Implement functional horizontal scrolling.

src/jless.rs

@@ -201,7 +201,8 @@ impl JLess {
                             None
                         }
                         Key::Char(';') => {
-                            self.screen_writer.scroll_focused_line_to_an_end(&self.viewer);
+                            self.screen_writer
+                                .scroll_focused_line_to_an_end(&self.viewer);
                             None
                         }
                         Key::Char(':') => {

src/lineprinter.rs

@@ -1,3 +1,5 @@
+use std::collections::hash_map::Entry;
+use std::collections::HashMap;
 use std::fmt;
 use std::fmt::Write;
 
@@ -180,6 +182,7 @@ impl LabelStyle {
     }
 }
 
+#[derive(Debug)]
 pub enum LineValue<'a> {
     Container {
         flatjson: &'a FlatJson,
@@ -210,10 +213,12 @@ pub struct LinePrinter<'a, TUI: TUIControl> {
     // Stuff to actually print out
     pub label: Option<LineLabel<'a>>,
     pub value: LineValue<'a>,
+
+    pub cached_formatted_value: Option<Entry<'a, usize, TruncatedStrView>>,
 }
 
 impl<'a, TUI: TUIControl> LinePrinter<'a, TUI> {
-    pub fn print_line<W: Write>(&self, buf: &mut W) -> fmt::Result {
+    pub fn print_line<W: Write>(&mut self, buf: &mut W) -> fmt::Result {
         self.tui.reset_style(buf)?;
 
         self.print_focus_and_container_indicators(buf)?;
@@ -380,7 +385,7 @@ impl<'a, TUI: TUIControl> LinePrinter<'a, TUI> {
     }
 
     fn fill_in_value<W: Write>(
-        &self,
+        &mut self,
         buf: &mut W,
         mut available_space: isize,
     ) -> Result<isize, fmt::Error> {
@@ -417,7 +422,19 @@ impl<'a, TUI: TUIControl> LinePrinter<'a, TUI> {
             available_space -= 1;
         }
 
-        let truncated_view = TruncatedStrView::init_start(value_ref, available_space);
+        // Option<Entry<>>
+        // - if no entry, then init_start
+        // - if entry, but vacant, then init_start
+        // - if entry with value, then value
+        let truncated_view = self
+            .cached_formatted_value
+            .take()
+            .map(|entry| {
+                entry
+                    .or_insert_with(|| TruncatedStrView::init_start(value_ref, available_space))
+                    .clone()
+            })
+            .unwrap_or_else(|| TruncatedStrView::init_start(value_ref, available_space));
         let space_used_for_value = truncated_view.used_space();
         if space_used_for_value.is_none() {
             return Ok(0);
@@ -879,6 +896,7 @@ mod tests {
                     quotes: true,
                     color: Color::White,
                 },
+                cached_formatted_value: None,
             }
         }
     }

src/screenwriter.rs

@@ -13,7 +13,7 @@ use crate::lineprinter::JS_IDENTIFIER;
 use crate::search::SearchState;
 use crate::truncate::TruncationResult::{DoesntFit, NoTruncation, Truncated};
 use crate::truncate::{truncate_left_to_fit, truncate_right_to_fit};
-use crate::truncatedstrview::TruncatedStrView;
+use crate::truncatedstrview::{TruncatedStrSlice, TruncatedStrView};
 use crate::tuicontrol::{Color as TUIColor, ColorControl};
 use crate::types::TTYDimensions;
 use crate::viewer::{JsonViewer, Mode};
@@ -116,8 +116,7 @@ impl ScreenWriter {
                     write!(self.tty_writer, "~")?;
                 }
                 OptionIndex::Index(index) => {
-                    let row = &viewer.flatjson[index];
-                    self.print_line(viewer, row_index, row, index == viewer.focused_row)?;
+                    self.print_line(viewer, row_index, index, index == viewer.focused_row)?;
                     line = match viewer.mode {
                         Mode::Line => viewer.flatjson.next_visible_row(index),
                         Mode::Data => viewer.flatjson.next_item(index),
@@ -164,10 +163,11 @@ impl ScreenWriter {
         &mut self,
         viewer: &JsonViewer,
         screen_index: u16,
-        row: &Row,
+        index: Index,
         is_focused: bool,
     ) -> std::io::Result<()> {
         self.tty_writer.position_cursor(1, screen_index + 1)?;
+        let row = &viewer.flatjson[index];
 
         let depth = row
             .depth
@@ -255,7 +255,7 @@ impl ScreenWriter {
             }
         }
 
-        let line = lp::LinePrinter {
+        let mut line = lp::LinePrinter {
             mode: viewer.mode,
             tui: ColorControl {},
 
@@ -269,6 +269,8 @@ impl ScreenWriter {
 
             label,
             value,
+
+            cached_formatted_value: Some(self.truncated_row_value_views.entry(index)),
         };
 
         let mut buf = String::new();
@@ -278,6 +280,24 @@ impl ScreenWriter {
         write!(self.tty_writer, "{}", buf)
     }
 
+    fn line_primitive_value_ref<'a, 'b>(
+        &'a self,
+        row: &'a Row,
+        viewer: &'b JsonViewer,
+    ) -> Option<&'b str> {
+        match &row.value {
+            Value::OpenContainer { .. } | Value::CloseContainer { .. } => None,
+            _ => {
+                let range = row.range.clone();
+                if let Value::String = &row.value {
+                    Some(&viewer.flatjson.1[range.start + 1..range.end - 1])
+                } else {
+                    Some(&viewer.flatjson.1[range])
+                }
+            }
+        }
+    }
+
     // input.data.viewer.gameDetail.plays[3].playStats[0].gsisPlayer.id filename.>
     // input.data.viewer.gameDetail.plays[3].playStats[0].gsisPlayer.id fi>
     // // Path also shrinks if needed
@@ -489,15 +509,57 @@ impl ScreenWriter {
     }
 
     pub fn scroll_focused_line_right(&mut self, viewer: &JsonViewer, count: usize) {
-        unimplemented!();
+        self.scroll_focused_line(viewer, count, true);
     }
 
     pub fn scroll_focused_line_left(&mut self, viewer: &JsonViewer, count: usize) {
-        unimplemented!();
+        self.scroll_focused_line(viewer, count, false);
+    }
+
+    pub fn scroll_focused_line(&mut self, viewer: &JsonViewer, count: usize, to_right: bool) {
+        let row = viewer.focused_row;
+        let tsv = self.truncated_row_value_views.get(&row);
+        if let Some(tsv) = tsv {
+            // Make tsv not a reference.
+            let mut tsv = *tsv;
+            let value_ref = self
+                .line_primitive_value_ref(&viewer.flatjson[row], &viewer)
+                .unwrap();
+            if tsv.range.is_none() {
+                return;
+            }
+            for _ in 0..count {
+                if to_right {
+                    tsv = tsv.scroll_right(value_ref);
+                } else {
+                    tsv = tsv.scroll_left(value_ref);
+                }
+            }
+            self.truncated_row_value_views
+                .insert(viewer.focused_row, tsv);
+        } else {
+            return;
+        }
     }
 
     pub fn scroll_focused_line_to_an_end(&mut self, viewer: &JsonViewer) {
-        unimplemented!();
+        let row = viewer.focused_row;
+        let tsv = self.truncated_row_value_views.get(&row);
+        if let Some(tsv) = tsv {
+            // Make tsv not a reference.
+            let mut tsv = *tsv;
+            let value_ref = self
+                .line_primitive_value_ref(&viewer.flatjson[row], &viewer)
+                .unwrap();
+            if tsv.range.is_none() {
+                return;
+            }
+            tsv = tsv.jump_to_an_end(value_ref);
+            self.truncated_row_value_views
+                .insert(viewer.focused_row, tsv);
+        } else {
+            return;
+        }
     }
 }
 

src/truncatedstrview.rs

@@ -21,7 +21,7 @@ use unicode_width::UnicodeWidthStr;
 /// much space the view takes up, including ellipses.
 #[derive(Debug, Copy, Clone)]
 pub struct TruncatedStrView {
-    range: Option<TruncatedRange>,
+    pub range: Option<TruncatedRange>,
     available_space: isize,
 }
 
@@ -54,7 +54,7 @@ pub struct TruncatedStrView {
 ///
 /// This range also keeps track of how much space it takes up.
 #[derive(Debug, Copy, Clone)]
-struct TruncatedRange {
+pub struct TruncatedRange {
     start: usize,
     end: usize,
     showing_replacement_character: bool,
@@ -223,7 +223,7 @@ impl TruncatedStrView {
     }
 
     /// Scrolls a string view to the left by at least one character.
-    fn scroll_left(&self, s: &str) -> TruncatedStrView {
+    pub fn scroll_left(&self, s: &str) -> TruncatedStrView {
         if self.range.is_none() {
             return self.clone();
         }
@@ -261,7 +261,7 @@ impl TruncatedStrView {
     /// Normally we will always jump to the back of the string, unless
     /// we are already showing the back of the string, in which case we
     /// will jump to the front.
-    fn jump_to_an_end(&self, s: &str) -> TruncatedStrView {
+    pub fn jump_to_an_end(&self, s: &str) -> TruncatedStrView {
         match self.range {
             None => self.clone(),
             Some(range) => {