Implement previews for plain text files

Author: kovidgoyal

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 @@
 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 {

kitty/guess_mime_type.py

@@ -18,6 +18,7 @@
     'yaml': 'text/yaml',
     'js': 'text/javascript',
     'json': 'text/json',
+    'nix': 'text/nix',
 }
 
 

tools/highlight/api.go

@@ -44,6 +44,7 @@ func NewSanitizeControlCodes(replace_tab_by string) *SanitizeControlCodes {
 
 type Highlighter interface {
 	HighlightFile(path string, srd StyleResolveData) (highlighted_string string, err error)
+	Sanitize(string) string
 }
 
 func NewHighlighter(sanitize func(string) string) Highlighter {

tools/highlight/impl.go

@@ -180,6 +180,8 @@ type highlighter struct {
 	sanitize   func(string) string
 }
 
+func (h *highlighter) Sanitize(x string) string { return h.sanitize(x) }
+
 func (h *highlighter) HighlightFile(path string, srd StyleResolveData) (highlighted_string string, err error) {
 	defer func() {
 		if r := recover(); r != nil {

tools/wcswidth/truncate.go

@@ -5,6 +5,7 @@ package wcswidth
 import (
 	"errors"
 	"fmt"
+	"io"
 	"strconv"
 
 	"github.com/kovidgoyal/kitty/tools/utils"
@@ -50,6 +51,17 @@ func (self *truncate_iterator) handle_st_terminated_escape_code(body []byte) err
 	return nil
 }
 
+func KeepOnlyCSI(text string, output io.Writer) {
+	var w WCWidthIterator
+	w.parser.HandleCSI = func(data []byte) (err error) {
+		_, err = output.Write([]byte{'\x1b', '['})
+		if err == nil {
+			_, err = output.Write(data)
+		}
+		return
+	}
+}
+
 func create_truncate_iterator() *truncate_iterator {
 	var ans truncate_iterator
 	ans.w.parser.HandleRune = ans.handle_rune