From 5c10684d6f6941d1243167702f7508018ee8e985 Mon Sep 17 00:00:00 2001
From: Nikolai Vazquez <hello@nikolaivazquez.com>
Date: Wed, 5 Jul 2023 00:42:14 -0400
Subject: [PATCH] api: add TryFrom impls for Regex

This enables builder APIs to take `T: TryInto<Regex>`, where `T` can be
a string or a preconstructed `Regex` instance.

Closes #1022
---
 CHANGELOG.md             |  2 ++
 regex-lite/src/string.rs | 18 ++++++++++++++++++
 src/regex/bytes.rs       | 20 +++++++++++++++++++-
 src/regex/string.rs      | 18 ++++++++++++++++++
 4 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1f5cd9887..25e7ecab9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,6 +40,8 @@ Anchored search APIs are now available in `regex-automata 0.3`.
 Add new `Captures::extract` method for easier capture group access.
 * [FEATURE #961](https://github.com/rust-lang/regex/issues/961):
 Add `regex-lite` crate with smaller binary sizes and faster compile times.
+* [FEATURE #1022](https://github.com/rust-lang/regex/pull/1022):
+Add `TryFrom` implementations for the `Regex` type.
 
 Performance improvements:
 
diff --git a/regex-lite/src/string.rs b/regex-lite/src/string.rs
index 358f7a0c7..acf6aa00a 100644
--- a/regex-lite/src/string.rs
+++ b/regex-lite/src/string.rs
@@ -117,6 +117,24 @@ impl core::str::FromStr for Regex {
     }
 }
 
+impl TryFrom<&str> for Regex {
+    type Error = Error;
+
+    /// Attempts to parse a string into a regular expression
+    fn try_from(s: &str) -> Result<Regex, Error> {
+        Regex::new(s)
+    }
+}
+
+impl TryFrom<String> for Regex {
+    type Error = Error;
+
+    /// Attempts to parse a string into a regular expression
+    fn try_from(s: String) -> Result<Regex, Error> {
+        Regex::new(&s)
+    }
+}
+
 /// Core regular expression methods.
 impl Regex {
     /// Compiles a regular expression. Once compiled, it can be used repeatedly
diff --git a/src/regex/bytes.rs b/src/regex/bytes.rs
index fc4238bcd..86437e1c2 100644
--- a/src/regex/bytes.rs
+++ b/src/regex/bytes.rs
@@ -1,4 +1,4 @@
-use alloc::{borrow::Cow, sync::Arc, vec::Vec};
+use alloc::{borrow::Cow, string::String, sync::Arc, vec::Vec};
 
 use regex_automata::{meta, util::captures, Input, PatternID};
 
@@ -124,6 +124,24 @@ impl core::str::FromStr for Regex {
     }
 }
 
+impl TryFrom<&str> for Regex {
+    type Error = Error;
+
+    /// Attempts to parse a string into a regular expression
+    fn try_from(s: &str) -> Result<Regex, Error> {
+        Regex::new(s)
+    }
+}
+
+impl TryFrom<String> for Regex {
+    type Error = Error;
+
+    /// Attempts to parse a string into a regular expression
+    fn try_from(s: String) -> Result<Regex, Error> {
+        Regex::new(&s)
+    }
+}
+
 /// Core regular expression methods.
 impl Regex {
     /// Compiles a regular expression. Once compiled, it can be used repeatedly
diff --git a/src/regex/string.rs b/src/regex/string.rs
index 438af7beb..e8d625655 100644
--- a/src/regex/string.rs
+++ b/src/regex/string.rs
@@ -126,6 +126,24 @@ impl core::str::FromStr for Regex {
     }
 }
 
+impl TryFrom<&str> for Regex {
+    type Error = Error;
+
+    /// Attempts to parse a string into a regular expression
+    fn try_from(s: &str) -> Result<Regex, Error> {
+        Regex::new(s)
+    }
+}
+
+impl TryFrom<String> for Regex {
+    type Error = Error;
+
+    /// Attempts to parse a string into a regular expression
+    fn try_from(s: String) -> Result<Regex, Error> {
+        Regex::new(&s)
+    }
+}
+
 /// Core regular expression methods.
 impl Regex {
     /// Compiles a regular expression. Once compiled, it can be used repeatedly