Dependencies update and fix for line linking.

Fixes #20.

vendor/github.com/alecthomas/chroma/formatters/api.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/alecthomas/chroma"
 	"github.com/alecthomas/chroma/formatters/html"
+	"github.com/alecthomas/chroma/formatters/svg"
 )
 
 var (
@@ -19,7 +20,8 @@ var (
 		return nil
 	}))
 	// Default HTML formatter outputs self-contained HTML.
-	htmlFull = Register("html", html.New(html.Standalone(), html.WithClasses())) // nolint
+	htmlFull = Register("html", html.New(html.Standalone(true), html.WithClasses(true))) // nolint
+	SVG      = Register("svg", svg.New(svg.EmbedFont("Liberation Mono", svg.FontLiberationMono, svg.WOFF)))
 )
 
 // Fallback formatter.

vendor/github.com/alecthomas/chroma/formatters/html/html.go

@@ -14,32 +14,56 @@ import (
 type Option func(f *Formatter)
 
 // Standalone configures the HTML formatter for generating a standalone HTML document.
-func Standalone() Option { return func(f *Formatter) { f.standalone = true } }
+func Standalone(b bool) Option { return func(f *Formatter) { f.standalone = b } }
 
 // ClassPrefix sets the CSS class prefix.
 func ClassPrefix(prefix string) Option { return func(f *Formatter) { f.prefix = prefix } }
 
 // WithClasses emits HTML using CSS classes, rather than inline styles.
-func WithClasses() Option { return func(f *Formatter) { f.Classes = true } }
+func WithClasses(b bool) Option { return func(f *Formatter) { f.Classes = b } }
 
 // TabWidth sets the number of characters for a tab. Defaults to 8.
 func TabWidth(width int) Option { return func(f *Formatter) { f.tabWidth = width } }
 
-// PreventSurroundingPre prevents the surrounding pre tags around the generated code
-func PreventSurroundingPre() Option { return func(f *Formatter) { f.preventSurroundingPre = true } }
+// PreventSurroundingPre prevents the surrounding pre tags around the generated code.
+func PreventSurroundingPre(b bool) Option {
+	return func(f *Formatter) {
+		if b {
+			f.preWrapper = nopPreWrapper
+		} else {
+			f.preWrapper = defaultPreWrapper
+		}
+	}
+}
+
+// WithPreWrapper allows control of the surrounding pre tags.
+func WithPreWrapper(wrapper PreWrapper) Option {
+	return func(f *Formatter) {
+		f.preWrapper = wrapper
+	}
+}
 
 // WithLineNumbers formats output with line numbers.
-func WithLineNumbers() Option {
+func WithLineNumbers(b bool) Option {
 	return func(f *Formatter) {
-		f.lineNumbers = true
+		f.lineNumbers = b
 	}
 }
 
 // LineNumbersInTable will, when combined with WithLineNumbers, separate the line numbers
 // and code in table td's, which make them copy-and-paste friendly.
-func LineNumbersInTable() Option {
+func LineNumbersInTable(b bool) Option {
 	return func(f *Formatter) {
-		f.lineNumbersInTable = true
+		f.lineNumbersInTable = b
+	}
+}
+
+// LinkableLineNumbers decorates the line numbers HTML elements with an "id"
+// attribute so they can be linked.
+func LinkableLineNumbers(b bool, prefix string) Option {
+	return func(f *Formatter) {
+		f.linkableLineNumbers = b
+		f.lineNumbersIDPrefix = prefix
 	}
 }
 
@@ -64,6 +88,7 @@ func BaseLineNumber(n int) Option {
 func New(options ...Option) *Formatter {
 	f := &Formatter{
 		baseLineNumber: 1,
+		preWrapper:     defaultPreWrapper,
 	}
 	for _, option := range options {
 		option(f)
@@ -71,17 +96,59 @@ func New(options ...Option) *Formatter {
 	return f
 }
 
+// PreWrapper defines the operations supported in WithPreWrapper.
+type PreWrapper interface {
+	// Start is called to write a start <pre> element.
+	// The code flag tells whether this block surrounds
+	// highlighted code. This will be false when surrounding
+	// line numbers.
+	Start(code bool, styleAttr string) string
+
+	// End is called to write the end </pre> element.
+	End(code bool) string
+}
+
+type preWrapper struct {
+	start func(code bool, styleAttr string) string
+	end   func(code bool) string
+}
+
+func (p preWrapper) Start(code bool, styleAttr string) string {
+	return p.start(code, styleAttr)
+}
+
+func (p preWrapper) End(code bool) string {
+	return p.end(code)
+}
+
+var (
+	nopPreWrapper = preWrapper{
+		start: func(code bool, styleAttr string) string { return "" },
+		end:   func(code bool) string { return "" },
+	}
+	defaultPreWrapper = preWrapper{
+		start: func(code bool, styleAttr string) string {
+			return fmt.Sprintf("<pre%s>", styleAttr)
+		},
+		end: func(code bool) string {
+			return "</pre>"
+		},
+	}
+)
+
 // Formatter that generates HTML.
 type Formatter struct {
-	standalone            bool
-	prefix                string
-	Classes               bool // Exported field to detect when classes are being used
-	preventSurroundingPre bool
-	tabWidth              int
-	lineNumbers           bool
-	lineNumbersInTable    bool
-	highlightRanges       highlightRanges
-	baseLineNumber        int
+	standalone          bool
+	prefix              string
+	Classes             bool // Exported field to detect when classes are being used
+	preWrapper          PreWrapper
+	tabWidth            int
+	lineNumbers         bool
+	lineNumbersInTable  bool
+	linkableLineNumbers bool
+	lineNumbersIDPrefix string
+	highlightRanges     highlightRanges
+	baseLineNumber      int
 }
 
 type highlightRanges [][2]int
@@ -91,11 +158,6 @@ func (h highlightRanges) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
 func (h highlightRanges) Less(i, j int) bool { return h[i][0] < h[j][0] }
 
 func (f *Formatter) Format(w io.Writer, style *chroma.Style, iterator chroma.Iterator) (err error) {
-	defer func() {
-		if perr := recover(); perr != nil {
-			err = perr.(error)
-		}
-	}()
 	return f.writeHTML(w, style, iterator.Tokens())
 }
 
@@ -126,7 +188,7 @@ func (f *Formatter) writeHTML(w io.Writer, style *chroma.Style, tokens []chroma.
 	wrapInTable := f.lineNumbers && f.lineNumbersInTable
 
 	lines := chroma.SplitTokensIntoLines(tokens)
-	lineDigits := len(fmt.Sprintf("%d", len(lines)))
+	lineDigits := len(fmt.Sprintf("%d", f.baseLineNumber+len(lines)-1))
 	highlightIndex := 0
 
 	if wrapInTable {
@@ -134,9 +196,7 @@ func (f *Formatter) writeHTML(w io.Writer, style *chroma.Style, tokens []chroma.
 		fmt.Fprintf(w, "<div%s>\n", f.styleAttr(css, chroma.Background))
 		fmt.Fprintf(w, "<table%s><tr>", f.styleAttr(css, chroma.LineTable))
 		fmt.Fprintf(w, "<td%s>\n", f.styleAttr(css, chroma.LineTableTD))
-		if !f.preventSurroundingPre {
-			fmt.Fprintf(w, "<pre%s>", f.styleAttr(css, chroma.Background))
-		}
+		fmt.Fprintf(w, f.preWrapper.Start(false, f.styleAttr(css, chroma.Background)))
 		for index := range lines {
 			line := f.baseLineNumber + index
 			highlight, next := f.shouldHighlight(highlightIndex, line)
@@ -147,22 +207,19 @@ func (f *Formatter) writeHTML(w io.Writer, style *chroma.Style, tokens []chroma.
 				fmt.Fprintf(w, "<span%s>", f.styleAttr(css, chroma.LineHighlight))
 			}
 
-			fmt.Fprintf(w, "<span%s>%*d\n</span>", f.styleAttr(css, chroma.LineNumbersTable), lineDigits, line)
+			fmt.Fprintf(w, "<span%s%s>%*d\n</span>", f.styleAttr(css, chroma.LineNumbersTable), f.lineIDAttribute(line), lineDigits, line)
 
 			if highlight {
 				fmt.Fprintf(w, "</span>")
 			}
 		}
-		if !f.preventSurroundingPre {
-			fmt.Fprint(w, "</pre>")
-		}
+		fmt.Fprint(w, f.preWrapper.End(false))
 		fmt.Fprint(w, "</td>\n")
 		fmt.Fprintf(w, "<td%s>\n", f.styleAttr(css, chroma.LineTableTD, "width:100%"))
 	}
 
-	if !f.preventSurroundingPre {
-		fmt.Fprintf(w, "<pre%s>", f.styleAttr(css, chroma.Background))
-	}
+	fmt.Fprintf(w, f.preWrapper.Start(true, f.styleAttr(css, chroma.Background)))
+
 	highlightIndex = 0
 	for index, tokens := range lines {
 		// 1-based line number.
@@ -176,7 +233,7 @@ func (f *Formatter) writeHTML(w io.Writer, style *chroma.Style, tokens []chroma.
 		}
 
 		if f.lineNumbers && !wrapInTable {
-			fmt.Fprintf(w, "<span%s>%*d</span>", f.styleAttr(css, chroma.LineNumbers), lineDigits, line)
+			fmt.Fprintf(w, "<span%s%s>%*d</span>", f.styleAttr(css, chroma.LineNumbers), f.lineIDAttribute(line), lineDigits, line)
 		}
 
 		for _, token := range tokens {
@@ -192,9 +249,7 @@ func (f *Formatter) writeHTML(w io.Writer, style *chroma.Style, tokens []chroma.
 		}
 	}
 
-	if !f.preventSurroundingPre {
-		fmt.Fprint(w, "</pre>")
-	}
+	fmt.Fprintf(w, f.preWrapper.End(true))
 
 	if wrapInTable {
 		fmt.Fprint(w, "</td></tr></table>\n")
@@ -209,6 +264,13 @@ func (f *Formatter) writeHTML(w io.Writer, style *chroma.Style, tokens []chroma.
 	return nil
 }
 
+func (f *Formatter) lineIDAttribute(line int) string {
+	if !f.linkableLineNumbers {
+		return ""
+	}
+	return fmt.Sprintf(" id=\"%s%d\"", f.lineNumbersIDPrefix, line)
+}
+
 func (f *Formatter) shouldHighlight(highlightIndex, line int) (bool, bool) {
 	next := false
 	for highlightIndex < len(f.highlightRanges) && line > f.highlightRanges[highlightIndex][1] {
@@ -283,6 +345,13 @@ func (f *Formatter) WriteCSS(w io.Writer, style *chroma.Style) error {
 			return err
 		}
 	}
+	// Special-case line number highlighting when targeted.
+	if f.lineNumbers || f.lineNumbersInTable {
+		targetedLineCSS := StyleEntryToCSS(style.Get(chroma.LineHighlight))
+		for _, tt := range []chroma.TokenType{chroma.LineNumbers, chroma.LineNumbersTable} {
+			fmt.Fprintf(w, "/* %s targeted by URL anchor */ .%schroma .%s:target { %s }\n", tt, f.prefix, f.class(tt), targetedLineCSS)
+		}
+	}
 	tts := []int{}
 	for tt := range css {
 		tts = append(tts, int(tt))

vendor/github.com/alecthomas/chroma/formatters/tty_indexed.go

@@ -200,6 +200,7 @@ func findClosest(table *ttyTable, seeking chroma.Colour) chroma.Colour {
 }
 
 func styleToEscapeSequence(table *ttyTable, style *chroma.Style) map[chroma.TokenType]string {
+	style = clearBackground(style)
 	out := map[chroma.TokenType]string{}
 	for _, ttype := range style.Types() {
 		entry := style.Get(ttype)
@@ -208,16 +209,22 @@ func styleToEscapeSequence(table *ttyTable, style *chroma.Style) map[chroma.Toke
 	return out
 }
 
+// Clear the background colour.
+func clearBackground(style *chroma.Style) *chroma.Style {
+	builder := style.Builder()
+	bg := builder.Get(chroma.Background)
+	bg.Background = 0
+	bg.NoInherit = true
+	builder.AddEntry(chroma.Background, bg)
+	style, _ = builder.Build()
+	return style
+}
+
 type indexedTTYFormatter struct {
 	table *ttyTable
 }
 
 func (c *indexedTTYFormatter) Format(w io.Writer, style *chroma.Style, it chroma.Iterator) (err error) {
-	defer func() {
-		if perr := recover(); perr != nil {
-			err = perr.(error)
-		}
-	}()
 	theme := styleToEscapeSequence(c.table, style)
 	for token := it(); token != chroma.EOF; token = it() {
 		// TODO: Cache token lookups?

vendor/github.com/alecthomas/chroma/formatters/tty_truecolour.go

@@ -11,6 +11,7 @@ import (
 var TTY16m = Register("terminal16m", chroma.FormatterFunc(trueColourFormatter))
 
 func trueColourFormatter(w io.Writer, style *chroma.Style, it chroma.Iterator) error {
+	style = clearBackground(style)
 	for token := it(); token != chroma.EOF; token = it() {
 		entry := style.Get(token.Type)
 		if !entry.IsZero() {