feat: Support ln=target in LS_COLORS

Setting "ln=target" highlights a link in the same color as the
referred file. Dangling/orphaned links are always colored using the
specified "or=" color.

(Credit to @LarsHaalck who wrote the original ogham/exa#960)

src/output/file_name.rs

@@ -460,7 +460,18 @@ impl<'a, 'dir, C: Colours> FileName<'a, 'dir, C> {
             f if f.is_directory()        => self.colours.directory(),
             #[cfg(unix)]
             f if f.is_executable_file()  => self.colours.executable_file(),
-            f if f.is_link()             => self.colours.symlink(),
+            f if f.is_link()             => {
+                if let crate::theme::LinkStyle::AnsiStyle(x) = self.colours.symlink() { x } else {
+                    if let FileTarget::Ok(file) = self.target.as_ref().unwrap() {
+                        return FileName {
+                            file,
+                            target: None,
+                            ..*self
+                        }.style()
+                    }
+                    return Style::default();
+                }
+            }
             #[cfg(unix)]
             f if f.is_pipe()             => self.colours.pipe(),
             #[cfg(unix)]

src/output/render/filetype.rs

@@ -1,6 +1,7 @@
 use nu_ansi_term::{AnsiString as ANSIString, Style};
 
 use crate::fs::fields as f;
+use crate::theme::LinkStyle;
 
 impl f::Type {
     pub fn render<C: Colours>(self, colours: &C) -> ANSIString<'static> {
@@ -9,7 +10,12 @@ impl f::Type {
             Self::File         => colours.normal().paint("."),
             Self::Directory    => colours.directory().paint("d"),
             Self::Pipe         => colours.pipe().paint("|"),
-            Self::Link         => colours.symlink().paint("l"),
+            Self::Link         => {
+                match colours.symlink() {
+                    LinkStyle::AnsiStyle(s) => s.paint("l"),
+                    LinkStyle::Target => colours.normal().paint("l")
+                }
+            }
             Self::BlockDevice  => colours.block_device().paint("b"),
             Self::CharDevice   => colours.char_device().paint("c"),
             Self::Socket       => colours.socket().paint("s"),
@@ -22,7 +28,7 @@ pub trait Colours {
     fn normal(&self) -> Style;
     fn directory(&self) -> Style;
     fn pipe(&self) -> Style;
-    fn symlink(&self) -> Style;
+    fn symlink(&self) -> LinkStyle;
     fn block_device(&self) -> Style;
     fn char_device(&self) -> Style;
     fn socket(&self) -> Style;

src/theme/default_theme.rs

@@ -14,7 +14,7 @@ impl UiStyles {
             filekinds: FileKinds {
                 normal:       Style::default(),
                 directory:    Blue.bold(),
-                symlink:      Cyan.normal(),
+                symlink:      LinkStyle::AnsiStyle(Cyan.normal()),
                 pipe:         Yellow.normal(),
                 block_device: Yellow.bold(),
                 char_device:  Yellow.bold(),

src/theme/mod.rs

@@ -7,6 +7,7 @@ use crate::output::file_name::Colours as FileNameColours;
 use crate::output::render;
 
 mod ui_styles;
+pub use self::ui_styles::LinkStyle;
 pub use self::ui_styles::UiStyles;
 
 mod lsc;
@@ -253,7 +254,7 @@ impl render::FiletypeColours for Theme {
     fn normal(&self)       -> Style { self.ui.filekinds.normal }
     fn directory(&self)    -> Style { self.ui.filekinds.directory }
     fn pipe(&self)         -> Style { self.ui.filekinds.pipe }
-    fn symlink(&self)      -> Style { self.ui.filekinds.symlink }
+    fn symlink(&self)      -> LinkStyle { self.ui.filekinds.symlink }
     fn block_device(&self) -> Style { self.ui.filekinds.block_device }
     fn char_device(&self)  -> Style { self.ui.filekinds.char_device }
     fn socket(&self)       -> Style { self.ui.filekinds.socket }
@@ -493,8 +494,9 @@ mod customs_test {
     test!(ls_so:   ls "so=35", exa ""  =>  colours c -> { c.filekinds.socket       = Purple.normal(); });
     test!(ls_bd:   ls "bd=36", exa ""  =>  colours c -> { c.filekinds.block_device = Cyan.normal();   });
     test!(ls_cd:   ls "cd=35", exa ""  =>  colours c -> { c.filekinds.char_device  = Purple.normal(); });
-    test!(ls_ln:   ls "ln=34", exa ""  =>  colours c -> { c.filekinds.symlink      = Blue.normal();   });
+    test!(ls_ln:   ls "ln=34", exa ""  =>  colours c -> { c.filekinds.symlink      = LinkStyle::AnsiStyle(Blue.normal()); });
     test!(ls_or:   ls "or=33", exa ""  =>  colours c -> { c.broken_symlink         = Yellow.normal(); });
+    test!(ls_ln_target: ls "ln=target", exa "" => colours c -> { c.filekinds.symlink = LinkStyle::Target; });
 
     // EZA_COLORS can affect all those colours too:
     test!(exa_di:  ls "", exa "di=32"  =>  colours c -> { c.filekinds.directory    = Green.normal();  });
@@ -504,7 +506,7 @@ mod customs_test {
     test!(exa_so:  ls "", exa "so=36"  =>  colours c -> { c.filekinds.socket       = Cyan.normal();   });
     test!(exa_bd:  ls "", exa "bd=35"  =>  colours c -> { c.filekinds.block_device = Purple.normal(); });
     test!(exa_cd:  ls "", exa "cd=34"  =>  colours c -> { c.filekinds.char_device  = Blue.normal();   });
-    test!(exa_ln:  ls "", exa "ln=33"  =>  colours c -> { c.filekinds.symlink      = Yellow.normal(); });
+    test!(exa_ln:  ls "", exa "ln=33"  =>  colours c -> { c.filekinds.symlink      = LinkStyle::AnsiStyle(Yellow.normal()); });
     test!(exa_or:  ls "", exa "or=32"  =>  colours c -> { c.broken_symlink         = Green.normal();  });
 
     // EZA_COLORS will even override options from LS_COLORS:

src/theme/ui_styles.rs

@@ -31,12 +31,24 @@ pub struct UiStyles {
     pub broken_path_overlay:  Style,  // bO
 }
 
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum LinkStyle {
+    AnsiStyle(Style),
+    Target,
+}
+
+impl Default for LinkStyle {
+    fn default() -> Self {
+        LinkStyle::AnsiStyle(Style::default())
+    }
+}
+
 #[rustfmt::skip]
 #[derive(Clone, Copy, Debug, Default, PartialEq)]
 pub struct FileKinds {
     pub normal: Style,        // fi
     pub directory: Style,     // di
-    pub symlink: Style,       // ln
+    pub symlink: LinkStyle,   // ln
     pub pipe: Style,          // pi
     pub block_device: Style,  // bd
     pub char_device: Style,   // cd
@@ -179,7 +191,12 @@ impl UiStyles {
             "so" => self.filekinds.socket       = pair.to_style(),  // SOCK
             "bd" => self.filekinds.block_device = pair.to_style(),  // BLK
             "cd" => self.filekinds.char_device  = pair.to_style(),  // CHR
-            "ln" => self.filekinds.symlink      = pair.to_style(),  // LINK
+            "ln" => {
+                self.filekinds.symlink = match pair.value {
+                    "target" => LinkStyle::Target,
+                    _ => LinkStyle::AnsiStyle(pair.to_style())
+                }
+            }
             "or" => self.broken_symlink         = pair.to_style(),  // ORPHAN
              _   => return false,
              // Codes we don’t do anything with: