diff --git a/helix-core/src/doc_formatter.rs b/helix-core/src/doc_formatter.rs index f934b38a1..0f9a52b5d 100644 --- a/helix-core/src/doc_formatter.rs +++ b/helix-core/src/doc_formatter.rs @@ -11,7 +11,7 @@ use std::borrow::Cow; use std::fmt::Debug; -use std::mem::{replace, take}; +use std::mem::replace; #[cfg(test)] mod test; @@ -166,9 +166,6 @@ pub struct DocumentFormatter<'t> { line_pos: usize, exhausted: bool, - /// Line breaks to be reserved for virtual text - /// at the next line break - virtual_lines: usize, inline_anntoation_graphemes: Option<(Graphemes<'t>, Option)>, // softwrap specific @@ -209,7 +206,6 @@ pub fn new_at_prev_checkpoint( graphemes: RopeGraphemes::new(text.slice(block_char_idx..)), char_pos: block_char_idx, exhausted: false, - virtual_lines: 0, indent_level: None, peeked_grapheme: None, word_buf: Vec::with_capacity(64), @@ -250,7 +246,6 @@ fn advance_grapheme(&mut self, col: usize, char_pos: usize) -> Option usize { 0 }; + let virtual_lines = + self.annotations + .virtual_lines_at(self.char_pos, self.visual_pos, self.line_pos); self.visual_pos.col = indent_carry_over as usize; - self.visual_pos.row += 1 + take(&mut self.virtual_lines); + self.visual_pos.row += 1 + virtual_lines; let mut i = 0; let mut word_width = 0; let wrap_indicator = UnicodeSegmentation::graphemes(&*self.text_fmt.wrap_indicator, true) @@ -404,24 +402,32 @@ fn next(&mut self) -> Option { self.advance_grapheme(self.visual_pos.col, self.char_pos)? }; - let visual_pos = self.visual_pos; - let char_pos = self.char_pos; + let grapheme = FormattedGrapheme { + raw: grapheme.grapheme, + source: grapheme.source, + visual_pos: self.visual_pos, + line_idx: self.line_pos, + char_idx: self.char_pos, + }; + self.char_pos += grapheme.doc_chars(); - let line_idx = self.line_pos; - if grapheme.grapheme == Grapheme::Newline { - self.visual_pos.row += 1; - self.visual_pos.row += take(&mut self.virtual_lines); + if !grapheme.is_virtual() { + self.annotations.process_virtual_text_anchors(&grapheme); + } + if grapheme.raw == Grapheme::Newline { + // move to end of newline char + self.visual_pos.col += 1; + let virtual_lines = + self.annotations + .virtual_lines_at(self.char_pos, self.visual_pos, self.line_pos); + self.visual_pos.row += 1 + virtual_lines; self.visual_pos.col = 0; - self.line_pos += 1; + if !grapheme.is_virtual() { + self.line_pos += 1; + } } else { self.visual_pos.col += grapheme.width(); } - Some(FormattedGrapheme { - raw: grapheme.grapheme, - source: grapheme.source, - visual_pos, - line_idx, - char_idx: char_pos, - }) + Some(grapheme) } } diff --git a/helix-core/src/text_annotations.rs b/helix-core/src/text_annotations.rs index 1576914e3..785e38fd7 100644 --- a/helix-core/src/text_annotations.rs +++ b/helix-core/src/text_annotations.rs @@ -1,8 +1,12 @@ use std::cell::Cell; +use std::cmp::Ordering; +use std::fmt::Debug; use std::ops::Range; +use std::ptr::NonNull; +use crate::doc_formatter::FormattedGrapheme; use crate::syntax::Highlight; -use crate::Tendril; +use crate::{Position, Tendril}; /// An inline annotation is continuous text shown /// on the screen before the grapheme that starts at @@ -75,19 +79,98 @@ pub fn new(char_idx: usize, grapheme: impl Into) -> Self { } } -/// Line annotations allow for virtual text between normal -/// text lines. They cause `height` empty lines to be inserted -/// below the document line that contains `anchor_char_idx`. +/// Line annotations allow inserting virtual text lines between normal text +/// lines. These lines can be filled with text in the rendering code as their +/// contents have no effect beyond visual appearance. /// -/// These lines can be filled with text in the rendering code -/// as their contents have no effect beyond visual appearance. +/// The height of virtual text is usually not known ahead of time as virtual +/// text often requires softwrapping. Furthermore the height of some virtual +/// text like side-by-side diffs depends on the height of the text (again +/// influenced by softwrap) and other virtual text. Therefore line annotations +/// are computed on the fly instead of ahead of time like other annotations. /// -/// To insert a line after a document line simply set -/// `anchor_char_idx` to `doc.line_to_char(line_idx)` -#[derive(Debug, Clone)] -pub struct LineAnnotation { - pub anchor_char_idx: usize, - pub height: usize, +/// The core of this trait `insert_virtual_lines` function. It is called at the +/// end of every visual line and allows the `LineAnnotation` to insert empty +/// virtual lines. Apart from that the `LineAnnotation` trait has multiple +/// methods that allow it to track anchors in the document. +/// +/// When a new traversal of a document starts `reset_pos` is called. Afterwards +/// the other functions are called with indices that are larger then the +/// one passed to `reset_pos`. This allows performing a binary search (use +/// `partition_point`) in `reset_pos` once and then to only look at the next +/// anchor during each method call. +/// +/// The `reset_pos`, `skip_conceal` and `process_anchor` functions all return a +/// `char_idx` anchor. This anchor is stored when transversing the document and +/// when the grapheme at the anchor is traversed the `process_anchor` function +/// is called. +/// +/// # Note +/// +/// All functions only receive immutable references to `self`. +/// `LineAnnotation`s that want to store an internal position or +/// state of some kind should use `Cell`. Using interior mutability for +/// caches is preferable as otherwise a lot of lifetimes become invariant +/// which complicates APIs a lot. +pub trait LineAnnotation { + /// Resets the internal position to `char_idx`. This function is called + /// when a new traversal of a document starts. + /// + /// All `char_idx` passed to `insert_virtual_lines` are strictly monotonically increasing + /// with the first `char_idx` greater or equal to the `char_idx` + /// passed to this function. + /// + /// # Returns + /// + /// The `char_idx` of the next anchor this `LineAnnotation` is interested in, + /// replaces the currently registered anchor. Return `usize::MAX` to ignore + fn reset_pos(&mut self, _char_idx: usize) -> usize { + usize::MAX + } + + /// Called when a text is concealed that contains an anchor registered by this `LineAnnotation`. + /// In this case the line decorations **must** ensure that virtual text anchored within that + /// char range is skipped. + /// + /// # Returns + /// + /// The `char_idx` of the next anchor this `LineAnnotation` is interested in, + /// **after the end of conceal_end_char_idx** + /// replaces the currently registered anchor. Return `usize::MAX` to ignore + fn skip_concealed_anchors(&mut self, conceal_end_char_idx: usize) -> usize { + self.reset_pos(conceal_end_char_idx) + } + + /// Process an anchor (horizontal position is provided) and returns the next anchor. + /// + /// # Returns + /// + /// The `char_idx` of the next anchor this `LineAnnotation` is interested in, + /// replaces the currently registered anchor. Return `usize::MAX` to ignore + fn process_anchor(&mut self, _grapheme: &FormattedGrapheme) -> usize { + usize::MAX + } + + /// This function is called at the end of a visual line to insert virtual text + /// + /// # Returns + /// + /// The number of additional virtual lines to reserve + /// + /// # Note + /// + /// The `line_end_visual_pos` parameter indicates the visual vertical distance + /// from the start of block where the traversal starts. This includes the offset + /// from other `LineAnnotations`. This allows inline annotations to consider + /// the height of the text and "align" two different documents (like for side + /// by side diffs). These annotations that want to "align" two documents should + /// therefore be added last so that other virtual text is also considered while aligning + fn insert_virtual_lines( + &mut self, + line_end_char_idx: usize, + line_end_visual_pos: Position, + doc_line: usize, + ) -> Position; } #[derive(Debug)] @@ -143,13 +226,68 @@ fn reset_pos(layers: &[Layer], pos: usize, get_pos: impl Fn(&A) -> u } } +/// Safety: We store LineAnnotation in a NonNull pointer. This is necessary to work +/// around an unfortunate inconsistency in rusts variance system that unnnecesarily +/// makes the lifetime invariant if implemented with safe code. This makes the +/// DocFormatter API very cumbersome/basically impossible to work with. +/// +/// Normally object types `dyn Foo + 'a` are covariant so if we used `Box` below +/// everything would be alright. However we want to use `Cell>` +/// to be able to call the mutable function on `LineAnnotation`. The problem is that +/// some types like `Cell` make all their arguments invariant. This is important for soundness +/// normally for the same reasons that `&'a mut T` is invariant over `T` +/// (see ). However for `&'a mut` (`dyn Foo + 'b`) +/// there is a specical rule in the language to make `'b` covariant (otherwise trait objects would be +/// super annoying to use). See for +/// why this is sound. Sadly that rule doesn't apply to `Cell` +/// (or other invariant types like `UnsafeCell` or `*mut (dyn Foo + 'a)`). +/// +/// We sidestep the problem by using `NonNull` which is covariant. In the +/// special case of trait objects this is sound (easily checked by adding a +/// `PhantomData<&'a mut Foo + 'a)>` field). We don't need an explicit `Cell` +/// type here because we never hand out any refereces to the trait objects. That +/// means any reference to the pointer can create a valid multable reference +/// that is covariant over `'a` (or in other words it's a raw pointer, as long as +/// we don't hand out references we are free to do whatever we want). +struct RawBox(NonNull); + +impl RawBox { + /// Safety: Only a single mutable reference + /// created by this function may exist at a given time. + #[allow(clippy::mut_from_ref)] + unsafe fn get(&self) -> &mut T { + &mut *self.0.as_ptr() + } +} +impl From> for RawBox { + fn from(box_: Box) -> Self { + // obviously safe because Box::into_raw never returns null + unsafe { Self(NonNull::new_unchecked(Box::into_raw(box_))) } + } +} + +impl Drop for RawBox { + fn drop(&mut self) { + unsafe { drop(Box::from_raw(self.0.as_ptr())) } + } +} + /// Annotations that change that is displayed when the document is render. /// Also commonly called virtual text. -#[derive(Default, Debug, Clone)] +#[derive(Default)] pub struct TextAnnotations<'a> { inline_annotations: Vec>>, overlays: Vec>>, - line_annotations: Vec>, + line_annotations: Vec<(Cell, RawBox)>, +} + +impl Debug for TextAnnotations<'_> { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + f.debug_struct("TextAnnotations") + .field("inline_annotations", &self.inline_annotations) + .field("overlays", &self.overlays) + .finish_non_exhaustive() + } } impl<'a> TextAnnotations<'a> { @@ -157,9 +295,9 @@ impl<'a> TextAnnotations<'a> { pub fn reset_pos(&self, char_idx: usize) { reset_pos(&self.inline_annotations, char_idx, |annot| annot.char_idx); reset_pos(&self.overlays, char_idx, |annot| annot.char_idx); - reset_pos(&self.line_annotations, char_idx, |annot| { - annot.anchor_char_idx - }); + for (next_anchor, layer) in &self.line_annotations { + next_anchor.set(unsafe { layer.get().reset_pos(char_idx) }); + } } pub fn collect_overlay_highlights( @@ -219,8 +357,9 @@ pub fn add_overlay(&mut self, layer: &'a [Overlay], highlight: Option /// /// The line annotations **must be sorted** by their `char_idx`. /// Multiple line annotations with the same `char_idx` **are not allowed**. - pub fn add_line_annotation(&mut self, layer: &'a [LineAnnotation]) -> &mut Self { - self.line_annotations.push((layer, ()).into()); + pub fn add_line_annotation(&mut self, layer: Box) -> &mut Self { + self.line_annotations + .push((Cell::new(usize::MAX), layer.into())); self } @@ -250,21 +389,35 @@ pub(crate) fn overlay_at(&self, char_idx: usize) -> Option<(&Overlay, Option usize { - self.line_annotations - .iter() - .map(|layer| { - let mut lines = 0; - while let Some(annot) = layer.annotations.get(layer.current_index.get()) { - if annot.anchor_char_idx == char_idx { - layer.current_index.set(layer.current_index.get() + 1); - lines += annot.height - } else { - break; + pub(crate) fn process_virtual_text_anchors(&self, grapheme: &FormattedGrapheme) { + for (next_anchor, layer) in &self.line_annotations { + loop { + match next_anchor.get().cmp(&grapheme.char_idx) { + Ordering::Less => next_anchor + .set(unsafe { layer.get().skip_concealed_anchors(grapheme.char_idx) }), + Ordering::Equal => { + next_anchor.set(unsafe { layer.get().process_anchor(grapheme) }) } - } - lines - }) - .sum() + Ordering::Greater => break, + }; + } + } + } + + pub(crate) fn virtual_lines_at( + &self, + char_idx: usize, + line_end_visual_pos: Position, + doc_line: usize, + ) -> usize { + let mut virt_off = Position::new(0, 0); + for (_, layer) in &self.line_annotations { + virt_off += unsafe { + layer + .get() + .insert_virtual_lines(char_idx, line_end_visual_pos + virt_off, doc_line) + }; + } + virt_off.row } }