From 95d2c3c246d2fdcd4c7eda238ee7487931b08fab Mon Sep 17 00:00:00 2001
From: gwenn <gtreguier@gmail.com>
Date: Mon, 11 Apr 2016 20:55:38 +0200
Subject: [PATCH] Avoid cloning by swapping.
---
src/lib.rs | 66 +++++++++++++++++++++++++++++++-----------------------
1 file changed, 38 insertions(+), 28 deletions(-)
diff --git a/src/lib.rs b/src/lib.rs
index 3f7aef44..1773a483 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -33,6 +33,7 @@ mod kill_ring;
use std::fmt;
use std::io::{self, Read, Write};
+use std::mem;
use std::path::Path;
use std::result;
use std::sync;
@@ -59,7 +60,8 @@ struct State<'out, 'prompt> {
cursor: Position, // Cursor position (relative to the start of the prompt for `row`)
cols: usize, // Number of columns in terminal
history_index: usize, // The history index we are currently editing.
- history_end: String, // Current edited line before history browsing
+ snapshot: String, // Current edited line before history browsing/completion
+ snapshot_pos: usize, // Current cursor position before history browsing/completion
}
#[derive(Copy, Clone, Debug, Default)]
@@ -85,18 +87,26 @@ impl<'out, 'prompt> State<'out, 'prompt> {
cursor: prompt_size,
cols: cols,
history_index: history_index,
- history_end: String::new(),
+ snapshot: String::with_capacity(capacity),
+ snapshot_pos: 0,
}
}
- fn update_buf<S: Into<String>>(&mut self, buf: S) {
- self.buf = buf.into();
- if self.buf.capacity() < MAX_LINE {
- let cap = self.buf.capacity();
- self.buf.reserve_exact(MAX_LINE - cap);
+ fn update_buf(&mut self, buf: &str) {
+ self.buf.clear();
+ if buf.len() > MAX_LINE {
+ self.buf.push_str(&buf[..MAX_LINE]);
+ } else {
+ self.buf.push_str(buf);
+
}
}
+ fn snapshot(&mut self) {
+ mem::swap(&mut self.buf, &mut self.snapshot);
+ mem::swap(&mut self.pos, &mut self.snapshot_pos);
+ }
+
/// Rewrite the currently edited line accordingly to the buffer content,
/// cursor position, and number of columns of the terminal.
fn refresh_line(&mut self) -> Result<()> {
@@ -162,7 +172,7 @@ impl<'out, 'prompt> fmt::Debug for State<'out, 'prompt> {
.field("cursor", &self.cursor)
.field("cols", &self.cols)
.field("history_index", &self.history_index)
- .field("history_end", &self.history_end)
+ .field("snapshot", &self.snapshot)
.finish()
}
}
@@ -554,7 +564,7 @@ fn edit_history_next(s: &mut State, history: &History, prev: bool) -> Result<()>
if s.history_index == history.len() {
if prev {
// Save the current edited line before to overwrite it
- s.history_end = s.buf.clone();
+ s.snapshot();
} else {
return Ok(());
}
@@ -568,12 +578,12 @@ fn edit_history_next(s: &mut State, history: &History, prev: bool) -> Result<()>
}
if s.history_index < history.len() {
let buf = history.get(s.history_index).unwrap();
- s.update_buf(buf.clone());
- } else {
- let buf = s.history_end.clone(); // TODO how to avoid cloning?
s.update_buf(buf);
+ s.pos = s.buf.len();
+ } else {
+ // Restore current edited line
+ s.snapshot();
};
- s.pos = s.buf.len();
s.refresh_line()
}
@@ -592,14 +602,14 @@ fn complete_line<R: io::Read>(chars: &mut io::Chars<R>,
loop {
// Show completion or original buffer
if i < candidates.len() {
- let buf = s.buf.clone(); // TODO how to avoid cloning?
- let pos = s.pos;
+ // Save the current edited line before to overwrite it
+ s.snapshot();
let (tmp_buf, tmp_pos) = completer.update(&s.buf, s.pos, start, &candidates[i]);
s.buf = tmp_buf;
s.pos = tmp_pos;
try!(s.refresh_line());
- s.update_buf(buf);
- s.pos = pos;
+ // Restore current edited line (but no refresh)
+ s.snapshot();
} else {
try!(s.refresh_line());
}
@@ -624,7 +634,7 @@ fn complete_line<R: io::Read>(chars: &mut io::Chars<R>,
// Update buffer and return
if i < candidates.len() {
let (buf, pos) = completer.update(&s.buf, s.pos, start, &candidates[i]);
- s.update_buf(buf);
+ s.update_buf(&buf);
s.pos = pos;
}
break;
@@ -642,8 +652,7 @@ fn reverse_incremental_search<R: io::Read>(chars: &mut io::Chars<R>,
history: &History)
-> Result<Option<KeyPress>> {
// Save the current edited line (and cursor position) before to overwrite it
- let original_buf = s.buf.clone();
- let original_pos = s.pos;
+ s.snapshot();
let mut search_buf = String::new();
let mut history_idx = history.len() - 1;
@@ -682,8 +691,8 @@ fn reverse_incremental_search<R: io::Read>(chars: &mut io::Chars<R>,
}
}
KeyPress::CTRL_G => {
- s.update_buf(original_buf);
- s.pos = original_pos;
+ // Restore current edited line (before search)
+ s.snapshot();
try!(s.refresh_line());
return Ok(None);
}
@@ -694,7 +703,7 @@ fn reverse_incremental_search<R: io::Read>(chars: &mut io::Chars<R>,
Some(idx) => {
history_idx = idx;
let entry = history.get(idx).unwrap();
- s.update_buf(entry.clone());
+ s.update_buf(entry);
s.pos = entry.find(&search_buf).unwrap();
true
}
@@ -1124,7 +1133,8 @@ mod test {
cursor: Default::default(),
cols: cols,
history_index: 0,
- history_end: String::new(),
+ snapshot: String::new(),
+ snapshot_pos: 0,
}
}
@@ -1248,24 +1258,24 @@ mod test {
}
super::edit_history_next(&mut s, &history, true).unwrap();
- assert_eq!(line, s.history_end);
+ assert_eq!(line, s.snapshot);
assert_eq!(1, s.history_index);
assert_eq!("line1", s.buf);
for _ in 0..2 {
super::edit_history_next(&mut s, &history, true).unwrap();
- assert_eq!(line, s.history_end);
+ assert_eq!(line, s.snapshot);
assert_eq!(0, s.history_index);
assert_eq!("line0", s.buf);
}
super::edit_history_next(&mut s, &history, false).unwrap();
- assert_eq!(line, s.history_end);
+ assert_eq!(line, s.snapshot);
assert_eq!(1, s.history_index);
assert_eq!("line1", s.buf);
super::edit_history_next(&mut s, &history, false).unwrap();
- assert_eq!(line, s.history_end);
+ // assert_eq!(line, s.snapshot);
assert_eq!(2, s.history_index);
assert_eq!(line, s.buf);
}
--
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