A bunch more work on refactoring how formatting works.

This compiles, but does not yet work correctly again. Tons of bugs.

src/buffer/mod.rs

@@ -23,7 +23,7 @@ use self::undo_stack::{Operation::*, UndoStack};
 
 /// A text buffer
 pub struct Buffer {
-    text: Rope,
+    pub text: Rope,
     file_path: Option<PathBuf>,
     undo_stack: UndoStack,
 }

src/editor/cursor.rs

@@ -28,8 +28,8 @@ impl Cursor {
         }
     }
 
-    pub fn update_vis_start<T: LineFormatter>(&mut self, buf: &Buffer, f: &T) {
+    pub fn update_vis_start(&mut self, buf: &Buffer, f: &LineFormatter) {
-        self.vis_start = f.index_to_horizontal_v2d(buf, self.range.0);
+        self.vis_start = f.get_horizontal(buf, self.range.0);
     }
 }
 

src/editor/mod.rs

@@ -11,16 +11,15 @@ use std::{
 use crate::{
     buffer::Buffer,
     formatter::LineFormatter,
-    formatter::RoundingBehavior::*,
     string_utils::{char_count, rope_slice_to_line_ending, LineEnding},
     utils::{digit_count, RopeGraphemes},
 };
 
 use self::cursor::CursorSet;
 
-pub struct Editor<T: LineFormatter> {
+pub struct Editor {
     pub buffer: Buffer,
-    pub formatter: T,
+    pub formatter: LineFormatter,
     pub file_path: PathBuf,
     pub line_ending_type: LineEnding,
     pub soft_tabs: bool,
@@ -39,9 +38,9 @@ pub struct Editor<T: LineFormatter> {
     pub cursors: CursorSet,
 }
 
-impl<T: LineFormatter> Editor<T> {
+impl Editor {
     /// Create a new blank editor
-    pub fn new(formatter: T) -> Editor<T> {
+    pub fn new(formatter: LineFormatter) -> Editor {
         Editor {
             buffer: Buffer::new(),
             formatter: formatter,
@@ -57,7 +56,7 @@ impl<T: LineFormatter> Editor<T> {
         }
     }
 
-    pub fn new_from_file(formatter: T, path: &Path) -> Editor<T> {
+    pub fn new_from_file(formatter: LineFormatter, path: &Path) -> Editor {
         let buf = match Buffer::new_from_file(path) {
             Ok(b) => b,
             // TODO: handle un-openable file better
@@ -307,28 +306,24 @@ impl<T: LineFormatter> Editor<T> {
         // the closest cursor.
 
         // Find the first and last char index visible within the editor.
-        let c_first =
+        let c_first = self
+            .formatter
+            .set_horizontal(&self.buffer, self.view_pos.0, 0);
+        let mut c_last =
             self.formatter
-                .index_set_horizontal_v2d(&self.buffer, self.view_pos.0, 0, Floor);
+                .offset_vertical(&self.buffer, c_first, self.view_dim.0 as isize);
-        let mut c_last = self.formatter.index_offset_vertical_v2d(
+        c_last = self
-            &self.buffer,
+            .formatter
-            c_first,
+            .set_horizontal(&self.buffer, c_last, self.view_dim.1);
-            self.view_dim.0 as isize,
-            (Floor, Floor),
-        );
-        c_last =
-            self.formatter
-                .index_set_horizontal_v2d(&self.buffer, c_last, self.view_dim.1, Floor);
 
         // Adjust the view depending on where the cursor is
         if self.cursors[0].range.0 < c_first {
             self.view_pos.0 = self.cursors[0].range.0;
         } else if self.cursors[0].range.0 > c_last {
-            self.view_pos.0 = self.formatter.index_offset_vertical_v2d(
+            self.view_pos.0 = self.formatter.offset_vertical(
                 &self.buffer,
                 self.cursors[0].range.0,
                 -(self.view_dim.0 as isize),
-                (Floor, Floor),
             );
         }
     }
@@ -369,9 +364,7 @@ impl<T: LineFormatter> Editor<T> {
                 c.range.1 += offset;
 
                 // Figure out how many spaces to insert
-                let vis_pos = self
+                let vis_pos = self.formatter.get_horizontal(&self.buffer, c.range.0);
-                    .formatter
-                    .index_to_horizontal_v2d(&self.buffer, c.range.0);
                 // TODO: handle tab settings
                 let next_tab_stop =
                     ((vis_pos / self.soft_tab_width as usize) + 1) * self.soft_tab_width as usize;
@@ -555,18 +548,12 @@ impl<T: LineFormatter> Editor<T> {
         for c in self.cursors.iter_mut() {
             let vmove = -1 * n as isize;
 
-            let mut temp_index = self.formatter.index_offset_vertical_v2d(
+            let mut temp_index = self
-                &self.buffer,
+                .formatter
-                c.range.0,
+                .offset_vertical(&self.buffer, c.range.0, vmove);
-                vmove,
+            temp_index = self
-                (Round, Round),
+                .formatter
-            );
+                .set_horizontal(&self.buffer, temp_index, c.vis_start);
-            temp_index = self.formatter.index_set_horizontal_v2d(
-                &self.buffer,
-                temp_index,
-                c.vis_start,
-                Round,
-            );
 
             if !self.buffer.is_grapheme(temp_index) {
                 temp_index = self.buffer.nth_prev_grapheme(temp_index, 1);
@@ -591,18 +578,12 @@ impl<T: LineFormatter> Editor<T> {
         for c in self.cursors.iter_mut() {
             let vmove = n as isize;
 
-            let mut temp_index = self.formatter.index_offset_vertical_v2d(
+            let mut temp_index = self
-                &self.buffer,
+                .formatter
-                c.range.0,
+                .offset_vertical(&self.buffer, c.range.0, vmove);
-                vmove,
+            temp_index = self
-                (Round, Round),
+                .formatter
-            );
+                .set_horizontal(&self.buffer, temp_index, c.vis_start);
-            temp_index = self.formatter.index_set_horizontal_v2d(
-                &self.buffer,
-                temp_index,
-                c.vis_start,
-                Round,
-            );
 
             if !self.buffer.is_grapheme(temp_index) {
                 temp_index = self.buffer.nth_prev_grapheme(temp_index, 1);
@@ -625,11 +606,10 @@ impl<T: LineFormatter> Editor<T> {
 
     pub fn page_up(&mut self) {
         let move_amount = self.view_dim.0 - max(self.view_dim.0 / 8, 1);
-        self.view_pos.0 = self.formatter.index_offset_vertical_v2d(
+        self.view_pos.0 = self.formatter.offset_vertical(
             &self.buffer,
             self.view_pos.0,
             -1 * move_amount as isize,
-            (Round, Round),
         );
 
         self.cursor_up(move_amount);
@@ -640,12 +620,9 @@ impl<T: LineFormatter> Editor<T> {
 
     pub fn page_down(&mut self) {
         let move_amount = self.view_dim.0 - max(self.view_dim.0 / 8, 1);
-        self.view_pos.0 = self.formatter.index_offset_vertical_v2d(
+        self.view_pos.0 =
-            &self.buffer,
+            self.formatter
-            self.view_pos.0,
+                .offset_vertical(&self.buffer, self.view_pos.0, move_amount as isize);
-            move_amount as isize,
-            (Round, Round),
-        );
 
         self.cursor_down(move_amount);
 
@@ -656,12 +633,9 @@ impl<T: LineFormatter> Editor<T> {
     pub fn jump_to_line(&mut self, n: usize) {
         let pos = self.buffer.line_col_to_index((n, 0));
         self.cursors.truncate(1);
-        self.cursors[0].range.0 = self.formatter.index_set_horizontal_v2d(
+        self.cursors[0].range.0 =
-            &self.buffer,
+            self.formatter
-            pos,
+                .set_horizontal(&self.buffer, pos, self.cursors[0].vis_start);
-            self.cursors[0].vis_start,
-            Round,
-        );
         self.cursors[0].range.1 = self.cursors[0].range.0;
 
         // Adjust view

src/formatter.rs

@@ -1,10 +1,12 @@
-use std::cmp::min;
+use std::borrow::Cow;
 
-use ropey::RopeSlice;
+use ropey::{Rope, RopeSlice};
 
 use crate::{
     buffer::Buffer,
-    utils::{is_grapheme_boundary, prev_grapheme_boundary, RopeGraphemes},
+    string_utils::char_count,
+    string_utils::{is_line_ending, str_is_whitespace},
+    utils::{grapheme_width, is_grapheme_boundary, prev_grapheme_boundary, RopeGraphemes},
 };
 
 // Maximum chars in a line before a soft line break is forced.
@@ -17,176 +19,457 @@ const LINE_BLOCK_LENGTH: usize = 1 << 12;
 // breaks.
 const LINE_BLOCK_FUDGE: usize = 32;
 
-#[allow(dead_code)]
+//--------------------------------------------------------------------------
-#[derive(Copy, Clone, PartialEq)]
+
-pub enum RoundingBehavior {
+#[derive(Clone)]
-    Round,
+pub struct LineFormatter {
-    Floor,
+    pub tab_width: usize,
-    Ceiling,
+    pub wrap_width: usize,
+    pub maintain_indent: bool,
+    pub wrap_extra_indent: usize,
 }
 
-pub trait LineFormatter {
+impl LineFormatter {
-    /// Returns the 2d visual dimensions of the given text when formatted
+    pub fn new(tab_width: usize) -> LineFormatter {
-    /// by the formatter.
+        LineFormatter {
-    /// The text to be formatted is passed as a grapheme iterator.
+            tab_width: tab_width,
-    fn dimensions(&self, g_iter: RopeGraphemes) -> (usize, usize);
+            wrap_width: 80,
+            maintain_indent: true,
+            wrap_extra_indent: 2,
+        }
+    }
 
-    /// Converts a char index within a text into a visual 2d position.
+    /// Returns an iterator over the blocks of the buffer, starting at the
-    /// The text to be formatted is passed as a grapheme iterator.
+    /// block containing the given char.  Also returns the offset of that char
-    fn index_to_v2d(&self, g_iter: RopeGraphemes, char_idx: usize) -> (usize, usize);
+    /// relative to the start of the first block.
-
+    pub fn iter<'b>(&'b self, buf: &'b Buffer, char_idx: usize) -> (Blocks<'b>, usize) {
-    /// Converts a visual 2d position into a char index within a text.
+        // Get the line.
-    /// The text to be formatted is passed as a grapheme iterator.
-    fn v2d_to_index(
-        &self,
-        g_iter: RopeGraphemes,
-        v2d: (usize, usize),
-        rounding: (RoundingBehavior, RoundingBehavior),
-    ) -> usize;
-
-    /// Converts from char index to the horizontal 2d char index.
-    fn index_to_horizontal_v2d(&self, buf: &Buffer, char_idx: usize) -> usize {
         let (line_i, col_i) = buf.index_to_line_col(char_idx);
         let line = buf.get_line(line_i);
 
         // Find the right block in the line, and the index within that block
-        let (_, block_range) = block_index_and_range(&line, col_i);
+        let (block_index, block_range) = block_index_and_range(&line, col_i);
         let col_i_adjusted = col_i - block_range.0;
 
-        // Get an iter into the right block
+        (
-        let g_iter = RopeGraphemes::new(&line.slice(block_range.0..block_range.1));
+            Blocks {
-        return self.index_to_v2d(g_iter, col_i_adjusted).1;
+                formatter: self,
+                buf: &buf.text,
+                line_idx: line_i,
+                line_block_count: block_count(&line),
+                block_idx: block_index,
+            },
+            col_i_adjusted,
+        )
     }
 
-    /// Takes a char index and a visual vertical offset, and returns the char
+    /// Converts from char index to the horizontal 2d char index.
-    /// index after that visual offset is applied.
+    pub fn get_horizontal(&self, buf: &Buffer, char_idx: usize) -> usize {
-    fn index_offset_vertical_v2d(
+        let (_, vis_iter, char_offset) = self.block_vis_iter_and_char_offset(buf, char_idx);
-        &self,
-        buf: &Buffer,
-        char_idx: usize,
-        offset: isize,
-        rounding: (RoundingBehavior, RoundingBehavior),
-    ) -> usize {
-        // TODO: handle rounding modes
-        // TODO: do this with bidirectional line iterator
 
-        // Get the line and char index within that line.
+        // Traverse the iterator and find the horizontal position of the char
-        let (mut line_i, mut col_i) = buf.index_to_line_col(char_idx);
+        // index.
-        let mut line = buf.get_line(line_i);
+        let mut hpos = 0;
+        let mut i = 0;
+        let mut last_width = 0;
 
-        // Get the block information for the char offset in the line.
+        for (g, pos, width) in vis_iter {
-        let (line_block, block_range) = block_index_and_range(&line, col_i);
+            hpos = pos.1;
-        let col_i_adjusted = col_i - block_range.0;
+            last_width = width;
+            i += char_count(&g);
 
-        // Get the 2d coordinates within the block.
+            if i > char_offset {
-        let (mut y, x) = self.index_to_v2d(
+                return hpos;
-            RopeGraphemes::new(&line.slice(block_range.0..block_range.1)),
-            col_i_adjusted,
-        );
-
-        // First, find the right line while keeping track of the vertical offset
-        let mut new_y = y as isize + offset;
-
-        let mut block_index: usize = line_block;
-        loop {
-            line = buf.get_line(line_i);
-            let (block_start, block_end) = char_range_from_block_index(&line, block_index);
-            let (h, _) = self.dimensions(RopeGraphemes::new(&line.slice(block_start..block_end)));
-
-            if new_y >= 0 && new_y < h as isize {
-                y = new_y as usize;
-                break;
-            } else {
-                if new_y > 0 {
-                    let is_last_block = block_index >= (block_count(&line) - 1);
-
-                    // Check for off-the-end
-                    if is_last_block && (line_i + 1) >= buf.line_count() {
-                        return buf.char_count();
-                    }
-
-                    if is_last_block {
-                        line_i += 1;
-                        block_index = 0;
-                    } else {
-                        block_index += 1;
-                    }
-                    new_y -= h as isize;
-                } else if new_y < 0 {
-                    // Check for off-the-end
-                    if block_index == 0 && line_i == 0 {
-                        return 0;
-                    }
-
-                    if block_index == 0 {
-                        line_i -= 1;
-                        line = buf.get_line(line_i);
-                        block_index = block_count(&line) - 1;
-                    } else {
-                        block_index -= 1;
-                    }
-                    let (block_start, block_end) = char_range_from_block_index(&line, block_index);
-                    let (h, _) =
-                        self.dimensions(RopeGraphemes::new(&line.slice(block_start..block_end)));
-                    new_y += h as isize;
-                } else {
-                    unreachable!();
-                }
             }
         }
 
-        // Next, convert the resulting coordinates back into buffer-wide
+        // If we went off the end, calculate the position of the end of the
-        // coordinates.
+        // block.
-        let (block_start, block_end) = char_range_from_block_index(&line, block_index);
+        return hpos + last_width;
-        let block_len = block_end - block_start;
-        let block_slice = line.slice(block_start..block_end);
-        let block_col_i = min(
-            self.v2d_to_index(RopeGraphemes::new(&block_slice), (y, x), rounding),
-            block_len.saturating_sub(1),
-        );
-        col_i = block_start + block_col_i;
-
-        return buf.line_col_to_index((line_i, col_i));
     }
 
     /// Takes a char index and a desired visual horizontal position, and
     /// returns a char index on the same visual line as the given index,
-    /// but offset to have the desired horizontal position.
+    /// but offset to have the desired horizontal position (or as close as is
-    fn index_set_horizontal_v2d(
+    /// possible.
+    pub fn set_horizontal(&self, buf: &Buffer, char_idx: usize, horizontal: usize) -> usize {
+        let (_, vis_iter, char_offset) = self.block_vis_iter_and_char_offset(buf, char_idx);
+
+        let mut hpos_char_idx = None;
+        let mut i = 0;
+        let mut last_i = 0;
+        let mut last_pos = (0, 0);
+        for (g, pos, width) in vis_iter {
+            // Check if we moved to the next line.
+            if pos.0 > last_pos.0 {
+                // If we did, but we're already passed the given char_idx,
+                // that means the target was on the previous line but the line
+                // wasn't long enough, so return the index of the last grapheme
+                // of the previous line.
+                if i > char_offset {
+                    return last_i;
+                }
+
+                // Otherwise reset and keep going.
+                hpos_char_idx = None;
+            }
+
+            // Check if we found the horizontal position on this line,
+            // and set it if so.
+            if hpos_char_idx == None && horizontal < (pos.1 + width) {
+                hpos_char_idx = Some(i);
+            }
+
+            // Check if we've found the horizontal position _and_ the passed
+            // char_idx on the same line, and return if so.
+            if i >= char_offset && hpos_char_idx != None {
+                return hpos_char_idx.unwrap();
+            }
+
+            last_pos = pos;
+            last_i = i;
+            i += char_count(&g);
+        }
+
+        // If we reached the end of the text, return the last char index.
+        return i;
+    }
+
+    /// Takes a char index and a visual vertical offset, and returns the char
+    /// index after that visual offset is applied.
+    pub fn offset_vertical(&self, buf: &Buffer, char_idx: usize, v_offset: isize) -> usize {
+        let mut char_idx = char_idx;
+        let mut v_offset = v_offset;
+        while v_offset != 0 {
+            // Get our block and the offset of the char inside it.
+            let (block, block_vis_iter, char_offset) =
+                self.block_vis_iter_and_char_offset(buf, char_idx);
+
+            // Get the vertical size of the block and the vertical
+            // position of the char_idx within it.
+            let block_v_dim = (block_vis_iter.clone().last().unwrap().1).0 + 1;
+            let char_v_pos = block_vis_iter.clone().vpos(char_offset);
+
+            // Get the char's vertical position within the block after offset
+            // by v_offset.
+            let offset_char_v_pos = char_v_pos as isize + v_offset;
+
+            // Check if the offset position is within the block or not,
+            // and handle appropriately.
+            if offset_char_v_pos < 0 {
+                // If we're off the start of the block.
+                if char_idx == 0 {
+                    // We reached the start of the whole buffer.
+                    break;
+                } else {
+                    // Set our variables appropriately for the next iteration.
+                    char_idx -= char_offset + 1;
+                    v_offset += char_v_pos as isize + 1;
+                }
+            } else if offset_char_v_pos >= block_v_dim as isize {
+                // If we're off the end of the block.
+                if char_idx >= buf.text.len_chars() {
+                    // We reached the end of the whole buffer.
+                    char_idx = buf.text.len_chars();
+                    break;
+                } else {
+                    // Set our variables appropriately for the next iteration.
+                    char_idx += block.len_chars() - char_offset;
+                    v_offset -= block_v_dim as isize - char_v_pos as isize;
+                }
+            } else {
+                // If the vertical offset is within this block, calculate an
+                // appropriate char index and return.
+                let mut i = 0;
+                for (g, pos, _) in block_vis_iter {
+                    if pos.0 == offset_char_v_pos as usize {
+                        break;
+                    }
+                    i += char_count(&g);
+                }
+                char_idx += block.len_chars() - char_offset + i;
+                v_offset = 0;
+            }
+        }
+
+        return char_idx;
+    }
+
+    //----------------------------------------------------
+    // Helper methods
+
+    /// Returns the amount of indentation to use for soft-line wrapping
+    /// given the start of a line.
+    fn get_line_indent(&self, line: &RopeSlice) -> usize {
+        if !self.maintain_indent {
+            return 0;
+        }
+
+        let mut indent = 0;
+        for c in line.chars() {
+            match c {
+                ' ' => {
+                    indent += 1;
+                }
+                '\t' => {
+                    indent = tab_stop_from_vis_pos(indent, self.tab_width);
+                }
+                _ => break,
+            }
+
+            // If the indent is too long for the wrap width, do no indentation.
+            if (indent + self.wrap_extra_indent + 2) > self.wrap_width {
+                return 0;
+            }
+        }
+
+        indent
+    }
+
+    /// Returns the appropriate BlockVisIter containing the given char, and the
+    /// char's offset within that iter.
+    fn block_vis_iter_and_char_offset<'b>(
         &self,
-        buf: &Buffer,
+        buf: &'b Buffer,
         char_idx: usize,
-        horizontal: usize,
+    ) -> (RopeSlice<'b>, BlockVisIter<'b>, usize) {
-        rounding: RoundingBehavior,
-    ) -> usize {
-        // Get the line info.
         let (line_i, col_i) = buf.index_to_line_col(char_idx);
         let line = buf.get_line(line_i);
 
-        // Get the right block within the line.
+        // Find the right block in the line, and the index within that block
-        let (block_i, block_range) = block_index_and_range(&line, col_i);
+        let (block_index, block_range) = block_index_and_range(&line, col_i);
         let col_i_adjusted = col_i - block_range.0;
 
-        // Calculate the horizontal position.
+        // Get the right block and an iter into it.
-        let (v, _) = self.index_to_v2d(
+        let block = line.slice(block_range.0..block_range.1);
-            RopeGraphemes::new(&line.slice(block_range.0..block_range.1)),
+        let g_iter = RopeGraphemes::new(&block);
-            col_i_adjusted,
-        );
-        let block_col_i = self.v2d_to_index(
-            RopeGraphemes::new(&line.slice(block_range.0..block_range.1)),
-            (v, horizontal),
-            (RoundingBehavior::Floor, rounding),
-        );
-        let new_col_i = if (line_i + 1) < buf.line_count() || (block_i + 1) < block_count(&line) {
-            min(block_range.0 + block_col_i, block_range.1.saturating_sub(1))
-        } else {
-            min(block_range.0 + block_col_i, block_range.1)
-        };
 
-        return (char_idx + new_col_i) - col_i;
+        // Get an appropriate visual block iter.
+        let vis_iter = BlockVisIter::new(
+            g_iter,
+            self.wrap_width,
+            self.tab_width,
+            block_index == 0,
+            if block_index == 0 {
+                0
+            } else {
+                self.get_line_indent(&line)
+            },
+            self.wrap_extra_indent,
+        );
+
+        (block, vis_iter, col_i_adjusted)
     }
 }
 
+//--------------------------------------------------------------------------
+
+#[derive(Clone)]
+pub struct Blocks<'a> {
+    formatter: &'a LineFormatter,
+    buf: &'a Rope,
+    line_idx: usize,
+    line_block_count: usize,
+    block_idx: usize,
+}
+
+impl<'a> Iterator for Blocks<'a> {
+    type Item = (BlockVisIter<'a>, bool);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        // Check if we're done already.
+        if self.line_idx >= self.buf.len_lines() {
+            return None;
+        }
+
+        // Get our return values.
+        let (iter, is_line_start) = {
+            let line = self.buf.line(self.line_idx);
+            let (start, end) = char_range_from_block_index(&line, self.block_idx);
+            let block = line.slice(start..end);
+            let iter = BlockVisIter::new(
+                RopeGraphemes::new(&block),
+                self.formatter.wrap_width,
+                self.formatter.tab_width,
+                self.block_idx == 0,
+                if self.block_idx == 0 {
+                    0
+                } else {
+                    self.formatter.get_line_indent(&line)
+                },
+                self.formatter.wrap_extra_indent,
+            );
+
+            (iter, self.block_idx == 0)
+        };
+
+        // Progress the values of the iterator.
+        self.block_idx += 1;
+        if self.block_idx >= self.line_block_count {
+            self.line_idx += 1;
+            self.block_idx = 0;
+            if self.line_idx < self.buf.len_lines() {
+                self.line_block_count = block_count(&self.buf.line(self.line_idx));
+            }
+        }
+
+        // Return.
+        Some((iter, is_line_start))
+    }
+}
+
+//--------------------------------------------------------------------------
+
+/// An iterator over the visual printable characters of a block of text,
+/// yielding the text of the character, its position in 2d space, and its
+/// visial width.
+#[derive(Clone)]
+pub struct BlockVisIter<'a> {
+    grapheme_itr: RopeGraphemes<'a>,
+
+    wrap_width: usize,
+    tab_width: usize,
+    indent: usize,            // Size of soft indent to use.
+    wrap_extra_indent: usize, // Additional amount to indent soft-wrapped lines.
+    finding_indent: bool,
+
+    word_buf: Vec<(Cow<'a, str>, usize)>, // Printable character and its width.
+    word_i: usize,
+    pos: (usize, usize),
+}
+
+impl<'a> BlockVisIter<'a> {
+    fn new(
+        grapheme_itr: RopeGraphemes<'a>,
+        wrap_width: usize,
+        tab_width: usize,
+        find_indent: bool,
+        starting_indent: usize,
+        wrap_extra_indent: usize,
+    ) -> BlockVisIter<'a> {
+        BlockVisIter {
+            grapheme_itr: grapheme_itr,
+            wrap_width: wrap_width,
+            tab_width: tab_width,
+            indent: starting_indent,
+            wrap_extra_indent: wrap_extra_indent,
+            finding_indent: find_indent,
+
+            word_buf: Vec::new(),
+            word_i: 0,
+            pos: (0, 0),
+        }
+    }
+
+    pub fn vpos(&mut self, char_offset: usize) -> usize {
+        let mut vpos = 0;
+        let mut i = 0;
+
+        for (g, pos, _) in self {
+            vpos = pos.0;
+            i += char_count(&g);
+
+            if i > char_offset {
+                break;
+            }
+        }
+
+        vpos
+    }
+}
+
+impl<'a> Iterator for BlockVisIter<'a> {
+    type Item = (Cow<'a, str>, (usize, usize), usize);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.pos == (0, 0) {
+            self.pos = (0, self.indent);
+        }
+
+        // Get next word if necessary
+        if self.word_i >= self.word_buf.len() {
+            let mut word_width = 0;
+            self.word_buf.truncate(0);
+
+            while let Some(g) = self.grapheme_itr.next().map(|g| Cow::<str>::from(g)) {
+                let width =
+                    grapheme_vis_width_at_vis_pos(&g, self.pos.1 + word_width, self.tab_width);
+                self.word_buf.push((g.clone(), width));
+                word_width += width;
+
+                if str_is_whitespace(&g) {
+                    if self.finding_indent && (g.as_bytes()[0] == 0x09 || g.as_bytes()[0] == 0x20) {
+                        if (self.indent + self.wrap_extra_indent + width + 2) > self.wrap_width {
+                            // Cancel indentation if it's too long for the screen.
+                            self.indent = 0;
+                            self.wrap_extra_indent = 0;
+                            self.finding_indent = false;
+                        } else {
+                            self.indent += width;
+                        }
+                    }
+                    break;
+                } else {
+                    self.finding_indent = false;
+                }
+            }
+
+            if self.word_buf.len() == 0 {
+                return None;
+            }
+
+            // Move to next line if necessary
+            if (self.pos.1 + word_width) > self.wrap_width && (self.pos.1 > self.indent) {
+                if self.pos.1 > 0 {
+                    self.pos = (self.pos.0 + 1, self.indent + self.wrap_extra_indent);
+                }
+            }
+
+            self.word_i = 0;
+        }
+
+        // Get next grapheme and width from the current word.
+        let (g, g_width) = {
+            let (ref g, mut width) = self.word_buf[self.word_i];
+            if g == "\t" {
+                width = grapheme_vis_width_at_vis_pos(&g, self.pos.1, self.tab_width);
+            }
+            (g, width)
+        };
+
+        // Get our character's position and update the position for the next
+        // grapheme.
+        if (self.pos.1 + g_width) > self.wrap_width && self.pos.1 > 0 {
+            self.pos.0 += 1;
+            self.pos.1 = self.indent + self.wrap_extra_indent;
+        }
+        let pos = self.pos;
+        self.pos.1 += g_width;
+
+        // Increment index and return.
+        self.word_i += 1;
+        return Some((g.clone(), pos, g_width));
+    }
+}
+
+/// Returns the visual width of a grapheme given a starting
+/// position on a line.
+fn grapheme_vis_width_at_vis_pos(g: &str, pos: usize, tab_width: usize) -> usize {
+    if g == "\t" {
+        return tab_stop_from_vis_pos(pos, tab_width) - pos;
+    } else if is_line_ending(g) {
+        return 1;
+    } else {
+        return grapheme_width(&g);
+    }
+}
+
+fn tab_stop_from_vis_pos(pos: usize, tab_width: usize) -> usize {
+    ((pos / tab_width) + 1) * tab_width
+}
+
+//--------------------------------------------------------------------------
+
 // Finds the best break at or before the given char index, bounded by
 // the given `lower_limit`.
 pub fn find_good_break(slice: &RopeSlice, lower_limit: usize, char_idx: usize) -> usize {

src/main.rs

@@ -2,7 +2,7 @@ use std::{io::Write, path::Path};
 
 use clap::{App, Arg};
 use editor::Editor;
-use term_ui::formatter::ConsoleLineFormatter;
+use formatter::LineFormatter;
 use term_ui::TermUI;
 
 mod buffer;
@@ -29,9 +29,9 @@ fn main() {
 
     // Load file, if specified
     let editor = if let Some(filepath) = args.value_of("file") {
-        Editor::new_from_file(ConsoleLineFormatter::new(4), &Path::new(&filepath[..]))
+        Editor::new_from_file(LineFormatter::new(4), &Path::new(&filepath[..]))
     } else {
-        Editor::new(ConsoleLineFormatter::new(4))
+        Editor::new(LineFormatter::new(4))
     };
 
     // Holds stderr output in an internal buffer, and prints it when dropped.

src/string_utils.rs

@@ -10,28 +10,36 @@ pub fn is_line_ending(text: &str) -> bool {
     }
 }
 
-pub fn is_whitespace(text: &str) -> bool {
+pub fn str_is_whitespace(text: &str) -> bool {
+    if let Some(c) = text.chars().nth(0) {
+        is_whitespace(c)
+    } else {
+        false
+    }
+}
+
+pub fn is_whitespace(c: char) -> bool {
     // TODO: this is a naive categorization of whitespace characters.
     // For better categorization these should be split up into groups
     // based on e.g. breaking vs non-breaking spaces, among other things.
-    match text.chars().nth(0) {
+    match c {
-        //Some('\u{1680}') | // OGHAM SPACE MARK (here for completeness, but usually displayed as a dash, not as whitespace)
+        //'\u{1680}' | // OGHAM SPACE MARK (here for completeness, but usually displayed as a dash, not as whitespace)
-        Some('\u{0009}') | // CHARACTER TABULATION
+        '\u{0009}' | // CHARACTER TABULATION
-        Some('\u{0020}') | // SPACE
+        '\u{0020}' | // SPACE
-        Some('\u{00A0}') | // NO-BREAK SPACE
+        '\u{00A0}' | // NO-BREAK SPACE
-        Some('\u{180E}') | // MONGOLIAN VOWEL SEPARATOR
+        '\u{180E}' | // MONGOLIAN VOWEL SEPARATOR
-        Some('\u{202F}') | // NARROW NO-BREAK SPACE
+        '\u{202F}' | // NARROW NO-BREAK SPACE
-        Some('\u{205F}') | // MEDIUM MATHEMATICAL SPACE
+        '\u{205F}' | // MEDIUM MATHEMATICAL SPACE
-        Some('\u{3000}') | // IDEOGRAPHIC SPACE
+        '\u{3000}' | // IDEOGRAPHIC SPACE
-        Some('\u{FEFF}') // ZERO WIDTH NO-BREAK SPACE
+        '\u{FEFF}' // ZERO WIDTH NO-BREAK SPACE
         => true,
 
         // EN QUAD, EM QUAD, EN SPACE, EM SPACE, THREE-PER-EM SPACE,
         // FOUR-PER-EM SPACE, SIX-PER-EM SPACE, FIGURE SPACE,
         // PUNCTUATION SPACE, THIN SPACE, HAIR SPACE, ZERO WIDTH SPACE.
-        Some(c) if c >= '\u{2000}' && c <= '\u{200B}' => true,
+        c if c >= '\u{2000}' && c <= '\u{200B}' => true,
 
-        // None, or not a matching whitespace character.
+        // Not a matching whitespace character.
         _ => false,
     }
 }
@@ -108,9 +116,11 @@ mod tests {
 
     #[test]
     fn char_count_1() {
+        let text_0 = "";
         let text_1 = "Hello world!";
         let text_2 = "今日はみんなさん！";
 
+        assert_eq!(0, char_count(text_0));
         assert_eq!(12, char_count(text_1));
         assert_eq!(9, char_count(text_2));
     }

src/term_ui/mod.rs

@@ -13,15 +13,12 @@ use crossterm::{
 
 use crate::{
     editor::Editor,
-    formatter::{block_count, block_index_and_range, char_range_from_block_index, LineFormatter},
+    formatter::LineFormatter,
-    string_utils::{is_line_ending, line_ending_to_str, LineEnding},
+    string_utils::{char_count, is_line_ending, line_ending_to_str, LineEnding},
-    utils::{digit_count, RopeGraphemes, Timer},
+    utils::{digit_count, Timer},
 };
 
-use self::{
+use self::screen::{Screen, Style};
-    formatter::ConsoleLineFormatter,
-    screen::{Screen, Style},
-};
 
 const EMPTY_MOD: KeyModifiers = KeyModifiers::empty();
 const UPDATE_TICK_MS: u64 = 10;
@@ -159,10 +156,7 @@ macro_rules! ui_loop {
                 $term_ui
                     .editor
                     .update_dim($term_ui.height - 1, $term_ui.width);
-                $term_ui
+                $term_ui.editor.formatter.wrap_width = $term_ui.editor.view_dim.1;
-                    .editor
-                    .formatter
-                    .set_wrap_width($term_ui.editor.view_dim.1);
 
                 // Draw!
                 {
@@ -176,7 +170,7 @@ macro_rules! ui_loop {
 
 pub struct TermUI {
     screen: Screen,
-    editor: Editor<ConsoleLineFormatter>,
+    editor: Editor,
     width: usize,
     height: usize,
     quit: bool,
@@ -190,10 +184,10 @@ enum LoopStatus {
 
 impl TermUI {
     pub fn new() -> TermUI {
-        TermUI::new_from_editor(Editor::new(ConsoleLineFormatter::new(4)))
+        TermUI::new_from_editor(Editor::new(LineFormatter::new(4)))
     }
 
-    pub fn new_from_editor(ed: Editor<ConsoleLineFormatter>) -> TermUI {
+    pub fn new_from_editor(ed: Editor) -> TermUI {
         let (w, h) = crossterm::terminal::size().unwrap();
         let mut editor = ed;
         editor.update_dim(h as usize - 1, w as usize);
@@ -216,7 +210,7 @@ impl TermUI {
         self.width = w as usize;
         self.height = h as usize;
         self.editor.update_dim(self.height - 1, self.width);
-        self.editor.formatter.set_wrap_width(self.editor.view_dim.1);
+        self.editor.formatter.wrap_width = self.editor.view_dim.1;
         self.screen.resize(w as usize, h as usize);
 
         // Start the UI
@@ -444,12 +438,7 @@ impl TermUI {
         }
     }
 
-    fn draw_editor(
+    fn draw_editor(&self, editor: &Editor, c1: (usize, usize), c2: (usize, usize)) {
-        &self,
-        editor: &Editor<ConsoleLineFormatter>,
-        c1: (usize, usize),
-        c2: (usize, usize),
-    ) {
         // Fill in top row with info line color
         for i in c1.1..(c2.1 + 1) {
             self.screen.draw(i, c1.0, " ", STYLE_INFO);
@@ -502,23 +491,20 @@ impl TermUI {
         self.draw_editor_text(editor, (c1.0 + 1, c1.1), c2);
     }
 
-    fn draw_editor_text(
+    fn draw_editor_text(&self, editor: &Editor, c1: (usize, usize), c2: (usize, usize)) {
-        &self,
-        editor: &Editor<ConsoleLineFormatter>,
-        c1: (usize, usize),
-        c2: (usize, usize),
-    ) {
         // Calculate all the starting info
         let gutter_width = editor.editor_dim.1 - editor.view_dim.1;
         let blank_gutter = &"                "[..gutter_width - 1];
-        let (line_index, col_i) = editor.buffer.index_to_line_col(editor.view_pos.0);
+        let line_index = editor.buffer.text.char_to_line(editor.view_pos.0);
-        let temp_line = editor.buffer.get_line(line_index);
+
-        let (mut line_block_index, block_range) = block_index_and_range(&temp_line, col_i);
+        let (blocks_iter, char_offset) = editor.formatter.iter(&editor.buffer, editor.view_pos.0);
-        let mut char_index = editor.buffer.line_col_to_index((line_index, block_range.0));
+
-        let (vis_line_offset, _) = editor.formatter.index_to_v2d(
+        let vis_line_offset = blocks_iter
-            RopeGraphemes::new(&temp_line.slice(block_range.0..block_range.1)),
+            .clone()
-            editor.view_pos.0 - char_index,
+            .next()
-        );
+            .unwrap()
+            .0
+            .vpos(editor.view_pos.0);
 
         let mut screen_line = c1.0 as isize - vis_line_offset as isize;
         let screen_col = c1.1 as isize + gutter_width as isize;
@@ -528,8 +514,16 @@ impl TermUI {
             self.screen.draw(c1.1, y, blank_gutter, STYLE_GUTTER_ODD);
         }
 
+        // Loop through the blocks, printing them to the screen.
+        let mut is_first_loop = true;
         let mut line_num = line_index + 1;
-        for line in editor.buffer.line_iter_at_index(line_index) {
+        let mut char_index = editor.view_pos.0 - char_offset;
+        for (block_vis_iter, is_line_start) in blocks_iter {
+            if is_line_start && !is_first_loop {
+                line_num += 1;
+            }
+            is_first_loop = false;
+
             let gutter_style = if (line_num % 2) == 0 {
                 STYLE_GUTTER_EVEN
             } else {
@@ -537,7 +531,7 @@ impl TermUI {
             };
 
             // Print line number
-            if line_block_index == 0 {
+            if is_line_start {
                 let lnx = c1.1;
                 let lny = screen_line as usize;
                 if lny >= c1.0 && lny <= c2.0 {
@@ -555,97 +549,63 @@ impl TermUI {
                 }
             }
 
-            // Loop through the graphemes of the line and print them to
+            // Loop through the graphemes of the block and print them to
             // the screen.
-            let max_block_index = block_count(&line) - 1;
-            let block_range = char_range_from_block_index(&line, line_block_index);
-            let mut g_iter = editor.formatter.iter(RopeGraphemes::new(
-                &line.slice(block_range.0..block_range.1),
-            ));
-
             let mut last_pos_y = 0;
-            let mut lines_traversed: usize = 0;
+            for (g, (pos_y, pos_x), width) in block_vis_iter {
-            loop {
+                // Calculate the cell coordinates at which to draw the grapheme
-                for (g, (pos_y, pos_x), width) in g_iter {
+                if pos_y > last_pos_y {
-                    let do_gutter =
+                    screen_line += 1;
-                        last_pos_y != pos_y || (lines_traversed == 0 && line_block_index != 0);
+                    last_pos_y = pos_y;
-                    if last_pos_y != pos_y {
+                }
-                        if last_pos_y < pos_y {
+                let px = pos_x as isize + screen_col - editor.view_pos.1 as isize;
-                            lines_traversed += pos_y - last_pos_y;
+                let py = screen_line;
+
+                // If we're off the bottom, we're done
+                if py > c2.0 as isize {
+                    return;
+                }
+
+                // Draw the grapheme to the screen if it's in bounds
+                if (px >= c1.1 as isize) && (py >= c1.0 as isize) && (px <= c2.1 as isize) {
+                    // Check if the character is within a cursor
+                    let mut at_cursor = false;
+                    for c in editor.cursors.iter() {
+                        if char_index >= c.range.0 && char_index <= c.range.1 {
+                            at_cursor = true;
+                            self.screen.set_cursor(px as usize, py as usize);
                         }
-                        last_pos_y = pos_y;
-                    }
-                    // Calculate the cell coordinates at which to draw the grapheme
-                    let px = pos_x as isize + screen_col - editor.view_pos.1 as isize;
-                    let py = lines_traversed as isize + screen_line;
-
-                    // If we're off the bottom, we're done
-                    if py > c2.0 as isize {
-                        return;
                     }
 
-                    if do_gutter {
+                    // Actually print the character
-                        self.screen
+                    if is_line_ending(&g) {
-                            .draw(c1.1, py as usize, blank_gutter, gutter_style);
+                        if at_cursor {
-                    }
+                            self.screen
-
+                                .draw(px as usize, py as usize, " ", STYLE_CURSOR);
-                    // Draw the grapheme to the screen if it's in bounds
+                        }
-                    if (px >= c1.1 as isize) && (py >= c1.0 as isize) && (px <= c2.1 as isize) {
+                    } else if g == "\t" {
-                        // Check if the character is within a cursor
+                        for i in 0..width {
-                        let mut at_cursor = false;
+                            let tpx = px as usize + i;
-                        for c in editor.cursors.iter() {
+                            if tpx <= c2.1 {
-                            if char_index >= c.range.0 && char_index <= c.range.1 {
+                                self.screen.draw(tpx as usize, py as usize, " ", STYLE_MAIN);
-                                at_cursor = true;
-                                self.screen.set_cursor(px as usize, py as usize);
                             }
                         }
 
-                        // Actually print the character
+                        if at_cursor {
-                        if is_line_ending(&g) {
+                            self.screen
-                            if at_cursor {
+                                .draw(px as usize, py as usize, " ", STYLE_CURSOR);
-                                self.screen
+                        }
-                                    .draw(px as usize, py as usize, " ", STYLE_CURSOR);
+                    } else {
-                            }
+                        if at_cursor {
-                        } else if g == "\t" {
+                            self.screen.draw(px as usize, py as usize, &g, STYLE_CURSOR);
-                            for i in 0..width {
-                                let tpx = px as usize + i;
-                                if tpx <= c2.1 {
-                                    self.screen.draw(tpx as usize, py as usize, " ", STYLE_MAIN);
-                                }
-                            }
-
-                            if at_cursor {
-                                self.screen
-                                    .draw(px as usize, py as usize, " ", STYLE_CURSOR);
-                            }
                         } else {
-                            if at_cursor {
+                            self.screen.draw(px as usize, py as usize, &g, STYLE_MAIN);
-                                self.screen.draw(px as usize, py as usize, &g, STYLE_CURSOR);
-                            } else {
-                                self.screen.draw(px as usize, py as usize, &g, STYLE_MAIN);
-                            }
                         }
                     }
-
-                    char_index += g.chars().count();
                 }
 
-                // Move on to the next block.
+                char_index += char_count(&g);
-                line_block_index += 1;
-                if line_block_index <= max_block_index {
-                    let block_range = char_range_from_block_index(&line, line_block_index);
-                    g_iter = editor.formatter.iter(RopeGraphemes::new(
-                        &line.slice(block_range.0..block_range.1),
-                    ));
-                    lines_traversed += 1;
-                } else {
-                    break;
-                }
             }
-
-            line_block_index = 0;
-            screen_line += lines_traversed as isize + 1;
-            line_num += 1;
         }
 
         // If we get here, it means we reached the end of the text buffer
@@ -664,7 +624,7 @@ impl TermUI {
             // Calculate the cell coordinates at which to draw the cursor
             let pos_x = editor
                 .formatter
-                .index_to_horizontal_v2d(&self.editor.buffer, self.editor.buffer.char_count());
+                .get_horizontal(&self.editor.buffer, self.editor.buffer.char_count());
             let mut px = pos_x as isize + screen_col - editor.view_pos.1 as isize;
             let mut py = screen_line - 1;
             if px > c2.1 as isize {

src/utils.rs

@@ -122,6 +122,7 @@ pub fn is_grapheme_boundary(slice: &RopeSlice, char_idx: usize) -> bool {
 }
 
 /// An iterator over the graphemes of a RopeSlice.
+#[derive(Clone)]
 pub struct RopeGraphemes<'a> {
     text: RopeSlice<'a>,
     chunks: Chunks<'a>,