Implement previews for plain text files

kittens/choose_files/__init__.py

@@ -0,0 +1,6 @@
+def syntax_aliases(x: str) -> dict[str, str]:
+    ans = {}
+    for x in x.split():
+        k, _, v = x.partition(':')
+        ans[k] = v
+    return ans

kittens/choose_files/main.go

@@ -102,26 +102,28 @@ type render_state struct {
 }
 
 type State struct {
-	base_dir                 string
-	current_dir              string
-	select_dirs              bool
-	multiselect              bool
-	search_text              string
-	mode                     Mode
-	suggested_save_file_name string
-	suggested_save_file_path string
-	window_title             string
-	screen                   Screen
-	current_filter           string
-	filter_map               map[string]Filter
-	filter_names             []string
-	show_hidden              bool
-	show_preview             bool
-	respect_ignores          bool
-	sort_by_last_modified    bool
-	global_ignores           ignorefiles.IgnoreFile
-	keyboard_shortcuts       []*config.KeyAction
-	display_title            bool
+	base_dir                            string
+	current_dir                         string
+	select_dirs                         bool
+	multiselect                         bool
+	search_text                         string
+	mode                                Mode
+	suggested_save_file_name            string
+	suggested_save_file_path            string
+	window_title                        string
+	screen                              Screen
+	current_filter                      string
+	filter_map                          map[string]Filter
+	filter_names                        []string
+	show_hidden                         bool
+	show_preview                        bool
+	respect_ignores                     bool
+	sort_by_last_modified               bool
+	global_ignores                      ignorefiles.IgnoreFile
+	keyboard_shortcuts                  []*config.KeyAction
+	display_title                       bool
+	pygments_style, dark_pygments_style string
+	syntax_aliases                      map[string]string
 
 	selections    []string
 	current_idx   CollectionIndex
@@ -130,6 +132,8 @@ type State struct {
 	redraw_needed bool
 }
 
+func (s State) HighlightStyles() (string, string)     { return s.pygments_style, s.dark_pygments_style }
+func (s State) SyntaxAliases() map[string]string      { return s.syntax_aliases }
 func (s State) DisplayTitle() bool                    { return s.display_title }
 func (s State) ShowHidden() bool                      { return s.show_hidden }
 func (s State) ShowPreview() bool                     { return s.show_preview }
@@ -709,6 +713,9 @@ func (h *Handler) set_state_from_config(conf *Config, opts *Options) (err error)
 	}
 	h.state.keyboard_shortcuts = conf.KeyboardShortcuts
 	h.state.display_title = opts.DisplayTitle
+	h.state.pygments_style = conf.Pygments_style
+	h.state.dark_pygments_style = conf.Dark_pygments_style
+	h.state.syntax_aliases = conf.Syntax_aliases
 	return
 }
 

kittens/choose_files/main.py

@@ -40,10 +40,34 @@ Anchored patterns match with respect to whatever directory is currently being di
 Can be specified multiple times to use multiple patterns. Note that every pattern
 has to be checked against every file, so use sparingly.
 ''')
+egr()  # }}}
+
+agr('appearance', 'Appearance')  # {{{
 
 opt('show_preview', 'last', choices=('last', 'yes', 'y', 'true', 'no', 'n', 'false'), long_text='''
 Whether to show a preview of the current file/directory. The default value of :code:`last` means remember the last
 used value. This setting can be toggled withing the program.''')
+
+opt('pygments_style', 'default', long_text='''
+The pygments color scheme to use for syntax highlighting of file previews. See :link:`pygments
+builtin styles <https://pygments.org/styles/>` for a list of schemes.
+This sets the colors used for light color schemes, use :opt:`dark_pygments_style` to change the
+colors for dark color schemes.
+''')
+
+opt('dark_pygments_style', 'github-dark', long_text='''
+The pygments color scheme to use for syntax highlighting with dark colors. See :link:`pygments
+builtin styles <https://pygments.org/styles/>` for a list of schemes.
+This sets the colors used for dark color schemes, use :opt:`pygments_style` to change the
+colors for light color schemes.''')
+
+opt('syntax_aliases', 'pyj:py pyi:py recipe:py', ctype='strdict_ _:', option_type='syntax_aliases',
+    long_text='''
+File extension aliases for syntax highlight. For example, to syntax highlight
+:file:`file.xyz` as :file:`file.abc` use a setting of :code:`xyz:abc`.
+Multiple aliases must be separated by spaces.
+''')
+
 egr()  # }}}
 
 agr('shortcuts', 'Keyboard shortcuts')  # {{{

kittens/choose_files/preview.go

@@ -9,8 +9,11 @@ import (
 	"slices"
 	"strings"
 	"sync"
+	"unicode/utf8"
 
+	"github.com/kovidgoyal/kitty/tools/highlight"
 	"github.com/kovidgoyal/kitty/tools/icons"
+	"github.com/kovidgoyal/kitty/tools/tui/loop"
 	"github.com/kovidgoyal/kitty/tools/utils"
 	"github.com/kovidgoyal/kitty/tools/utils/humanize"
 	"github.com/kovidgoyal/kitty/tools/utils/style"
@@ -30,12 +33,14 @@ type PreviewManager struct {
 	WakeupMainThread func() bool
 	cache            map[string]Preview
 	lock             sync.Mutex
+	highlighter      highlight.Highlighter
 }
 
-func NewPreviewManager(err_chan chan error, settings Settings, WakeupMainThread func() bool) *PreviewManager {
+func NewPreviewManager(err_chan chan error, settings Settings, WakeupMainThread func() bool) (ans *PreviewManager) {
+	defer func() { sanitize = ans.highlighter.Sanitize }()
 	return &PreviewManager{
 		report_errors: err_chan, settings: settings, WakeupMainThread: WakeupMainThread,
-		cache: make(map[string]Preview),
+		cache: make(map[string]Preview), highlighter: highlight.NewHighlighter(nil),
 	}
 }
 
@@ -104,6 +109,8 @@ func NewErrorPreview(err error) Preview {
 	return &MessagePreview{msg: text}
 }
 
+var sanitize func(string) string
+
 func write_file_metadata(abspath string, metadata fs.FileInfo, entries []fs.DirEntry) (header string, trailers []string) {
 	buf := strings.Builder{}
 	buf.Grow(4096)
@@ -115,7 +122,7 @@ func write_file_metadata(abspath string, metadata fs.FileInfo, entries []fs.DirE
 		add("Size", humanize.Bytes(uint64(metadata.Size())))
 	case fs.ModeSymlink:
 		if tgt, err := os.Readlink(abspath); err == nil {
-			add("Target", tgt)
+			add("Target", sanitize(tgt))
 		} else {
 			add("Target", err.Error())
 		}
@@ -145,7 +152,7 @@ func write_file_metadata(abspath string, metadata fs.FileInfo, entries []fs.DirE
 		slices.SortFunc(names, func(a, b string) int { return strings.Compare(type_map[a].lname, type_map[b].lname) })
 		fmt.Fprintln(&buf, "Contents:")
 		for _, n := range names {
-			trailers = append(trailers, icons.IconForFileWithMode(n, type_map[n].ftype, false)+"  "+n)
+			trailers = append(trailers, icons.IconForFileWithMode(n, type_map[n].ftype, false)+"  "+sanitize(n))
 		}
 	}
 	return buf.String(), trailers
@@ -167,6 +174,96 @@ func NewFileMetadataPreview(abspath string, metadata fs.FileInfo) Preview {
 	return &MessagePreview{title: title, msg: h, trailers: t}
 }
 
+type highlighed_data struct {
+	text  string
+	light bool
+	err   error
+}
+
+type TextFilePreview struct {
+	plain_text, highlighted_text string
+	highlighted_chan             chan highlighed_data
+	light                        bool
+}
+
+func (p TextFilePreview) IsValidForColorScheme(light bool) bool { return p.light == light }
+
+func (p TextFilePreview) Render(h *Handler, x, y, width, height int) {
+	if p.highlighted_chan != nil {
+		select {
+		case hd := <-p.highlighted_chan:
+			p.highlighted_chan = nil
+			if hd.err == nil {
+				p.highlighted_text = hd.text
+			}
+		default:
+		}
+	}
+	text := p.highlighted_text
+	if text == "" {
+		text = p.plain_text
+	}
+	s := utils.NewLineScanner(text)
+	buf := strings.Builder{}
+	buf.Grow(1024 * height)
+	for num := 0; s.Scan() && num < height; num++ {
+		line := s.Text()
+		truncated := wcswidth.TruncateToVisualLength(line, width)
+		buf.WriteString(fmt.Sprintf(loop.MoveCursorToTemplate, y+num, x))
+		buf.WriteString(truncated)
+		if len(truncated) < len(line) {
+			wcswidth.KeepOnlyCSI(line[len(truncated):], &buf)
+		}
+	}
+	buf.WriteString("\x1b[m") // reset any highlight styles
+	h.lp.QueueWriteString(buf.String())
+}
+
+func NewTextFilePreview(abspath string, metadata fs.FileInfo, highlighted_chan chan highlighed_data, sanitize func(string) string) Preview {
+	data, err := os.ReadFile(abspath)
+	if err != nil {
+		return NewFileMetadataPreview(abspath, metadata)
+	}
+	text := utils.UnsafeBytesToString(data)
+	if !utf8.ValidString(text) {
+		text = "Error: not valid utf-8 text"
+	}
+	return &TextFilePreview{plain_text: sanitize(text), highlighted_chan: highlighted_chan, light: use_light_colors}
+}
+
+type style_resolver struct {
+	light                   bool
+	light_style, dark_style string
+	syntax_aliases          map[string]string
+}
+
+func (s style_resolver) StyleName() string {
+	return utils.IfElse(s.light, s.light_style, s.dark_style)
+}
+func (s style_resolver) UseLightColors() bool             { return s.light }
+func (s style_resolver) SyntaxAliases() map[string]string { return s.syntax_aliases }
+func (s style_resolver) TextForPath(path string) (string, error) {
+	ans, err := os.ReadFile(path)
+	if err == nil {
+		return utils.UnsafeBytesToString(ans), nil
+	}
+	return "", err
+}
+
+func (pm *PreviewManager) highlight_file_async(path string, output chan highlighed_data) {
+	s := style_resolver{light: use_light_colors, syntax_aliases: pm.settings.SyntaxAliases()}
+	s.light_style, s.dark_style = pm.settings.HighlightStyles()
+	go func() {
+		highlighted, err := pm.highlighter.HighlightFile(path, &s)
+		if err != nil {
+			debugprintln(fmt.Sprintf("Failed to highlight: %s with error: %s", path, err))
+		}
+		output <- highlighed_data{text: highlighted, err: err, light: s.light}
+		close(output)
+		pm.WakeupMainThread()
+	}()
+}
+
 func (pm *PreviewManager) invalidate_color_scheme_based_cached_items() {
 	pm.lock.Lock()
 	defer pm.lock.Unlock()
@@ -192,6 +289,13 @@ func (pm *PreviewManager) preview_for(abspath string, ftype fs.FileMode) (ans Pr
 		}
 		return NewDirectoryPreview(abspath, s)
 	}
+	mt := utils.GuessMimeType(filepath.Base(abspath))
+	const MAX_TEXT_FILE_SIZE = 16 * 1024 * 1024
+	if s.Size() <= MAX_TEXT_FILE_SIZE && (utils.KnownTextualMimes[mt] || strings.HasPrefix(mt, "text/")) {
+		ch := make(chan highlighed_data, 2)
+		pm.highlight_file_async(abspath, ch)
+		return NewTextFilePreview(abspath, s, ch, pm.highlighter.Sanitize)
+	}
 	return NewFileMetadataPreview(abspath, s)
 }
 

kittens/choose_files/results.go

@@ -26,6 +26,7 @@ func (h *Handler) draw_results_title() {
 	if strings.HasPrefix(text, home) {
 		text = "~" + text[len(home):]
 	}
+	text = sanitize(text)
 	available_width := h.screen_size.width - 9
 	if available_width < 2 {
 		return
@@ -137,7 +138,7 @@ func (h *Handler) draw_column_of_matches(matches ResultsType, current_idx int, x
 		} else {
 			icon = icon_for(filepath.Join(root_dir, m.text), m.ftype)
 		}
-		text := m.text
+		text := sanitize(m.text)
 		add_ellipsis := false
 		width := wcswidth.Stringwidth(text)
 		if width > available_width-3 {

kittens/choose_files/scan.go

@@ -630,6 +630,8 @@ type Settings interface {
 	SortByLastModified() bool
 	Filter() Filter
 	GlobalIgnores() ignorefiles.IgnoreFile
+	HighlightStyles() (string, string)
+	SyntaxAliases() map[string]string
 }
 
 type ResultManager struct {