From 19be44515ad5760b52acbca501cb0d834797491e Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Wed, 13 Jan 2021 20:08:43 +0300
Subject: [PATCH] Allow binary-searching an array of disjoint ranges

---
 lib/text-size/CHANGELOG.md |  6 ++++-
 lib/text-size/Cargo.toml   |  2 +-
 lib/text-size/src/range.rs | 46 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/lib/text-size/CHANGELOG.md b/lib/text-size/CHANGELOG.md
index 2eb012a6d9..0167599e55 100644
--- a/lib/text-size/CHANGELOG.md
+++ b/lib/text-size/CHANGELOG.md
@@ -1,8 +1,12 @@
 # Changelog
 
+## 1.1.0
+
+* add `TextRange::ordering` method
+
 ## 1.0.0 :tada:
 
-* the carate is renmaed to `text-size` from `text_unit`
+* the carate is renamed to `text-size` from `text_unit`
 
 Transition table:
 - `TextUnit::of_char(c)`                ⟹ `TextSize::of(c)`
diff --git a/lib/text-size/Cargo.toml b/lib/text-size/Cargo.toml
index 010e3bb4c6..19c5a92670 100644
--- a/lib/text-size/Cargo.toml
+++ b/lib/text-size/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "text-size"
-version = "1.0.0"
+version = "1.1.0"
 edition = "2018"
 
 authors = [
diff --git a/lib/text-size/src/range.rs b/lib/text-size/src/range.rs
index fcf286d62e..4a98deec56 100644
--- a/lib/text-size/src/range.rs
+++ b/lib/text-size/src/range.rs
@@ -1,3 +1,5 @@
+use cmp::Ordering;
+
 use {
     crate::TextSize,
     std::{
@@ -294,6 +296,50 @@ impl TextRange {
             end: self.end.checked_sub(offset)?,
         })
     }
+
+    /// Relative order of the two ranges (overlapping ranges are considered
+    /// equal).
+    ///
+    ///
+    /// This is useful when, for example, binary searching an array of disjoint
+    /// ranges.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use text_size::*;
+    /// # use std::cmp::Ordering;
+    ///
+    /// let a = TextRange::new(0.into(), 3.into());
+    /// let b = TextRange::new(4.into(), 5.into());
+    /// assert_eq!(a.ordering(b), Ordering::Less);
+    ///
+    /// let a = TextRange::new(0.into(), 3.into());
+    /// let b = TextRange::new(3.into(), 5.into());
+    /// assert_eq!(a.ordering(b), Ordering::Less);
+    ///
+    /// let a = TextRange::new(0.into(), 3.into());
+    /// let b = TextRange::new(2.into(), 5.into());
+    /// assert_eq!(a.ordering(b), Ordering::Equal);
+    ///
+    /// let a = TextRange::new(0.into(), 3.into());
+    /// let b = TextRange::new(2.into(), 2.into());
+    /// assert_eq!(a.ordering(b), Ordering::Equal);
+    ///
+    /// let a = TextRange::new(2.into(), 3.into());
+    /// let b = TextRange::new(2.into(), 2.into());
+    /// assert_eq!(a.ordering(b), Ordering::Greater);
+    /// ```
+    #[inline]
+    pub fn ordering(self, other: TextRange) -> Ordering {
+        if self.end() <= other.start() {
+            Ordering::Less
+        } else if other.end() <= self.start() {
+            Ordering::Greater
+        } else {
+            Ordering::Equal
+        }
+    }
 }
 
 impl Index<TextRange> for str {