finish parts 12, 13

[rust-101.git] / workspace / src / part13.rs

diff --git a/workspace/src/part13.rs b/workspace/src/part13.rs
index 3ef778527ca7d8643b4e8752049fc7c8fa343a0b..311eba5b9b4dca87e4426cf8dde94a65f9565cce 100644 (file)
--- a/workspace/src/part13.rs
+++ b/workspace/src/part13.rs
@@ -1,8 +1,9 @@
 // Rust-101, Part 13: Slices, Arrays, External Dependencies
-// =================
+// ========================================================
 
 
 // ## Slices
+
 pub fn sort<T: PartialOrd>(data: &mut [T]) {
     if data.len() < 2 { return; }
 
@@ -10,9 +11,11 @@ pub fn sort<T: PartialOrd>(data: &mut [T]) {
     // making sure that everything on the left is no larger than the pivot, and everything on the right is no smaller.
     let mut lpos = 1;
     let mut rpos = data.len();
-    /* Invariant: pivot is data[0]; everything with index (0,lpos) is <= pivot; [rpos,len) is >= pivot; lpos < rpos */
+    /* Invariant: pivot is data[0]; everything with index (0,lpos) is <= pivot;
+       [rpos,len) is >= pivot; lpos < rpos */
     loop {
-        // **Exercise 13.1**: Complete this Quicksort loop. You can use `swap` on slices to swap two elements.
+        // **Exercise 13.1**: Complete this Quicksort loop. You can use `swap` on slices to swap two elements. Write a
+        // test function for `sort`.
         unimplemented!()
     }
 
@@ -24,7 +27,7 @@ pub fn sort<T: PartialOrd>(data: &mut [T]) {
     unimplemented!()
 }
 
-// **Exercise 13.2*: Since `String` implements `PartialEq`, you can now change the function `output_lines` in the previous part
+// **Exercise 13.2**: Since `String` implements `PartialEq`, you can now change the function `output_lines` in the previous part
 // to call the sort function above. If you did exercise 12.1, you will have slightly more work. Make sure you sort by the matched line
 // only, not by filename or line number!
 
@@ -35,16 +38,16 @@ fn sort_nums(data: &mut Vec<i32>) {
 
 // ## Arrays
 fn sort_array() {
-    let mut data: [f64; 5] = [1.0, 3.4, 12.7, -9.12, 0.1];
-    sort(&mut data);
+    let mut array_of_data: [f64; 5] = [1.0, 3.4, 12.7, -9.12, 0.1];
+    sort(&mut array_of_data);
 }
 
 // ## External Dependencies
 
 
 // I disabled the following module (using a rather bad hack), because it only compiles if `docopt` is linked. However, before enabling it,
-// you still have get the external library into the global namespace. This is done with `extern crate docopt;`, and that statement *has* to be
-// in `main.rs`. So please go there, and enable this commented-out line. Then remove the attribute of the following module.
+// you still have get the external library into the global namespace. This is done with `extern crate docopt`, and that statement *has* to be
+// in `main.rs`. So please go there, and enable this commented-out line. Then remove the attribute of the `rgrep` module.
 #[cfg(feature = "disabled")]
 pub mod rgrep {
     // Now that `docopt` is linked and declared in `main.rs`, we can import it with `use`. We also import some other pieces that we will need.
@@ -52,7 +55,7 @@ pub mod rgrep {
     use part12::{run, Options, OutputMode};
     use std::process;
 
-    // The USAGE string documents how the program is to be called. It's written in a format that `docopt` can parse.
+    // The `USAGE` string documents how the program is to be called. It's written in a format that `docopt` can parse.
     static USAGE: &'static str = "
 Usage: rgrep [-c] [-s] <pattern> <file>...
 
@@ -63,7 +66,7 @@ Options:
 
     // This function extracts the rgrep options from the command-line arguments.
     fn get_options() -> Options {
-        // Parse argv and exit the program with an error message if it fails. This is taken from the [`docopt` documentation](http://burntsushi.net/rustdoc/docopt/).
+        // Parse `argv` and exit the program with an error message if it fails. This is taken from the [`docopt` documentation](http://burntsushi.net/rustdoc/docopt/).
         let args = Docopt::new(USAGE).and_then(|d| d.parse()).unwrap_or_else(|e| e.exit());
         // Now we can get all the values out.
         let count = args.get_bool("-c");
@@ -76,10 +79,17 @@ Options:
         }
 
         // We need to make the strings owned to construct the `Options` instance.
+        let mode = if count {
+            OutputMode::Count
+        } else if sort {
+            OutputMode::SortAndPrint
+        } else {
+            OutputMode::Print
+        };
         Options {
             files: files.iter().map(|file| file.to_string()).collect(),
             pattern: pattern.to_string(),
-            output_mode: if count { OutputMode::Count } else if sort { OutputMode::SortAndPrint } else { OutputMode::Print },
+            output_mode: mode,
         }
     }
 
@@ -93,4 +103,5 @@ Options:
 // **Exercise 13.3**: Wouldn't it be nice if rgrep supported regular expressions? There's already a crate that does all the parsing and matching on regular
 // expression, it's called [regex](https://crates.io/crates/regex). Add this crate to the dependencies of your workspace, add an option ("-r") to switch
 // the pattern to regular-expression mode, and change `filter_lines` to honor this option. The documentation of regex is available from its crates.io site.
+// (You won't be able to use the `regex!` macro if you are on the stable or beta channel of Rust. But it wouldn't help for our use-case anyway.)