1 files changed, 177 insertions, 0 deletions
diff --git a/vendor/github.com/golang/geo/r1/interval.go b/vendor/github.com/golang/geo/r1/interval.go
new file mode 100644
index 000000000..48ea51982
--- /dev/null
+++ b/vendor/github.com/golang/geo/r1/interval.go
@@ -0,0 +1,177 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package r1
+
+import (
+	"fmt"
+	"math"
+)
+
+// Interval represents a closed interval on ℝ.
+// Zero-length intervals (where Lo == Hi) represent single points.
+// If Lo > Hi then the interval is empty.
+type Interval struct {
+	Lo, Hi float64
+}
+
+// EmptyInterval returns an empty interval.
+func EmptyInterval() Interval { return Interval{1, 0} }
+
+// IntervalFromPoint returns an interval representing a single point.
+func IntervalFromPoint(p float64) Interval { return Interval{p, p} }
+
+// IsEmpty reports whether the interval is empty.
+func (i Interval) IsEmpty() bool { return i.Lo > i.Hi }
+
+// Equal returns true iff the interval contains the same points as oi.
+func (i Interval) Equal(oi Interval) bool {
+	return i == oi || i.IsEmpty() && oi.IsEmpty()
+}
+
+// Center returns the midpoint of the interval.
+// It is undefined for empty intervals.
+func (i Interval) Center() float64 { return 0.5 * (i.Lo + i.Hi) }
+
+// Length returns the length of the interval.
+// The length of an empty interval is negative.
+func (i Interval) Length() float64 { return i.Hi - i.Lo }
+
+// Contains returns true iff the interval contains p.
+func (i Interval) Contains(p float64) bool { return i.Lo <= p && p <= i.Hi }
+
+// ContainsInterval returns true iff the interval contains oi.
+func (i Interval) ContainsInterval(oi Interval) bool {
+	if oi.IsEmpty() {
+		return true
+	}
+	return i.Lo <= oi.Lo && oi.Hi <= i.Hi
+}
+
+// InteriorContains returns true iff the interval strictly contains p.
+func (i Interval) InteriorContains(p float64) bool {
+	return i.Lo < p && p < i.Hi
+}
+
+// InteriorContainsInterval returns true iff the interval strictly contains oi.
+func (i Interval) InteriorContainsInterval(oi Interval) bool {
+	if oi.IsEmpty() {
+		return true
+	}
+	return i.Lo < oi.Lo && oi.Hi < i.Hi
+}
+
+// Intersects returns true iff the interval contains any points in common with oi.
+func (i Interval) Intersects(oi Interval) bool {
+	if i.Lo <= oi.Lo {
+		return oi.Lo <= i.Hi && oi.Lo <= oi.Hi // oi.Lo ∈ i and oi is not empty
+	}
+	return i.Lo <= oi.Hi && i.Lo <= i.Hi // i.Lo ∈ oi and i is not empty
+}
+
+// InteriorIntersects returns true iff the interior of the interval contains any points in common with oi, including the latter's boundary.
+func (i Interval) InteriorIntersects(oi Interval) bool {
+	return oi.Lo < i.Hi && i.Lo < oi.Hi && i.Lo < i.Hi && oi.Lo <= oi.Hi
+}
+
+// Intersection returns the interval containing all points common to i and j.
+func (i Interval) Intersection(j Interval) Interval {
+	// Empty intervals do not need to be special-cased.
+	return Interval{
+		Lo: math.Max(i.Lo, j.Lo),
+		Hi: math.Min(i.Hi, j.Hi),
+	}
+}
+
+// AddPoint returns the interval expanded so that it contains the given point.
+func (i Interval) AddPoint(p float64) Interval {
+	if i.IsEmpty() {
+		return Interval{p, p}
+	}
+	if p < i.Lo {
+		return Interval{p, i.Hi}
+	}
+	if p > i.Hi {
+		return Interval{i.Lo, p}
+	}
+	return i
+}
+
+// ClampPoint returns the closest point in the interval to the given point "p".
+// The interval must be non-empty.
+func (i Interval) ClampPoint(p float64) float64 {
+	return math.Max(i.Lo, math.Min(i.Hi, p))
+}
+
+// Expanded returns an interval that has been expanded on each side by margin.
+// If margin is negative, then the function shrinks the interval on
+// each side by margin instead. The resulting interval may be empty. Any
+// expansion of an empty interval remains empty.
+func (i Interval) Expanded(margin float64) Interval {
+	if i.IsEmpty() {
+		return i
+	}
+	return Interval{i.Lo - margin, i.Hi + margin}
+}
+
+// Union returns the smallest interval that contains this interval and the given interval.
+func (i Interval) Union(other Interval) Interval {
+	if i.IsEmpty() {
+		return other
+	}
+	if other.IsEmpty() {
+		return i
+	}
+	return Interval{math.Min(i.Lo, other.Lo), math.Max(i.Hi, other.Hi)}
+}
+
+func (i Interval) String() string { return fmt.Sprintf("[%.7f, %.7f]", i.Lo, i.Hi) }
+
+const (
+	// epsilon is a small number that represents a reasonable level of noise between two
+	// values that can be considered to be equal.
+	epsilon = 1e-15
+	// dblEpsilon is a smaller number for values that require more precision.
+	// This is the C++ DBL_EPSILON equivalent.
+	dblEpsilon = 2.220446049250313e-16
+)
+
+// ApproxEqual reports whether the interval can be transformed into the
+// given interval by moving each endpoint a small distance.
+// The empty interval is considered to be positioned arbitrarily on the
+// real line, so any interval with a small enough length will match
+// the empty interval.
+func (i Interval) ApproxEqual(other Interval) bool {
+	if i.IsEmpty() {
+		return other.Length() <= 2*epsilon
+	}
+	if other.IsEmpty() {
+		return i.Length() <= 2*epsilon
+	}
+	return math.Abs(other.Lo-i.Lo) <= epsilon &&
+		math.Abs(other.Hi-i.Hi) <= epsilon
+}
+
+// DirectedHausdorffDistance returns the Hausdorff distance to the given interval. For two
+// intervals x and y, this distance is defined as
+//     h(x, y) = max_{p in x} min_{q in y} d(p, q).
+func (i Interval) DirectedHausdorffDistance(other Interval) float64 {
+	if i.IsEmpty() {
+		return 0
+	}
+	if other.IsEmpty() {
+		return math.Inf(1)
+	}
+	return math.Max(0, math.Max(i.Hi-other.Hi, other.Lo-i.Lo))
+}