Merge pull request #31 from mmarkdown/ref

Mmark: corss references

ast/node.go

@@ -233,6 +233,13 @@ type Link struct {
 	Footnote    Node   // If it's a footnote, this is a direct link to the footnote Node. Otherwise nil.
 }
 
+// CrossReference is a reference node.
+type CrossReference struct {
+	Container
+
+	Destination []byte // Destination is where the reference points to
+}
+
 // Image represents markdown image node
 type Image struct {
 	Container

html/renderer.go

@@ -879,6 +879,9 @@ func (r *Renderer) RenderNode(w io.Writer, node ast.Node, entering bool) ast.Wal
 		r.outOneOfCr(w, entering, tag, "</aside>")
 	case *ast.Link:
 		r.link(w, node, entering)
+	case *ast.CrossReference:
+		link := &ast.Link{Destination: node.Destination}
+		r.link(w, link, entering)
 	case *ast.Image:
 		if r.opts.Flags&SkipImages != 0 {
 			return ast.SkipChildren

parser/parser.go

@@ -38,10 +38,11 @@ const (
 	MathJax                                       // Parse MathJax
 	OrderedListStart                              // Keep track of the first number used when starting an ordered list.
 	Attributes                                    // Block Attributes
-	MmarkSpecialHeading                           // Allow Mmark special headings to be parsed. See mmark.nl/syntax
 	MmarkAsides                                   // Mmark asides paragraphs. See https://mmark.nl/syntax
-	MmarkMatters                                  // Mmark document divisions
 	MmarkCaptions                                 // Allow Mmark captions under code and quote blocks be parsed.
+	MmarkMatters                                  // Mmark document divisions, see https://mmark.nl/syntax#document-matters
+	MmarkReferenceIndex                           // Mmark cross references and indices. See https://mmark.nl/syntax#cross-references
+	MmarkSpecialHeading                           // Allow Mmark special headings to be parsed. See mmark.nl/syntax
 
 	CommonExtensions Extensions = NoIntraEmphasis | Tables | FencedCode |
 		Autolink | Strikethrough | SpaceHeadings | HeadingIDs |
@@ -146,6 +147,9 @@ func NewWithExtensions(extension Extensions) *Parser {
 	p.inlineCallback['\\'] = escape
 	p.inlineCallback['&'] = entity
 	p.inlineCallback['!'] = maybeImage
+	if p.extensions&MmarkReferenceIndex != 0 {
+		p.inlineCallback['('] = maybeShortRefOrIndex
+	}
 	p.inlineCallback['^'] = maybeInlineFootnote
 	if p.extensions&Autolink != 0 {
 		p.inlineCallback['h'] = maybeAutoLink

parser/ref.go

@@ -0,0 +1,44 @@
+package parser
+
+import "github.com/gomarkdown/markdown/ast"
+
+// parse '(#r)', where r does not contain spaces and is an existing label. Or.
+// (!item) (!item, subitem), for an index, (!!item) signals primary.
+func maybeShortRefOrIndex(p *Parser, data []byte, offset int) (int, ast.Node) {
+	if len(data[offset:]) < 4 {
+		return 0, nil
+	}
+	// short ref first
+	data = data[offset:]
+	i := 1
+	if data[i] != '#' {
+		return 0, nil
+	}
+	i++
+Loop:
+	for i < len(data) {
+		c := data[i]
+		switch {
+		case c == ')':
+			break Loop
+		case !isAlnum(c):
+			if c == '_' || c == '-' || c == ':' {
+				i++
+				continue
+			}
+			i = 0
+			break Loop
+		}
+		i++
+	}
+	// end not found or no valid syntax
+	if i == 0 || data[i-1] != ')' {
+		return 0, nil
+	}
+
+	id := data[2:i]
+	node := &ast.CrossReference{}
+	node.Destination = id
+
+	return i, node
+}

parser/ref_test.go

@@ -0,0 +1,38 @@
+package parser
+
+import (
+	"testing"
+
+	"github.com/gomarkdown/markdown/ast"
+)
+
+func TestCrossReference(t *testing.T) {
+	p := New()
+
+	tests := []struct {
+		data []byte
+		r    *ast.CrossReference
+		fail bool
+	}{
+		// ok
+		{
+			data: []byte("(#yes)"),
+			r:    &ast.CrossReference{Destination: []byte("yes")},
+		},
+		// ok
+		{
+			data: []byte("(#y:es)"),
+			r:    &ast.CrossReference{Destination: []byte("y:es")},
+		},
+		// fails
+		{data: []byte("(#y es)"), r: nil, fail: true},
+		{data: []byte("(#yes"), r: nil, fail: true},
+	}
+
+	for i, test := range tests {
+		_, n := maybeShortRefOrIndex(p, test.data, 0)
+		if test.fail && n != nil {
+			t.Errorf("test %d, should have failed to parse %s", i, test.data)
+		}
+	}
+}