Add usage_column and usage_width

src/lib.rs

@@ -131,6 +131,8 @@ pub struct Options {
     grps: Vec<OptGroup>,
     parsing_style: ParsingStyle,
     long_only: bool,
+    usage_column: usize,
+    usage_width: usize,
 }
 
 impl Default for Options {
@@ -146,6 +148,8 @@ impl Options {
             grps: Vec::new(),
             parsing_style: ParsingStyle::FloatingFrees,
             long_only: false,
+            usage_column: 24,
+            usage_width: 54,
         }
     }
 
@@ -604,7 +608,7 @@ impl Options {
 
     /// Derive usage items from a set of options.
     fn usage_items<'a>(&'a self) -> Box<dyn Iterator<Item = String> + 'a> {
-        let desc_sep = format!("\n{}", repeat(" ").take(24).collect::<String>());
+        let desc_sep = format!("\n{}", repeat(" ").take(self.usage_column).collect::<String>());
 
         let any_short = self.grps.iter().any(|optref| !optref.short_name.is_empty());
 
@@ -664,22 +668,44 @@ impl Options {
             }
 
             let rowlen = row.width();
-            if rowlen < 24 {
-                for _ in 0..24 - rowlen {
+            if rowlen < self.usage_column {
+                for _ in 0..self.usage_column - rowlen {
                     row.push(' ');
                 }
             } else {
                 row.push_str(&desc_sep)
             }
 
-            let desc_rows = each_split_within(&desc, 54);
+            let desc_rows = each_split_within(&desc, self.usage_width);
             row.push_str(&desc_rows.join(&desc_sep));
 
             row
         });
 
         Box::new(rows)
     }
+
+    /// Get the display column of usage
+    pub fn usage_column(&self) -> usize {
+        self.usage_column.clone()
+    }
+
+    /// Set the display column of usage
+    pub fn set_usage_column(&mut self, column: usize) -> &mut Options {
+        self.usage_column = column;
+        self
+    }
+
+    /// Get the display width of usage
+    pub fn usage_width(&self) -> usize {
+        self.usage_width.clone()
+    }
+
+    /// Set the display width of usage
+    pub fn set_usage_width(&mut self, width: usize) -> &mut Options {
+        self.usage_width = width;
+        self
+    }
 }
 
 fn validate_names(short_name: &str, long_name: &str) {

src/tests/mod.rs

@@ -921,6 +921,41 @@ Options:
     assert!(usage == expected)
 }
 
+#[test]
+fn test_usage_description_newline_handling_custom_width() {
+    let mut opts = Options::new();
+    opts.set_usage_width(30);
+    opts.optflag(
+        "k",
+        "k\u{2013}w\u{2013}",
+        "The word kiwi is normally spelled with two i's",
+    );
+    opts.optflag(
+        "a",
+        "apple",
+        "This description forces a new line.\n Here is a premature\n\
+         newline",
+    );
+
+    let expected = "Usage: fruits
+
+Options:
+    -k, --k–w–          The word kiwi is normally
+                        spelled with two i's
+    -a, --apple         This description forces a new
+                        line.
+                        Here is a premature
+                        newline
+";
+
+    let usage = opts.usage("Usage: fruits");
+
+    debug!("expected: <<{}>>", expected);
+    debug!("generated: <<{}>>", usage);
+    assert!(usage == expected)
+}
+
+
 #[test]
 fn test_usage_description_newline_handling() {
     let mut opts = Options::new();
@@ -952,6 +987,41 @@ Options:
     assert!(usage == expected)
 }
 
+
+#[test]
+fn test_usage_description_newline_handling_custom_column() {
+    let mut opts = Options::new();
+    opts.set_usage_column(10);
+    opts.optflag(
+        "k",
+        "k\u{2013}w\u{2013}",
+        "The word kiwi is normally spelled with two i's",
+    );
+    opts.optflag(
+        "a",
+        "apple",
+        "This description forces a new line.\n Here is a premature\n\
+         newline",
+    );
+
+    let expected = "Usage: fruits
+
+Options:
+    -k, --k–w–\u{0020}
+          The word kiwi is normally spelled with two i's
+    -a, --apple\u{0020}
+          This description forces a new line.
+          Here is a premature
+          newline
+";
+
+    let usage = opts.usage("Usage: fruits");
+
+    debug!("expected: <<{}>>", expected);
+    debug!("generated: <<{}>>", usage);
+    assert!(usage == expected)
+}
+
 #[test]
 fn test_usage_multiwidth() {
     let mut opts = Options::new();