433 lines
14 KiB
Rust
433 lines
14 KiB
Rust
//! Types dealing with ranges of values
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extern mod extra;
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use std::cmp;
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use extra::time::Timespec;
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/// A trait that normalizes a range bound for a type
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pub trait Normalizable {
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/// Given a range bound, returns the normalized version of that bound. For
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/// discrete types such as i32, the normalized lower bound is always
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/// inclusive and the normalized upper bound is always exclusive. Other
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/// types, such as Timespec, have no normalization process so their
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/// implementation is a no-op.
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///
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/// The logic here should match the logic performed by the equivalent
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/// Postgres type.
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fn normalize<S: BoundSided>(bound: RangeBound<S, Self>)
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-> RangeBound<S, Self>;
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}
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macro_rules! bounded_normalizable(
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($t:ty) => (
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impl Normalizable for $t {
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fn normalize<S: BoundSided>(bound: RangeBound<S, $t>)
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-> RangeBound<S, $t> {
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match BoundSided::side(None::<S>) {
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Upper if bound.type_ == Inclusive => {
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assert!(bound.value != Bounded::max_value());
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RangeBound::new(bound.value + 1, Exclusive)
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}
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Lower if bound.type_ == Exclusive => {
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assert!(bound.value != Bounded::max_value());
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RangeBound::new(bound.value + 1, Inclusive)
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}
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_ => bound
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}
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}
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}
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)
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)
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bounded_normalizable!(i32)
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bounded_normalizable!(i64)
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impl Normalizable for Timespec {
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fn normalize<S: BoundSided>(bound: RangeBound<S, Timespec>)
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-> RangeBound<S, Timespec> {
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bound
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}
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}
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#[deriving(Eq)]
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enum BoundSide {
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Upper,
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Lower
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}
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trait BoundSided {
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// param is a hack to get around lack of hints for self type
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fn side(_: Option<Self>) -> BoundSide;
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}
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/// A tag type representing an upper bound
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#[deriving(Eq,Clone)]
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pub struct UpperBound;
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/// A tag type representing a lower bound
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#[deriving(Eq,Clone)]
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pub struct LowerBound;
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impl BoundSided for UpperBound {
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fn side(_: Option<UpperBound>) -> BoundSide {
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Upper
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}
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}
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impl BoundSided for LowerBound {
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fn side(_: Option<LowerBound>) -> BoundSide {
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Lower
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}
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}
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/// The type of a range bound
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#[deriving(Eq,Clone)]
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pub enum BoundType {
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/// The bound includes its value
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Inclusive,
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/// The bound excludes its value
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Exclusive
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}
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/// Represents a one-sided bound.
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///
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/// The side is determined by the `S` phantom parameter.
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#[deriving(Eq,Clone)]
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pub struct RangeBound<S, T> {
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/// The value of the bound
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value: T,
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/// The type of the bound
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type_: BoundType
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}
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impl<S: BoundSided, T: Ord> Ord for RangeBound<S, T> {
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fn lt(&self, other: &RangeBound<S, T>) -> bool {
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match (BoundSided::side(None::<S>), self.type_, other.type_) {
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(Upper, Exclusive, Inclusive)
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| (Lower, Inclusive, Exclusive) => self.value <= other.value,
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_ => self.value < other.value
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}
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}
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}
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impl<S: BoundSided, T: Ord> RangeBound<S, T> {
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/// Constructs a new range bound
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pub fn new(value: T, type_: BoundType) -> RangeBound<S, T> {
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RangeBound { value: value, type_: type_ }
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}
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/// Determines if a value lies within the range specified by this bound.
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pub fn in_bounds(&self, value: &T) -> bool {
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match (self.type_, BoundSided::side(None::<S>)) {
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(Inclusive, Upper) if value <= &self.value => true,
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(Exclusive, Upper) if value < &self.value => true,
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(Inclusive, Lower) if value >= &self.value => true,
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(Exclusive, Lower) if value > &self.value => true,
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_ => false
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}
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}
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}
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struct OptBound<'self, S, T>(&'self Option<RangeBound<S, T>>);
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impl<'self, S: BoundSided, T: Ord> Ord for OptBound<'self, S, T> {
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fn lt(&self, other: &OptBound<'self, S, T>) -> bool {
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match (**self, **other) {
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(&None, &None) => false,
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(&None, _) => BoundSided::side(None::<S>) == Lower,
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(_, &None) => BoundSided::side(None::<S>) == Upper,
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(&Some(ref a), &Some(ref b)) => a < b
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}
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}
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}
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/// Represents a range of values.
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#[deriving(Eq,Clone)]
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pub enum Range<T> {
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priv Empty,
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priv Normal(Option<RangeBound<LowerBound, T>>,
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Option<RangeBound<UpperBound, T>>)
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}
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impl<T: Ord+Normalizable> Range<T> {
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/// Creates a new range.
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///
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/// If a bound is `None`, the range is unbounded in that direction.
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pub fn new(lower: Option<RangeBound<LowerBound, T>>,
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upper: Option<RangeBound<UpperBound, T>>) -> Range<T> {
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let lower = lower.map(|bound| { Normalizable::normalize(bound) });
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let upper = upper.map(|bound| { Normalizable::normalize(bound) });
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match (&lower, &upper) {
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(&Some(ref lower), &Some(ref upper)) => {
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let empty = match (lower.type_, upper.type_) {
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(Inclusive, Inclusive) => lower.value > upper.value,
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_ => lower.value >= upper.value
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};
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if empty {
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return Empty;
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}
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}
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_ => {}
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}
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Normal(lower, upper)
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}
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/// Creates a new empty range.
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pub fn empty() -> Range<T> {
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Empty
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}
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/// Determines if this range is the empty range.
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pub fn is_empty(&self) -> bool {
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match *self {
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Empty => true,
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Normal(*) => false
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}
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}
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/// Returns the lower bound if it exists.
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pub fn lower<'a>(&'a self) -> &'a Option<RangeBound<LowerBound, T>> {
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match *self {
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Empty => &None,
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Normal(ref lower, _) => lower
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}
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}
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/// Returns the upper bound if it exists.
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pub fn upper<'a>(&'a self) -> &'a Option<RangeBound<UpperBound, T>> {
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match *self {
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Empty => &None,
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Normal(_, ref upper) => upper
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}
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}
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/// Determines if a value lies within this range.
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pub fn contains(&self, value: &T) -> bool {
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match *self {
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Empty => false,
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Normal(ref lower, ref upper) => {
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lower.as_ref().map_default(true, |b| { b.in_bounds(value) }) &&
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upper.as_ref().map_default(true, |b| { b.in_bounds(value) })
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}
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}
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}
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/// Determines if a range lies completely within this range.
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pub fn contains_range(&self, other: &Range<T>) -> bool {
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if other.is_empty() {
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return true;
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}
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if self.is_empty() {
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return false;
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}
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OptBound(self.lower()) <= OptBound(other.lower()) &&
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OptBound(self.upper()) >= OptBound(other.upper())
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}
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}
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impl<T: Ord+Normalizable+Clone> Range<T> {
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/// Returns the intersection of this range with another
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pub fn intersect(&self, other: &Range<T>) -> Range<T> {
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if self.is_empty() || other.is_empty() {
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return Range::empty();
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}
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let lower = cmp::max(OptBound(self.lower()), OptBound(other.lower()))
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.clone();
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let upper = cmp::min(OptBound(self.upper()), OptBound(other.upper()))
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.clone();
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Range::new(lower, upper)
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_range_bound_lower_lt() {
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fn check(val1: int, inc1: BoundType, val2: int, inc2: BoundType, expected: bool) {
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let a: RangeBound<LowerBound, int> = RangeBound::new(val1, inc1);
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let b: RangeBound<LowerBound, int> = RangeBound::new(val2, inc2);
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assert_eq!(expected, a < b);
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}
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check(1, Inclusive, 2, Exclusive, true);
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check(1, Exclusive, 2, Inclusive, true);
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check(1, Inclusive, 1, Exclusive, true);
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check(2, Inclusive, 1, Inclusive, false);
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check(2, Exclusive, 1, Exclusive, false);
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check(1, Exclusive, 1, Inclusive, false);
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check(1, Exclusive, 1, Exclusive, false);
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check(1, Inclusive, 1, Inclusive, false);
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}
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#[test]
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fn test_range_bound_upper_lt() {
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fn check(val1: int, inc1: BoundType, val2: int, inc2: BoundType, expected: bool) {
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let a: RangeBound<UpperBound, int> = RangeBound::new(val1, inc1);
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let b: RangeBound<UpperBound, int> = RangeBound::new(val2, inc2);
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assert_eq!(expected, a < b);
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}
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check(1, Inclusive, 2, Exclusive, true);
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check(1, Exclusive, 2, Exclusive, true);
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check(1, Exclusive, 1, Inclusive, true);
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check(2, Inclusive, 1, Inclusive, false);
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check(2, Exclusive, 1, Exclusive, false);
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check(1, Inclusive, 1, Exclusive, false);
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check(1, Inclusive, 1, Inclusive, false);
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check(1, Exclusive, 1, Exclusive, false);
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}
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#[test]
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fn test_range_bound_lower_in_bounds() {
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fn check(bound: int, inc: BoundType, val: int, expected: bool) {
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let b: RangeBound<LowerBound, int> = RangeBound::new(bound, inc);
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assert_eq!(expected, b.in_bounds(&val));
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}
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check(1, Inclusive, 1, true);
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check(1, Exclusive, 1, false);
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check(1, Inclusive, 2, true);
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check(1, Inclusive, 0, false);
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}
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#[test]
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fn test_range_bound_upper_in_bounds() {
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fn check(bound: int, inc: BoundType, val: int, expected: bool) {
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let b: RangeBound<UpperBound, int> = RangeBound::new(bound, inc);
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assert_eq!(expected, b.in_bounds(&val));
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}
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check(1, Inclusive, 1, true);
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check(1, Exclusive, 1, false);
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check(1, Inclusive, 2, false);
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check(1, Inclusive, 0, true);
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}
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#[test]
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fn test_range_contains() {
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let r = Range::new(Some(RangeBound::new(1i32, Inclusive)),
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Some(RangeBound::new(3i32, Inclusive)));
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assert!(!r.contains(&4));
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assert!(r.contains(&3));
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assert!(r.contains(&2));
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assert!(r.contains(&1));
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assert!(!r.contains(&0));
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let r = Range::new(Some(RangeBound::new(1i32, Exclusive)),
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Some(RangeBound::new(3i32, Exclusive)));
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assert!(!r.contains(&4));
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assert!(!r.contains(&3));
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assert!(r.contains(&2));
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assert!(!r.contains(&1));
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assert!(!r.contains(&0));
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let r = Range::new(None, Some(RangeBound::new(3i32, Inclusive)));
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assert!(!r.contains(&4));
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assert!(r.contains(&2));
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assert!(r.contains(&Bounded::min_value()));
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let r = Range::new(Some(RangeBound::new(1i32, Inclusive)), None);
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assert!(r.contains(&Bounded::max_value()));
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assert!(r.contains(&4));
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assert!(!r.contains(&0));
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let r = Range::new(None, None);
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assert!(r.contains(&Bounded::max_value()));
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assert!(r.contains(&0i32));
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assert!(r.contains(&Bounded::min_value()));
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}
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#[test]
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fn test_normalize_lower() {
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let r: RangeBound<LowerBound, i32> = RangeBound::new(10i32, Inclusive);
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assert_eq!(RangeBound::new(10i32, Inclusive), Normalizable::normalize(r));
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let r: RangeBound<LowerBound, i32> = RangeBound::new(10i32, Exclusive);
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assert_eq!(RangeBound::new(11i32, Inclusive), Normalizable::normalize(r));
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}
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#[test]
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fn test_normalize_upper() {
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let r: RangeBound<UpperBound, i32> = RangeBound::new(10i32, Inclusive);
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assert_eq!(RangeBound::new(11i32, Exclusive), Normalizable::normalize(r));
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let r: RangeBound<UpperBound, i32> = RangeBound::new(10i32, Exclusive);
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assert_eq!(RangeBound::new(10i32, Exclusive), Normalizable::normalize(r));
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}
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#[test]
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fn test_range_normalizes() {
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let r1 = Range::new(Some(RangeBound::new(10i32, Exclusive)),
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Some(RangeBound::new(15i32, Inclusive)));
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let r2 = Range::new(Some(RangeBound::new(11i32, Inclusive)),
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Some(RangeBound::new(16i32, Exclusive)));
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assert_eq!(r1, r2);
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}
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#[test]
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fn test_range_empty() {
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assert!(Range::new(Some(RangeBound::new(9i32, Exclusive)),
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Some(RangeBound::new(10i32, Exclusive))).is_empty());
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assert!(Range::new(Some(RangeBound::new(10i32, Inclusive)),
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Some(RangeBound::new(10i32, Exclusive))).is_empty());
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assert!(Range::new(Some(RangeBound::new(10i32, Exclusive)),
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Some(RangeBound::new(10i32, Inclusive))).is_empty());
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assert!(Range::new(Some(RangeBound::new(10i32, Inclusive)),
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Some(RangeBound::new(9i32, Inclusive))).is_empty());
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}
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#[test]
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fn test_intersection() {
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let r1 = Range::new(Some(RangeBound::new(10i32, Inclusive)),
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Some(RangeBound::new(15i32, Exclusive)));
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let r2 = Range::new(Some(RangeBound::new(20i32, Exclusive)),
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Some(RangeBound::new(25i32, Inclusive)));
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assert!(r1.intersect(&r2).is_empty());
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assert!(r2.intersect(&r1).is_empty());
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assert_eq!(r1, r1.intersect(&Range::new(None, None)));
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assert_eq!(r1, Range::new(None, None).intersect(&r1));
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let r2 = Range::new(Some(RangeBound::new(10i32, Exclusive)), None);
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let exp = Range::new(r2.lower().clone(), r1.upper().clone());
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assert_eq!(exp, r1.intersect(&r2));
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assert_eq!(exp, r2.intersect(&r1));
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let r2 = Range::new(None, Some(RangeBound::new(15i32, Inclusive)));
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assert_eq!(r1, r1.intersect(&r2));
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assert_eq!(r1, r2.intersect(&r1));
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let r2 = Range::new(Some(RangeBound::new(11i32, Inclusive)),
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Some(RangeBound::new(14i32, Exclusive)));
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assert_eq!(r2, r1.intersect(&r2));
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assert_eq!(r2, r2.intersect(&r1));
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}
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#[test]
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fn test_contains_range() {
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assert!(Range::<i32>::empty().contains_range(&Range::empty()));
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let r1 = Range::new(Some(RangeBound::new(10i32, Inclusive)),
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Some(RangeBound::new(15i32, Exclusive)));
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assert!(r1.contains_range(&r1));
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let r2 = Range::new(Some(RangeBound::new(10i32, Exclusive)),
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None);
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assert!(!r1.contains_range(&r2));
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assert!(!r2.contains_range(&r1));
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let r2 = Range::new(None,
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Some(RangeBound::new(15i32, Inclusive)));
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assert!(!r1.contains_range(&r2));
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assert!(r2.contains_range(&r1));
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}
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}
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