Initial commit

Cargo.lock

+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "progress"
+version = "0.1.0"

Cargo.toml

+[package]
+name = "progress"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

src/main.rs

+//! This crates demonstrates the use of extension traits and Type State encoding.
+//!
+//! The original idea is borrowed from Will Crichton's talk at Strangeloop 2021
+//!
+//! https://www.youtube.com/watch?v=bnnacleqg6k
+//!
+const CLEAR: &str = "\x1b[2J\x1b[1;1H";
+
+fn compute<T>(_val: T) {
+    std::thread::sleep(std::time::Duration::from_millis(600));
+}
+
+/// This type defines the /unbounded/ state for our progress bar
+struct Unbounded;
+/// This type defines the /bounded/ state for our progress bar
+struct Bounded {
+    bound: usize,
+}
+
+/// Defines how to display a progress bar
+trait ProgressDisplay: Sized {
+    /// Displays the progress bar. It is for each item yielded by the iterator
+    fn display<Iter>(&self, progress: &Progress<Iter, Self>);
+}
+
+impl ProgressDisplay for Unbounded {
+    fn display<Iter>(&self, progress: &Progress<Iter, Self>) {
+        println!("{}{}", CLEAR, "*".repeat(progress.i));
+    }
+}
+
+impl ProgressDisplay for Bounded {
+    fn display<Iter>(&self, progress: &Progress<Iter, Self>) {
+        println!(
+            "{}[{}{}]",
+            CLEAR,
+            "*".repeat(progress.i),
+            "-".repeat(self.bound - progress.i)
+        );
+    }
+}
+
+#[derive(Debug)]
+/// An Iterator that display progress
+struct Progress<Iter, Bound> {
+    iter: Iter,
+    i: usize,
+    bound: Bound,
+}
+
+impl<Iter: ExactSizeIterator> Progress<Iter, Unbounded> {
+    /// Creates a new bounded progress bar from an unbounded one
+    fn with_bounds(self) -> Progress<Iter, Bounded> {
+        let bound = Bounded {
+            bound: self.iter.len(),
+        };
+
+        Progress {
+            iter: self.iter,
+            i: self.i,
+            bound,
+        }
+    }
+}
+
+impl<Iter: Iterator, Bound: ProgressDisplay> Iterator for Progress<Iter, Bound> {
+    type Item = Iter::Item;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.bound.display(self);
+        self.i += 1;
+        self.iter.next()
+    }
+}
+
+/// A trait that allows the creation of a progress bar from a type
+trait ProgressIteratorExt: Sized {
+    /// Create a new unbounded progress bar from self
+    fn progress(self) -> Progress<Self, Unbounded>;
+}
+
+impl<Iter: Iterator> ProgressIteratorExt for Iter {
+    fn progress(self) -> Progress<Self, Unbounded> {
+        Progress {
+            iter: self,
+            i: 0,
+            bound: Unbounded,
+        }
+    }
+}
+
+fn main() {
+    let values = [1, 2, 3];
+
+    for v in values.iter().progress().with_bounds() {
+        compute(v);
+    }
+
+    for v in (0..).progress() {
+        compute(v);
+    }
+}