Convert Align and Placeholder into enums

Also move number and style logic out of `format_and_paint_line_numbers()`
and into a separate `linenumbers_and_styles()` function.

1 files changed, 56 insertions, 10 deletions

diff --git a/src/format.rs b/src/format.rs
index 0b77e699..57a39790 100644
--- a/src/format.rs
+++ b/src/format.rs
@@ -1,13 +1,57 @@
+use std::convert::{TryFrom, TryInto};
+
 use regex::Regex;
 use smol_str::SmolStr;
 use unicode_segmentation::UnicodeSegmentation;
 
+#[derive(Debug, PartialEq)]
+pub enum Placeholder<'a> {
+    NumberMinus,
+    NumberPlus,
+    Str(&'a str),
+}
+
+impl<'a> TryFrom<Option<&'a str>> for Placeholder<'a> {
+    type Error = ();
+    fn try_from(from: Option<&'a str>) -> Result<Self, Self::Error> {
+        match from {
+            Some(placeholder) if placeholder == "nm" => Ok(Placeholder::NumberMinus),
+            Some(placeholder) if placeholder == "np" => Ok(Placeholder::NumberPlus),
+            Some(placeholder) => Ok(Placeholder::Str(placeholder)),
+            _ => Err(()),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq)]
+pub enum Align {
+    Left,
+    Center,
+    Right,
+}
+
+impl TryFrom<Option<&str>> for Align {
+    type Error = ();
+    fn try_from(from: Option<&str>) -> Result<Self, Self::Error> {
+        match from {
+            Some(alignment) if alignment == "<" => Ok(Align::Left),
+            Some(alignment) if alignment == ">" => Ok(Align::Right),
+            Some(alignment) if alignment == "^" => Ok(Align::Center),
+            Some(alignment) => {
+                debug_assert!(false, "Unknown Alignment: {}", alignment);
+                Err(())
+            }
+            None => Err(()),
+        }
+    }
+}
+
 #[derive(Debug, Default, PartialEq)]
 pub struct FormatStringPlaceholderData<'a> {
     pub prefix: SmolStr,
     pub prefix_len: usize,
-    pub placeholder: Option<&'a str>,
-    pub alignment_spec: Option<&'a str>,
+    pub placeholder: Option<Placeholder<'a>>,
+    pub alignment_spec: Option<Align>,
     pub width: Option<usize>,
     pub suffix: SmolStr,
     pub suffix_len: usize,
@@ -20,7 +64,9 @@ impl<'a> FormatStringPlaceholderData<'a> {
         (
             self.prefix_len
                 + std::cmp::max(
-                    self.placeholder.map_or(0, |_| hunk_max_line_number_width),
+                    self.placeholder
+                        .as_ref()
+                        .map_or(0, |_| hunk_max_line_number_width),
                     self.width.unwrap_or(0),
                 ),
             self.suffix_len,
@@ -66,8 +112,8 @@ pub fn parse_line_number_format<'a>(
         format_data.push(FormatStringPlaceholderData {
             prefix,
             prefix_len,
-            placeholder: captures.get(1).map(|m| m.as_str()),
-            alignment_spec: captures.get(3).map(|m| m.as_str()),
+            placeholder: captures.get(1).map(|m| m.as_str()).try_into().ok(),
+            alignment_spec: captures.get(3).map(|m| m.as_str()).try_into().ok(),
             width: captures.get(4).map(|m| {
                 m.as_str()
                     .parse()
@@ -90,14 +136,14 @@ pub fn parse_line_number_format<'a>(
             suffix_len: format_string.graphemes(true).count(),
         })
     }
+
     format_data
 }
 
-pub fn pad(s: &str, width: usize, alignment: &str) -> String {
+pub fn pad(s: &str, width: usize, alignment: &Align) -> String {
     match alignment {
-        "<" => format!("{0:<1$}", s, width),
-        "^" => format!("{0:^1$}", s, width),
-        ">" => format!("{0:>1$}", s, width),
-        _ => unreachable!(),
+        Align::Left => format!("{0:<1$}", s, width),
+        Align::Center => format!("{0:^1$}", s, width),
+        Align::Right => format!("{0:>1$}", s, width),
     }
 }