Add ProgressReader to the utils module

Should allow to monitor a file download in a progress bar

src/utils/lines_iterator.rs

@@ -1,8 +1,8 @@
-//! Toolbox to make text layout easier.
-
 use unicode_width::UnicodeWidthStr;
 use unicode_segmentation::UnicodeSegmentation;
 
+use utils::prefix_length;
+
 /// Generates rows of text in constrained width.
 ///
 /// Given a long text and a width constraint, it iterates over
@@ -91,56 +91,3 @@ impl<'a> Iterator for LinesIterator<'a> {
         })
     }
 }
-
-/// Computes a sub-string length that fits in the given `width`.
-///
-/// Takes non-breakable elements from `iter`, while keeping the
-/// string width under `width` (and adding the length of `delimiter`
-/// between each element).
-///
-/// Given `total_text = iter.collect().join(delimiter)`, the result
-/// is the length of the longest prefix of `width` or less cells,
-/// without breaking inside an element.
-///
-/// Example:
-///
-/// ```
-/// # extern crate cursive;
-/// extern crate unicode_segmentation;
-/// use unicode_segmentation::UnicodeSegmentation;
-///
-/// # use cursive::utils::prefix_length;
-/// # fn main() {
-/// let my_text = "blah...";
-/// // This returns the number of bytes for a prefix of `my_text` that
-/// // fits within 5 cells.
-/// prefix_length(my_text.graphemes(true), 5, "");
-/// # }
-/// ```
-pub fn prefix_length<'a, I: Iterator<Item = &'a str>>(iter: I, width: usize,
-                                               delimiter: &str)
-                                               -> usize {
-    let delimiter_width = delimiter.width();
-    let delimiter_len = delimiter.len();
-
-    let sum = iter.scan(0, |w, token| {
-            *w += token.width();
-            if *w > width {
-                None
-            } else {
-                // Add a space
-                *w += delimiter_width;
-                Some(token)
-            }
-        })
-        .map(|token| token.len() + delimiter_len)
-        .fold(0, |a, b| a + b);
-
-    // We counted delimiter once too many times,
-    // but only if the iterator was non empty.
-    if sum == 0 {
-        sum
-    } else {
-        sum - delimiter_len
-    }
-}

src/utils/mod.rs

@@ -0,0 +1,62 @@
+//! Toolbox to make text layout easier.
+
+use unicode_width::UnicodeWidthStr;
+
+mod lines_iterator;
+mod reader;
+
+pub use self::lines_iterator::{LinesIterator, Row};
+pub use self::reader::ProgressReader;
+
+/// Computes a sub-string length that fits in the given `width`.
+///
+/// Takes non-breakable elements from `iter`, while keeping the
+/// string width under `width` (and adding the length of `delimiter`
+/// between each element).
+///
+/// Given `total_text = iter.collect().join(delimiter)`, the result
+/// is the length of the longest prefix of `width` or less cells,
+/// without breaking inside an element.
+///
+/// Example:
+///
+/// ```
+/// # extern crate cursive;
+/// extern crate unicode_segmentation;
+/// use unicode_segmentation::UnicodeSegmentation;
+///
+/// # use cursive::utils::prefix_length;
+/// # fn main() {
+/// let my_text = "blah...";
+/// // This returns the number of bytes for a prefix of `my_text` that
+/// // fits within 5 cells.
+/// prefix_length(my_text.graphemes(true), 5, "");
+/// # }
+/// ```
+pub fn prefix_length<'a, I: Iterator<Item = &'a str>>(iter: I, width: usize,
+                                                      delimiter: &str)
+                                                      -> usize {
+    let delimiter_width = delimiter.width();
+    let delimiter_len = delimiter.len();
+
+    let sum = iter.scan(0, |w, token| {
+            *w += token.width();
+            if *w > width {
+                None
+            } else {
+                // Add a space
+                *w += delimiter_width;
+                Some(token)
+            }
+        })
+        .map(|token| token.len() + delimiter_len)
+        .fold(0, |a, b| a + b);
+
+    // We counted delimiter once too many times,
+    // but only if the iterator was non empty.
+    if sum == 0 {
+        sum
+    } else {
+        sum - delimiter_len
+    }
+}

src/utils/reader.rs

@@ -0,0 +1,36 @@
+use std::io::{self, Read};
+
+use views::Counter;
+
+/// Wrapper around a `Read` that reports the progress made.
+///
+/// Used to monitor a file downloading or other slow IO task
+/// in a progress bar.
+pub struct ProgressReader<R: Read> {
+    reader: R,
+    counter: Counter,
+}
+
+
+impl<R: Read> ProgressReader<R> {
+    /// Creates a new `ProgressReader` around `reader`.
+    ///
+    /// `counter` will be updated with the number of bytes read.
+    ///
+    /// You should make sure the progress bar knows how
+    /// many bytes should be received.
+    pub fn new(counter: Counter, reader: R) -> Self {
+        ProgressReader {
+            reader: reader,
+            counter: counter,
+        }
+    }
+}
+
+impl<R: Read> Read for ProgressReader<R> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let result = try!(self.reader.read(buf));
+        self.counter.tick(result);
+        Ok(result)
+    }
+}