sprintf not happenin we go prefix/postfix now with templating

Cargo.lock

@@ -789,6 +789,12 @@ dependencies = [
  "byteorder",
 ]
 
+[[package]]
+name = "gcc"
+version = "0.3.55"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f5f3913fa0bfe7ee1fd8248b6b9f42a5af4b9d65ec2dd2c3c26132b950ecfc2"
+
 [[package]]
 name = "gethostname"
 version = "0.2.3"
@@ -1745,6 +1751,16 @@ version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
 
+[[package]]
+name = "printf"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "15343a566c054c72bdc3f3f138002a87e5320d7389c9713112c9b77e83539141"
+dependencies = [
+ "gcc",
+ "libc",
+]
+
 [[package]]
 name = "proc-macro-crate"
 version = "1.3.1"
@@ -1937,6 +1953,7 @@ dependencies = [
  "hidapi",
  "iced",
  "iced_native",
+ "printf",
  "rdkafka",
  "rusb",
  "serde",

Cargo.toml

@@ -14,3 +14,4 @@ hidapi = "0.5.0"
 gilrs = "0.10.1"
 iced = "0.8.0"
 iced_native = "0.9.1"
+printf = "0.1.0"

src/config.rs

@@ -77,7 +77,7 @@ fn build_config_std() -> Config {
             },
          },
          output: Stream {
-            format: None,
+            format: Some(String::from("%s")),
             engine: Engine{
                name: String::from("stdout"),
                kafka: None,

src/stream.rs

@@ -3,6 +3,8 @@ use crate::config::Stream;
 use hidapi::HidApi;
 use rusb::UsbContext;
 use gilrs::{Gilrs, Button, Event};
+use printf;
+use std::os::raw::c_void;
 
 pub trait InputStream {
    fn get(&mut self) -> Vec<char>;
@@ -192,7 +194,37 @@ pub trait OutputStream {
 }
 
 pub fn build_output_stream(cfg: &Stream) -> Box<dyn OutputStream> {
-   return _build_output_stream(cfg)
+   return build_formatted_output_stream(cfg, _build_output_stream(cfg))
+}
+
+pub struct OutputStreamFormatted {
+   format: Option<String>,
+   stream: Box<dyn OutputStream>,
+}
+
+pub fn build_formatted_output_stream(cfg: &Stream, stream: Box<dyn OutputStream>) -> Box<dyn OutputStream> {
+   return Box::new(OutputStreamFormatted{
+      format: cfg.format.clone(),
+      stream: stream,
+   });
+}
+
+impl OutputStream for OutputStreamFormatted {
+   fn put(&mut self, v: Vec<char>) {
+      match self.format.as_ref() {
+         Some(x) => self.stream.put(sprintf(x, v)),
+         None => self.stream.put(v),
+      };
+   }
+}
+
+fn sprintf(format: &String, arg: Vec<char>) -> Vec<char> {
+   unsafe {
+      return printf::printf(
+         format.as_bytes().as_ptr() as *const i8,
+         arg.iter().cloned().collect::<String>().as_bytes().as_ptr() as *mut c_void,
+      ).chars().collect();
+   }
 }
 
 pub fn _build_output_stream(cfg: &Stream) -> Box<dyn OutputStream> {
@@ -232,6 +264,17 @@ mod test_output {
    fn _test_output_stream_impl(engine: &mut dyn OutputStream) {
       engine.put("teehee".to_string().chars().collect());
    }
+
+   #[test]
+   fn test_sprintf() {
+      assert_eq!(
+         "hello world".to_string().chars().collect::<Vec<char>>(),
+         sprintf(
+            &String::from("hello %s"),
+            String::from("world").chars().collect(),
+         ),
+      );
+   }
 }
 
 pub struct OutputStreamUDP {