Started Rust in Action MEAP.

1 files changed, 65 insertions, 0 deletions

diff --git a/meap/meap-code/ch3/fileresult/src/main.rs b/meap/meap-code/ch3/fileresult/src/main.rs
new file mode 100644
index 0000000..c02d959
--- /dev/null
+++ b/meap/meap-code/ch3/fileresult/src/main.rs
@@ -0,0 +1,65 @@
+extern crate rand; // <1>
+use rand::Rng;  // <2>
+
+fn one_in(n: u32) -> bool { // <3>
+  rand::thread_rng().gen_weighted_bool(n)
+}
+
+#[derive(Debug)]
+struct File {
+  name: String,
+  data: Vec<u8>,
+}
+
+impl File {
+  fn new(name: &str) -> File {
+    File { name: String::from(name), data: Vec::new() } // <4>
+  }
+
+  fn new_with_data(name: &str, data: &Vec<u8>) -> File {
+    let mut f = File::new(name);
+    f.data = data.clone();
+    f
+  }
+
+  fn read(self: &File, save_to: &mut Vec<u8>) -> Result<usize, String> { // <5>
+    let mut tmp = self.data.clone();
+    let read_length = tmp.len();
+    save_to.reserve(read_length);
+    save_to.append(&mut tmp);
+    Ok(read_length)  // <6>
+  }
+}
+
+fn open(f: File) -> Result<File, String> {
+  if one_in(10_000) {  // <7> 
+    let err_msg = String::from("Permission denied");
+    return Err(err_msg);
+  }
+  Ok(f)
+}
+
+fn close(f: File) -> Result<File, String> {
+  if one_in(100_000) { // <8>
+    let err_msg = String::from("Interrupted by signal!"); 
+    return Err(err_msg);
+  }
+  Ok(f)
+}
+
+fn main() {
+  let f4_data: Vec<u8> = vec![114, 117, 115, 116, 33];
+  let mut f4 = File::new_with_data("4.txt", &f4_data); 
+
+  let mut buffer: Vec<u8> = vec![];
+
+  f4 = open(f4).unwrap();                        // <9>
+  let f4_length = f4.read(&mut buffer).unwrap(); // <9>
+  f4 = close(f4).unwrap();                       // <9>
+  
+  let text = String::from_utf8_lossy(&buffer);
+
+  println!("{:?}", f4);
+  println!("{} is {} bytes long", &f4.name, f4_length);
+  println!("{}", text);
+}
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