feat: XML style definitions

Fixes #635.

README.md

@@ -230,17 +230,22 @@ formatter outputs raw tokens. The latter is useful for debugging lexers.
 <a id="markdown-styles" name="styles"></a>
 ### Styles
 
-Chroma styles use the [same syntax](http://pygments.org/docs/styles/) as Pygments.
+Chroma styles are defined in XML. The style entries use the
+[same syntax](http://pygments.org/docs/styles/) as Pygments.
 
-All Pygments styles have been converted to Chroma using the `_tools/style.py` script.
+All Pygments styles have been converted to Chroma using the `_tools/style.py`
+script.
 
-When you work with one of [Chroma's styles](https://github.com/alecthomas/chroma/tree/master/styles), know that the `chroma.Background` token type provides the default style for tokens. It does so by defining a foreground color and background color.
+When you work with one of [Chroma's styles](https://github.com/alecthomas/chroma/tree/master/styles), 
+know that the `Background` token type provides the default style for tokens. It does so
+by defining a foreground color and background color.
 
-For example, this gives each token name not defined in the style a default color of `#f8f8f8` and uses `#000000` for the highlighted code block's background:
+For example, this gives each token name not defined in the style a default color
+of `#f8f8f8` and uses `#000000` for the highlighted code block's background:
 
-~~~go
-chroma.Background: "#f8f8f2 bg:#000000",
-~~~
+```xml
+<entry type="Background" style="#f8f8f2 bg:#000000"/>
+```
 
 Also, token types in a style file are hierarchical. For instance, when `CommentSpecial` is not defined, Chroma uses the token style from `Comment`. So when several comment tokens use the same color, you'll only need to define `Comment` and override the one that has a different color.
 

bin/enumer

@@ -0,0 +1 @@
+.enumer-1.5.7.pkg

formatters/html/html.go

@@ -520,7 +520,7 @@ func (f *Formatter) styleToCSS(style *chroma.Style) map[chroma.TokenType]string
 	classes[chroma.LineNumbersTable] = lineNumbersStyle + classes[chroma.LineNumbersTable]
 	classes[chroma.LineTable] = "border-spacing: 0; padding: 0; margin: 0; border: 0;" + classes[chroma.LineTable]
 	classes[chroma.LineTableTD] = "vertical-align: top; padding: 0; margin: 0; border: 0;" + classes[chroma.LineTableTD]
-	classes[chroma.LineLink] = "outline: none; text-decoration:none; color:inherit" + classes[chroma.LineLink]
+	classes[chroma.LineLink] = "outline: none; text-decoration: none; color: inherit" + classes[chroma.LineLink]
 	return classes
 }
 

formatters/html/html_test.go

@@ -222,7 +222,7 @@ func TestTableLinkeableLineNumbers(t *testing.T) {
 
 	assert.Contains(t, buf.String(), `id="line1"><a class="lnlinks" href="#line1">1</a>`)
 	assert.Contains(t, buf.String(), `id="line5"><a class="lnlinks" href="#line5">5</a>`)
-	assert.Contains(t, buf.String(), `/* LineLinks */ .chroma .lnlinks { outline: none; text-decoration:none; color:inherit }`, buf.String())
+	assert.Contains(t, buf.String(), `/* LineLink */ .chroma .lnlinks { outline: none; text-decoration: none; color: inherit }`, buf.String())
 }
 
 func TestTableLineNumberSpacing(t *testing.T) {

serialise.go

@@ -372,13 +372,12 @@ func (t *TokenType) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 	if err := d.DecodeElement(&el, &start); err != nil {
 		return err
 	}
-	for tt, text := range _TokenType_map {
-		if text == el.Type {
-			*t = tt
-			return nil
-		}
+	tt, err := TokenTypeString(el.Type)
+	if err != nil {
+		return err
 	}
-	return fmt.Errorf("unknown TokenType %q", el.Type)
+	*t = tt
+	return nil
 }
 
 func (t TokenType) MarshalXML(e *xml.Encoder, start xml.StartElement) error {

style.go

@@ -1,7 +1,10 @@
 package chroma
 
 import (
+	"encoding/xml"
 	"fmt"
+	"io"
+	"sort"
 	"strings"
 )
 
@@ -49,6 +52,10 @@ type StyleEntry struct {
 	NoInherit bool
 }
 
+func (s StyleEntry) MarshalText() ([]byte, error) {
+	return []byte(s.String()), nil
+}
+
 func (s StyleEntry) String() string {
 	out := []string{}
 	if s.Bold != Pass {
@@ -216,6 +223,13 @@ func (s *StyleBuilder) Build() (*Style, error) {
 // StyleEntries mapping TokenType to colour definition.
 type StyleEntries map[TokenType]string
 
+// NewXMLStyle parses an XML style definition.
+func NewXMLStyle(r io.Reader) (*Style, error) {
+	dec := xml.NewDecoder(r)
+	style := &Style{}
+	return style, dec.Decode(style)
+}
+
 // NewStyle creates a new style definition.
 func NewStyle(name string, entries StyleEntries) (*Style, error) {
 	return NewStyleBuilder(name).AddAll(entries).Build()
@@ -239,6 +253,89 @@ type Style struct {
 	parent  *Style
 }
 
+func (s *Style) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	if s.parent != nil {
+		return fmt.Errorf("cannot marshal style with parent")
+	}
+	start.Name = xml.Name{Local: "style"}
+	start.Attr = []xml.Attr{{Name: xml.Name{Local: "name"}, Value: s.Name}}
+	if err := e.EncodeToken(start); err != nil {
+		return err
+	}
+	sorted := make([]TokenType, 0, len(s.entries))
+	for ttype := range s.entries {
+		sorted = append(sorted, ttype)
+	}
+	sort.Slice(sorted, func(i, j int) bool { return sorted[i] < sorted[j] })
+	for _, ttype := range sorted {
+		entry := s.entries[ttype]
+		el := xml.StartElement{Name: xml.Name{Local: "entry"}}
+		el.Attr = []xml.Attr{
+			{Name: xml.Name{Local: "type"}, Value: ttype.String()},
+			{Name: xml.Name{Local: "style"}, Value: entry.String()},
+		}
+		if err := e.EncodeToken(el); err != nil {
+			return err
+		}
+		if err := e.EncodeToken(xml.EndElement{Name: el.Name}); err != nil {
+			return err
+		}
+	}
+	return e.EncodeToken(xml.EndElement{Name: start.Name})
+}
+
+func (s *Style) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	for _, attr := range start.Attr {
+		if attr.Name.Local == "name" {
+			s.Name = attr.Value
+		} else {
+			return fmt.Errorf("unexpected attribute %s", attr.Name.Local)
+		}
+	}
+	if s.Name == "" {
+		return fmt.Errorf("missing style name attribute")
+	}
+	s.entries = map[TokenType]StyleEntry{}
+	for {
+		tok, err := d.Token()
+		if err != nil {
+			return err
+		}
+		switch el := tok.(type) {
+		case xml.StartElement:
+			if el.Name.Local != "entry" {
+				return fmt.Errorf("unexpected element %s", el.Name.Local)
+			}
+			var ttype TokenType
+			var entry StyleEntry
+			for _, attr := range el.Attr {
+				switch attr.Name.Local {
+				case "type":
+					ttype, err = TokenTypeString(attr.Value)
+					if err != nil {
+						return err
+					}
+
+				case "style":
+					entry, err = ParseStyleEntry(attr.Value)
+					if err != nil {
+						return err
+					}
+
+				default:
+					return fmt.Errorf("unexpected attribute %s", attr.Name.Local)
+				}
+			}
+			s.entries[ttype] = entry
+
+		case xml.EndElement:
+			if el.Name.Local == start.Name.Local {
+				return nil
+			}
+		}
+	}
+}
+
 // Types that are styled.
 func (s *Style) Types() []TokenType {
 	dedupe := map[TokenType]bool{}
@@ -319,6 +416,15 @@ func (s *Style) synthesisable(ttype TokenType) bool {
 	return ttype == LineHighlight || ttype == LineNumbers || ttype == LineNumbersTable
 }
 
+// MustParseStyleEntry parses a Pygments style entry or panics.
+func MustParseStyleEntry(entry string) StyleEntry {
+	out, err := ParseStyleEntry(entry)
+	if err != nil {
+		panic(err)
+	}
+	return out
+}
+
 // ParseStyleEntry parses a Pygments style entry.
 func ParseStyleEntry(entry string) (StyleEntry, error) { // nolint: gocyclo
 	out := StyleEntry{}

style_test.go

@@ -1,6 +1,7 @@
 package chroma
 
 import (
+	"encoding/xml"
 	"testing"
 
 	assert "github.com/alecthomas/assert/v2"
@@ -101,3 +102,21 @@ func TestStyleBuilderTransform(t *testing.T) {
 	assert.Equal(t, "#ff0000", orig.Get(NameVariable).Colour.String())
 	assert.Equal(t, "#ff3300", deriv.Get(NameVariableGlobal).Colour.String())
 }
+
+func TestStyleMarshaller(t *testing.T) {
+	expected, err := NewStyle("test", StyleEntries{
+		Whitespace: "bg:#ffffff",
+		Text:       "#000000 underline",
+	})
+	assert.NoError(t, err)
+	data, err := xml.MarshalIndent(expected, "", "  ")
+	assert.NoError(t, err)
+	assert.Equal(t, `<style name="test">
+  <entry type="Text" style="underline #000000"></entry>
+  <entry type="TextWhitespace" style="bg:#ffffff"></entry>
+</style>`, string(data))
+	actual := &Style{}
+	err = xml.Unmarshal(data, actual)
+	assert.NoError(t, err)
+	assert.Equal(t, expected, actual)
+}

styles/abap.xml

@@ -0,0 +1,11 @@
+<style name="abap">
+  <entry type="Error" style="#ff0000"/>
+  <entry type="Background" style="bg:#ffffff"/>
+  <entry type="Keyword" style="#0000ff"/>
+  <entry type="Name" style="#000000"/>
+  <entry type="LiteralString" style="#55aa22"/>
+  <entry type="LiteralNumber" style="#33aaff"/>
+  <entry type="OperatorWord" style="#0000ff"/>
+  <entry type="Comment" style="italic #888888"/>
+  <entry type="CommentSpecial" style="#888888"/>
+</style>

styles/algol.xml

@@ -0,0 +1,18 @@
+<style name="algol">
+  <entry type="Error" style="border:#ff0000"/>
+  <entry type="Background" style="bg:#ffffff"/>
+  <entry type="Keyword" style="bold underline"/>
+  <entry type="KeywordDeclaration" style="italic"/>
+  <entry type="NameBuiltin" style="bold italic"/>
+  <entry type="NameBuiltinPseudo" style="bold italic"/>
+  <entry type="NameClass" style="bold italic #666666"/>
+  <entry type="NameConstant" style="bold italic #666666"/>
+  <entry type="NameFunction" style="bold italic #666666"/>
+  <entry type="NameNamespace" style="bold italic #666666"/>
+  <entry type="NameVariable" style="bold italic #666666"/>
+  <entry type="LiteralString" style="italic #666666"/>
+  <entry type="OperatorWord" style="bold"/>
+  <entry type="Comment" style="italic #888888"/>
+  <entry type="CommentSpecial" style="bold noitalic #888888"/>
+  <entry type="CommentPreproc" style="bold noitalic #888888"/>
+</style>

styles/algol_nu.xml

@@ -0,0 +1,18 @@
+<style name="algol_nu">
+  <entry type="Error" style="border:#ff0000"/>
+  <entry type="Background" style="bg:#ffffff"/>
+  <entry type="Keyword" style="bold"/>
+  <entry type="KeywordDeclaration" style="italic"/>
+  <entry type="NameBuiltin" style="bold italic"/>
+  <entry type="NameBuiltinPseudo" style="bold italic"/>
+  <entry type="NameClass" style="bold italic #666666"/>
+  <entry type="NameConstant" style="bold italic #666666"/>
+  <entry type="NameFunction" style="bold italic #666666"/>
+  <entry type="NameNamespace" style="bold italic #666666"/>
+  <entry type="NameVariable" style="bold italic #666666"/>
+  <entry type="LiteralString" style="italic #666666"/>
+  <entry type="OperatorWord" style="bold"/>
+  <entry type="Comment" style="italic #888888"/>
+  <entry type="CommentSpecial" style="bold noitalic #888888"/>
+  <entry type="CommentPreproc" style="bold noitalic #888888"/>
+</style>