Implement customizable tab expansion (console-rs#150)

src/progress_bar.rs

@@ -70,15 +70,21 @@ impl ProgressBar {
         self
     }
 
+    /// A convenience builder-like function for a progress bar with a given tab width
+    pub fn with_tab_width(self, tab_width: usize) -> ProgressBar {
+        self.state().set_tab_width_without_draw(tab_width);
+        self
+    }
+
     /// A convenience builder-like function for a progress bar with a given prefix
     pub fn with_prefix(self, prefix: impl Into<Cow<'static, str>>) -> ProgressBar {
-        self.state().state.prefix = prefix.into();
+        self.state().set_prefix_without_draw(prefix.into());
         self
     }
 
     /// A convenience builder-like function for a progress bar with a given message
     pub fn with_message(self, message: impl Into<Cow<'static, str>>) -> ProgressBar {
-        self.state().state.message = message.into();
+        self.state().set_message_without_draw(message.into());
         self
     }
 
@@ -123,7 +129,12 @@ impl ProgressBar {
     ///
     /// This does not redraw the bar. Call [`ProgressBar::tick()`] to force it.
     pub fn set_style(&self, style: ProgressStyle) {
-        self.state().style = style;
+        self.state().set_style(style);
+    }
+
+    /// Sets the tab width (default: 8). All tabs will be expanded to this many spaces.
+    pub fn set_tab_width(&mut self, tab_width: usize) {
+        self.state().set_tab_width(Instant::now(), tab_width);
     }
 
     /// Spawns a background thread to tick the progress bar
@@ -516,8 +527,8 @@ impl ProgressBar {
     }
 
     /// Current message
-    pub fn message(&self) -> Cow<'static, str> {
-        self.state().state.message.clone()
+    pub fn message(&self) -> String {
+        self.state().state.message().to_string()
     }
 
     /// Current message (with ANSI escape codes stripped)
@@ -526,8 +537,8 @@ impl ProgressBar {
     }
 
     /// Current prefix
-    pub fn prefix(&self) -> Cow<'static, str> {
-        self.state().state.prefix.clone()
+    pub fn prefix(&self) -> String {
+        self.state().state.prefix().to_string()
     }
 
     /// Current prefix (with ANSI escape codes stripped)

src/state.rs

@@ -7,11 +7,14 @@ use std::{fmt, io};
 use crate::draw_target::ProgressDrawTarget;
 use crate::style::ProgressStyle;
 
+pub(crate) const DEFAULT_TAB_WIDTH: usize = 8;
+
 pub(crate) struct BarState {
     pub(crate) draw_target: ProgressDrawTarget,
     pub(crate) on_finish: ProgressFinish,
     pub(crate) style: ProgressStyle,
     pub(crate) state: ProgressState,
+    tab_width: usize,
 }
 
 impl BarState {
@@ -25,6 +28,7 @@ impl BarState {
             on_finish: ProgressFinish::default(),
             style: ProgressStyle::default_bar(),
             state: ProgressState::new(len, pos),
+            tab_width: DEFAULT_TAB_WIDTH,
         }
     }
 
@@ -42,7 +46,7 @@ impl BarState {
                 if let Some(len) = self.state.len {
                     self.state.pos.set(len);
                 }
-                self.state.message = msg;
+                self.state.message = TabExpandedString::new(msg, self.tab_width);
             }
             ProgressFinish::AndClear => {
                 if let Some(len) = self.state.len {
@@ -51,7 +55,9 @@ impl BarState {
                 self.state.status = Status::DoneHidden;
             }
             ProgressFinish::Abandon => {}
-            ProgressFinish::AbandonWithMessage(msg) => self.state.message = msg,
+            ProgressFinish::AbandonWithMessage(msg) => {
+                self.state.message = TabExpandedString::new(msg, self.tab_width)
+            }
         }
 
         // There's no need to update the estimate here; once the `status` is no longer
@@ -93,15 +99,42 @@ impl BarState {
     }
 
     pub(crate) fn set_message(&mut self, now: Instant, msg: Cow<'static, str>) {
-        self.state.message = msg;
+        self.state.message = TabExpandedString::new(msg, self.tab_width);
         self.update_estimate_and_draw(now);
     }
 
+    // Called in builder context
+    pub(crate) fn set_message_without_draw(&mut self, msg: Cow<'static, str>) {
+        self.state.message = TabExpandedString::new(msg, self.tab_width);
+    }
+
     pub(crate) fn set_prefix(&mut self, now: Instant, prefix: Cow<'static, str>) {
-        self.state.prefix = prefix;
+        self.state.prefix = TabExpandedString::new(prefix, self.tab_width);
+        self.update_estimate_and_draw(now);
+    }
+
+    // Called in builder context
+    pub(crate) fn set_prefix_without_draw(&mut self, prefix: Cow<'static, str>) {
+        self.state.prefix = TabExpandedString::new(prefix, self.tab_width);
+    }
+
+    pub(crate) fn set_tab_width(&mut self, now: Instant, tab_width: usize) {
+        self.set_tab_width_without_draw(tab_width);
         self.update_estimate_and_draw(now);
     }
 
+    pub(crate) fn set_tab_width_without_draw(&mut self, tab_width: usize) {
+        self.tab_width = tab_width;
+        self.state.message.change_tab_width(tab_width);
+        self.state.prefix.change_tab_width(tab_width);
+        self.style.change_tab_width(tab_width);
+    }
+
+    pub(crate) fn set_style(&mut self, style: ProgressStyle) {
+        self.style = style;
+        self.style.change_tab_width(self.tab_width);
+    }
+
     pub(crate) fn tick(&mut self, now: Instant) {
         self.state.tick = self.state.tick.saturating_add(1);
         self.update_estimate_and_draw(now);
@@ -190,8 +223,8 @@ pub struct ProgressState {
     pub(crate) started: Instant,
     status: Status,
     est: Estimator,
-    pub(crate) message: Cow<'static, str>,
-    pub(crate) prefix: Cow<'static, str>,
+    message: TabExpandedString,
+    prefix: TabExpandedString,
 }
 
 impl ProgressState {
@@ -203,8 +236,8 @@ impl ProgressState {
             status: Status::InProgress,
             started: Instant::now(),
             est: Estimator::new(Instant::now()),
-            message: "".into(),
-            prefix: "".into(),
+            message: TabExpandedString::NoTabs("".into()),
+            prefix: TabExpandedString::NoTabs("".into()),
         }
     }
 
@@ -287,6 +320,71 @@ impl ProgressState {
     pub fn set_len(&mut self, len: u64) {
         self.len = Some(len);
     }
+
+    pub fn set_message(&mut self, msg: TabExpandedString) {
+        self.message = msg;
+    }
+
+    pub fn message(&self) -> &str {
+        self.message.expanded()
+    }
+
+    pub fn set_prefix(&mut self, prefix: TabExpandedString) {
+        self.prefix = prefix;
+    }
+
+    pub fn prefix(&self) -> &str {
+        self.prefix.expanded()
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub enum TabExpandedString {
+    NoTabs(Cow<'static, str>),
+    WithTabs {
+        original: Cow<'static, str>,
+        expanded: String,
+        tab_width: usize,
+    },
+}
+
+impl TabExpandedString {
+    pub(crate) fn new(s: Cow<'static, str>, tab_width: usize) -> Self {
+        let expanded = s.replace('\t', &" ".repeat(tab_width));
+        if s == expanded {
+            Self::NoTabs(s)
+        } else {
+            Self::WithTabs {
+                original: s,
+                expanded,
+                tab_width,
+            }
+        }
+    }
+
+    pub(crate) fn expanded(&self) -> &str {
+        match &self {
+            Self::NoTabs(s) => {
+                debug_assert!(!s.contains('\t'));
+                s
+            }
+            Self::WithTabs { expanded, .. } => expanded,
+        }
+    }
+
+    pub(crate) fn change_tab_width(&mut self, new_tab_width: usize) {
+        if let TabExpandedString::WithTabs {
+            original,
+            expanded,
+            tab_width,
+        } = self
+        {
+            if *tab_width != new_tab_width {
+                *tab_width = new_tab_width;
+                *expanded = original.replace('\t', &" ".repeat(new_tab_width));
+            }
+        }
+    }
 }
 
 /// Estimate the number of seconds per step