Adding coloring to help examples (nushell#1754)

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

@@ -43,10 +43,16 @@ impl WholeStreamCommand for Alias {
     }
 
     fn examples(&self) -> &[Example] {
-        &[Example {
-            description: "Some people prefer to write one letter instead of two",
-            example: "alias l [x] { ls $x }",
-        }]
+        &[
+            Example {
+                description: "An alias without parameters",
+                example: "alias say-hi [] { echo 'Hello!' }",
+            },
+            Example {
+                description: "An alias with a single parameter",
+                example: "alias l [x] { ls $x }",
+            },
+        ]
     }
 }
 

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

@@ -272,14 +272,19 @@ pub(crate) fn get_help(
 
     let examples = cmd.examples();
     if !examples.is_empty() {
-        long_desc.push_str("\nExamples:\n");
+        long_desc.push_str("\nExamples:");
     }
     for example in examples {
+        long_desc.push_str("\n");
         long_desc.push_str("  ");
         long_desc.push_str(example.description);
-        long_desc.push_str(&format!("\n  > {}\n", example.example));
+        let colored_example =
+            crate::shell::helper::Painter::paint_string(example.example, registry);
+        long_desc.push_str(&format!("\n  > {}\n", colored_example));
     }
 
+    long_desc.push_str("\n");
+
     help.push_back(ReturnSuccess::value(
         UntaggedValue::string(long_desc).into_value(Tag::from((0, cmd_name.len(), None))),
     ));

crates/nu-cli/src/shell/helper.rs

@@ -61,24 +61,7 @@ impl Highlighter for Helper {
     }
 
     fn highlight<'l>(&self, line: &'l str, _pos: usize) -> Cow<'l, str> {
-        let lite_block = nu_parser::lite_parse(line, 0);
-
-        match lite_block {
-            Err(_) => Cow::Borrowed(line),
-            Ok(lb) => {
-                let classified =
-                    nu_parser::classify_block(&lb, &self.context.registry().clone_box());
-
-                let shapes = nu_parser::shapes(&classified.block);
-                let mut painter = Painter::new(line);
-
-                for shape in shapes {
-                    painter.paint_shape(&shape);
-                }
-
-                Cow::Owned(painter.into_string())
-            }
-        }
+        Painter::paint_string(line, &self.context.registry().clone_box())
     }
 
     fn highlight_char(&self, _line: &str, _pos: usize) -> bool {
@@ -98,7 +81,7 @@ fn vec_tag<T>(input: Vec<Tagged<T>>) -> Option<Tag> {
     })
 }
 
-struct Painter {
+pub struct Painter {
     original: Vec<u8>,
     styles: Vec<Style>,
 }
@@ -113,6 +96,26 @@ impl Painter {
         }
     }
 
+    pub fn paint_string<'l>(line: &'l str, registry: &dyn SignatureRegistry) -> Cow<'l, str> {
+        let lite_block = nu_parser::lite_parse(line, 0);
+
+        match lite_block {
+            Err(_) => Cow::Borrowed(line),
+            Ok(lb) => {
+                let classified = nu_parser::classify_block(&lb, registry);
+
+                let shapes = nu_parser::shapes(&classified.block);
+                let mut painter = Painter::new(line);
+
+                for shape in shapes {
+                    painter.paint_shape(&shape);
+                }
+
+                Cow::Owned(painter.into_string())
+            }
+        }
+    }
+
     fn paint_shape(&mut self, shape: &Spanned<FlatShape>) {
         let style = match &shape.item {
             FlatShape::OpenDelimiter(_) => Color::White.normal(),