Add simple line-wrapping for file extensions.

src/main.rs

@@ -572,9 +572,30 @@ fn run() -> Result<()> {
                     .max()
                     .unwrap_or(32); // Fallback width if they have no language definitions.
 
+                let separator = " | ";
                 for lang in languages {
-                    print!("{:width$} | ", lang.name, width = longest);
-                    println!("{}", lang.file_extensions.join(", "));
+                    print!("{:width$}{}", lang.name, separator, width = longest);
+
+                    // Line-wrapping for the possible file extension overflow.
+                    let desired_width = 48;
+                    // Number of characters on this line so far, wrap before `desired_width`
+                    let mut num_chars = 0;
+
+                    let mut extension = lang.file_extensions.iter().peekable();
+                    while let Some(word) = extension.next() {
+                        // If we can't fit this word in, then create a line break and align it in.
+                        if word.len() + num_chars >= desired_width {
+                            num_chars = 0;
+                            print!("\n{:width$}{}", "", separator, width = longest);
+                        }
+
+                        num_chars += word.len();
+                        print!("{}", word);
+                        if extension.peek().is_some() {
+                            print!(", ");
+                        }
+                    }
+                    println!();
                 }
 
                 return Ok(());