Handling of numbered markdown lists.

Fixes issue rust-lang#5416

src/comment.rs

@@ -432,7 +432,9 @@ impl CodeBlockAttribute {
 
 /// Block that is formatted as an item.
 ///
-/// An item starts with either a star `*` a dash `-` or a greater-than `>`.
+/// An item starts with either a star `*`, a dash `-`, a greater-than `>`,
+/// a letter `a.` or `a)`, or a number `123.` or `123)`.
+///
 /// Different level of indentation are handled by shrinking the shape accordingly.
 struct ItemizedBlock {
     /// the lines that are identified as part of an itemized block
@@ -446,36 +448,53 @@ struct ItemizedBlock {
 }
 
 impl ItemizedBlock {
-    /// Returns `true` if the line is formatted as an item
-    fn is_itemized_line(line: &str) -> bool {
-        let trimmed = line.trim_start();
-        trimmed.starts_with("* ") || trimmed.starts_with("- ") || trimmed.starts_with("> ")
-    }
-
-    /// Creates a new ItemizedBlock described with the given line.
-    /// The `is_itemized_line` needs to be called first.
-    fn new(line: &str) -> ItemizedBlock {
-        let space_to_sigil = line.chars().take_while(|c| c.is_whitespace()).count();
-        // +2 = '* ', which will add the appropriate amount of whitespace to keep itemized
-        // content formatted correctly.
-        let mut indent = space_to_sigil + 2;
-        let mut line_start = " ".repeat(indent);
-
-        // Markdown blockquote start with a "> "
-        if line.trim_start().starts_with(">") {
-            // remove the original +2 indent because there might be multiple nested block quotes
-            // and it's easier to reason about the final indent by just taking the length
-            // of th new line_start. We update the indent because it effects the max width
-            // of each formatted line.
-            line_start = itemized_block_quote_start(line, line_start, 2);
-            indent = line_start.len();
+    /// Returns the sigil's (e.g. "- ", "* ", or "1. ") length or None of there is no sigil.
+    fn get_sigil_length(trimmed: &str) -> Option<usize> {
+        if trimmed.starts_with("* ") || trimmed.starts_with("- ") || trimmed.starts_with("> ") {
+            return Some(2);
         }
-        ItemizedBlock {
-            lines: vec![line[indent..].to_string()],
-            indent,
-            opener: line[..indent].to_string(),
-            line_start,
+
+        for suffix in [". ", ") "] {
+            if let Some((prefix, _)) = trimmed.split_once(suffix) {
+                for prefix_predicate in [
+                    char::is_ascii_digit,
+                    char::is_ascii_lowercase,
+                    char::is_ascii_uppercase,
+                ] {
+                    if prefix.chars().all(|c| prefix_predicate(&c)) {
+                        return Some(prefix.len() + suffix.len());
+                    }
+                }
+            }
         }
+
+        None
+    }
+
+    /// Creates a new ItemizedBlock described with the given `line`
+    /// or None if `line` doesn't start an item.
+    fn new(line: &str) -> Option<ItemizedBlock> {
+        ItemizedBlock::get_sigil_length(line.trim_start()).map(|sigil_length| {
+            let space_to_sigil = line.chars().take_while(|c| c.is_whitespace()).count();
+            let mut indent = space_to_sigil + sigil_length;
+            let mut line_start = " ".repeat(indent);
+
+            // Markdown blockquote start with a "> "
+            if line.trim_start().starts_with(">") {
+                // remove the original +2 indent because there might be multiple nested block quotes
+                // and it's easier to reason about the final indent by just taking the length
+                // of the new line_start. We update the indent because it effects the max width
+                // of each formatted line.
+                line_start = itemized_block_quote_start(line, line_start, 2);
+                indent = line_start.len();
+            }
+            ItemizedBlock {
+                lines: vec![line[indent..].to_string()],
+                indent,
+                opener: line[..indent].to_string(),
+                line_start,
+            }
+        })
     }
 
     /// Returns a `StringFormat` used for formatting the content of an item.
@@ -494,7 +513,7 @@ impl ItemizedBlock {
     /// Returns `true` if the line is part of the current itemized block.
     /// If it is, then it is added to the internal lines list.
     fn add_line(&mut self, line: &str) -> bool {
-        if !ItemizedBlock::is_itemized_line(line)
+        if ItemizedBlock::get_sigil_length(line.trim_start()).is_none()
             && self.indent <= line.chars().take_while(|c| c.is_whitespace()).count()
         {
             self.lines.push(line.to_string());
@@ -765,10 +784,11 @@ impl<'a> CommentRewrite<'a> {
         self.item_block = None;
         if let Some(stripped) = line.strip_prefix("```") {
             self.code_block_attr = Some(CodeBlockAttribute::new(stripped))
-        } else if self.fmt.config.wrap_comments() && ItemizedBlock::is_itemized_line(line) {
-            let ib = ItemizedBlock::new(line);
-            self.item_block = Some(ib);
-            return false;
+        } else if self.fmt.config.wrap_comments() {
+            if let Some(ib) = ItemizedBlock::new(line) {
+                self.item_block = Some(ib);
+                return false;
+            }
         }
 
         if self.result == self.opener {
@@ -2004,4 +2024,49 @@ fn main() {
 "#;
         assert_eq!(s, filter_normal_code(s_with_comment));
     }
+
+    #[test]
+    fn test_itemized_block_first_line_handling() {
+        fn run_test(
+            test_input: &str,
+            expected_line: &str,
+            expected_indent: usize,
+            expected_opener: &str,
+            expected_line_start: &str,
+        ) {
+            let block = ItemizedBlock::new(test_input).unwrap();
+            assert_eq!(1, block.lines.len(), "test_input: {:?}", test_input);
+            assert_eq!(
+                expected_line, &block.lines[0],
+                "test_input: {:?}",
+                test_input
+            );
+            assert_eq!(
+                expected_indent, block.indent,
+                "test_input: {:?}",
+                test_input
+            );
+            assert_eq!(
+                expected_opener, &block.opener,
+                "test_input: {:?}",
+                test_input
+            );
+            assert_eq!(
+                expected_line_start, &block.line_start,
+                "test_input: {:?}",
+                test_input
+            );
+        }
+
+        run_test("- foo", "foo", 2, "- ", "  ");
+        run_test("* foo", "foo", 2, "* ", "  ");
+        run_test("> foo", "foo", 2, "> ", "> ");
+
+        run_test("1. foo", "foo", 3, "1. ", "   ");
+        run_test("a) foo", "foo", 3, "a) ", "   ");
+        run_test("A) foo", "foo", 3, "A) ", "   ");
+
+        run_test("123. foo", "foo", 5, "123. ", "     ");
+        run_test("    - foo", "foo", 6, "    - ", "      ");
+    }
 }

tests/source/itemized-blocks/no_wrap.rs

@@ -13,6 +13,14 @@
 //! - when the log level is info, the level name is green and the rest of the line is white
 //! - when the log level is debug, the whole line is white
 //! - when the log level is trace, the whole line is gray ("bright black")
+//!
+//! This is a numbered list:
+//! 1. Long long long long long long long long long long long long long long long long long line
+//! 2. Another very long long long long long long long long long long long long long long long line
+//! 3. Nested list
+//!    A. foo
+//!    B. bar
+//! 4. Last item
 
 /// All the parameters ***except for `from_theater`*** should be inserted as sent by the remote
 /// theater, i.e., as passed to [`Theater::send`] on the remote actor:

tests/source/itemized-blocks/wrap.rs

@@ -14,6 +14,14 @@
 //! - when the log level is info, the level name is green and the rest of the line is white
 //! - when the log level is debug, the whole line is white
 //! - when the log level is trace, the whole line is gray ("bright black")
+//!
+//! This is a numbered list:
+//! 1. Long long long long long long long long long long long long long long long long long line
+//! 2. Another very long long long long long long long long long long long long long long long line
+//! 3. Nested list
+//!    A. foo
+//!    B. bar
+//! 4. Last item
 
 // This example shows how to configure fern to output really nicely colored logs
 // - when the log level is error, the whole line is red

tests/target/itemized-blocks/no_wrap.rs

@@ -13,6 +13,14 @@
 //! - when the log level is info, the level name is green and the rest of the line is white
 //! - when the log level is debug, the whole line is white
 //! - when the log level is trace, the whole line is gray ("bright black")
+//!
+//! This is a numbered list:
+//! 1. Long long long long long long long long long long long long long long long long long line
+//! 2. Another very long long long long long long long long long long long long long long long line
+//! 3. Nested list
+//!    A. foo
+//!    B. bar
+//! 4. Last item
 
 /// All the parameters ***except for `from_theater`*** should be inserted as sent by the remote
 /// theater, i.e., as passed to [`Theater::send`] on the remote actor:

tests/target/itemized-blocks/wrap.rs

@@ -23,6 +23,18 @@
 //!   is white
 //! - when the log level is trace, the whole line
 //!   is gray ("bright black")
+//!
+//! This is a numbered list:
+//! 1. Long long long long long long long long
+//!    long long long long long long long long
+//!    long line
+//! 2. Another very long long long long long long
+//!    long long long long long long long long
+//!    long line
+//! 3. Nested list
+//!    A. foo
+//!    B. bar
+//! 4. Last item
 
 // This example shows how to configure fern to
 // output really nicely colored logs