Add SpanListIterator

This commit is contained in:
Alexandre Bury 2018-01-08 00:48:20 +01:00
parent 1acde148be
commit 943da46e82
6 changed files with 756 additions and 103 deletions

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@ -33,6 +33,7 @@ owning_ref = "0.3"
toml = "0.4"
unicode-segmentation = "1.0"
unicode-width = "0.1"
xi-unicode = "0.1.0"
[dependencies.bear-lib-terminal]
optional = true

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@ -63,6 +63,7 @@
extern crate log;
#[macro_use]
extern crate maplit;
extern crate xi_unicode;
extern crate num;
extern crate owning_ref;
extern crate toml;

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@ -123,7 +123,7 @@ use toml;
/// Combine a color and an effect.
///
/// Represents any transformation that can be applied to text.
#[derive(Clone, Copy, Debug)]
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct Style {
/// Effect to apply.
///
@ -165,7 +165,7 @@ impl From<ColorStyle> for Style {
}
/// Text effect
#[derive(Clone, Copy, Debug)]
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Effect {
/// No effect
Simple,

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@ -26,8 +26,8 @@ impl<'a> LinesIterator<'a> {
/// Yields rows of `width` cells or less.
pub fn new(content: &'a str, width: usize) -> Self {
LinesIterator {
content: content,
width: width,
content,
width,
offset: 0,
show_spaces: false,
}

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@ -5,6 +5,7 @@ use unicode_width::UnicodeWidthStr;
mod lines_iterator;
mod reader;
pub mod span_lines_iterator;
pub use self::lines_iterator::{LinesIterator, Row};
pub use self::reader::ProgressReader;

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@ -1,150 +1,800 @@
//! bla
use std::borrow::Cow;
use std::iter::Peekable;
use theme::Style;
use unicode_segmentation::UnicodeSegmentation;
use unicode_width::UnicodeWidthStr;
use xi_unicode::LineBreakLeafIter;
/// Input to the algorithm
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Span<'a> {
text: Cow<'a, str>,
width: usize,
style: Style,
}
pub struct Row<'a> {
spans: Vec<Span<'a>>,
width: usize,
/// Refers to a part of a span
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Segment {
/// ID of the span this segment refers to
pub span_id: usize,
/// Beginning of this segment within the span (included)
pub start: usize,
/// End of this segment within the span (excluded)
pub end: usize,
/// Width of this segment
pub width: usize,
}
pub struct SpanLinesIterator<'a: 'b, 'b> {
/// Input that we want to split
content: &'b [Span<'a>],
impl Segment {
#[cfg(test)]
fn with_text<'a>(self, text: &'a str) -> SegmentWithText<'a> {
SegmentWithText { text, seg: self }
}
}
/// Available width
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct SegmentWithText<'a> {
seg: Segment,
text: &'a str,
}
/// Non-splittable piece of text.
#[derive(Debug, Clone, PartialEq, Eq)]
struct Chunk<'a> {
width: usize,
segments: Vec<SegmentWithText<'a>>,
hard_stop: bool,
ends_with_space: bool,
}
impl<'a> Chunk<'a> {
/// Remove some text from the front.
///
/// We're given the length (number of bytes) and the width.
fn remove_front(&mut self, mut to_remove: ChunkPart) {
// Remove something from each segment until we've removed enough.
for segment in &mut self.segments {
if to_remove.length <= segment.seg.end - segment.seg.start {
// This segment is bigger than what we need to remove
// So just trim the prefix and stop there.
segment.seg.start += to_remove.length;
segment.seg.width -= to_remove.width;
segment.text = &segment.text[to_remove.length..];
break;
} else {
// This segment is too small, so it'll disapear entirely.
to_remove.length -= segment.seg.end - segment.seg.start;
to_remove.width -= segment.seg.width;
// Empty this segment
segment.seg.start = segment.seg.end;
segment.seg.width = 0;
segment.text = &"";
}
}
}
/// Remove the last character from this chunk.
///
/// Usually done to remove a trailing space/newline.
fn remove_last_char(&mut self) {
// We remove the last char in 2 situations:
// * Trailing space.
// * Trailing newline.
// Only in the first case does this affect width.
// (Because newlines have 0 width)
if self.ends_with_space {
// Only reduce the width if the last char was a space.
// Otherwise it's a newline, and we don't want to reduce
// that.
self.width -= 1;
}
// Is the last segment empty after trimming it?
// If yes, just drop it.
let last_empty = {
let last = self.segments.last_mut().unwrap();
last.seg.end -= 1;
if self.ends_with_space {
last.seg.width -= 1;
}
last.seg.start == last.seg.end
};
if last_empty {
self.segments.pop().unwrap();
}
}
}
/// Iterator that returns non-breakable chunks of text.
///
/// Works accross spans of text.
struct ChunkIterator<'a, 'b>
where
'a: 'b,
{
/// Input that we want to split
spans: &'b [Span<'a>],
current_span: usize,
/// How much of the current span has been processed already.
offset: usize,
}
impl<'a: 'b, 'b> SpanLinesIterator<'a, 'b> {
pub fn new(content: &'b [Span<'a>], width: usize) -> Self {
SpanLinesIterator {
content,
width,
impl<'a, 'b> ChunkIterator<'a, 'b>
where
'a: 'b,
{
fn new(spans: &'b [Span<'a>]) -> Self {
ChunkIterator {
spans,
current_span: 0,
offset: 0,
}
}
}
// Intermediate representation of a Span, easier to manipulate.
struct Segment {
span_id: usize,
start: usize,
end: usize,
width: usize,
}
/// This iterator produces chunks of non-breakable text.
///
/// These chunks may go accross spans (a single word may be broken into more
/// than one span, for instance if parts of it are marked up differently).
impl<'a, 'b> Iterator for ChunkIterator<'a, 'b>
where
'a: 'b,
{
type Item = Chunk<'b>;
impl<'a, 'b> Iterator for SpanLinesIterator<'a, 'b> {
type Item = Row<'a>;
fn next(&mut self) -> Option<Row<'a>> {
if self.current_span >= self.content.len() {
fn next(&mut self) -> Option<Self::Item> {
if self.current_span >= self.spans.len() {
return None;
}
let current_span = &self.content[self.current_span];
let mut span: &Span<'a> = &self.spans[self.current_span];
let mut available = self.width;
let mut iter = LineBreakLeafIter::new(&current_span.text, self.offset);
let mut total_width = 0;
let mut spans = Vec::new();
let mut width = 0;
// We'll use an iterator from xi-unicode to detect possible breaks.
let mut iter = LineBreakLeafIter::new(&span.text, self.offset);
// We'll build a list of segments.
// There will be a 1-for-1 mapping from segments to spans.
// But segments are easier to manipulate and extend for now.
let mut segments: Vec<Segment> = Vec::new();
// We'll accumulate segments from spans.
let mut segments = Vec::new();
// When a span does not end on a possible break, its last segment
// can only be included depending on what comes after.
// So we keep a list of consecutive segments ids without breaks.
let mut carry_over: Vec<usize> = Vec::new();
// Whenever a segment is accepted, all of these can be inserted too.
'outer: for (span_id, span) in
self.content.iter().enumerate().skip(self.current_span)
{
// Make a new segment!
// When we reach the end of a span, xi-unicode returns a break, but it
// actually depends on the next span. Such breaks are "fake" breaks.
// So we'll loop until we find a "true" break
// (a break that doesn't happen an the end of a span).
// Most of the time, it will happen on the first iteration.
loop {
// Get the next possible break point.
let (pos, hard) = iter.next(&span.text);
// Look at next possible break
// `hard_stop = true` means that the break is non-optional,
// like after a `\n`.
let (pos, hard_stop) = iter.next(&span.text);
// Lookup the corresponding text segment.
let segment = &span.text[self.offset..pos];
let width = segment.width();
// If it doesn't fit, it's time to go home.
if width > available {
// Early return!
break 'outer;
}
available -= width;
// It fits, but... for real?
if pos == span.text.len() {
// It was too good to be true!
// It's just the end of a span, not an actual break.
// So save this stub for now, and move on to the next span.
carry_over.push(span_id);
// Start on the next span.
self.offset = 0;
break;
}
// We got it! We got a chunk!
// First, append any carry-over segment
for carry in carry_over.drain(..) {
// We need to include this entire segment.
if segments.last().map(|s| s.span_id) == Some(carry) {
// When xi-unicode reaches the end of a span, it returns a "fake"
// break. To know if it's actually a true break, we need to give
// it the next span. If, given the next span, it returns a break
// at position 0, then the previous one was a true break.
// So when pos = 0, we don't really have a new segment, but we
// can end the current chunk.
let (width, ends_with_space) = if pos == 0 {
// If pos = 0, we had a span before.
let prev_span = &self.spans[self.current_span - 1];
(0, prev_span.text.ends_with(' '))
} else {
segments.push(Segment {});
}
}
// We actually got something.
// Remember its width, and whether it ends with a space.
//
// (When a chunk ends with a space, we may compress it a bit
// near the end of a row, so this information will be useful
// later.)
let text = &span.text[self.offset..pos];
(text.width(), text.ends_with(' '))
};
// Include the present segment.
if pos != 0 {
segments.push(Segment {
span_id,
width,
// If pos != 0, we got an actual segment of a span.
total_width += width;
segments.push(SegmentWithText {
seg: Segment {
span_id: self.current_span,
start: self.offset,
end: pos,
width,
},
text: &span.text[self.offset..pos],
});
}
if pos == span.text.len() {
// If we reached the end of the slice,
// we need to look at the next span first.
self.current_span += 1;
if self.current_span >= self.spans.len() {
// If this was the last chunk, return as is!
return Some(Chunk {
width: total_width,
segments,
hard_stop,
ends_with_space,
});
}
span = &self.spans[self.current_span];
self.offset = 0;
continue;
}
// Remember where we are.
self.offset = pos;
// We found a valid stop, return the current chunk.
return Some(Chunk {
width: total_width,
segments,
hard_stop,
ends_with_space,
});
}
}
}
/// A list of segments representing a row of text
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Row {
/// List of segments
pub segments: Vec<Segment>,
/// Total width for this row
pub width: usize,
}
/// Generates rows of text in constrainted width.
///
/// Works on spans of text.
pub struct SpanLinesIterator<'a, 'b>
where
'a: 'b,
{
iter: Peekable<ChunkIterator<'a, 'b>>,
/// Available width
width: usize,
/// If a chunk wouldn't fit, we had to cut it in pieces.
/// This is how far in the current chunk we are.
chunk_offset: ChunkPart,
}
impl<'a, 'b> SpanLinesIterator<'a, 'b>
where
'a: 'b,
{
/// Creates a new iterator with the given content and width.
pub fn new(spans: &'b [Span<'a>], width: usize) -> Self {
SpanLinesIterator {
iter: ChunkIterator::new(spans).peekable(),
width,
chunk_offset: ChunkPart::default(),
}
}
}
/// Result of a fitness test
///
/// Describes how well a chunk fits in the available space.
enum ChunkFitResult {
/// This chunk can fit as-is
Fits,
/// This chunk fits, but it'll be the last one.
/// Additionally, its last char may need to be removed.
FitsBarely,
/// This chunk doesn't fit. Don't even.
DoesNotFit,
}
/// Look at a chunk, and decide how it could fit.
fn consider_chunk(available: usize, chunk: &Chunk) -> ChunkFitResult {
if chunk.width <= available {
// We fits. No question about it.
if chunk.hard_stop {
// Still, we have to stop here.
// And possibly trim a newline.
ChunkFitResult::FitsBarely
} else {
// Nothing special here.
ChunkFitResult::Fits
}
} else if chunk.width == available + 1 {
// We're just SLIGHTLY too big!
// Can we just pop something?
if chunk.ends_with_space {
// Yay!
ChunkFitResult::FitsBarely
} else {
// Noo(
ChunkFitResult::DoesNotFit
}
} else {
// Can't bargain with me.
ChunkFitResult::DoesNotFit
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
/// Describes a part of a chunk.
///
/// Includes both length and width to ease some computations.
///
/// This is used to represent how much of a chunk we've already processed.
struct ChunkPart {
width: usize,
length: usize,
}
/// Concatenates chunks as long as they fit in the given width.
fn prefix<'a, I>(
tokens: &mut Peekable<I>, width: usize, offset: &mut ChunkPart
) -> Vec<Chunk<'a>>
where
I: Iterator<Item = Chunk<'a>>,
{
let mut available = width;
let mut chunks = Vec::new();
// Accumulate chunks until it doesn't fit.
loop {
// Look at the next chunk and see if it would fit.
let result = {
let next_chunk = match tokens.peek() {
None => break,
Some(chunk) => chunk,
};
// When considering if the chunk fits, remember that we may
// already have processed part of it.
// So (chunk - width) fits available
// if chunks fits (available + width)
consider_chunk(available + offset.width, next_chunk)
};
match result {
ChunkFitResult::Fits => {
// It fits! Add it and move to the next one.
let mut chunk = tokens.next().unwrap();
// Remember to strip the prefix, in case we took some earlier.
chunk.remove_front(*offset);
// And reset out offset.
offset.length = 0;
offset.width = 0;
available -= chunk.width;
chunks.push(chunk);
continue;
}
ChunkFitResult::FitsBarely => {
// That's it, it's the last one and we're off.
let mut chunk = tokens.next().unwrap();
chunk.remove_front(*offset);
offset.length = 0;
offset.width = 0;
// We know we need to remove the last character.
// Because it's either:
// * A hard stop: there is a newline
// * A compressed chunk: it ends with a space
chunk.remove_last_char();
chunks.push(chunk);
// No need to update `available`,
// as we're ending the line anyway.
break;
}
ChunkFitResult::DoesNotFit => {
break;
}
}
}
if hard {
// Stop here.
break 'outer;
chunks
}
impl<'a, 'b> Iterator for SpanLinesIterator<'a, 'b>
where
'a: 'b,
{
type Item = Row;
fn next(&mut self) -> Option<Row> {
// Let's build a beautiful row.
let mut chunks =
prefix(&mut self.iter, self.width, &mut self.chunk_offset);
if chunks.is_empty() {
// Desperate action to make something fit:
// Look at the current chunk. We'll try to return a part of it.
// So now, consider each individual grapheme as a valid chunk.
// Note: it may not be the first time we try to fit this chunk,
// so remember to trim the offset we may have stored.
match self.iter.peek() {
None => return None,
Some(chunk) => {
let mut chunk = chunk.clone();
chunk.remove_front(self.chunk_offset);
// Try to fit part of it?
let graphemes = chunk.segments.iter().flat_map(|seg| {
let mut offset = seg.seg.start;
seg.text.graphemes(true).map(move |g| {
let width = g.width();
let start = offset;
let end = offset + g.len();
offset = end;
Chunk {
width,
segments: vec![
SegmentWithText {
text: g,
seg: Segment {
width,
span_id: seg.seg.span_id,
start,
end,
},
},
],
hard_stop: false,
ends_with_space: false,
}
})
});
chunks = prefix(
&mut graphemes.peekable(),
self.width,
&mut ChunkPart::default(),
);
if chunks.is_empty() {
// Seriously? After everything we did for you?
return None;
}
// We are going to return a part of a chunk.
// So remember what we selected,
// so we can skip it next time.
let width: usize =
chunks.iter().map(|chunk| chunk.width).sum();
let length: usize = chunks
.iter()
.flat_map(|chunk| chunk.segments.iter())
.map(|segment| segment.text.len())
.sum();
self.chunk_offset.width += width;
self.chunk_offset.length += length;
}
}
}
let width = chunks.iter().map(|c| c.width).sum();
assert!(width <= self.width);
// Concatenate all segments
let segments = SegmentMergeIterator::new(
chunks
.into_iter()
.flat_map(|chunk| chunk.segments)
.map(|segment| segment.seg)
.filter(|segment| segment.start != segment.end),
).collect();
// TODO: merge consecutive segments of the same span
Some(Row { segments, width })
}
}
struct SegmentMergeIterator<I> {
current: Option<Segment>,
inner: I,
}
impl<I> SegmentMergeIterator<I> {
fn new(inner: I) -> Self {
SegmentMergeIterator {
inner,
current: None,
}
}
}
impl<I> Iterator for SegmentMergeIterator<I>
where
I: Iterator<Item = Segment>,
{
type Item = Segment;
fn next(&mut self) -> Option<Self::Item> {
if self.current.is_none() {
self.current = self.inner.next();
if self.current.is_none() {
return None;
}
}
loop {
let current_span = &self.content[self.current_span];
let (pos, hard) = iter.next(&current_span.text);
// This is what we consider adding
let text = &current_span.text[self.offset..pos];
if hard {
// Stop there!
break;
match self.inner.next() {
None => return self.current.take(),
Some(next) => {
if next.span_id == self.current.unwrap().span_id {
let current = self.current.as_mut().unwrap();
current.end = next.end;
current.width += next.width;
} else {
let current = self.current.take();
self.current = Some(next);
return current;
}
}
}
}
Some(Row { spans, width })
}
}
#[cfg(test)]
mod tests {
use super::*;
fn input() -> Vec<Span<'static>> {
vec![
Span {
text: Cow::Borrowed("A beautiful "),
style: Style::none(),
},
Span {
text: Cow::Borrowed("boat"),
style: Style::none(),
},
Span {
text: Cow::Borrowed(" isn't it?\nYes indeed, my "),
style: Style::none(),
},
Span {
text: Cow::Borrowed("Super"),
style: Style::none(),
},
Span {
text: Cow::Borrowed("Captain !"),
style: Style::none(),
},
]
}
#[test]
fn test_lines_iter() {
let input = input();
let iter = SpanLinesIterator::new(&input, 16);
let rows: Vec<Row> = iter.collect();
assert_eq!(
&rows[..],
&[
Row {
segments: vec![
Segment {
span_id: 0,
start: 0,
end: 12,
width: 12,
},
Segment {
span_id: 1,
start: 0,
end: 4,
width: 4,
},
],
width: 16,
},
Row {
segments: vec![
Segment {
span_id: 2,
start: 1,
end: 10,
width: 9,
},
],
width: 9,
},
Row {
segments: vec![
Segment {
span_id: 2,
start: 11,
end: 26,
width: 15,
},
],
width: 15,
},
Row {
segments: vec![
Segment {
span_id: 3,
start: 0,
end: 5,
width: 5,
},
Segment {
span_id: 4,
start: 0,
end: 9,
width: 9,
},
],
width: 14,
}
]
);
}
#[test]
fn test_chunk_iter() {
let input = input();
let iter = ChunkIterator::new(&input);
let chunks: Vec<Chunk> = iter.collect();
assert_eq!(
&chunks[..],
&[
Chunk {
width: 2,
segments: vec![
Segment {
span_id: 0,
start: 0,
end: 2,
width: 2,
}.with_text("A "),
],
hard_stop: false,
ends_with_space: true,
},
Chunk {
width: 10,
segments: vec![
Segment {
span_id: 0,
start: 2,
end: 12,
width: 10,
}.with_text("beautiful "),
],
hard_stop: false,
ends_with_space: true,
},
Chunk {
width: 5,
segments: vec![
Segment {
span_id: 1,
start: 0,
end: 4,
width: 4,
}.with_text("boat"),
Segment {
span_id: 2,
start: 0,
end: 1,
width: 1,
}.with_text(" "),
],
hard_stop: false,
ends_with_space: true,
},
Chunk {
width: 6,
segments: vec![
// "isn't "
Segment {
span_id: 2,
start: 1,
end: 7,
width: 6,
}.with_text("isn't "),
],
hard_stop: false,
ends_with_space: true,
},
Chunk {
width: 3,
segments: vec![
// "it?\n"
Segment {
span_id: 2,
start: 7,
end: 11,
width: 3,
}.with_text("it?\n"),
],
hard_stop: true,
ends_with_space: false,
},
Chunk {
width: 4,
segments: vec![
// "Yes "
Segment {
span_id: 2,
start: 11,
end: 15,
width: 4,
}.with_text("Yes "),
],
hard_stop: false,
ends_with_space: true,
},
Chunk {
width: 8,
segments: vec![
// "indeed, "
Segment {
span_id: 2,
start: 15,
end: 23,
width: 8,
}.with_text("indeed, "),
],
hard_stop: false,
ends_with_space: true,
},
Chunk {
width: 3,
segments: vec![
// "my "
Segment {
span_id: 2,
start: 23,
end: 26,
width: 3,
}.with_text("my "),
],
hard_stop: false,
ends_with_space: true,
},
Chunk {
width: 14,
segments: vec![
// "Super"
Segment {
span_id: 3,
start: 0,
end: 5,
width: 5,
}.with_text("Super"),
// "Captain !"
Segment {
span_id: 4,
start: 0,
end: 9,
width: 9,
}.with_text("Captain !"),
],
hard_stop: false,
ends_with_space: false,
}
]
);
}
}