refactor: Extract our own display width

This added about 4 KiB to `.text` which makes sense since we duplicated
logic.

Cargo.toml

@@ -73,7 +73,7 @@ derive = ["clap_derive"]
 cargo = [] # Disable if you're not using Cargo, enables Cargo-env-var-dependent macros
 wrap_help = ["dep:terminal_size", "textwrap/terminal_size"]
 env = [] # Use environment variables during arg parsing
-unicode = ["textwrap/unicode-width", "dep:unicase"]  # Support for unicode characters in arguments and help messages
+unicode = ["textwrap/unicode-width", "dep:unicode-width", "dep:unicase"]  # Support for unicode characters in arguments and help messages
 perf = [] # Optimize for runtime performance
 
 # In-work features
@@ -95,6 +95,7 @@ atty = { version = "0.2",  optional = true }
 termcolor = { version = "1.1.1", optional = true }
 terminal_size = { version = "0.2.1", optional = true }
 backtrace = { version = "0.3", optional = true }
+unicode-width = { version = "0.1.9", optional = true }
 
 [dev-dependencies]
 trybuild = "1.0.18"
@@ -105,6 +106,7 @@ humantime = "2"
 snapbox = "0.2"
 shlex = "1.1.0"
 static_assertions = "1.1.0"
+unic-emoji-char = "0.9.0"
 
 [[example]]
 name = "demo"

src/builder/styled_str.rs

@@ -1,3 +1,5 @@
+use crate::output::display_width;
+
 /// Terminal-styling container
 #[derive(Clone, Default, Debug, PartialEq, Eq)]
 pub struct StyledStr {
@@ -37,6 +39,14 @@ impl StyledStr {
         }
     }
 
+    pub(crate) fn display_width(&self) -> usize {
+        let mut width = 0;
+        for (_, c) in &self.pieces {
+            width += display_width(c);
+        }
+        width
+    }
+
     /// HACK: Until call sites are updated to handle formatted text, extract the unformatted
     #[track_caller]
     pub(crate) fn unwrap_none(&self) -> &str {

src/output/help.rs

@@ -9,13 +9,11 @@ use crate::builder::PossibleValue;
 use crate::builder::Str;
 use crate::builder::StyledStr;
 use crate::builder::{render_arg_val, Arg, Command};
+use crate::output::display_width;
 use crate::output::Usage;
 use crate::util::FlatSet;
 use crate::ArgAction;
 
-// Third party
-use textwrap::core::display_width;
-
 /// `clap` Help Writer.
 ///
 /// Wraps a writer stream providing different methods to generate help for `clap` objects.
@@ -461,7 +459,7 @@ impl<'cmd, 'writer> Help<'cmd, 'writer> {
                     .expect("Only called with possible value");
                 let help_longest = possible_vals
                     .iter()
-                    .filter_map(|f| f.get_visible_help().map(|h| display_width(h.unwrap_none())))
+                    .filter_map(|f| f.get_visible_help().map(|h| h.display_width()))
                     .max()
                     .expect("Only called with possible value with help");
                 // should new line
@@ -532,7 +530,7 @@ impl<'cmd, 'writer> Help<'cmd, 'writer> {
         } else {
             // force_next_line
             let h = arg.get_help().unwrap_or_default();
-            let h_w = display_width(h.unwrap_none()) + display_width(spec_vals);
+            let h_w = h.display_width() + display_width(spec_vals);
             let taken = longest + 12;
             self.term_w >= taken
                 && (taken as f32 / self.term_w as f32) > 0.40
@@ -749,7 +747,7 @@ impl<'cmd, 'writer> Help<'cmd, 'writer> {
         } else {
             // force_next_line
             let h = cmd.get_about().unwrap_or_default();
-            let h_w = display_width(h.unwrap_none()) + display_width(spec_vals);
+            let h_w = h.display_width() + display_width(spec_vals);
             let taken = longest + 12;
             self.term_w >= taken
                 && (taken as f32 / self.term_w as f32) > 0.40
@@ -1094,6 +1092,7 @@ mod test {
     }
 
     #[test]
+    #[cfg(feature = "unicode")]
     fn display_width_handles_non_ascii() {
         // Popular Danish tongue-twister, the name of a fruit dessert.
         let text = "rødgrød med fløde";
@@ -1104,6 +1103,7 @@ mod test {
     }
 
     #[test]
+    #[cfg(feature = "unicode")]
     fn display_width_handles_emojis() {
         let text = "😂";
         // There is a single `char`...

src/output/mod.rs

@@ -1,7 +1,9 @@
 mod help;
+mod textwrap;
 mod usage;
 
 pub(crate) mod fmt;
 
 pub(crate) use self::help::Help;
+pub(crate) use self::textwrap::core::display_width;
 pub(crate) use self::usage::Usage;

src/output/textwrap/core.rs

@@ -0,0 +1,144 @@
+/// Compute the display width of `text`
+///
+/// # Examples
+///
+/// **Note:** When the `unicode` Cargo feature is disabled, all characters are presumed to take up
+/// 1 width.  With the feature enabled, function will correctly deal with [combining characters] in
+/// their decomposed form (see [Unicode equivalence]).
+///
+/// An example of a decomposed character is “é”, which can be decomposed into: “e” followed by a
+/// combining acute accent: “◌́”.  Without the `unicode` Cargo feature, every `char` has a width of
+/// 1. This includes the combining accent:
+///
+/// ## Emojis and CJK Characters
+///
+/// Characters such as emojis and [CJK characters] used in the
+/// Chinese, Japanese, and Korean langauges are seen as double-width,
+/// even if the `unicode-width` feature is disabled:
+///
+/// # Limitations
+///
+/// The displayed width of a string cannot always be computed from the
+/// string alone. This is because the width depends on the rendering
+/// engine used. This is particularly visible with [emoji modifier
+/// sequences] where a base emoji is modified with, e.g., skin tone or
+/// hair color modifiers. It is up to the rendering engine to detect
+/// this and to produce a suitable emoji.
+///
+/// A simple example is “❤️”, which consists of “❤” (U+2764: Black
+/// Heart Symbol) followed by U+FE0F (Variation Selector-16). By
+/// itself, “❤” is a black heart, but if you follow it with the
+/// variant selector, you may get a wider red heart.
+///
+/// A more complex example would be “👨‍🦰” which should depict a man
+/// with red hair. Here the computed width is too large — and the
+/// width differs depending on the use of the `unicode-width` feature:
+///
+/// This happens because the grapheme consists of three code points:
+/// “👨” (U+1F468: Man), Zero Width Joiner (U+200D), and “🦰”
+/// (U+1F9B0: Red Hair). You can see them above in the test. With
+/// `unicode-width` enabled, the ZWJ is correctly seen as having zero
+/// width, without it is counted as a double-width character.
+///
+/// ## Terminal Support
+///
+/// Modern browsers typically do a great job at combining characters
+/// as shown above, but terminals often struggle more. As an example,
+/// Gnome Terminal version 3.38.1, shows “❤️” as a big red heart, but
+/// shows "👨‍🦰" as “👨🦰”.
+///
+/// [combining characters]: https://en.wikipedia.org/wiki/Combining_character
+/// [Unicode equivalence]: https://en.wikipedia.org/wiki/Unicode_equivalence
+/// [CJK characters]: https://en.wikipedia.org/wiki/CJK_characters
+/// [emoji modifier sequences]: https://unicode.org/emoji/charts/full-emoji-modifiers.html
+pub(crate) fn display_width(text: &str) -> usize {
+    let mut width = 0;
+    for ch in text.chars() {
+        width += ch_width(ch);
+    }
+    width
+}
+
+#[cfg(feature = "unicode")]
+fn ch_width(ch: char) -> usize {
+    unicode_width::UnicodeWidthChar::width(ch).unwrap_or(0)
+}
+
+#[cfg(not(feature = "unicode"))]
+fn ch_width(_: char) -> usize {
+    1
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[cfg(feature = "unicode")]
+    use unicode_width::UnicodeWidthChar;
+
+    #[test]
+    fn emojis_have_correct_width() {
+        use unic_emoji_char::is_emoji;
+
+        // Emojis in the Basic Latin (ASCII) and Latin-1 Supplement
+        // blocks all have a width of 1 column. This includes
+        // characters such as '#' and '©'.
+        for ch in '\u{1}'..'\u{FF}' {
+            if is_emoji(ch) {
+                let desc = format!("{:?} U+{:04X}", ch, ch as u32);
+
+                #[cfg(feature = "unicode")]
+                assert_eq!(ch.width().unwrap(), 1, "char: {}", desc);
+
+                #[cfg(not(feature = "unicode"))]
+                assert_eq!(ch_width(ch), 1, "char: {}", desc);
+            }
+        }
+
+        // Emojis in the remaining blocks of the Basic Multilingual
+        // Plane (BMP), in the Supplementary Multilingual Plane (SMP),
+        // and in the Supplementary Ideographic Plane (SIP), are all 1
+        // or 2 columns wide when unicode-width is used, and always 2
+        // columns wide otherwise. This includes all of our favorite
+        // emojis such as 😊.
+        for ch in '\u{FF}'..'\u{2FFFF}' {
+            if is_emoji(ch) {
+                let desc = format!("{:?} U+{:04X}", ch, ch as u32);
+
+                #[cfg(feature = "unicode")]
+                assert!(ch.width().unwrap() <= 2, "char: {}", desc);
+
+                #[cfg(not(feature = "unicode"))]
+                assert_eq!(ch_width(ch), 1, "char: {}", desc);
+            }
+        }
+
+        // The remaining planes contain almost no assigned code points
+        // and thus also no emojis.
+    }
+
+    #[test]
+    #[cfg(feature = "unicode")]
+    fn display_width_works() {
+        assert_eq!("Café Plain".len(), 11); // “é” is two bytes
+        assert_eq!(display_width("Café Plain"), 10);
+    }
+
+    #[test]
+    #[cfg(feature = "unicode")]
+    fn display_width_narrow_emojis() {
+        assert_eq!(display_width("⁉"), 1);
+    }
+
+    #[test]
+    #[cfg(feature = "unicode")]
+    fn display_width_narrow_emojis_variant_selector() {
+        assert_eq!(display_width("⁉\u{fe0f}"), 1);
+    }
+
+    #[test]
+    #[cfg(feature = "unicode")]
+    fn display_width_emojis() {
+        assert_eq!(display_width("😂😭🥺🤣✨😍🙏🥰😊🔥"), 20);
+    }
+}

src/output/textwrap/mod.rs

@@ -0,0 +1 @@
+pub(crate) mod core;