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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use std::cmp::{max, min};
use std::iter;
use std::fmt;
use std::num;
use std::num::Bounded;
pub enum RangeRelation<T> {
OverlapsBegin(/* overlap */ T),
OverlapsEnd(/* overlap */ T),
ContainedBy,
Contains,
Coincides,
EntirelyBefore,
EntirelyAfter
}
#[deriving(Clone)]
pub struct Range<T> {
off: T,
len: T,
}
impl<T: Int + TotalOrd> fmt::Show for Range<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f.buf, "[{} .. {})", self.begin(), self.end())
}
}
impl<T: Int + TotalOrd> Range<T> {
#[inline]
pub fn new(off: T, len: T) -> Range<T> {
Range {
off: off,
len: len,
}
}
#[inline]
pub fn empty() -> Range<T> {
Range::new(num::zero(), num::zero())
}
#[inline]
pub fn begin(&self) -> T { self.off }
#[inline]
pub fn length(&self) -> T { self.len }
#[inline]
pub fn end(&self) -> T { self.off + self.len }
#[inline]
pub fn eachi(&self) -> iter::Range<T> {
range(self.off, self.off + self.len)
}
#[inline]
pub fn contains(&self, i: T) -> bool {
i >= self.begin() && i < self.end()
}
#[inline]
pub fn is_valid_for_string(&self, s: &str) -> bool {
let s_len = s.len();
match num::cast(s_len) {
Some(len) => {
self.begin() < len && self.end() <= len && self.length() <= len
},
None => {
debug!("Range<T>::is_valid_for_string: string length ({}) is longer than the max \
value for T ({})", s_len, { let val: T = Bounded::max_value(); val });
false
},
}
}
#[inline]
pub fn is_empty(&self) -> bool {
self.len.is_zero()
}
#[inline]
pub fn shift_by(&mut self, i: int) {
self.off = num::cast(self.off.to_int().unwrap() + i).unwrap();
}
#[inline]
pub fn extend_by(&mut self, i: int) {
self.len = num::cast(self.len.to_int().unwrap() + i).unwrap();
}
#[inline]
pub fn extend_to(&mut self, i: T) {
self.len = i - self.off;
}
#[inline]
pub fn adjust_by(&mut self, off_i: int, len_i: int) {
self.off = num::cast(self.off.to_int().unwrap() + off_i).unwrap();
self.len = num::cast(self.len.to_int().unwrap() + len_i).unwrap();
}
#[inline]
pub fn reset(&mut self, off_i: T, len_i: T) {
self.off = off_i;
self.len = len_i;
}
#[inline]
pub fn intersect(&self, other: &Range<T>) -> Range<T> {
let begin = max(self.begin(), other.begin());
let end = min(self.end(), other.end());
if end < begin {
Range::empty()
} else {
Range::new(begin, end - begin)
}
}
/// Computes the relationship between two ranges (`self` and `other`),
/// from the point of view of `self`. So, 'EntirelyBefore' means
/// that the `self` range is entirely before `other` range.
#[inline]
pub fn relation_to_range(&self, other: &Range<T>) -> RangeRelation<T> {
if other.begin() > self.end() {
return EntirelyBefore;
}
if self.begin() > other.end() {
return EntirelyAfter;
}
if self.begin() == other.begin() && self.end() == other.end() {
return Coincides;
}
if self.begin() <= other.begin() && self.end() >= other.end() {
return Contains;
}
if self.begin() >= other.begin() && self.end() <= other.end() {
return ContainedBy;
}
if self.begin() < other.begin() && self.end() < other.end() {
let overlap = self.end() - other.begin();
return OverlapsBegin(overlap);
}
if self.begin() > other.begin() && self.end() > other.end() {
let overlap = other.end() - self.begin();
return OverlapsEnd(overlap);
}
fail!("relation_to_range(): didn't classify self={:?}, other={:?}",
self, other);
}
#[inline]
pub fn repair_after_coalesced_range(&mut self, other: &Range<T>) {
let relation = self.relation_to_range(other);
debug!("repair_after_coalesced_range: possibly repairing range {:?}", self);
debug!("repair_after_coalesced_range: relation of original range and coalesced range({:?}): {:?}",
other, relation);
match relation {
EntirelyBefore => { },
EntirelyAfter => { self.shift_by(-other.length().to_int().unwrap()); },
Coincides | ContainedBy => { self.reset(other.begin(), num::one()); },
Contains => { self.extend_by(-other.length().to_int().unwrap()); },
OverlapsBegin(overlap) => { self.extend_by(1 - overlap.to_int().unwrap()); },
OverlapsEnd(overlap) => {
let len = self.length() - overlap + num::one();
self.reset(other.begin(), len);
}
};
debug!("repair_after_coalesced_range: new range: ---- {:?}", self);
}
}
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