add NO_COLOR support — https://no-color.org/

src/color.rs

@@ -11,12 +11,16 @@ use std::fmt;
 ///   let x = color_string!("Hyperlink-ish", Blue, Underline);
 macro_rules! color_string {
     ($s:expr, $( $color:ident ),+) => {{
-        let mut out = String::from("\x1b[");
-        $( out.push_str(crate::color::$color::code()); out.push_str(";"); )+
-        out.push('m');
-        out.push_str(&$s);
-        out.push_str(crate::color::Reset.as_ref());
-        out.replace(";m", "m")
+        if *crate::NO_COLOR {
+            $s.to_string()
+        } else {
+            let mut out = String::from("\x1b[");
+            $( out.push_str(crate::color::$color::code()); out.push_str(";"); )+
+            out.push('m');
+            out.push_str(&$s);
+            out.push_str(crate::color::Reset.as_ref());
+            out.replace(";m", "m")
+        }
     }};
 }
 
@@ -29,7 +33,11 @@ macro_rules! color_string {
 ///   o.push_str(color!(Reset));
 macro_rules! color {
     ($color:ident) => {
-        crate::color::$color.as_ref()
+        if *crate::NO_COLOR {
+            ""
+        } else {
+            crate::color::$color.as_ref()
+        }
     };
 }
 

src/lib.rs

@@ -77,3 +77,8 @@ pub const TOR_SUPPORT: bool = true;
 #[cfg(not(feature = "tor"))]
 /// Whether we compiled with Tor support.
 pub const TOR_SUPPORT: bool = false;
+
+lazy_static! {
+    /// Is the NO_COLOR env variable set? https://no-color.org/
+    pub static ref NO_COLOR: bool = std::env::var("NO_COLOR").is_ok();
+}