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use minimad::{
Compound,
};
use crate::{
Alignment,
FmtComposite,
MadSkin,
};
pub static ELLIPSIS: &str = "…";
/// A fitter can shorten a composite to make it fit a target width
pub struct Fitter {
// sum of kept head and kept tail, should be at least 1
// If not fair, we keep one more at head.
pub min_kept_after_ellision: usize,
pub allow_ellision: bool,
pub prefer_mid_token_ellision: bool,
// if true we can aggressively remove content and whole
// compounds
pub allow_removals: bool,
}
impl Default for Fitter {
fn default() -> Self {
Self {
min_kept_after_ellision: 4,
allow_ellision: true,
prefer_mid_token_ellision: true,
allow_removals: true,
}
}
}
impl Fitter {
pub fn fit(
&self,
fc: &mut FmtComposite<'_>,
max_width: usize,
align: Alignment,
skin: &MadSkin
) {
// all the widths and indices in this algorithms are of characters,
// that is neither bytes nor graphemes
if fc.visible_length <= max_width {
if let Some(ref mut spacing) = fc.spacing {
if spacing.width > max_width {
spacing.width = max_width;
}
}
return;
}
let mut to_remove = fc.visible_length - max_width;
if self.allow_ellision {
// First strategy: ellision
while to_remove > 0 {
let mut compound_width = self.min_kept_after_ellision + 2;
let mut longest: Option<usize> = None;
for (idx, compound) in fc.composite.compounds.iter().enumerate() {
let len = compound.char_length();
if len >= compound_width {
longest = Some(idx);
compound_width = len;
}
}
if let Some(idx) = longest {
// to remove part of the compound, we make it 3 compounds:
// the head, the ellipsis, and the tail
let gain = to_remove.min(compound_width - self.min_kept_after_ellision - 1);
let left = compound_width - gain - 1;
let mut left_tail = left / 2;
let mut left_head = left - left_tail;
if self.prefer_mid_token_ellision && gain < compound_width + 1 {
// we search for a part of the compound big enough and without space
let mut token_start: Option<usize> = None; // start of non whitespace area
let mut biggest_token_width = gain + 1;
let mut biggest_token_start: Option<usize> = None;
for (char_idx, char) in fc.composite.compounds[idx].as_str().chars().enumerate() {
if char.is_whitespace() {
if let Some(ts) = token_start {
let token_width = char_idx - ts;
if token_width > biggest_token_width {
biggest_token_start = Some(ts);
biggest_token_width = token_width;
}
token_start = None;
}
} else {
if token_start.is_none() {
token_start = Some(char_idx);
}
}
}
if let Some(token_start) = token_start {
let token_width = compound_width - 1 - token_start;
if token_width > biggest_token_width {
biggest_token_start = Some(token_start);
biggest_token_width = token_width;
}
}
if let Some(biggest_token_start) = biggest_token_start {
// there's a big enough token, we'll ellide in its middle
let r = biggest_token_width - gain - 1;
left_head = biggest_token_start + r / 2 + 1;
left_tail = left - left_head;
}
}
let head = fc.composite.compounds[idx].sub_chars(0, left_head);
let tail = fc.composite.compounds[idx].tail_chars(compound_width - left_tail);
fc.composite.compounds[idx]= head;
fc.composite.compounds.insert(idx+1, Compound::raw_str(ELLIPSIS));
fc.composite.compounds.insert(idx+2, tail);
to_remove -= gain;
} else {
break; // there's no compound long enough to be ellided
}
}
}
if self.allow_removals && to_remove > 0 {
fc.composite.remove_chars(to_remove, align);
}
// the visible width must be recomputed
fc.recompute_width(&skin);
if let Some(ref mut spacing) = fc.spacing {
spacing.width = fc.visible_length;
}
}
}
/// Tests of fitting, that is cutting the composite at best to make it
/// fit a given width (if possible)
///
/// The print which happens in case of failure isn't really well
/// formatted. A solution if a test fails is to do
/// cargo test fit_tests -- --nocapture
#[cfg(test)]
mod fit_tests {
use minimad::{
Alignment,
Composite,
};
use crate::{
Fitter,
FmtComposite,
};
fn check_fit(src: &str, target_width: usize) {
let skin = crate::get_default_skin();
let mut fc = FmtComposite::from(Composite::from_inline(src), &skin);
let fitter = Fitter::default();
fitter.fit(&mut fc, target_width, Alignment::Right, &skin);
assert_eq!(fc.visible_length, target_width);
}
#[test]
fn test_fit() {
let sentence = "This beautiful sentence has **short** and **much much much longer** parts.";
check_fit(sentence, 60);
check_fit(sentence, 40);
// the following test showcases a problem of termimad: we currently don't deal with the
// fact that some chars take more space on screen even in monospaced font
let five_issues = "一曰道，二曰天，三曰地，四曰將，五曰法。";
check_fit(five_issues, 15);
check_fit(five_issues, 8);
let status = "ab *cd* `12345 123456789`";
check_fit(status, 17);
check_fit(status, 2);
}
}