1use crate::{Anchor, BufferSnapshot, TextDimension};
  2use std::cmp::Ordering;
  3use std::ops::Range;
  4
  5#[derive(Copy, Clone, Debug, PartialEq)]
  6pub enum SelectionGoal {
  7    None,
  8    HorizontalPosition(f32),
  9    HorizontalRange { start: f32, end: f32 },
 10    WrappedHorizontalPosition((u32, f32)),
 11}
 12
 13#[derive(Clone, Debug, PartialEq)]
 14pub struct Selection<T> {
 15    pub id: usize,
 16    pub start: T,
 17    pub end: T,
 18    pub reversed: bool,
 19    pub goal: SelectionGoal,
 20}
 21
 22impl Default for SelectionGoal {
 23    fn default() -> Self {
 24        Self::None
 25    }
 26}
 27
 28impl<T: Clone> Selection<T> {
 29    pub fn head(&self) -> T {
 30        if self.reversed {
 31            self.start.clone()
 32        } else {
 33            self.end.clone()
 34        }
 35    }
 36
 37    pub fn tail(&self) -> T {
 38        if self.reversed {
 39            self.end.clone()
 40        } else {
 41            self.start.clone()
 42        }
 43    }
 44
 45    pub fn map<F, S>(&self, f: F) -> Selection<S>
 46    where
 47        F: Fn(T) -> S,
 48    {
 49        Selection::<S> {
 50            id: self.id,
 51            start: f(self.start.clone()),
 52            end: f(self.end.clone()),
 53            reversed: self.reversed,
 54            goal: self.goal,
 55        }
 56    }
 57
 58    pub fn collapse_to(&mut self, point: T, new_goal: SelectionGoal) {
 59        self.start = point.clone();
 60        self.end = point;
 61        self.goal = new_goal;
 62        self.reversed = false;
 63    }
 64}
 65
 66impl<T: Copy + Ord> Selection<T> {
 67    pub fn is_empty(&self) -> bool {
 68        self.start == self.end
 69    }
 70
 71    pub fn set_head(&mut self, head: T, new_goal: SelectionGoal) {
 72        if head.cmp(&self.tail()) < Ordering::Equal {
 73            if !self.reversed {
 74                self.end = self.start;
 75                self.reversed = true;
 76            }
 77            self.start = head;
 78        } else {
 79            if self.reversed {
 80                self.start = self.end;
 81                self.reversed = false;
 82            }
 83            self.end = head;
 84        }
 85        self.goal = new_goal;
 86    }
 87
 88    pub fn set_tail(&mut self, tail: T, new_goal: SelectionGoal) {
 89        if tail.cmp(&self.head()) <= Ordering::Equal {
 90            if self.reversed {
 91                self.end = self.start;
 92                self.reversed = false;
 93            }
 94            self.start = tail;
 95        } else {
 96            if !self.reversed {
 97                self.start = self.end;
 98                self.reversed = true;
 99            }
100            self.end = tail;
101        }
102        self.goal = new_goal;
103    }
104
105    pub fn swap_head_tail(&mut self) {
106        if self.reversed {
107            self.reversed = false;
108        } else {
109            std::mem::swap(&mut self.start, &mut self.end);
110        }
111    }
112}
113
114impl<T: Copy> Selection<T> {
115    pub fn range(&self) -> Range<T> {
116        self.start..self.end
117    }
118}
119
120impl Selection<usize> {
121    #[cfg(feature = "test-support")]
122    pub fn from_offset(offset: usize) -> Self {
123        Selection {
124            id: 0,
125            start: offset,
126            end: offset,
127            goal: SelectionGoal::None,
128            reversed: false,
129        }
130    }
131
132    pub fn equals(&self, offset_range: &Range<usize>) -> bool {
133        self.start == offset_range.start && self.end == offset_range.end
134    }
135}
136
137impl Selection<Anchor> {
138    pub fn resolve<'a, D: 'a + TextDimension>(
139        &'a self,
140        snapshot: &'a BufferSnapshot,
141    ) -> Selection<D> {
142        Selection {
143            id: self.id,
144            start: snapshot.summary_for_anchor(&self.start),
145            end: snapshot.summary_for_anchor(&self.end),
146            reversed: self.reversed,
147            goal: self.goal,
148        }
149    }
150}