Merge pull request #33 from mmarkdown/citations

Citations

ast/node.go

@@ -39,6 +39,16 @@ const (
 	DocumentMatterBack
 )
 
+// CitationTypes holds the type of a citation, informative, normative or suppressed
+type CitationTypes int
+
+const (
+	CitationTypeNone CitationTypes = iota
+	CitationTypeSuppressed
+	CitationTypeInformative
+	CitationTypeNormative
+)
+
 // Node defines an ast node
 type Node interface {
 	AsContainer() *Container
@@ -240,6 +250,14 @@ type CrossReference struct {
 	Destination []byte // Destination is where the reference points to
 }
 
+// Citation is a citation node.
+type Citation struct {
+	Leaf
+
+	Destination [][]byte        // Destination is where the citation points to. Multiple ones are allowed.
+	Type        []CitationTypes // 1:1 mapping of destination and citation type
+}
+
 // Image represents markdown image node
 type Image struct {
 	Container

html/renderer.go

@@ -849,6 +849,24 @@ func (r *Renderer) matter(w io.Writer, node *ast.DocumentMatter, entering bool)
 	r.documentMatter = node.Matter
 }
 
+func (r *Renderer) citation(w io.Writer, node *ast.Citation) {
+	for i, c := range node.Destination {
+		attr := []string{`class="none"`}
+		switch node.Type[i] {
+		case ast.CitationTypeNormative:
+			attr[0] = `class="normative"`
+		case ast.CitationTypeInformative:
+			attr[0] = `class="informative"`
+		case ast.CitationTypeSuppressed:
+			attr[0] = `class="suppressed"`
+		}
+		r.outTag(w, "<cite", attr)
+		r.out(w, []byte("["))
+		r.out(w, c)
+		r.outs(w, "]</cite>")
+	}
+}
+
 // RenderNode renders a markdown node to HTML
 func (r *Renderer) RenderNode(w io.Writer, node ast.Node, entering bool) ast.WalkStatus {
 	if r.opts.RenderNodeHook != nil {
@@ -882,6 +900,8 @@ func (r *Renderer) RenderNode(w io.Writer, node ast.Node, entering bool) ast.Wal
 	case *ast.CrossReference:
 		link := &ast.Link{Destination: node.Destination}
 		r.link(w, link, entering)
+	case *ast.Citation:
+		r.citation(w, node)
 	case *ast.Image:
 		if r.opts.Flags&SkipImages != 0 {
 			return ast.SkipChildren

parser/citation.go

@@ -0,0 +1,72 @@
+package parser
+
+import (
+	"bytes"
+
+	"github.com/gomarkdown/markdown/ast"
+)
+
+// citation parses a citation. In its most simple form [@ref], we allow multiple
+// being separated by semicolons and a sub reference inside ala pandoc: [@ref p. 23].
+// Each citation can have a modifier: !, ? or - wich mean:
+//
+// ! - normative
+// ? - formative
+// - - suppressed
+func citation(p *Parser, data []byte, offset int) (int, ast.Node) {
+	// look for the matching closing bracket
+	i := offset + 1
+	for level := 1; level > 0 && i < len(data); i++ {
+		switch {
+		case data[i] == '\n':
+			// no newlines allowed.
+			return 0, nil
+
+		case data[i-1] == '\\':
+			continue
+
+		case data[i] == '[':
+			level++
+
+		case data[i] == ']':
+			level--
+			if level <= 0 {
+				i-- // compensate for extra i++ in for loop
+			}
+		}
+	}
+
+	if i >= len(data) {
+		return 0, nil
+	}
+
+	node := &ast.Citation{}
+
+	citations := bytes.Split(data[1:i], []byte(";"))
+	for _, citation := range citations {
+		citation = bytes.TrimSpace(citation)
+		j := 0
+		if citation[j] != '@' {
+			// not a citation, drop out entirely.
+			return 0, nil
+		}
+
+		citeType := ast.CitationTypeInformative
+		j = 1
+		switch citation[j] {
+		case '!':
+			citeType = ast.CitationTypeNormative
+			j++
+		case '?':
+			citeType = ast.CitationTypeInformative
+			j++
+		case '-':
+			citeType = ast.CitationTypeSuppressed
+			j++
+		}
+		node.Destination = append(node.Destination, citation[j:])
+		node.Type = append(node.Type, citeType)
+	}
+
+	return i + 1, node
+}

parser/inline.go

@@ -177,6 +177,7 @@ const (
 	linkImg
 	linkDeferredFootnote
 	linkInlineFootnote
+	linkCitation
 )
 
 func isReferenceStyleLink(data []byte, pos int, t linkType) bool {
@@ -200,7 +201,7 @@ func maybeInlineFootnote(p *Parser, data []byte, offset int) (int, ast.Node) {
 	return 0, nil
 }
 
-// '[': parse a link or an image or a footnote
+// '[': parse a link or an image or a footnote or a citation
 func link(p *Parser, data []byte, offset int) (int, ast.Node) {
 	// no links allowed inside regular links, footnote, and deferred footnotes
 	if p.insideLink && (offset > 0 && data[offset-1] == '[' || len(data)-1 > offset && data[offset+1] == '^') {
@@ -217,6 +218,10 @@ func link(p *Parser, data []byte, offset int) (int, ast.Node) {
 	case offset >= 0 && data[offset] == '!':
 		t = linkImg
 		offset++
+	// [@citation], [@-citation], [@?citation], [@!citation]
+	case p.extensions&Mmark != 0 && len(data)-1 > offset && data[offset+1] == '@':
+		t = linkCitation
+	// [text] == regular link
 	// ^[text] == inline footnote
 	// [^refId] == deferred footnote
 	case p.extensions&Footnotes != 0:
@@ -226,13 +231,16 @@ func link(p *Parser, data []byte, offset int) (int, ast.Node) {
 		} else if len(data)-1 > offset && data[offset+1] == '^' {
 			t = linkDeferredFootnote
 		}
-	// [text] == regular link
 	default:
 		t = linkNormal
 	}
 
 	data = data[offset:]
 
+	if t == linkCitation {
+		return citation(p, data, 0)
+	}
+
 	var (
 		i                       = 1
 		noteID                  int

testdata/mmark.test

@@ -44,3 +44,24 @@ Caption: Shakespeare.
 </blockquote>
 <figcaption>Shakespeare.</figcaption>
 </figure>
+---
+# Test Citations
+[@RFC1034]
+---
+<h1>Test_Citations</h1>
+
+<p><cite class="informative">[RFC1034]</cite></p>
+---
+# Test Multiple Citations
+[@RFC1034; @!RFC1035]
+---
+<h1>Test Multiple Citations</h1>
+
+<p><cite class="informative">[RFC1034]</cite><cite class="normative">[RFC1035]</cite></p>
+---
+# Test Multiple Citations with modifier
+[@-RFC1034] [@?RFC1035]
+---
+<h1>Test Multiple Citations with modifier</h1>
+
+<p><cite class="suppressed">[RFC1034]</cite> <cite class="informative">[RFC1035]</cite></p>