added rdwrcount and ioeg examples

Author: BartMassey

rust-spring2023/ioeg/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "ioeg"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+
+[[bin]]
+name = "ioeg"
+path = "ioeg.rs"

rust-spring2023/ioeg/ioeg.rs

@@ -0,0 +1,29 @@
+fn read_bytes<R: std::io::Read>(r: &mut R, n: usize) ->
+    Result<Vec<u8>, std::io::Error>
+{
+    let mut result = Vec::with_capacity(n);
+    result.resize(n, 0);
+    let mut target: &mut [u8] = &mut result[..];
+    loop {
+        let nread = r.read(target)?;
+        if nread == 0 {
+            result.resize(target.len(), 0);
+            return Ok(result);
+        }
+        target = &mut target[nread..];
+        if target.len() == 0 {
+            return Ok(result);
+        }
+    }
+}
+
+fn print_string<W: std::io::Write>(w: &mut W, s: &str) {
+    w.write_all(s.as_bytes()).unwrap();
+    w.write(b"\n").unwrap();
+}
+
+fn main() {
+    println!("hello world");
+    let mut stdout = std::io::stdout();
+    print_string(&mut stdout, "print string!");
+}

rust-spring2023/rdwrcount/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "rdwrcount"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+
+[[bin]]
+name = "rdwrcount"
+path = "rdwrcount.rs"

rust-spring2023/rdwrcount/rdwrcount.rs

@@ -0,0 +1,71 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+
+#[derive(Debug, Default)]
+struct AccessCounter(usize);
+
+impl AccessCounter {
+    fn inc(&mut self) {
+        self.0 += 1;
+    }
+
+    fn get(&self) -> usize {
+        self.0
+    }
+
+    fn reset(&mut self) {
+        self.0 = 0;
+    }
+}
+
+#[derive(Debug)]
+struct Reader {
+    counter: usize,
+    accesses: Rc<RefCell<AccessCounter>>,
+}
+
+impl Reader {
+    fn read(&mut self) -> String {
+        self.accesses.borrow_mut().inc();
+        self.counter += 1;
+        self.counter.to_string()
+    }
+
+    fn get(&self) -> usize {
+        self.counter
+    }
+}
+
+#[derive(Debug)]
+struct Writer {
+    written: String,
+    accesses: Rc<RefCell<AccessCounter>>,
+}    
+
+impl Writer {
+    fn write(&mut self, s: &str) {
+        self.accesses.borrow_mut().inc();
+        self.written = s.to_owned();
+    }
+
+    fn get(&self) -> &str {
+        &self.written
+    }
+}
+
+fn main() {
+    let accesses = Rc::new(RefCell::new(AccessCounter::default()));
+    let mut writer = Writer {
+        written: "".to_string(),
+        accesses: Rc::clone(&accesses),
+    };
+    let mut reader = Reader {
+        counter: 0,
+        accesses: Rc::clone(&accesses),
+    };
+    writer.write(&reader.read());
+    println!("{} {} {}", writer.get(), reader.get(), accesses.borrow().get());
+    accesses.borrow_mut().reset();
+    drop(accesses);
+    println!("{} {}", writer.get(), reader.get());
+}