use super::{ExcerptId, MultiBufferSnapshot, ToOffset, ToOffsetUtf16, ToPoint};use language::{OffsetUtf16, Point, TextDimension};use std::{    cmp::Ordering,    ops::{Range, Sub},};use sum_tree::Bias;use text::BufferId; #[derive(Clone, Copy, Eq, PartialEq, Debug, Hash)]pub struct Anchor {    pub buffer_id: Option<BufferId>,    pub excerpt_id: ExcerptId,    pub text_anchor: text::Anchor,} impl Anchor {    pub fn min() -> Self {        Self {            buffer_id: None,            excerpt_id: ExcerptId::min(),            text_anchor: text::Anchor::MIN,        }    }     pub fn max() -> Self {        Self {            buffer_id: None,            excerpt_id: ExcerptId::max(),            text_anchor: text::Anchor::MAX,        }    }     pub fn cmp(&self, other: &Anchor, snapshot: &MultiBufferSnapshot) -> Ordering {        let excerpt_id_cmp = self.excerpt_id.cmp(&other.excerpt_id, snapshot);        if excerpt_id_cmp.is_eq() {            if self.excerpt_id == ExcerptId::min() || self.excerpt_id == ExcerptId::max() {                Ordering::Equal            } else if let Some(excerpt) = snapshot.excerpt(self.excerpt_id) {                self.text_anchor.cmp(&other.text_anchor, &excerpt.buffer)            } else {                Ordering::Equal            }        } else {            excerpt_id_cmp        }    }     pub fn bias(&self) -> Bias {        self.text_anchor.bias    }     pub fn bias_left(&self, snapshot: &MultiBufferSnapshot) -> Anchor {        if self.text_anchor.bias != Bias::Left {            if let Some(excerpt) = snapshot.excerpt(self.excerpt_id) {                return Self {                    buffer_id: self.buffer_id,                    excerpt_id: self.excerpt_id,                    text_anchor: self.text_anchor.bias_left(&excerpt.buffer),                };            }        }        *self    }     pub fn bias_right(&self, snapshot: &MultiBufferSnapshot) -> Anchor {        if self.text_anchor.bias != Bias::Right {            if let Some(excerpt) = snapshot.excerpt(self.excerpt_id) {                return Self {                    buffer_id: self.buffer_id,                    excerpt_id: self.excerpt_id,                    text_anchor: self.text_anchor.bias_right(&excerpt.buffer),                };            }        }        *self    }     pub fn summary<D>(&self, snapshot: &MultiBufferSnapshot) -> D    where        D: TextDimension + Ord + Sub<D, Output = D>,    {        snapshot.summary_for_anchor(self)    }     pub fn is_valid(&self, snapshot: &MultiBufferSnapshot) -> bool {        if *self == Anchor::min() || *self == Anchor::max() {            true        } else if let Some(excerpt) = snapshot.excerpt(self.excerpt_id) {            excerpt.contains(self)                && (self.text_anchor == excerpt.range.context.start                    || self.text_anchor == excerpt.range.context.end                    || self.text_anchor.is_valid(&excerpt.buffer))        } else {            false        }    }} impl ToOffset for Anchor {    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize {        self.summary(snapshot)    }} impl ToOffsetUtf16 for Anchor {    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {        self.summary(snapshot)    }} impl ToPoint for Anchor {    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {        self.summary(snapshot)    }} pub trait AnchorRangeExt {    fn cmp(&self, b: &Range<Anchor>, buffer: &MultiBufferSnapshot) -> Ordering;    fn to_offset(&self, content: &MultiBufferSnapshot) -> Range<usize>;    fn to_point(&self, content: &MultiBufferSnapshot) -> Range<Point>;} impl AnchorRangeExt for Range<Anchor> {    fn cmp(&self, other: &Range<Anchor>, buffer: &MultiBufferSnapshot) -> Ordering {        match self.start.cmp(&other.start, buffer) {            Ordering::Equal => other.end.cmp(&self.end, buffer),            ord => ord,        }    }     fn to_offset(&self, content: &MultiBufferSnapshot) -> Range<usize> {        self.start.to_offset(content)..self.end.to_offset(content)    }     fn to_point(&self, content: &MultiBufferSnapshot) -> Range<Point> {        self.start.to_point(content)..self.end.to_point(content)    }}