree::Literal(lit) => {
// Unfortunately, `Literal` doesn't have nice methods right now, so
// the easiest way for us to get an integer out of it is to convert
// it into string and parse it again.
if let Ok(count) = lit.to_string().parse::<usize>() {
count
} else {
let msg = format!("expected unsigned integer, found `{}`", lit);
return err(lit.span(), msg);
}
}
other => {
let msg = format!("expected integer literal, found `{}`", other);
return err(other.span(), msg);
}
};
// Return multiple `println` statements.
iter::repeat(quote! { println!("Hello"); })
.map(TokenStream::from)
.take(count)
.collect()
}
/// Report an error with the given `span` and message.
fn err(span: Span, msg: impl Into<String>) -> TokenStream {
let msg = msg.into();
quote_spanned!(span.into()=> {
compile_error!(#msg);
}).into()
}
Running cargo run --example main prints three "Hello"s.
For those looking for a way to do this, there is also the seq_macro crate.
It is fairly easy to use and works out of the box with stable Rust.
use seq_macro::seq;
macro_rules! many_greetings {
($times:literal) => {
seq!{ N in 0..$times {
println!("Hello");
}}
};
}
fn main() {
many_greetings!(3);
many_greetings!(12);
}
As far as I know, no. The macro language is based on pattern matching and variable substitution, and only evaluates macros.
Now, you can implement counting with evaluation: it just is boring... see the playpen
macro_rules! many_greetings {
(3) => {{
println!("Hello");
many_greetings!(2);
}};
(2) => {{
println!("Hello");
many_greetings!(1);
}};
(1) => {{
println!("Hello");
many_greetings!(0);
}};
(0) => ();
}
Based on this, I am pretty sure one could invent a set of macro to "count" and invoke various operations at each step (with the count).
I'd like to create a setter/getter pair of functions where the names are automatically generated based on a shared component, but I couldn't find any example of macro rules generating a new name.
Is there a way to generate code like fn get_$iden() and SomeEnum::XX_GET_$enum_iden?
If you are using Rust >= 1.31.0 I would recommend using my paste crate which provides a stable way to create concatenated identifiers in a macro.
macro_rules! make_a_struct_and_getters {
($name:ident { $($field:ident),* }) => {
// Define the struct. This expands to:
//
// pub struct S {
// a: String,
// b: String,
// c: String,
// }
pub struct $name {
$(
$field: String,
)*
}
paste::item! {
// An impl block with getters. Stuff in [<...>] is concatenated
// together as one identifier. This expands to:
//
// impl S {
// pub fn get_a(&self) -> &str { &self.a }
// pub fn get_b(&self) -> &str { &self.b }
// pub fn get_c(&self) -> &str { &self.c }
// }
impl $name {
$(
pub fn [<get_ $field>](&self) -> &str {
&self.$field
}
)*
}
}
};
}
make_a_struct_and_getters!(S { a, b, c });
My mashup crate provides a stable way to create new identifiers that works with any Rust version >= 1.15.0.
#[macro_use]
extern crate mashup;
macro_rules! make_a_struct_and_getters {
($name:ident { $($field:ident),* }) => {
// Define the struct. This expands to:
//
// pub struct S {
// a: String,
// b: String,
// c: String,
// }
pub struct $name {
$(
$field: String,
)*
}
// Use mashup to define a substitution macro `m!` that replaces every
// occurrence of the tokens `"get" $field` in its input with the
// concatenated identifier `get_ $field`.
mashup! {
$(
m["get" $field] = get_ $field;
)*
}
// Invoke the substitution macro to build an impl block with getters.
// This expands to:
//
// impl S {
// pub fn get_a(&self) -> &str { &self.a }
// pub fn get_b(&self) -> &str { &self.b }
// pub fn get_c(&self) -> &str { &self.c }
// }
m! {
impl $name {
$(
pub fn "get" $field(&self) -> &str {
&self.$field
}
)*
}
}
}
}
make_a_struct_and_getters!(S { a, b, c });
No, not as of Rust 1.22.
If you can use nightly builds...
Yes: concat_idents!(get_, $iden) and such will allow you to create a new identifier.
But no: the parser doesn't allow macro calls everywhere, so many of the places you might have sought to do this won't work. In such cases, you are sadly on your own. fn concat_idents!(get_, $iden)(…) { … }, for example, won't work.
There's a little known crate gensym that can generate unique UUID names and pass them as the first argument to a macro, followed by a comma:
macro_rules! gen_fn {
($a:ty, $b:ty) => {
gensym::gensym!{ _gen_fn!{ $a, $b } }
};
}
macro_rules! _gen_fn {
($gensym:ident, $a:ty, $b:ty) => {
fn $gensym(a: $a, b: $b) {
unimplemented!()
}
};
}
mod test {
gen_fn!{ u64, u64 }
gen_fn!{ u64, u64 }
}
If all you need is a unique name, and you don't care what it is, that can be useful. I used it to solve a problem where each invocation of a macro needed to create a unique static to hold a singleton struct. I couldn't use paste, since I didn't have unique identifiers I could paste together in the first place.