feat: add __compress/zstd-demo

__compress/zstd-demo/src/main.rs

@@ -0,0 +1,29 @@
+use std::collections::VecDeque;
+use std::io;
+use zstd::Encoder;
+
+fn main() {
+    let inputs = "hello world".repeat(100);
+    let outputs = compress_manually(1, inputs.as_bytes().to_vec().into());
+
+    println!("Inputs len: {}", inputs.len());
+    println!("Outputs len: {}", outputs.len());
+    println!("{:x?}", outputs);
+}
+
+// fn compress(level: i32) {
+//     zstd::stream::copy_encode(io::stdin(), io::stdout(), level).unwrap();
+// }
+// fn decompress() {
+//     zstd::stream::copy_decode(io::stdin(), io::stdout()).unwrap();
+// }
+
+// This function does the same thing, directly using an `Encoder`:
+fn compress_manually(level: i32, mut input: VecDeque<u8>) -> Vec<u8> {
+    let mut output: Vec<u8> = vec![];
+    let mut encoder = Encoder::new(&mut output, level).unwrap();
+    io::copy(&mut input, &mut encoder).unwrap();
+    encoder.finish().unwrap();
+    output
+}
+