Started Rust in Action MEAP.

1 files changed, 59 insertions, 0 deletions

diff --git a/meap/meap-code/ch3/ch3-file-states.rs b/meap/meap-code/ch3/ch3-file-states.rs
new file mode 100644
index 0000000..36510a5
--- /dev/null
+++ b/meap/meap-code/ch3/ch3-file-states.rs
@@ -0,0 +1,59 @@
+#[derive(Debug,PartialEq)]

+enum FileState {

+  Open,

+  Closed,

+}

+

+#[derive(Debug)]

+struct File {

+  name: String,

+  data: Vec<u8>,

+  state: FileState,

+}

+

+impl File {

+  fn new(name: &str) -> File {

+    File { name: String::from(name), data: Vec::new(), state: FileState::Closed }

+  }

+

+  fn read(self: &File, save_to: &mut Vec<u8>) -> Result<usize, String> {

+    if self.state != FileState::Open {

+      return Err(String::from("File must be open for reading"));

+    }

+    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(mut f: File) -> Result<File, String> {

+  f.state = FileState::Open;

+  Ok(f)

+}

+

+fn close(mut f: File) -> Result<File, String> {

+  f.state = FileState::Closed;

+  Ok(f)

+}

+

+fn main() {

+  let mut f5 = File::new("5.txt"); 

+

+  let mut buffer: Vec<u8> = vec![];

+

+  if f5.read(&mut buffer).is_err() {

+    println!("Error checking is working");

+  }

+

+  f5 = open(f5).unwrap();                        // <9>

+  let f5_length = f5.read(&mut buffer).unwrap(); // <9>

+  f5 = close(f5).unwrap();                       // <9>

+  

+  let text = String::from_utf8_lossy(&buffer);

+

+  println!("{:?}", f5);

+  println!("{} is {} bytes long", &f5.name, f5_length);

+  println!("{}", text);

+}
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