From 67cdcc2e12118becb823e20a40cc2687f2b8425a Mon Sep 17 00:00:00 2001
From: Adam Carpenter <53hornet@gmail.com>
Date: Wed, 27 Mar 2019 15:32:37 -0400
Subject: Started Rust in Action MEAP.

---
 meap/meap-code/ch3/ch3-not-quite-file-2.rs | 42 ++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 meap/meap-code/ch3/ch3-not-quite-file-2.rs

(limited to 'meap/meap-code/ch3/ch3-not-quite-file-2.rs')

diff --git a/meap/meap-code/ch3/ch3-not-quite-file-2.rs b/meap/meap-code/ch3/ch3-not-quite-file-2.rs
new file mode 100644
index 0000000..f4f86fd
--- /dev/null
+++ b/meap/meap-code/ch3/ch3-not-quite-file-2.rs
@@ -0,0 +1,42 @@
+#![allow(unused_variables)] // <1> Silences a warnings caused by `open()` and `close()` not making use of needing their argument
+
+#[derive(Debug)] // <2> This enables `File` to work with `println!` and its `fmt!` sibling macros, used at the bottom of the code listing
+struct File {
+  name: String,
+  data: Vec<u8>,
+}
+
+fn open(f: &mut File) -> bool { // <3> These two functions will remain inert for now
+  true 
+}
+
+fn close(f: &mut File) -> bool { // <3>
+  true
+}
+
+fn read(f: &File, save_to: &mut Vec<u8>) -> usize { // <4> Return the "number of bytes read"
+  let mut tmp = f.data.clone(); // <5> Make a copy of the data here, as `save_to.append()` will shrink the input vec
+  let read_length = tmp.len();
+  save_to.reserve(read_length); // <6> Not strictly necessary, but useful to know about
+  save_to.append(&mut tmp); // <7> Allocate sufficient data in the `save_to` buffer to hold the contents of `f`
+  read_length
+}
+
+fn main() {
+  let mut f2 = File { 
+    name: String::from("2.txt"),
+    data: vec![114, 117, 115, 116, 33],
+  };
+
+  let mut buffer: Vec<u8> = vec![];
+
+  open(&mut f2);                          // <8> Do the hard work of interacting the the file.
+  let f2_length = read(&f2, &mut buffer); // <8>
+  close(&mut f2);                         // <8>
+  
+  let text = String::from_utf8_lossy(&buffer); // <9> Convert `Vec<u8>` to `String`. Any bytes that are not valid UTF-8 are replaced with �
+
+  println!("{:?}", f2);
+  println!("{} is {} bytes long", &f2.name, f2_length);
+  println!("{}", text) // <10>  View [114, 117, 115, 116, 33] as an actual word
+}
\ No newline at end of file
-- 
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