all: add support for document attribute "last-update-label"

By default the last-update-label value set to "Last updated" and the
value is the document modification time.

If the label is suppressed with "!", no "Last updated" will be print
on the footer.

5 files changed, 56 insertions, 47 deletions

diff --git a/README b/README
index 0d16fd0..4770e22 100644
--- a/README
+++ b/README
@@ -129,6 +129,7 @@ Supported metadata or attribute references,
 * `idprefix`
 * `idseparator`
 * `lastname(_x)`
+* `last-update-label`
 * `middlename(_x)`
 * `nofooter`
 * `noheader`
diff --git a/attribute_entry.go b/attribute_entry.go
index a4dd722..c1d329f 100644
--- a/attribute_entry.go
+++ b/attribute_entry.go
@@ -11,11 +11,13 @@ type AttributeEntry map[string]string
 
 func newAttributeEntry() AttributeEntry {
 	return AttributeEntry{
-		MetaNameGenerator:    `asciidoctor-go ` + Version,
-		metaNameSectIDs:      ``,
-		metaNameShowTitle:    ``,
-		metaNameTableCaption: ``,
-		metaNameVersionLabel: ``,
+		MetaNameGenerator:       `asciidoctor-go ` + Version,
+		metaNameLastUpdateLabel: `Last updated`,
+		metaNameLastUpdateValue: ``,
+		metaNameSectIDs:         ``,
+		metaNameShowTitle:       ``,
+		metaNameTableCaption:    ``,
+		metaNameVersionLabel:    ``,
 	}
 }
 
diff --git a/document.go b/document.go
index 2b34300..aa6672a 100644
--- a/document.go
+++ b/document.go
@@ -43,7 +43,6 @@ type Document struct {
 
 	Revision Revision
 
-	LastUpdated string
 	file        string
 	fpath       string
 	rawAuthors  string
@@ -128,7 +127,7 @@ func Open(file string) (doc *Document, err error) {
 	doc = newDocument()
 	doc.fpath = filepath.Join(wd, file)
 	doc.file = file
-	doc.LastUpdated = fi.ModTime().Round(time.Second).Format(`2006-01-02 15:04:05 Z0700`)
+	doc.Attributes[metaNameLastUpdateValue] = fi.ModTime().Round(time.Second).Format(`2006-01-02 15:04:05 Z0700`)
 
 	parse(doc, raw)
 
diff --git a/html_backend.go b/html_backend.go
index 1bbefcb..1635328 100644
--- a/html_backend.go
+++ b/html_backend.go
@@ -880,28 +880,33 @@ func htmlWriteBody(doc *Document, out *bytes.Buffer) {
 }
 
 func htmlWriteFooter(doc *Document, out io.Writer) {
+	var (
+		label string
+		value string
+		ok    bool
+	)
+
 	fmt.Fprint(out, `
 <div id="footer">
 <div id="footer-text">`)
 
 	if len(doc.Revision.Number) > 0 {
-		var (
-			prefix string
-			ok     bool
-		)
-
-		prefix, ok = doc.Attributes[metaNameVersionLabel]
-		if ok && len(prefix) == 0 {
-			prefix = `Version `
+		label, ok = doc.Attributes[metaNameVersionLabel]
+		if ok && len(label) == 0 {
+			label = `Version `
 		} else {
-			prefix = ` `
+			label = ` `
 		}
 
-		fmt.Fprintf(out, "\n%s%s<br>", prefix, doc.Revision.Number)
+		fmt.Fprintf(out, "\n%s%s<br>", label, doc.Revision.Number)
 	}
 
-	if len(doc.LastUpdated) > 0 {
-		fmt.Fprintf(out, "\nLast updated %s", doc.LastUpdated)
+	label, ok = doc.Attributes[metaNameLastUpdateLabel]
+	if ok {
+		value = doc.Attributes[metaNameLastUpdateValue]
+		if len(value) != 0 {
+			fmt.Fprintf(out, "\n%s %s", label, value)
+		}
 	}
 
 	fmt.Fprint(out, "\n</div>\n</div>")
diff --git a/parser.go b/parser.go
index bc7da9e..fe6e0ff 100644
--- a/parser.go
+++ b/parser.go
@@ -178,34 +178,36 @@ const (
 	MetaNameGenerator   = `generator`
 	MetaNameKeywords    = `keywords`
 
-	metaNameAuthorInitials = `authorinitials`
-	metaNameDocTitle       = `doctitle`
-	metaNameEmail          = attrValueEmail
-	metaNameFirstName      = `firstname`
-	metaNameIDPrefix       = `idprefix`
-	metaNameIDSeparator    = `idseparator`
-	metaNameLastName       = `lastname`
-	metaNameMiddleName     = `middlename`
-	metaNameNoFooter       = `nofooter`
-	metaNameNoHeader       = `noheader`
-	metaNameNoHeaderFooter = `no-header-footer`
-	metaNameNoTitle        = `notitle`
-	metaNameRevDate        = `revdate`
-	metaNameRevNumber      = `revnumber`
-	metaNameRevRemark      = `revremark`
-	metaNameSectAnchors    = `sectanchors`
-	metaNameSectIDs        = `sectids`
-	metaNameSectLinks      = `sectlinks`
-	metaNameSectNumLevel   = `sectnumlevels`
-	metaNameSectNums       = `sectnums`
-	metaNameShowTitle      = `showtitle`
-	metaNameTOC            = `toc`
-	metaNameTOCLevels      = `toclevels`
-	metaNameTOCTitle       = `toc-title`
-	metaNameTableCaption   = `table-caption`
-	metaNameTitle          = attrNameTitle
-	metaNameTitleSeparator = `title-separator`
-	metaNameVersionLabel   = `version-label`
+	metaNameAuthorInitials  = `authorinitials`
+	metaNameDocTitle        = `doctitle`
+	metaNameEmail           = attrValueEmail
+	metaNameFirstName       = `firstname`
+	metaNameIDPrefix        = `idprefix`
+	metaNameIDSeparator     = `idseparator`
+	metaNameLastName        = `lastname`
+	metaNameLastUpdateLabel = `last-update-label`
+	metaNameLastUpdateValue = `last-update-value`
+	metaNameMiddleName      = `middlename`
+	metaNameNoFooter        = `nofooter`
+	metaNameNoHeader        = `noheader`
+	metaNameNoHeaderFooter  = `no-header-footer`
+	metaNameNoTitle         = `notitle`
+	metaNameRevDate         = `revdate`
+	metaNameRevNumber       = `revnumber`
+	metaNameRevRemark       = `revremark`
+	metaNameSectAnchors     = `sectanchors`
+	metaNameSectIDs         = `sectids`
+	metaNameSectLinks       = `sectlinks`
+	metaNameSectNumLevel    = `sectnumlevels`
+	metaNameSectNums        = `sectnums`
+	metaNameShowTitle       = `showtitle`
+	metaNameTOC             = `toc`
+	metaNameTOCLevels       = `toclevels`
+	metaNameTOCTitle        = `toc-title`
+	metaNameTableCaption    = `table-caption`
+	metaNameTitle           = attrNameTitle
+	metaNameTitleSeparator  = `title-separator`
+	metaNameVersionLabel    = `version-label`
 )
 
 // List of possible metadata value.