Add an `Up' link to the HTML navigation bar of sufficiently deep documents.

(This doesn't affect any of the source texts I know about.)
Also add <link rel="up">, even in the cases where it's just the same as
<link rel="ToC">. (This does.)

[originally from svn r7193]

3 files changed, 39 insertions, 5 deletions

diff --git a/bk_html.c b/bk_html.c
index 1d4aa5b..0c66eb7 100644
--- a/bk_html.c
+++ b/bk_html.c
@@ -61,7 +61,7 @@ typedef struct {
     char *body_tag, *nav_attr;
     wchar_t *author, *description;
     wchar_t *index_text, *contents_text, *preamble_text, *title_separator;
-    wchar_t *nav_prev_text, *nav_next_text, *nav_separator;
+    wchar_t *nav_prev_text, *nav_next_text, *nav_up_text, *nav_separator;
     wchar_t *index_main_sep, *index_multi_sep;
     wchar_t *pre_versionid, *post_versionid;
     int restrict_charset, output_charset;
@@ -282,6 +282,7 @@ static htmlconfig html_configure(paragraph *source) {
     ret.title_separator = L" - ";
     ret.nav_prev_text = L"Previous";
     ret.nav_next_text = L"Next";
+    ret.nav_up_text = L"Up";
     ret.nav_separator = L" | ";
     ret.index_main_sep = L": ";
     ret.index_multi_sep = L", ";
@@ -494,6 +495,8 @@ static htmlconfig html_configure(paragraph *source) {
 		ret.nav_prev_text = uadv(k);
 	    } else if (!ustricmp(k, L"html-nav-next-text")) {
 		ret.nav_next_text = uadv(k);
+	    } else if (!ustricmp(k, L"html-nav-up-text")) {
+		ret.nav_up_text = uadv(k);
 	    } else if (!ustricmp(k, L"html-nav-separator")) {
 		ret.nav_separator = uadv(k);
 	    } else if (!ustricmp(k, L"html-index-main-separator")) {
@@ -970,8 +973,6 @@ void html_backend(paragraph *sourceform, keywordlist *keywords,
 		    html_nl(&ho);
 		}
 
-		/* FIXME: link rel="up" */
-
 		if (f != files.head) {
 		    element_empty(&ho, "link");
 		    element_attr(&ho, "rel", "ToC");
@@ -979,6 +980,17 @@ void html_backend(paragraph *sourceform, keywordlist *keywords,
 		    html_nl(&ho);
 		}
 
+		if (conf.leaf_level > 0) {
+		    htmlsect *p = f->first->parent;
+		    assert(p == f->last->parent);
+		    if (p) {
+			element_empty(&ho, "link");
+			element_attr(&ho, "rel", "up");
+			element_attr(&ho, "href", p->file->filename);
+			html_nl(&ho);
+		    }
+		}
+
 		if (has_index && files.index && f != files.index) {
 		    element_empty(&ho, "link");
 		    element_attr(&ho, "rel", "index");
@@ -1057,6 +1069,22 @@ void html_backend(paragraph *sourceform, keywordlist *keywords,
 		if (f != files.head)
 		    element_close(&ho, "a");
 
+		/* We don't bother with "Up" links for leaf-level 1,
+		 * as they would be identical to the "Contents" links. */
+		if (conf.leaf_level >= 2) {
+		    htmlsect *p = f->first->parent;
+		    assert(p == f->last->parent);
+		    html_text(&ho, conf.nav_separator);
+		    if (p) {
+			element_open(&ho, "a");
+			element_attr(&ho, "href", p->file->filename);
+		    }
+		    html_text(&ho, conf.nav_up_text);
+		    if (p) {
+			element_close(&ho, "a");
+		    }
+		}
+
 		if (has_index && files.index) {
 		    html_text(&ho, conf.nav_separator);
 		    if (f != files.index) {
diff --git a/doc/index.but b/doc/index.but
index e9d6e51..351e3d2 100644
--- a/doc/index.but
+++ b/doc/index.but
@@ -305,6 +305,9 @@ configuration directive
 \IM{\\cfg\{html-nav-next-text\}} \c{html-nav-next-text} configuration directive
 \IM{\\cfg\{html-nav-next-text\}} \cw{\\cfg\{html-nav-next-text\}}
 
+\IM{\\cfg\{html-nav-up-text\}} \c{html-nav-up-text} configuration directive
+\IM{\\cfg\{html-nav-up-text\}} \cw{\\cfg\{html-nav-up-text\}}
+
 \IM{\\cfg\{html-nav-separator\}} \c{html-nav-separator} configuration directive
 \IM{\\cfg\{html-nav-separator\}} \cw{\\cfg\{html-nav-separator\}}
 
diff --git a/doc/output.but b/doc/output.but
index 0cea3c2..98637df 100644
--- a/doc/output.but
+++ b/doc/output.but
@@ -664,8 +664,10 @@ the index.
 
 \dt \I{\cw{\\cfg\{html-nav-next-text\}}}\cw{\\cfg\{html-nav-next-text\}\{}\e{text}\cw{\}}
 
-\dd The text used for the \q{previous page} and \q{next page} links on
-the navigation bar.
+\dt \I{\cw{\\cfg\{html-nav-up-text\}}}\cw{\\cfg\{html-nav-up-text\}\{}\e{text}\cw{\}}
+
+\dd The text used for the \q{previous page}, \q{next page}, and \q{up}
+links on the navigation bar.
 
 \dt \I{\cw{\\cfg\{html-nav-separator\}}}\cw{\\cfg\{html-nav-separator\}\{}\e{text}\cw{\}}
 
@@ -965,6 +967,7 @@ The \i{default settings} for Halibut's HTML output format are:
 \c \cfg{html-post-versionid}{]}
 \c \cfg{html-nav-prev-text}{Previous}
 \c \cfg{html-nav-next-text}{Next}
+\c \cfg{html-nav-up-text}{Up}
 \c \cfg{html-nav-separator}{ | }
 \c
 \c \cfg{html-output-charset}{ASCII}