add unicode to char command to print any unicode character (#2709)

* parsing unicode literal strings into chars

* refactored code to use -u option

* nudge ci

crates/nu-cli/src/commands/char_.rs

@@ -9,6 +9,7 @@ pub struct Char;
 #[derive(Deserialize)]
 struct CharArgs {
     name: Tagged<String>,
+    unicode: bool,
 }
 
 #[async_trait]
@@ -18,11 +19,13 @@ impl WholeStreamCommand for Char {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("ansi").required(
+        Signature::build("ansi")
+            .required(
                 "character",
                 SyntaxShape::Any,
                 "the name of the character to output",
             )
+            .switch("unicode", "unicode string i.e. 1f378", Some('u'))
     }
 
     fn usage(&self) -> &str {
@@ -45,6 +48,11 @@ impl WholeStreamCommand for Char {
                     UntaggedValue::string("\u{2261}").into(),
                 ]),
             },
+            Example {
+                description: "Output unicode character",
+                example: r#"char -u 1f378"#,
+                result: Some(vec![Value::from("\u{1f378}")]),
+            },
         ]
     }
 
@@ -53,23 +61,43 @@ impl WholeStreamCommand for Char {
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        let (CharArgs { name }, _) = args.process(&registry).await?;
+        let (CharArgs { name, unicode }, _) = args.process(&registry).await?;
 
+        if unicode {
+            let decoded_char = string_to_unicode_char(&name.item);
+            if let Some(output) = decoded_char {
+                Ok(OutputStream::one(ReturnSuccess::value(
+                    UntaggedValue::string(output).into_value(name.tag()),
+                )))
+            } else {
+                Err(ShellError::labeled_error(
+                    "error decoding unicode character",
+                    "error decoding unicode character",
+                    name.tag(),
+                ))
+            }
+        } else {
             let special_character = str_to_character(&name.item);
-
             if let Some(output) = special_character {
                 Ok(OutputStream::one(ReturnSuccess::value(
                     UntaggedValue::string(output).into_value(name.tag()),
                 )))
             } else {
                 Err(ShellError::labeled_error(
-                "Unknown character",
+                    "error finding named character",
-                "unknown character",
+                    "error finding named character",
                     name.tag(),
                 ))
             }
         }
     }
+}
+
+fn string_to_unicode_char(s: &str) -> Option<char> {
+    u32::from_str_radix(s, 16)
+        .ok()
+        .and_then(std::char::from_u32)
+}
 
 fn str_to_character(s: &str) -> Option<String> {
     match s {