From db5dbf35401245dea75d922b385e4cf70624640f Mon Sep 17 00:00:00 2001
From: Martin von Zweigbergk <martinvonz@google.com>
Date: Sat, 7 Jan 2023 08:02:47 -0800
Subject: [PATCH] formatter: make `Style::fg_color` an `Option`

We want to be able combine styles by replacing only some of the
attributes (foreground color, underlining, etc.) in the config. We
could implement that having keeping the current style and then update
it based on what we find in the config for a label we just
added. However, it's simpler if we can parse a configured style
without knowing the current style and just return a `Style` with some
fields blank. This commit prepares for that by making the foreground
color field optional.
---
 src/formatter.rs | 57 ++++++++++++++++++++++--------------------------
 1 file changed, 26 insertions(+), 31 deletions(-)

diff --git a/src/formatter.rs b/src/formatter.rs
index acca8fdb2..0224c8ffb 100644
--- a/src/formatter.rs
+++ b/src/formatter.rs
@@ -150,17 +150,9 @@ impl<W: Write> Formatter for PlainTextFormatter<W> {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub struct Style {
-    pub fg_color: Color,
-}
-
-impl Default for Style {
-    fn default() -> Self {
-        Self {
-            fg_color: Color::Reset,
-        }
-    }
+    pub fg_color: Option<Color>,
 }
 
 pub struct ColorFormatter<W> {
@@ -239,16 +231,19 @@ impl<W: Write> ColorFormatter<W> {
             } else if !is_bright(&new_style.fg_color) && is_bright(&self.current_style.fg_color) {
                 queue!(self.output, SetAttribute(Attribute::Reset))?;
             }
-            queue!(self.output, SetForegroundColor(new_style.fg_color))?;
+            queue!(
+                self.output,
+                SetForegroundColor(new_style.fg_color.unwrap_or(Color::Reset))
+            )?;
             self.current_style = new_style;
         }
         Ok(())
     }
 }
 
-fn is_bright(color: &Color) -> bool {
+fn is_bright(color: &Option<Color>) -> bool {
     matches!(
-        color,
+        color.unwrap_or(Color::Reset),
         Color::DarkGrey
             | Color::Red
             | Color::Green
@@ -291,25 +286,25 @@ fn rules_from_config(config: &config::Config) -> HashMap<Vec<String>, Style> {
     result
 }
 
-fn color_for_name(color_name: &str) -> Color {
+fn color_for_name(color_name: &str) -> Option<Color> {
     match color_name {
-        "black" => Color::Black,
-        "red" => Color::DarkRed,
-        "green" => Color::DarkGreen,
-        "yellow" => Color::DarkYellow,
-        "blue" => Color::DarkBlue,
-        "magenta" => Color::DarkMagenta,
-        "cyan" => Color::DarkCyan,
-        "white" => Color::Grey,
-        "bright black" => Color::DarkGrey,
-        "bright red" => Color::Red,
-        "bright green" => Color::Green,
-        "bright yellow" => Color::Yellow,
-        "bright blue" => Color::Blue,
-        "bright magenta" => Color::Magenta,
-        "bright cyan" => Color::Cyan,
-        "bright white" => Color::White,
-        _ => Color::Reset,
+        "black" => Some(Color::Black),
+        "red" => Some(Color::DarkRed),
+        "green" => Some(Color::DarkGreen),
+        "yellow" => Some(Color::DarkYellow),
+        "blue" => Some(Color::DarkBlue),
+        "magenta" => Some(Color::DarkMagenta),
+        "cyan" => Some(Color::DarkCyan),
+        "white" => Some(Color::Grey),
+        "bright black" => Some(Color::DarkGrey),
+        "bright red" => Some(Color::Red),
+        "bright green" => Some(Color::Green),
+        "bright yellow" => Some(Color::Yellow),
+        "bright blue" => Some(Color::Blue),
+        "bright magenta" => Some(Color::Magenta),
+        "bright cyan" => Some(Color::Cyan),
+        "bright white" => Some(Color::White),
+        _ => None,
     }
 }