Initial import of xtrkcad version 1:4.0.2-2

1 files changed, 2791 insertions, 0 deletions

diff --git a/app/tools/halibut/bk_html.c b/app/tools/halibut/bk_html.c
new file mode 100644
index 0000000..8b5443b
--- /dev/null
+++ b/app/tools/halibut/bk_html.c
@@ -0,0 +1,2791 @@
+/*
+ * HTML backend for Halibut
+ */
+
+/*
+ * TODO:
+ * 
+ *  - I'm never entirely convinced that having a fragment link to
+ *    come in at the start of the real text in the file is
+ *    sensible. Perhaps for the topmost section in the file, no
+ *    fragment should be used? (Though it should probably still be
+ *    _there_ even if unused.)
+ * 
+ *  - In HHK index mode: subsidiary hhk entries (as in replacing
+ *    `foo, bar' with `foo\n\tbar') can be done by embedding
+ *    sub-<UL>s in the hhk file. This requires me getting round to
+ *    supporting that idiom in the rest of Halibut, but I thought
+ *    I'd record how it's done here in case I turn out to have
+ *    forgotten when I get there.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <limits.h>
+#include "halibut.h"
+
+#define is_heading_type(type) ( (type) == para_Title || \
+				(type) == para_Chapter || \
+				(type) == para_Appendix || \
+				(type) == para_UnnumberedChapter || \
+				(type) == para_Heading || \
+				(type) == para_Subsect)
+
+#define heading_depth(p) ( (p)->type == para_Subsect ? (p)->aux + 1 : \
+			   (p)->type == para_Heading ? 1 : \
+			   (p)->type == para_Title ? -1 : 0 )
+
+typedef struct {
+    int just_numbers;
+    wchar_t *number_suffix;
+} sectlevel;
+
+typedef struct {
+    int nasect;
+    sectlevel achapter, *asect;
+    int *contents_depths;	       /* 0=main, 1=chapter, 2=sect etc */
+    int ncdepths;
+    int address_section, visible_version_id;
+    int leaf_contains_contents, leaf_smallest_contents;
+    int navlinks;
+    int rellinks;
+    char *contents_filename;
+    char *index_filename;
+    char *template_filename;
+    char *single_filename;
+    char *chm_filename, *hhp_filename, *hhc_filename, *hhk_filename;
+    char **template_fragments;
+    int ntfragments;
+    char *head_end, *body_start, *body_end, *addr_start, *addr_end;
+    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 *index_main_sep, *index_multi_sep;
+    wchar_t *pre_versionid, *post_versionid;
+    int restrict_charset, output_charset;
+    enum {
+	HTML_3_2, HTML_4, ISO_HTML,
+	XHTML_1_0_TRANSITIONAL, XHTML_1_0_STRICT
+    } htmlver;
+    wchar_t *lquote, *rquote;
+    int leaf_level;
+} htmlconfig;
+
+#define contents_depth(conf, level) \
+    ( (conf).ncdepths > (level) ? (conf).contents_depths[level] : (level)+2 )
+
+#define is_xhtml(ver) ((ver) >= XHTML_1_0_TRANSITIONAL)
+
+typedef struct htmlfile htmlfile;
+typedef struct htmlsect htmlsect;
+
+struct htmlfile {
+    htmlfile *next;
+    char *filename;
+    int last_fragment_number;
+    int min_heading_depth;
+    htmlsect *first, *last;	       /* first/last highest-level sections */
+    /*
+     * The `temp' field is available for use in individual passes
+     * over the file list. For example, the HHK index generation
+     * uses it to ensure no index term references the same file
+     * more than once.
+     */
+    int temp;
+};
+
+struct htmlsect {
+    htmlsect *next, *parent;
+    htmlfile *file;
+    paragraph *title, *text;
+    enum { NORMAL, TOP, INDEX } type;
+    int contents_depth;
+    char **fragments;
+};
+
+typedef struct {
+    htmlfile *head, *tail;
+    htmlfile *single, *index;
+    tree234 *frags;
+    tree234 *files;
+} htmlfilelist;
+
+typedef struct {
+    htmlsect *head, *tail;
+} htmlsectlist;
+
+typedef struct {
+    htmlfile *file;
+    char *fragment;
+} htmlfragment;
+
+typedef struct {
+    int nrefs, refsize;
+    word **refs;
+} htmlindex;
+
+typedef struct {
+    htmlsect *section;
+    char *fragment;
+    int generated, referenced;
+} htmlindexref;
+
+typedef struct {
+    /*
+     * This level deals with charset conversion, starting and
+     * ending tags, and writing to the file. It's the lexical
+     * level.
+     */
+    FILE *fp;
+    int charset, restrict_charset;
+    charset_state cstate;
+    int ver;
+    enum {
+	HO_NEUTRAL, HO_IN_TAG, HO_IN_EMPTY_TAG, HO_IN_TEXT
+    } state;
+    int hackflags;		       /* used for icky .HH* stuff */
+    int hacklimit;		       /* text size limit, again for .HH* */
+    /*
+     * Stuff beyond here deals with the higher syntactic level: it
+     * tracks how many levels of <ul> are currently open when
+     * producing a contents list, for example.
+     */
+    int contents_level;
+} htmloutput;
+
+/*
+ * Nasty hacks that modify the behaviour of htmloutput files. All
+ * of these are flag bits set in ho.hackflags. HO_HACK_QUOTEQUOTES
+ * has the same effect as the `quote_quotes' parameter to
+ * html_text_limit_internal, except that it's set globally on an
+ * entire htmloutput structure; HO_HACK_QUOTENOTHING suppresses
+ * quoting of any HTML special characters (for .HHP files);
+ * HO_HACK_OMITQUOTES completely suppresses the generation of
+ * double quotes at all (turning them into single quotes, for want
+ * of a better idea).
+ */
+#define HO_HACK_QUOTEQUOTES 1
+#define HO_HACK_QUOTENOTHING 2
+#define HO_HACK_OMITQUOTES 4
+
+static int html_fragment_compare(void *av, void *bv)
+{
+    htmlfragment *a = (htmlfragment *)av;
+    htmlfragment *b = (htmlfragment *)bv;
+    int cmp;
+
+    if ((cmp = strcmp(a->file->filename, b->file->filename)) != 0)
+	return cmp;
+    else
+	return strcmp(a->fragment, b->fragment);
+}
+
+static int html_filename_compare(void *av, void *bv)
+{
+    char *a = (char *)av;
+    char *b = (char *)bv;
+
+    return strcmp(a, b);
+}
+
+static void html_file_section(htmlconfig *cfg, htmlfilelist *files,
+			      htmlsect *sect, int depth);
+
+static htmlfile *html_new_file(htmlfilelist *list, char *filename);
+static htmlsect *html_new_sect(htmlsectlist *list, paragraph *title,
+			       htmlconfig *cfg);
+
+/* Flags for html_words() flags parameter */
+#define NOTHING 0x00
+#define MARKUP 0x01
+#define LINKS 0x02
+#define INDEXENTS 0x04
+#define ALL 0x07
+static void html_words(htmloutput *ho, word *words, int flags,
+		       htmlfile *file, keywordlist *keywords, htmlconfig *cfg);
+static void html_codepara(htmloutput *ho, word *words);
+
+static void return_to_neutral(htmloutput *ho);
+static void element_open(htmloutput *ho, char const *name);
+static void element_close(htmloutput *ho, char const *name);
+static void element_empty(htmloutput *ho, char const *name);
+static void element_attr(htmloutput *ho, char const *name, char const *value);
+static void element_attr_w(htmloutput *ho, char const *name,
+			   wchar_t const *value);
+static void html_text(htmloutput *ho, wchar_t const *str);
+static void html_text_nbsp(htmloutput *ho, wchar_t const *str);
+static void html_text_limit(htmloutput *ho, wchar_t const *str, int maxlen);
+static void html_text_limit_internal(htmloutput *ho, wchar_t const *text,
+				     int maxlen, int quote_quotes, int nbsp);
+static void html_nl(htmloutput *ho);
+static void html_raw(htmloutput *ho, char *text);
+static void html_raw_as_attr(htmloutput *ho, char *text);
+static void cleanup(htmloutput *ho);
+
+static void html_href(htmloutput *ho, htmlfile *thisfile,
+		      htmlfile *targetfile, char *targetfrag);
+static void html_fragment(htmloutput *ho, char const *fragment);
+
+static char *html_format(paragraph *p, char *template_string);
+static char *html_sanitise_fragment(htmlfilelist *files, htmlfile *file,
+				    char *text);
+static char *html_sanitise_filename(htmlfilelist *files, char *text);
+
+static void html_contents_entry(htmloutput *ho, int depth, htmlsect *s,
+				htmlfile *thisfile, keywordlist *keywords,
+				htmlconfig *cfg);
+static void html_section_title(htmloutput *ho, htmlsect *s,
+			       htmlfile *thisfile, keywordlist *keywords,
+			       htmlconfig *cfg, int real);
+
+static htmlconfig html_configure(paragraph *source) {
+    htmlconfig ret;
+    paragraph *p;
+
+    /*
+     * Defaults.
+     */
+    ret.leaf_level = 2;
+    ret.achapter.just_numbers = FALSE;
+    ret.achapter.number_suffix = L": ";
+    ret.nasect = 1;
+    ret.asect = snewn(ret.nasect, sectlevel);
+    ret.asect[0].just_numbers = TRUE;
+    ret.asect[0].number_suffix = L" ";
+    ret.ncdepths = 0;
+    ret.contents_depths = 0;
+    ret.visible_version_id = TRUE;
+    ret.address_section = TRUE;
+    ret.leaf_contains_contents = FALSE;
+    ret.leaf_smallest_contents = 4;
+    ret.navlinks = TRUE;
+    ret.rellinks = TRUE;
+    ret.single_filename = dupstr("Manual.html");
+    ret.contents_filename = dupstr("Contents.html");
+    ret.index_filename = dupstr("IndexPage.html");
+    ret.template_filename = dupstr("%n.html");
+    ret.chm_filename = ret.hhp_filename = NULL;
+    ret.hhc_filename = ret.hhk_filename = NULL;
+    ret.ntfragments = 1;
+    ret.template_fragments = snewn(ret.ntfragments, char *);
+    ret.template_fragments[0] = dupstr("%b");
+    ret.head_end = ret.body_tag = ret.body_start = ret.body_end =
+	ret.addr_start = ret.addr_end = ret.nav_attr = NULL;
+    ret.author = ret.description = NULL;
+    ret.restrict_charset = CS_UTF8;
+    ret.output_charset = CS_ASCII;
+    ret.htmlver = HTML_4;
+    ret.index_text = L"Index";
+    ret.contents_text = L"Contents";
+    ret.preamble_text = L"Preamble";
+    ret.title_separator = L" - ";
+    ret.nav_prev_text = L"Previous";
+    ret.nav_next_text = L"Next";
+    ret.nav_separator = L" | ";
+    ret.index_main_sep = L": ";
+    ret.index_multi_sep = L", ";
+    ret.pre_versionid = L"[";
+    ret.post_versionid = L"]";
+    /*
+     * Default quote characters are Unicode matched single quotes,
+     * falling back to ordinary ASCII ".
+     */
+    ret.lquote = L"\x2018\0\x2019\0\"\0\"\0\0";
+    ret.rquote = uadv(ret.lquote);
+
+    /*
+     * Two-pass configuration so that we can pick up global config
+     * (e.g. `quotes') before having it overridden by specific
+     * config (`html-quotes'), irrespective of the order in which
+     * they occur.
+     */
+    for (p = source; p; p = p->next) {
+	if (p->type == para_Config) {
+	    if (!ustricmp(p->keyword, L"quotes")) {
+		if (*uadv(p->keyword) && *uadv(uadv(p->keyword))) {
+		    ret.lquote = uadv(p->keyword);
+		    ret.rquote = uadv(ret.lquote);
+		}
+	    } else if (!ustricmp(p->keyword, L"index")) {
+		ret.index_text = uadv(p->keyword);
+	    } else if (!ustricmp(p->keyword, L"contents")) {
+		ret.contents_text = uadv(p->keyword);
+	    }
+	}
+    }
+
+    for (p = source; p; p = p->next) {
+	if (p->type == para_Config) {
+	    wchar_t *k = p->keyword;
+
+	    if (!ustrnicmp(k, L"xhtml-", 6))
+		k++;		    /* treat `xhtml-' and `html-' the same */
+
+	    if (!ustricmp(k, L"html-restrict-charset")) {
+		ret.restrict_charset = charset_from_ustr(&p->fpos, uadv(k));
+	    } else if (!ustricmp(k, L"html-output-charset")) {
+		ret.output_charset = charset_from_ustr(&p->fpos, uadv(k));
+	    } else if (!ustricmp(k, L"html-version")) {
+		wchar_t *vername = uadv(k);
+		static const struct {
+		    const wchar_t *name;
+		    int ver;
+		} versions[] = {
+		    {L"html3.2", HTML_3_2},
+		    {L"html4", HTML_4},
+		    {L"iso-html", ISO_HTML},
+		    {L"xhtml1.0transitional", XHTML_1_0_TRANSITIONAL},
+		    {L"xhtml1.0strict", XHTML_1_0_STRICT}
+		};
+		int i;
+
+		for (i = 0; i < (int)lenof(versions); i++)
+		    if (!ustricmp(versions[i].name, vername))
+			break;
+
+		if (i == lenof(versions))
+		    error(err_htmlver, &p->fpos, vername);
+		else
+		    ret.htmlver = versions[i].ver;
+	    } else if (!ustricmp(k, L"html-single-filename")) {
+		sfree(ret.single_filename);
+		ret.single_filename = dupstr(adv(p->origkeyword));
+	    } else if (!ustricmp(k, L"html-contents-filename")) {
+		sfree(ret.contents_filename);
+		ret.contents_filename = dupstr(adv(p->origkeyword));
+	    } else if (!ustricmp(k, L"html-index-filename")) {
+		sfree(ret.index_filename);
+		ret.index_filename = dupstr(adv(p->origkeyword));
+	    } else if (!ustricmp(k, L"html-template-filename")) {
+		sfree(ret.template_filename);
+		ret.template_filename = dupstr(adv(p->origkeyword));
+	    } else if (!ustricmp(k, L"html-template-fragment")) {
+		char *frag = adv(p->origkeyword);
+		if (*frag) {
+		    while (ret.ntfragments--)
+			sfree(ret.template_fragments[ret.ntfragments]);
+		    sfree(ret.template_fragments);
+		    ret.template_fragments = NULL;
+		    ret.ntfragments = 0;
+		    while (*frag) {
+			ret.ntfragments++;
+			ret.template_fragments =
+			    sresize(ret.template_fragments,
+				    ret.ntfragments, char *);
+			ret.template_fragments[ret.ntfragments-1] =
+			    dupstr(frag);
+			frag = adv(frag);
+		    }
+		} else
+		    error(err_cfginsufarg, &p->fpos, p->origkeyword, 1);
+	    } else if (!ustricmp(k, L"html-chapter-numeric")) {
+		ret.achapter.just_numbers = utob(uadv(k));
+	    } else if (!ustricmp(k, L"html-suppress-navlinks")) {
+		ret.navlinks = !utob(uadv(k));
+	    } else if (!ustricmp(k, L"html-rellinks")) {
+		ret.rellinks = utob(uadv(k));
+	    } else if (!ustricmp(k, L"html-chapter-suffix")) {
+		ret.achapter.number_suffix = uadv(k);
+	    } else if (!ustricmp(k, L"html-leaf-level")) {
+		wchar_t *u = uadv(k);
+		if (!ustricmp(u, L"infinite") ||
+		    !ustricmp(u, L"infinity") ||
+		    !ustricmp(u, L"inf"))
+		    ret.leaf_level = -1;   /* represents infinity */
+		else
+		    ret.leaf_level = utoi(u);
+	    } else if (!ustricmp(k, L"html-section-numeric")) {
+		wchar_t *q = uadv(k);
+		int n = 0;
+		if (uisdigit(*q)) {
+		    n = utoi(q);
+		    q = uadv(q);
+		}
+		if (n >= ret.nasect) {
+		    int i;
+		    ret.asect = sresize(ret.asect, n+1, sectlevel);
+		    for (i = ret.nasect; i <= n; i++)
+			ret.asect[i] = ret.asect[ret.nasect-1];
+		    ret.nasect = n+1;
+		}
+		ret.asect[n].just_numbers = utob(q);
+	    } else if (!ustricmp(k, L"html-section-suffix")) {
+		wchar_t *q = uadv(k);
+		int n = 0;
+		if (uisdigit(*q)) {
+		    n = utoi(q);
+		    q = uadv(q);
+		}
+		if (n >= ret.nasect) {
+		    int i;
+		    ret.asect = sresize(ret.asect, n+1, sectlevel);
+		    for (i = ret.nasect; i <= n; i++) {
+			ret.asect[i] = ret.asect[ret.nasect-1];
+		    }
+		    ret.nasect = n+1;
+		}
+		ret.asect[n].number_suffix = q;
+	    } else if (!ustricmp(k, L"html-contents-depth") ||
+		       !ustrnicmp(k, L"html-contents-depth-", 20)) {
+		/*
+		 * Relic of old implementation: this directive used
+		 * to be written as \cfg{html-contents-depth-3}{2}
+		 * rather than the usual Halibut convention of
+		 * \cfg{html-contents-depth}{3}{2}. We therefore
+		 * support both.
+		 */
+		wchar_t *q = k[19] ? k+20 : uadv(k);
+		int n = 0;
+		if (uisdigit(*q)) {
+		    n = utoi(q);
+		    q = uadv(q);
+		}
+		if (n >= ret.ncdepths) {
+		    int i;
+		    ret.contents_depths =
+			sresize(ret.contents_depths, n+1, int);
+		    for (i = ret.ncdepths; i <= n; i++) {
+			ret.contents_depths[i] = i+2;
+		    }
+		    ret.ncdepths = n+1;
+		}
+		ret.contents_depths[n] = utoi(q);
+	    } else if (!ustricmp(k, L"html-head-end")) {
+		ret.head_end = adv(p->origkeyword);
+	    } else if (!ustricmp(k, L"html-body-tag")) {
+		ret.body_tag = adv(p->origkeyword);
+	    } else if (!ustricmp(k, L"html-body-start")) {
+		ret.body_start = adv(p->origkeyword);
+	    } else if (!ustricmp(k, L"html-body-end")) {
+		ret.body_end = adv(p->origkeyword);
+	    } else if (!ustricmp(k, L"html-address-start")) {
+		ret.addr_start = adv(p->origkeyword);
+	    } else if (!ustricmp(k, L"html-address-end")) {
+		ret.addr_end = adv(p->origkeyword);
+	    } else if (!ustricmp(k, L"html-navigation-attributes")) {
+		ret.nav_attr = adv(p->origkeyword);
+	    } else if (!ustricmp(k, L"html-author")) {
+		ret.author = uadv(k);
+	    } else if (!ustricmp(k, L"html-description")) {
+		ret.description = uadv(k);
+	    } else if (!ustricmp(k, L"html-suppress-address")) {
+		ret.address_section = !utob(uadv(k));
+	    } else if (!ustricmp(k, L"html-versionid")) {
+		ret.visible_version_id = utob(uadv(k));
+	    } else if (!ustricmp(k, L"html-quotes")) {
+		if (*uadv(k) && *uadv(uadv(k))) {
+		    ret.lquote = uadv(k);
+		    ret.rquote = uadv(ret.lquote);
+		}
+	    } else if (!ustricmp(k, L"html-leaf-contains-contents")) {
+		ret.leaf_contains_contents = utob(uadv(k));
+	    } else if (!ustricmp(k, L"html-leaf-smallest-contents")) {
+		ret.leaf_smallest_contents = utoi(uadv(k));
+	    } else if (!ustricmp(k, L"html-index-text")) {
+		ret.index_text = uadv(k);
+	    } else if (!ustricmp(k, L"html-contents-text")) {
+		ret.contents_text = uadv(k);
+	    } else if (!ustricmp(k, L"html-preamble-text")) {
+		ret.preamble_text = uadv(k);
+	    } else if (!ustricmp(k, L"html-title-separator")) {
+		ret.title_separator = uadv(k);
+	    } else if (!ustricmp(k, L"html-nav-prev-text")) {
+		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-separator")) {
+		ret.nav_separator = uadv(k);
+	    } else if (!ustricmp(k, L"html-index-main-separator")) {
+		ret.index_main_sep = uadv(k);
+	    } else if (!ustricmp(k, L"html-index-multiple-separator")) {
+		ret.index_multi_sep = uadv(k);
+	    } else if (!ustricmp(k, L"html-pre-versionid")) {
+		ret.pre_versionid = uadv(k);
+	    } else if (!ustricmp(k, L"html-post-versionid")) {
+		ret.post_versionid = uadv(k);
+	    } else if (!ustricmp(k, L"html-mshtmlhelp-chm")) {
+		sfree(ret.chm_filename);
+		ret.chm_filename = dupstr(adv(p->origkeyword));
+	    } else if (!ustricmp(k, L"html-mshtmlhelp-project")) {
+		sfree(ret.hhp_filename);
+		ret.hhp_filename = dupstr(adv(p->origkeyword));
+	    } else if (!ustricmp(k, L"html-mshtmlhelp-contents")) {
+		sfree(ret.hhc_filename);
+		ret.hhc_filename = dupstr(adv(p->origkeyword));
+	    } else if (!ustricmp(k, L"html-mshtmlhelp-index")) {
+		sfree(ret.hhk_filename);
+		ret.hhk_filename = dupstr(adv(p->origkeyword));
+	    }
+	}
+    }
+
+    /*
+     * Enforce that the CHM and HHP filenames must either be both
+     * present or both absent. If one is present but not the other,
+     * turn both off.
+     */
+    if (!ret.chm_filename ^ !ret.hhp_filename) {
+	error(err_chmnames);
+	sfree(ret.chm_filename); ret.chm_filename = NULL;
+	sfree(ret.hhp_filename); ret.hhp_filename = NULL;
+    }
+    /*
+     * And if we're not generating an HHP, there's no need for HHC
+     * or HHK.
+     */
+    if (!ret.hhp_filename) {
+	sfree(ret.hhc_filename); ret.hhc_filename = NULL;
+	sfree(ret.hhk_filename); ret.hhk_filename = NULL;
+    }
+
+    /*
+     * Now process fallbacks on quote characters.
+     */
+    while (*uadv(ret.rquote) && *uadv(uadv(ret.rquote)) &&
+	   (!cvt_ok(ret.restrict_charset, ret.lquote) ||
+	    !cvt_ok(ret.restrict_charset, ret.rquote))) {
+	ret.lquote = uadv(ret.rquote);
+	ret.rquote = uadv(ret.lquote);
+    }
+
+    return ret;
+}
+
+paragraph *html_config_filename(char *filename)
+{
+    /*
+     * If the user passes in a single filename as a parameter to
+     * the `--html' command-line option, then we should assume it
+     * to imply _two_ config directives:
+     * \cfg{html-single-filename}{whatever} and
+     * \cfg{html-leaf-level}{0}; the rationale being that the user
+     * wants their output _in that file_.
+     */
+    paragraph *p, *q;
+
+    p = cmdline_cfg_simple("html-single-filename", filename, NULL);
+    q = cmdline_cfg_simple("html-leaf-level", "0", NULL);
+    p->next = q;
+    return p;
+}
+
+void html_backend(paragraph *sourceform, keywordlist *keywords,
+		  indexdata *idx, void *unused)
+{
+    paragraph *p;
+    htmlsect *topsect;
+    htmlconfig conf;
+    htmlfilelist files = { NULL, NULL, NULL, NULL, NULL, NULL };
+    htmlsectlist sects = { NULL, NULL }, nonsects = { NULL, NULL };
+    char *hhk_filename;
+    int has_index;
+
+    IGNORE(unused);
+
+    conf = html_configure(sourceform);
+
+    /*
+     * We're going to make heavy use of paragraphs' private data
+     * fields in the forthcoming code. Clear them first, so we can
+     * reliably tell whether we have auxiliary data for a
+     * particular paragraph.
+     */
+    for (p = sourceform; p; p = p->next)
+	p->private_data = NULL;
+
+    files.frags = newtree234(html_fragment_compare);
+    files.files = newtree234(html_filename_compare);
+
+    /*
+     * Start by figuring out into which file each piece of the
+     * document should be put. We'll do this by inventing an
+     * `htmlsect' structure and stashing it in the private_data
+     * field of each section paragraph; we also need one additional
+     * htmlsect for the document index, which won't show up in the
+     * source form but needs to be consistently mentioned in
+     * contents links.
+     * 
+     * While we're here, we'll also invent the HTML fragment name(s)
+     * for each section.
+     */
+    {
+	htmlsect *sect;
+	int d;
+
+	topsect = html_new_sect(&sects, NULL, &conf);
+	topsect->type = TOP;
+	topsect->title = NULL;
+	topsect->text = sourceform;
+	topsect->contents_depth = contents_depth(conf, 0);
+	html_file_section(&conf, &files, topsect, -1);
+
+	for (p = sourceform; p; p = p->next)
+	    if (is_heading_type(p->type)) {
+		d = heading_depth(p);
+
+		if (p->type == para_Title) {
+		    topsect->title = p;
+		    continue;
+		}
+
+		sect = html_new_sect(&sects, p, &conf);
+		sect->text = p->next;
+
+		sect->contents_depth = contents_depth(conf, d+1) - (d+1);
+
+		if (p->parent) {
+		    sect->parent = (htmlsect *)p->parent->private_data;
+		    assert(sect->parent != NULL);
+		} else
+		    sect->parent = topsect;
+		p->private_data = sect;
+
+		html_file_section(&conf, &files, sect, d);
+
+		{
+		    int i;
+		    for (i=0; i < conf.ntfragments; i++) {
+			sect->fragments[i] =
+			    html_format(p, conf.template_fragments[i]);
+			sect->fragments[i] =
+			    html_sanitise_fragment(&files, sect->file,
+						   sect->fragments[i]);
+		    }
+		}
+	    }
+
+	/*
+	 * And the index, if we have one. Note that we don't output
+	 * an index as an HTML file if we're outputting one as a
+	 * .HHK.
+	 */
+	has_index = (count234(idx->entries) > 0);
+	if (has_index && !conf.hhk_filename) {
+	    sect = html_new_sect(&sects, NULL, &conf);
+	    sect->text = NULL;
+	    sect->type = INDEX;
+	    sect->parent = topsect;
+            sect->contents_depth = 0;
+	    html_file_section(&conf, &files, sect, 0);   /* peer of chapters */
+	    sect->fragments[0] = utoa_dup(conf.index_text, CS_ASCII);
+	    sect->fragments[0] = html_sanitise_fragment(&files, sect->file,
+							sect->fragments[0]);
+	    files.index = sect->file;
+	}
+    }
+
+    /*
+     * Go through the keyword list and sort out fragment IDs for
+     * all the potentially referenced paragraphs which _aren't_
+     * headings.
+     */
+    {
+	int i;
+	keyword *kw;
+	htmlsect *sect;
+
+	for (i = 0; (kw = index234(keywords->keys, i)) != NULL; i++) {
+	    paragraph *q, *p = kw->para;
+
+	    if (!is_heading_type(p->type)) {
+		htmlsect *parent;
+
+		/*
+		 * Find the paragraph's parent htmlsect, to
+		 * determine which file it will end up in.
+		 */
+		q = p->parent;
+		if (!q) {
+		    /*
+		     * Preamble paragraphs have no parent. So if we
+		     * have a non-heading with no parent, it must
+		     * be preamble, and therefore its parent
+		     * htmlsect must be the preamble one.
+		     */
+		    assert(sects.head &&
+			   sects.head->type == TOP);
+		    parent = sects.head;
+		} else
+		    parent = (htmlsect *)q->private_data;
+
+		/*
+		 * Now we can construct an htmlsect for this
+		 * paragraph itself, taking care to put it in the
+		 * list of non-sections rather than the list of
+		 * sections (so that traverses of the `sects' list
+		 * won't attempt to add it to the contents or
+		 * anything weird like that).
+		 */
+		sect = html_new_sect(&nonsects, p, &conf);
+		sect->file = parent->file;
+		sect->parent = parent;
+		p->private_data = sect;
+
+		/*
+		 * Fragment IDs for these paragraphs will simply be
+		 * `p' followed by an integer.
+		 */
+		sect->fragments[0] = snewn(40, char);
+		sprintf(sect->fragments[0], "p%d",
+			sect->file->last_fragment_number++);
+		sect->fragments[0] = html_sanitise_fragment(&files, sect->file,
+							    sect->fragments[0]);
+	    }
+	}
+    }
+
+    /*
+     * Reset the fragment numbers in each file. I've just used them
+     * to generate `p' fragment IDs for non-section paragraphs
+     * (numbered list elements, bibliocited), and now I want to use
+     * them for `i' fragment IDs for index entries.
+     */
+    {
+	htmlfile *file;
+	for (file = files.head; file; file = file->next)
+	    file->last_fragment_number = 0;
+    }
+
+    /*
+     * Now sort out the index. This involves:
+     * 
+     * 	- For each index term, we set up an htmlindex structure to
+     * 	  store all the references to that term.
+     * 
+     * 	- Then we make a pass over the actual document, finding
+     * 	  every word_IndexRef; for each one, we actually figure out
+     * 	  the HTML filename/fragment pair we will use to reference
+     * 	  it, store that information in the private data field of
+     * 	  the word_IndexRef itself (so we can recreate it when the
+     * 	  time comes to output our HTML), and add a reference to it
+     * 	  to the index term in question.
+     */
+    {
+	int i;
+	indexentry *entry;
+	htmlsect *lastsect;
+	word *w;
+
+	/*
+	 * Set up the htmlindex structures.
+	 */
+
+	for (i = 0; (entry = index234(idx->entries, i)) != NULL; i++) {
+	    htmlindex *hi = snew(htmlindex);
+
+	    hi->nrefs = hi->refsize = 0;
+	    hi->refs = NULL;
+
+	    entry->backend_data = hi;
+	}
+
+	/*
+	 * Run over the document inventing fragments. Each fragment
+	 * is of the form `i' followed by an integer.
+	 */
+	lastsect = sects.head;	       /* this is always the top section */
+	for (p = sourceform; p; p = p->next) {
+	    if (is_heading_type(p->type) && p->type != para_Title)
+		lastsect = (htmlsect *)p->private_data;
+
+	    for (w = p->words; w; w = w->next)
+		if (w->type == word_IndexRef) {
+		    htmlindexref *hr = snew(htmlindexref);
+		    indextag *tag;
+		    int i;
+
+		    hr->referenced = hr->generated = FALSE;
+		    hr->section = lastsect;
+		    {
+			char buf[40];
+			sprintf(buf, "i%d",
+				lastsect->file->last_fragment_number++);
+			hr->fragment = dupstr(buf);
+			hr->fragment =
+			    html_sanitise_fragment(&files, hr->section->file,
+						   hr->fragment);
+		    }
+		    w->private_data = hr;
+
+		    tag = index_findtag(idx, w->text);
+		    if (!tag)
+			break;
+
+		    for (i = 0; i < tag->nrefs; i++) {
+			indexentry *entry = tag->refs[i];
+			htmlindex *hi = (htmlindex *)entry->backend_data;
+
+			if (hi->nrefs >= hi->refsize) {
+			    hi->refsize += 32;
+			    hi->refs = sresize(hi->refs, hi->refsize, word *);
+			}
+
+			hi->refs[hi->nrefs++] = w;
+		    }
+		}
+	}
+    }
+
+    /*
+     * Now we're ready to write out the actual HTML files.
+     * 
+     * For each file:
+     * 
+     *  - we open that file and write its header
+     *  - we run down the list of sections
+     * 	- for each section directly contained within that file, we
+     * 	  output the section text
+     * 	- for each section which is not in the file but which has a
+     * 	  parent that is, we output a contents entry for the
+     * 	  section if appropriate
+     *  - finally, we output the file trailer and close the file.
+     */
+    {
+	htmlfile *f, *prevf;
+	htmlsect *s;
+	paragraph *p;
+
+	prevf = NULL;
+
+	for (f = files.head; f; f = f->next) {
+	    htmloutput ho;
+	    int displaying;
+	    enum LISTTYPE { NOLIST, UL, OL, DL };
+	    enum ITEMTYPE { NOITEM, LI, DT, DD };
+	    struct stackelement {
+		struct stackelement *next;
+		enum LISTTYPE listtype;
+		enum ITEMTYPE itemtype;
+	    } *stackhead;
+
+#define listname(lt) ( (lt)==UL ? "ul" : (lt)==OL ? "ol" : "dl" )
+#define itemname(lt) ( (lt)==LI ? "li" : (lt)==DT ? "dt" : "dd" )
+
+	    ho.fp = fopen(f->filename, "w");
+	    if (!ho.fp)
+		error(err_cantopenw, f->filename);
+
+	    ho.charset = conf.output_charset;
+	    ho.restrict_charset = conf.restrict_charset;
+	    ho.cstate = charset_init_state;
+	    ho.ver = conf.htmlver;
+	    ho.state = HO_NEUTRAL;
+	    ho.contents_level = 0;
+	    ho.hackflags = 0;	       /* none of these thankyouverymuch */
+	    ho.hacklimit = -1;
+
+	    /* <!DOCTYPE>. */
+	    switch (conf.htmlver) {
+	      case HTML_3_2:
+		if (ho.fp)
+		    fprintf(ho.fp, "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD "
+			    "HTML 3.2 Final//EN\">\n");
+		break;
+	      case HTML_4:
+		if (ho.fp)
+		    fprintf(ho.fp, "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML"
+			    " 4.01//EN\"\n\"http://www.w3.org/TR/html4/"
+			    "strict.dtd\">\n");
+		break;
+	      case ISO_HTML:
+		if (ho.fp)
+		    fprintf(ho.fp, "<!DOCTYPE HTML PUBLIC \"ISO/IEC "
+			    "15445:2000//DTD HTML//EN\">\n");
+		break;
+	      case XHTML_1_0_TRANSITIONAL:
+		if (ho.fp) {
+		    fprintf(ho.fp, "<?xml version=\"1.0\" encoding=\"%s\"?>\n",
+			    charset_to_mimeenc(conf.output_charset));
+		    fprintf(ho.fp, "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML"
+			    " 1.0 Transitional//EN\"\n\"http://www.w3.org/TR/"
+			    "xhtml1/DTD/xhtml1-transitional.dtd\">\n");
+		}
+		break;
+	      case XHTML_1_0_STRICT:
+		if (ho.fp) {
+		    fprintf(ho.fp, "<?xml version=\"1.0\" encoding=\"%s\"?>\n",
+			    charset_to_mimeenc(conf.output_charset));
+		    fprintf(ho.fp, "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML"
+			    " 1.0 Strict//EN\"\n\"http://www.w3.org/TR/xhtml1/"
+			    "DTD/xhtml1-strict.dtd\">\n");
+		}
+		break;
+	    }
+
+	    element_open(&ho, "html");
+	    if (is_xhtml(conf.htmlver)) {
+		element_attr(&ho, "xmlns", "http://www.w3.org/1999/xhtml");
+	    }
+	    html_nl(&ho);
+
+	    element_open(&ho, "head");
+	    html_nl(&ho);
+
+	    element_empty(&ho, "meta");
+	    element_attr(&ho, "http-equiv", "content-type");
+	    {
+		char buf[200];
+		sprintf(buf, "text/html; charset=%.150s",
+			charset_to_mimeenc(conf.output_charset));
+		element_attr(&ho, "content", buf);
+	    }
+	    html_nl(&ho);
+
+	    if (conf.author) {
+		element_empty(&ho, "meta");
+		element_attr(&ho, "name", "author");
+		element_attr_w(&ho, "content", conf.author);
+		html_nl(&ho);
+	    }
+
+	    if (conf.description) {
+		element_empty(&ho, "meta");
+		element_attr(&ho, "name", "description");
+		element_attr_w(&ho, "content", conf.description);
+		html_nl(&ho);
+	    }
+
+	    element_open(&ho, "title");
+	    if (f->first && f->first->title) {
+		html_words(&ho, f->first->title->words, NOTHING,
+			   f, keywords, &conf);
+
+		assert(f->last);
+		if (f->last != f->first && f->last->title) {
+		    html_text(&ho, conf.title_separator);
+		    html_words(&ho, f->last->title->words, NOTHING,
+			       f, keywords, &conf);
+		}
+	    }
+	    element_close(&ho, "title");
+	    html_nl(&ho);
+
+	    if (conf.rellinks) {
+
+		if (prevf) {
+		    element_empty(&ho, "link");
+		    element_attr(&ho, "rel", "previous");
+		    element_attr(&ho, "href", prevf->filename);
+		    html_nl(&ho);
+		}
+
+		/* FIXME: link rel="up" */
+
+		if (f != files.head) {
+		    element_empty(&ho, "link");
+		    element_attr(&ho, "rel", "ToC");
+		    element_attr(&ho, "href", files.head->filename);
+		    html_nl(&ho);
+		}
+
+		if (has_index && files.index && f != files.index) {
+		    element_empty(&ho, "link");
+		    element_attr(&ho, "rel", "index");
+		    element_attr(&ho, "href", files.index->filename);
+		    html_nl(&ho);
+		}
+
+		if (f->next) {
+		    element_empty(&ho, "link");
+		    element_attr(&ho, "rel", "next");
+		    element_attr(&ho, "href", f->next->filename);
+		    html_nl(&ho);
+		}
+
+	    }
+
+	    if (conf.head_end)
+		html_raw(&ho, conf.head_end);
+
+	    /*
+	     * Add any <head> data defined in specific sections
+	     * that go in this file. (This is mostly to allow <meta
+	     * name="AppleTitle"> tags for Mac online help.)
+	     */
+	    for (s = sects.head; s; s = s->next) {
+		if (s->file == f && s->text) {
+		    for (p = s->text;
+			 p && (p == s->text || p->type == para_Title ||
+			       !is_heading_type(p->type));
+			 p = p->next) {
+			if (p->type == para_Config) {
+			    if (!ustricmp(p->keyword, L"html-local-head")) {
+				html_raw(&ho, adv(p->origkeyword));
+			    }
+			}
+		    }
+		}
+	    }
+
+	    element_close(&ho, "head");
+	    html_nl(&ho);
+
+	    if (conf.body_tag)
+		html_raw(&ho, conf.body_tag);
+	    else
+		element_open(&ho, "body");
+	    html_nl(&ho);
+
+	    if (conf.body_start)
+		html_raw(&ho, conf.body_start);
+
+	    /*
+	     * Write out a nav bar. Special case: we don't do this
+	     * if there is only one file.
+	     */
+	    if (conf.navlinks && files.head != files.tail) {
+		element_open(&ho, "p");
+		if (conf.nav_attr)
+		    html_raw_as_attr(&ho, conf.nav_attr);
+
+		if (prevf) {
+		    element_open(&ho, "a");
+		    element_attr(&ho, "href", prevf->filename);
+		}
+		html_text(&ho, conf.nav_prev_text);
+		if (prevf)
+		    element_close(&ho, "a");
+
+		html_text(&ho, conf.nav_separator);
+
+		if (f != files.head) {
+		    element_open(&ho, "a");
+		    element_attr(&ho, "href", files.head->filename);
+		}
+		html_text(&ho, conf.contents_text);
+		if (f != files.head)
+		    element_close(&ho, "a");
+
+		if (has_index && files.index) {
+		    html_text(&ho, conf.nav_separator);
+		    if (f != files.index) {
+			element_open(&ho, "a");
+			element_attr(&ho, "href", files.index->filename);
+		    }
+		    html_text(&ho, conf.index_text);
+		    if (f != files.index)
+			element_close(&ho, "a");
+		}
+
+		html_text(&ho, conf.nav_separator);
+
+		if (f->next) {
+		    element_open(&ho, "a");
+		    element_attr(&ho, "href", f->next->filename);
+		}
+		html_text(&ho, conf.nav_next_text);
+		if (f->next)
+		    element_close(&ho, "a");
+
+		element_close(&ho, "p");
+		html_nl(&ho);
+	    }
+	    prevf = f;
+
+	    /*
+	     * Write out a prefix TOC for the file (if a leaf file).
+	     * 
+	     * We start by going through the section list and
+	     * collecting the sections which need to be added to
+	     * the contents. On the way, we also test to see if
+	     * this file is a leaf file (defined as one which
+	     * contains all descendants of any section it
+	     * contains), because this will play a part in our
+	     * decision on whether or not to _output_ the TOC.
+	     * 
+	     * Special case: we absolutely do not do this if we're
+	     * in single-file mode.
+	     */
+	    if (files.head != files.tail) {
+		int ntoc = 0, tocsize = 0;
+		htmlsect **toc = NULL;
+		int leaf = TRUE;
+
+		for (s = sects.head; s; s = s->next) {
+		    htmlsect *a, *ac;
+		    int depth, adepth;
+
+		    /*
+		     * Search up from this section until we find
+		     * the highest-level one which belongs in this
+		     * file.
+		     */
+		    depth = adepth = 0;
+		    a = NULL;
+		    for (ac = s; ac; ac = ac->parent) {
+			if (ac->file == f) {
+			    a = ac;
+			    adepth = depth;
+			}
+			depth++;
+		    }
+
+		    if (s->file != f && a != NULL)
+			leaf = FALSE;
+
+		    if (a) {
+			if (adepth <= a->contents_depth) {
+			    if (ntoc >= tocsize) {
+				tocsize += 64;
+				toc = sresize(toc, tocsize, htmlsect *);
+			    }
+			    toc[ntoc++] = s;
+			}
+		    }
+		}
+
+		if (leaf && conf.leaf_contains_contents &&
+		    ntoc >= conf.leaf_smallest_contents) {
+		    int i;
+
+		    for (i = 0; i < ntoc; i++) {
+			htmlsect *s = toc[i];
+			int hlevel = (s->type == TOP ? -1 :
+				      s->type == INDEX ? 0 :
+				      heading_depth(s->title))
+			    - f->min_heading_depth + 1;
+
+			assert(hlevel >= 1);
+			html_contents_entry(&ho, hlevel, s,
+					    f, keywords, &conf);
+		    }
+		    html_contents_entry(&ho, 0, NULL, f, keywords, &conf);
+		}
+	    }
+
+	    /*
+	     * Now go through the document and output some real
+	     * text.
+	     */
+	    displaying = FALSE;
+	    for (s = sects.head; s; s = s->next) {
+		if (s->file == f) {
+		    /*
+		     * This section belongs in this file.
+		     * Display it.
+		     */
+		    displaying = TRUE;
+		} else {
+		    /*
+		     * Doesn't belong in this file, but it may be
+		     * a descendant of a section which does, in
+		     * which case we should consider it for the
+		     * main TOC of this file (for non-leaf files).
+		     */
+		    htmlsect *a, *ac;
+		    int depth, adepth;
+
+		    displaying = FALSE;
+
+		    /*
+		     * Search up from this section until we find
+		     * the highest-level one which belongs in this
+		     * file.
+		     */
+		    depth = adepth = 0;
+		    a = NULL;
+		    for (ac = s; ac; ac = ac->parent) {
+			if (ac->file == f) {
+			    a = ac;
+			    adepth = depth;
+			}
+			depth++;
+		    }
+
+		    if (a != NULL) {
+			/*
+			 * This section does not belong in this
+			 * file, but an ancestor of it does. Write
+			 * out a contents table entry, if the depth
+			 * doesn't exceed the maximum contents
+			 * depth for the ancestor section.
+			 */
+			if (adepth <= a->contents_depth) {
+			    html_contents_entry(&ho, adepth, s,
+						f, keywords, &conf);
+			}
+		    }
+		}
+
+		if (displaying) {
+		    int hlevel;
+		    char htag[3];
+
+		    html_contents_entry(&ho, 0, NULL, f, keywords, &conf);
+
+		    /*
+		     * Display the section heading.
+		     */
+
+		    hlevel = (s->type == TOP ? -1 :
+			      s->type == INDEX ? 0 :
+			      heading_depth(s->title))
+			- f->min_heading_depth + 1;
+		    assert(hlevel >= 1);
+		    /* HTML headings only go up to <h6> */
+		    if (hlevel > 6)
+			hlevel = 6;
+		    htag[0] = 'h';
+		    htag[1] = '0' + hlevel;
+		    htag[2] = '\0';
+		    element_open(&ho, htag);
+
+		    /*
+		     * Provide anchor(s) for cross-links to target.
+		     * 
+		     * (Also we'll have to do this separately in
+		     * other paragraph types - NumberedList and
+		     * BiblioCited.)
+		     */
+		    {
+			int i;
+			for (i=0; i < conf.ntfragments; i++)
+			    if (s->fragments[i])
+				html_fragment(&ho, s->fragments[i]);
+		    }
+
+		    html_section_title(&ho, s, f, keywords, &conf, TRUE);
+
+		    element_close(&ho, htag);
+
+		    /*
+		     * Now display the section text.
+		     */
+		    if (s->text) {
+			stackhead = snew(struct stackelement);
+			stackhead->next = NULL;
+			stackhead->listtype = NOLIST;
+			stackhead->itemtype = NOITEM;
+
+			for (p = s->text;; p = p->next) {
+			    enum LISTTYPE listtype;
+			    struct stackelement *se;
+
+			    /*
+			     * Preliminary switch to figure out what
+			     * sort of list we expect to be inside at
+			     * this stage.
+			     *
+			     * Since p may still be NULL at this point,
+			     * I invent a harmless paragraph type for
+			     * it if it is.
+			     */
+			    switch (p ? p->type : para_Normal) {
+			      case para_Rule:
+			      case para_Normal:
+			      case para_Copyright:
+			      case para_BiblioCited:
+			      case para_Code:
+			      case para_QuotePush:
+			      case para_QuotePop:
+			      case para_Chapter:
+			      case para_Appendix:
+			      case para_UnnumberedChapter:
+			      case para_Heading:
+			      case para_Subsect:
+			      case para_LcontPop:
+				listtype = NOLIST;
+				break;
+
+			      case para_Bullet:
+				listtype = UL;
+				break;
+
+			      case para_NumberedList:
+				listtype = OL;
+				break;
+
+			      case para_DescribedThing:
+			      case para_Description:
+				listtype = DL;
+				break;
+
+			      case para_LcontPush:
+				se = snew(struct stackelement);
+				se->next = stackhead;
+				se->listtype = NOLIST;
+				se->itemtype = NOITEM;
+				stackhead = se;
+				continue;
+
+			      default:     /* some totally non-printing para */
+				continue;
+			    }
+
+			    html_nl(&ho);
+
+			    /*
+			     * Terminate the most recent list item, if
+			     * any. (We left this until after
+			     * processing LcontPush, since in that case
+			     * the list item won't want to be
+			     * terminated until after the corresponding
+			     * LcontPop.)
+			     */
+			    if (stackhead->itemtype != NOITEM) {
+				element_close(&ho, itemname(stackhead->itemtype));
+				html_nl(&ho);
+			    }
+			    stackhead->itemtype = NOITEM;
+
+			    /*
+			     * Terminate the current list, if it's not
+			     * the one we want to be in.
+			     */
+			    if (listtype != stackhead->listtype &&
+				stackhead->listtype != NOLIST) {
+				element_close(&ho, listname(stackhead->listtype));
+				html_nl(&ho);
+			    }
+
+			    /*
+			     * Leave the loop if our time has come.
+			     */
+			    if (!p || (is_heading_type(p->type) &&
+				       p->type != para_Title))
+				break;     /* end of section text */
+
+			    /*
+			     * Start a fresh list if necessary.
+			     */
+			    if (listtype != stackhead->listtype &&
+				listtype != NOLIST)
+				element_open(&ho, listname(listtype));
+
+			    stackhead->listtype = listtype;
+
+			    switch (p->type) {
+			      case para_Rule:
+				element_empty(&ho, "hr");
+				break;
+			      case para_Code:
+				html_codepara(&ho, p->words);
+				break;
+			      case para_Normal:
+			      case para_Copyright:
+				element_open(&ho, "p");
+				html_nl(&ho);
+				html_words(&ho, p->words, ALL,
+					   f, keywords, &conf);
+				html_nl(&ho);
+				element_close(&ho, "p");
+				break;
+			      case para_BiblioCited:
+				element_open(&ho, "p");
+				if (p->private_data) {
+				    htmlsect *s = (htmlsect *)p->private_data;
+				    int i;
+				    for (i=0; i < conf.ntfragments; i++)
+					if (s->fragments[i])
+					    html_fragment(&ho, s->fragments[i]);
+				}
+				html_nl(&ho);
+				html_words(&ho, p->kwtext, ALL,
+					   f, keywords, &conf);
+				html_text(&ho, L" ");
+				html_words(&ho, p->words, ALL,
+					   f, keywords, &conf);
+				html_nl(&ho);
+				element_close(&ho, "p");
+				break;
+			      case para_Bullet:
+			      case para_NumberedList:
+				element_open(&ho, "li");
+				if (p->private_data) {
+				    htmlsect *s = (htmlsect *)p->private_data;
+				    int i;
+				    for (i=0; i < conf.ntfragments; i++)
+					if (s->fragments[i])
+					    html_fragment(&ho, s->fragments[i]);
+				}
+				html_nl(&ho);
+				stackhead->itemtype = LI;
+				html_words(&ho, p->words, ALL,
+					   f, keywords, &conf);
+				break;
+			      case para_DescribedThing:
+				element_open(&ho, "dt");
+				html_nl(&ho);
+				stackhead->itemtype = DT;
+				html_words(&ho, p->words, ALL,
+					   f, keywords, &conf);
+				break;
+			      case para_Description:
+				element_open(&ho, "dd");
+				html_nl(&ho);
+				stackhead->itemtype = DD;
+				html_words(&ho, p->words, ALL,
+					   f, keywords, &conf);
+				break;
+
+			      case para_QuotePush:
+				element_open(&ho, "blockquote");
+				break;
+			      case para_QuotePop:
+				element_close(&ho, "blockquote");
+				break;
+
+			      case para_LcontPop:
+				se = stackhead;
+				stackhead = stackhead->next;
+				assert(stackhead);
+				sfree(se);
+				break;
+			    }
+			}
+
+			assert(stackhead && !stackhead->next);
+			sfree(stackhead);
+		    }
+		    
+		    if (s->type == INDEX) {
+			indexentry *entry;
+			int i;
+
+			/*
+			 * This section is the index. I'll just
+			 * render it as a single paragraph, with a
+			 * colon between the index term and the
+			 * references, and <br> in between each
+			 * entry.
+			 */
+			element_open(&ho, "p");
+
+			for (i = 0; (entry =
+				     index234(idx->entries, i)) != NULL; i++) {
+			    htmlindex *hi = (htmlindex *)entry->backend_data;
+			    int j;
+
+			    if (i > 0)
+				element_empty(&ho, "br");
+			    html_nl(&ho);
+
+			    html_words(&ho, entry->text, MARKUP|LINKS,
+				       f, keywords, &conf);
+
+			    html_text(&ho, conf.index_main_sep);
+
+			    for (j = 0; j < hi->nrefs; j++) {
+				htmlindexref *hr =
+				    (htmlindexref *)hi->refs[j]->private_data;
+				paragraph *p = hr->section->title;
+
+				if (j > 0)
+				    html_text(&ho, conf.index_multi_sep);
+
+				html_href(&ho, f, hr->section->file,
+					  hr->fragment);
+				hr->referenced = TRUE;
+				if (p && p->kwtext)
+				    html_words(&ho, p->kwtext, MARKUP|LINKS,
+					       f, keywords, &conf);
+				else if (p && p->words)
+				    html_words(&ho, p->words, MARKUP|LINKS,
+					       f, keywords, &conf);
+				else {
+				    /*
+				     * If there is no title at all,
+				     * this must be because our
+				     * target section is the
+				     * preamble section and there
+				     * is no title. So we use the
+				     * preamble_text.
+				     */
+				    html_text(&ho, conf.preamble_text);
+				}
+				element_close(&ho, "a");
+			    }
+			}
+			element_close(&ho, "p");
+		    }
+		}
+	    }
+
+	    html_contents_entry(&ho, 0, NULL, f, keywords, &conf);
+	    html_nl(&ho);
+
+	    {
+		/*
+		 * Footer.
+		 */
+		int done_version_ids = FALSE;
+
+		if (conf.address_section)
+		    element_empty(&ho, "hr");
+
+		if (conf.body_end)
+		    html_raw(&ho, conf.body_end);
+
+		if (conf.address_section) {
+		    int started = FALSE;
+		    if (conf.htmlver == ISO_HTML) {
+			/*
+			 * The ISO-HTML validator complains if
+			 * there isn't a <div> tag surrounding the
+			 * <address> tag. I'm uncertain of why this
+			 * should be - there appears to be no
+			 * mention of this in the ISO-HTML spec,
+			 * suggesting that it doesn't represent a
+			 * change from HTML 4, but nonetheless the
+			 * HTML 4 validator doesn't seem to mind.
+			 */
+			element_open(&ho, "div");
+		    }
+		    element_open(&ho, "address");
+		    if (conf.addr_start) {
+			html_raw(&ho, conf.addr_start);
+			html_nl(&ho);
+			started = TRUE;
+		    }
+		    if (conf.visible_version_id) {
+			for (p = sourceform; p; p = p->next)
+			    if (p->type == para_VersionID) {
+				if (started)
+				    element_empty(&ho, "br");
+				html_nl(&ho);
+				html_text(&ho, conf.pre_versionid);
+				html_words(&ho, p->words, NOTHING,
+					   f, keywords, &conf);
+				html_text(&ho, conf.post_versionid);
+				started = TRUE;
+			    }
+			done_version_ids = TRUE;
+		    }
+		    if (conf.addr_end) {
+			if (started)
+			    element_empty(&ho, "br");
+			html_raw(&ho, conf.addr_end);
+		    }
+		    element_close(&ho, "address");
+		    if (conf.htmlver == ISO_HTML)
+			element_close(&ho, "div");
+		}
+
+		if (!done_version_ids) {
+		    /*
+		     * If the user didn't want the version IDs
+		     * visible, I think we still have a duty to put
+		     * them in an HTML comment.
+		     */
+		    int started = FALSE;
+		    for (p = sourceform; p; p = p->next)
+			if (p->type == para_VersionID) {
+			    if (!started) {
+				html_raw(&ho, "<!-- version IDs:\n");
+				started = TRUE;
+			    }
+			    html_words(&ho, p->words, NOTHING,
+				       f, keywords, &conf);
+			    html_nl(&ho);
+			}
+		    if (started)
+			html_raw(&ho, "-->\n");
+		}
+	    }
+
+	    element_close(&ho, "body");
+	    html_nl(&ho);
+	    element_close(&ho, "html");
+	    html_nl(&ho);
+	    cleanup(&ho);
+	}
+    }
+
+    /*
+     * Before we start outputting the HTML Help files, check
+     * whether there's even going to _be_ an index file: we omit it
+     * if the index contains nothing.
+     */
+    hhk_filename = conf.hhk_filename;
+    if (hhk_filename) {
+	int ok = FALSE;
+	int i;
+	indexentry *entry;
+
+	for (i = 0; (entry = index234(idx->entries, i)) != NULL; i++) {
+	    htmlindex *hi = (htmlindex *)entry->backend_data;
+
+	    if (hi->nrefs > 0) {
+		ok = TRUE;	       /* found an index entry */
+		break;
+	    }
+	}
+
+	if (!ok)
+	    hhk_filename = NULL;
+    }
+
+    /*
+     * Output the MS HTML Help supporting files, if requested.
+     *
+     * A good unofficial reference for these is <http://chmspec.nongnu.org/>.
+     */
+    if (conf.hhp_filename) {
+	htmlfile *f;
+	htmloutput ho;
+
+	ho.charset = CS_CP1252;	       /* as far as I know, HHP files are */
+	ho.restrict_charset = CS_CP1252;   /* hardwired to this charset */
+	ho.cstate = charset_init_state;
+	ho.ver = HTML_4;	       /* *shrug* */
+	ho.state = HO_NEUTRAL;
+	ho.contents_level = 0;
+	ho.hackflags = HO_HACK_QUOTENOTHING;
+
+	ho.fp = fopen(conf.hhp_filename, "w");
+	if (!ho.fp)
+	    error(err_cantopenw, conf.hhp_filename);
+
+	fprintf(ho.fp,
+		"[OPTIONS]\n"
+		/* Binary TOC required for Next/Previous nav to work */
+		"Binary TOC=Yes\n"
+		"Compatibility=1.1 or later\n"
+		"Compiled file=%s\n"
+		"Default Window=main\n"
+		"Default topic=%s\n"
+		"Display compile progress=Yes\n"
+		"Full-text search=Yes\n"
+		"Title=", conf.chm_filename, files.head->filename);
+
+	ho.hacklimit = 255;
+	html_words(&ho, topsect->title->words, NOTHING,
+		   NULL, keywords, &conf);
+
+	fprintf(ho.fp, "\n");
+
+	/*
+	 * These two entries don't seem to be remotely necessary
+	 * for a successful run of the help _compiler_, but
+	 * omitting them causes the GUI Help Workshop to behave
+	 * rather strangely if you try to load the help project
+	 * into that and edit it.
+	 */
+	if (conf.hhc_filename)
+	    fprintf(ho.fp, "Contents file=%s\n", conf.hhc_filename);
+	if (hhk_filename)
+	    fprintf(ho.fp, "Index file=%s\n", hhk_filename);
+
+	fprintf(ho.fp, "\n[WINDOWS]\nmain=\"");
+
+	ho.hackflags |= HO_HACK_OMITQUOTES;
+	ho.hacklimit = 255;
+	html_words(&ho, topsect->title->words, NOTHING,
+		   NULL, keywords, &conf);
+
+	fprintf(ho.fp, "\",\"%s\",\"%s\",\"%s\",,,,,,"
+		/* This first magic number is fsWinProperties, controlling
+		 * Navigation Pane options and the like.
+		 * Constants HHWIN_PROP_* in htmlhelp.h. */
+		"0x62520,,"
+		/* This second number is fsToolBarFlags, mainly controlling
+		 * toolbar buttons. Constants HHWIN_BUTTON_*.
+		 * NOTE: there are two pairs of bits for Next/Previous
+		 * buttons: 7/8 (which do nothing useful), and 21/22
+		 * (which work). (Neither of these are exposed in the HHW
+		 * UI, but they work fine in HH.) We use the latter. */
+		"0x60304e,,,,,,,,0\n",
+		conf.hhc_filename ? conf.hhc_filename : "",
+		hhk_filename ? hhk_filename : "",
+		files.head->filename);
+
+	/*
+	 * The [FILES] section is also not necessary for
+	 * compilation (hhc appears to build up a list of needed
+	 * files just by following links from the given starting
+	 * points), but useful for loading the project into HHW.
+	 */
+	fprintf(ho.fp, "\n[FILES]\n");
+	for (f = files.head; f; f = f->next)
+	    fprintf(ho.fp, "%s\n", f->filename);
+
+	fclose(ho.fp);
+    }
+    if (conf.hhc_filename) {
+	htmlfile *f;
+	htmlsect *s, *a;
+	htmloutput ho;
+	int currdepth = 0;
+
+	ho.fp = fopen(conf.hhc_filename, "w");
+	if (!ho.fp)
+	    error(err_cantopenw, conf.hhc_filename);
+
+	ho.charset = CS_CP1252;	       /* as far as I know, HHC files are */
+	ho.restrict_charset = CS_CP1252;   /* hardwired to this charset */
+	ho.cstate = charset_init_state;
+	ho.ver = HTML_4;	       /* *shrug* */
+	ho.state = HO_NEUTRAL;
+	ho.contents_level = 0;
+	ho.hackflags = HO_HACK_QUOTEQUOTES;
+
+	/*
+	 * Magic DOCTYPE which seems to work for .HHC files. I'm
+	 * wary of trying to change it!
+	 */
+	fprintf(ho.fp, "<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML//EN\">\n"
+		"<HTML><HEAD>\n"
+		"<META HTTP-EQUIV=\"Content-Type\" "
+		"CONTENT=\"text/html; charset=%s\">\n"
+		"</HEAD><BODY><UL>\n",
+		charset_to_mimeenc(conf.output_charset));
+
+	for (f = files.head; f; f = f->next) {
+	    /*
+	     * For each HTML file, write out a contents entry.
+	     */
+	    int depth, leaf = TRUE;
+
+	    /*
+	     * Determine the depth of this file in the contents
+	     * tree.
+	     * 
+	     * If the file contains no sections, it is assumed to
+	     * have depth zero.
+	     */
+	    depth = 0;
+	    if (f->first)
+		for (a = f->first->parent; a && a->type != TOP; a = a->parent)
+		    depth++;
+
+	    /*
+	     * Determine if this file is a leaf file, by
+	     * trawling the section list to see if there's any
+	     * section with an ancestor in this file but which
+	     * is not itself in this file.
+	     *
+	     * Special case: for contents purposes, the TOP
+	     * file is not considered to be the parent of the
+	     * chapter files, so it's always a leaf.
+	     * 
+	     * A file with no sections in it is also a leaf.
+	     */
+	    if (f->first && f->first->type != TOP) {
+		for (s = f->first; s; s = s->next) {
+		    htmlsect *a;
+
+		    if (leaf && s->file != f) {
+			for (a = s; a; a = a->parent)
+			    if (a->file == f) {
+				leaf = FALSE;
+				break;
+			    }
+		    }
+		}
+	    }
+
+	    /*
+	     * Now write out our contents entry.
+	     */
+	    while (currdepth < depth) {
+		fprintf(ho.fp, "<UL>\n");
+		currdepth++;
+	    }
+	    while (currdepth > depth) {
+		fprintf(ho.fp, "</UL>\n");
+		currdepth--;
+	    }
+	    /* fprintf(ho.fp, "<!-- depth=%d -->", depth); */
+	    fprintf(ho.fp, "<LI><OBJECT TYPE=\"text/sitemap\">"
+		    "<PARAM NAME=\"Name\" VALUE=\"");
+	    ho.hacklimit = 255;
+	    if (f->first->title)
+		html_words(&ho, f->first->title->words, NOTHING,
+			   NULL, keywords, &conf);
+	    else if (f->first->type == INDEX)
+		html_text(&ho, conf.index_text);
+	    fprintf(ho.fp, "\"><PARAM NAME=\"Local\" VALUE=\"%s\">"
+		    "<PARAM NAME=\"ImageNumber\" VALUE=\"%d\"></OBJECT>\n",
+		    f->filename, leaf ? 11 : 1);
+	}
+
+	while (currdepth > 0) {
+	    fprintf(ho.fp, "</UL>\n");
+	    currdepth--;
+	}
+
+	fprintf(ho.fp, "</UL></BODY></HTML>\n");
+
+	cleanup(&ho);
+    }
+    if (hhk_filename) {
+	htmlfile *f;
+	htmloutput ho;
+	indexentry *entry;
+	int i;
+
+	/*
+	 * First make a pass over all HTML files and set their
+	 * `temp' fields to zero, because we're about to use them.
+	 */
+	for (f = files.head; f; f = f->next)
+	    f->temp = 0;
+
+	ho.fp = fopen(hhk_filename, "w");
+	if (!ho.fp)
+	    error(err_cantopenw, hhk_filename);
+
+	ho.charset = CS_CP1252;	       /* as far as I know, HHK files are */
+	ho.restrict_charset = CS_CP1252;   /* hardwired to this charset */
+	ho.cstate = charset_init_state;
+	ho.ver = HTML_4;	       /* *shrug* */
+	ho.state = HO_NEUTRAL;
+	ho.contents_level = 0;
+	ho.hackflags = HO_HACK_QUOTEQUOTES;
+
+	/*
+	 * Magic DOCTYPE which seems to work for .HHK files. I'm
+	 * wary of trying to change it!
+	 */
+	fprintf(ho.fp, "<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML//EN\">\n"
+		"<HTML><HEAD>\n"
+		"<META HTTP-EQUIV=\"Content-Type\" "
+		"CONTENT=\"text/html; charset=%s\">\n"
+		"</HEAD><BODY><UL>\n",
+		charset_to_mimeenc(conf.output_charset));
+
+	/*
+	 * Go through the index terms and output each one.
+	 */
+	for (i = 0; (entry = index234(idx->entries, i)) != NULL; i++) {
+	    htmlindex *hi = (htmlindex *)entry->backend_data;
+	    int j;
+
+	    if (hi->nrefs > 0) {
+		fprintf(ho.fp, "<LI><OBJECT TYPE=\"text/sitemap\">\n"
+			"<PARAM NAME=\"Name\" VALUE=\"");
+		ho.hacklimit = 255;
+		html_words(&ho, entry->text, NOTHING,
+			   NULL, keywords, &conf);
+		fprintf(ho.fp, "\">\n");
+
+		for (j = 0; j < hi->nrefs; j++) {
+		    htmlindexref *hr =
+			(htmlindexref *)hi->refs[j]->private_data;
+
+		    /*
+		     * Use the temp field to ensure we don't
+		     * reference the same file more than once.
+		     */
+		    if (!hr->section->file->temp) {
+			fprintf(ho.fp, "<PARAM NAME=\"Local\" VALUE=\"%s\">\n",
+				hr->section->file->filename);
+			hr->section->file->temp = 1;
+		    }
+
+		    hr->referenced = TRUE;
+		}
+
+		fprintf(ho.fp, "</OBJECT>\n");
+
+		/*
+		 * Now go through those files and re-clear the temp
+		 * fields ready for the _next_ index term.
+		 */
+		for (j = 0; j < hi->nrefs; j++) {
+		    htmlindexref *hr =
+			(htmlindexref *)hi->refs[j]->private_data;
+		    hr->section->file->temp = 0;
+		}
+	    }
+	}
+
+	fprintf(ho.fp, "</UL></BODY></HTML>\n");
+	cleanup(&ho);
+    }
+
+    /*
+     * Go through and check that no index fragments were referenced
+     * without being generated, or indeed vice versa.
+     * 
+     * (When I actually get round to freeing everything, this can
+     * probably be the freeing loop as well.)
+     */
+    for (p = sourceform; p; p = p->next) {
+	word *w;
+	for (w = p->words; w; w = w->next)
+	    if (w->type == word_IndexRef) {
+		htmlindexref *hr = (htmlindexref *)w->private_data;
+
+		assert(!hr->referenced == !hr->generated);
+	    }
+    }
+
+    /*
+     * Free all the working data.
+     */
+    {
+	htmlfragment *frag;
+	while ( (frag = (htmlfragment *)delpos234(files.frags, 0)) != NULL ) {
+	    /*
+	     * frag->fragment is dynamically allocated, but will be
+	     * freed when we process the htmlsect structure which
+	     * it is attached to.
+	     */
+	    sfree(frag);
+	}
+	freetree234(files.frags);
+    }
+    /*
+     * The strings in files.files are all owned by their containing
+     * htmlfile structures, so there's no need to free them here.
+     */
+    freetree234(files.files);
+    {
+	htmlsect *sect, *tmp;
+	sect = sects.head;
+	while (sect) {
+	    int i;
+	    tmp = sect->next;
+	    for (i=0; i < conf.ntfragments; i++)
+		sfree(sect->fragments[i]);
+	    sfree(sect->fragments);
+	    sfree(sect);
+	    sect = tmp;
+	}
+	sect = nonsects.head;
+	while (sect) {
+	    int i;
+	    tmp = sect->next;
+	    for (i=0; i < conf.ntfragments; i++)
+		sfree(sect->fragments[i]);
+	    sfree(sect->fragments);
+	    sfree(sect);
+	    sect = tmp;
+	}
+    }
+    {
+	htmlfile *file, *tmp;
+	file = files.head;
+	while (file) {
+	    tmp = file->next;
+	    sfree(file->filename);
+	    sfree(file);
+	    file = tmp;
+	}
+    }
+    {
+	int i;
+	indexentry *entry;
+	for (i = 0; (entry = index234(idx->entries, i)) != NULL; i++) {
+	    htmlindex *hi = (htmlindex *)entry->backend_data;
+	    sfree(hi);
+	}
+    }
+    {
+	paragraph *p;
+	word *w;
+	for (p = sourceform; p; p = p->next)
+	    for (w = p->words; w; w = w->next)
+		if (w->type == word_IndexRef) {
+		    htmlindexref *hr = (htmlindexref *)w->private_data;
+		    assert(hr != NULL);
+		    sfree(hr->fragment);
+		    sfree(hr);
+		}
+    }
+    sfree(conf.asect);
+    sfree(conf.single_filename);
+    sfree(conf.contents_filename);
+    sfree(conf.index_filename);
+    sfree(conf.template_filename);
+    while (conf.ntfragments--)
+	sfree(conf.template_fragments[conf.ntfragments]);
+    sfree(conf.template_fragments);
+}
+
+static void html_file_section(htmlconfig *cfg, htmlfilelist *files,
+			      htmlsect *sect, int depth)
+{
+    htmlfile *file;
+    int ldepth;
+
+    /*
+     * `depth' is derived from the heading_depth() macro at the top
+     * of this file, which counts title as -1, chapter as 0,
+     * heading as 1 and subsection as 2. However, the semantics of
+     * cfg->leaf_level are defined to count chapter as 1, heading
+     * as 2 etc. So first I increment depth :-(
+     */
+    ldepth = depth + 1;
+
+    if (cfg->leaf_level == 0) {
+	/*
+	 * leaf_level==0 is a special case, in which everything is
+	 * put into a single file.
+	 */
+	if (!files->single)
+	    files->single = html_new_file(files, cfg->single_filename);
+
+	file = files->single;
+    } else {
+	/*
+	 * If the depth of this section is at or above leaf_level,
+	 * we invent a fresh file and put this section at its head.
+	 * Otherwise, we put it in the same file as its parent
+	 * section.
+	 * 
+	 * Another special value of cfg->leaf_level is -1, which
+	 * means infinity (i.e. it's considered to always be
+	 * greater than depth).
+	 */
+	if (cfg->leaf_level > 0 && ldepth > cfg->leaf_level) {
+	    /*
+	     * We know that sect->parent cannot be NULL. The only
+	     * circumstance in which it can be is if sect is at
+	     * chapter or appendix level, i.e. ldepth==1; and if
+	     * that's the case, then we cannot have entered this
+	     * branch unless cfg->leaf_level==0, in which case we
+	     * would be in the single-file case above and not here
+	     * at all.
+	     */
+	    assert(sect->parent);
+
+	    file = sect->parent->file;
+	} else {
+	    if (sect->type == TOP) {
+		file = html_new_file(files, cfg->contents_filename);
+	    } else if (sect->type == INDEX) {
+		file = html_new_file(files, cfg->index_filename);
+	    } else {
+		char *title;
+
+		assert(ldepth > 0 && sect->title);
+		title = html_format(sect->title, cfg->template_filename);
+		file = html_new_file(files, title);
+		sfree(title);
+	    }
+	}
+    }
+
+    sect->file = file;
+
+    if (file->min_heading_depth > depth) {
+	/*
+	 * This heading is at a higher level than any heading we
+	 * have so far placed in this file; so we set the `first'
+	 * pointer.
+	 */
+	file->min_heading_depth = depth;
+	file->first = sect;
+    }
+
+    if (file->min_heading_depth == depth)
+	file->last = sect;
+}
+
+static htmlfile *html_new_file(htmlfilelist *list, char *filename)
+{
+    htmlfile *ret = snew(htmlfile);
+
+    ret->next = NULL;
+    if (list->tail)
+	list->tail->next = ret;
+    else
+	list->head = ret;
+    list->tail = ret;
+
+    ret->filename = html_sanitise_filename(list, dupstr(filename));
+    add234(list->files, ret->filename);
+    ret->last_fragment_number = 0;
+    ret->min_heading_depth = INT_MAX;
+    ret->first = ret->last = NULL;
+
+    return ret;
+}
+
+static htmlsect *html_new_sect(htmlsectlist *list, paragraph *title,
+			       htmlconfig *cfg)
+{
+    htmlsect *ret = snew(htmlsect);
+
+    ret->next = NULL;
+    if (list->tail)
+	list->tail->next = ret;
+    else
+	list->head = ret;
+    list->tail = ret;
+
+    ret->title = title;
+    ret->file = NULL;
+    ret->parent = NULL;
+    ret->type = NORMAL;
+
+    ret->fragments = snewn(cfg->ntfragments, char *);
+    {
+	int i;
+	for (i=0; i < cfg->ntfragments; i++)
+	    ret->fragments[i] = NULL;
+    }
+
+    return ret;
+}
+
+static void html_words(htmloutput *ho, word *words, int flags,
+		       htmlfile *file, keywordlist *keywords, htmlconfig *cfg)
+{
+    word *w;
+    char *c;
+    int style, type;
+
+    for (w = words; w; w = w->next) switch (w->type) {
+      case word_HyperLink:
+	if (flags & LINKS) {
+	    element_open(ho, "a");
+	    c = utoa_dup(w->text, CS_ASCII);
+	    element_attr(ho, "href", c);
+	    sfree(c);
+	}
+	break;
+		case word_Graphic:
+			element_open( ho, "img");
+			c = utoa_dup(w->text, CS_ASCII);
+			element_attr(ho, "src", c);
+			return_to_neutral(ho);
+			sfree(c);
+		break;
+      case word_UpperXref:
+      case word_LowerXref:
+	if (flags & LINKS) {
+	    keyword *kwl = kw_lookup(keywords, w->text);
+	    paragraph *p;
+	    htmlsect *s;
+
+	    assert(kwl);
+	    p = kwl->para;
+	    s = (htmlsect *)p->private_data;
+
+	    assert(s);
+
+	    html_href(ho, file, s->file, s->fragments[0]);
+	}
+	break;
+      case word_HyperEnd:
+      case word_XrefEnd:
+	if (flags & LINKS)
+	    element_close(ho, "a");
+	break;
+      case word_IndexRef:
+	if (flags & INDEXENTS) {
+	    htmlindexref *hr = (htmlindexref *)w->private_data;
+	    html_fragment(ho, hr->fragment);
+	    hr->generated = TRUE;
+	}
+	break;
+      case word_Normal:
+      case word_Emph:
+		case word_Strong:
+      case word_Code:
+      case word_WeakCode:
+      case word_WhiteSpace:
+      case word_EmphSpace:
+		case word_StrongSpace:
+      case word_CodeSpace:
+      case word_WkCodeSpace:
+      case word_Quote:
+      case word_EmphQuote:
+		case word_StrongQuote:
+      case word_CodeQuote:
+      case word_WkCodeQuote:
+	style = towordstyle(w->type);
+	type = removeattr(w->type);
+	if (style == word_Emph &&
+	    (attraux(w->aux) == attr_First ||
+	     attraux(w->aux) == attr_Only) &&
+	    (flags & MARKUP))
+	    element_open(ho, "em");
+	else if ((style == word_Code || style == word_WeakCode) &&
+		 (attraux(w->aux) == attr_First ||
+		  attraux(w->aux) == attr_Only) &&
+		 (flags & MARKUP))
+	    element_open(ho, "code");
+		else if (style == word_Strong &&
+		    (attraux(w->aux) == attr_First ||
+	   	  attraux(w->aux) == attr_Only) &&
+		    (flags & MARKUP))
+			    element_open(ho, "strong");
+
+	if (type == word_WhiteSpace)
+	    html_text(ho, L" ");
+	else if (type == word_Quote) {
+	    if (quoteaux(w->aux) == quote_Open)
+		html_text(ho, cfg->lquote);
+	    else
+		html_text(ho, cfg->rquote);
+	} else {
+	    if (!w->alt || cvt_ok(ho->restrict_charset, w->text))
+		html_text_nbsp(ho, w->text);
+	    else
+		html_words(ho, w->alt, flags, file, keywords, cfg);
+	}
+
+	if (style == word_Emph &&
+	    (attraux(w->aux) == attr_Last ||
+	     attraux(w->aux) == attr_Only) &&
+	    (flags & MARKUP))
+	    element_close(ho, "em");
+	else if ((style == word_Code || style == word_WeakCode) &&
+		 (attraux(w->aux) == attr_Last ||
+		  attraux(w->aux) == attr_Only) &&
+		 (flags & MARKUP))
+	    element_close(ho, "code");
+		else if (style == word_Strong &&
+	 	    (attraux(w->aux) == attr_Last ||
+		     attraux(w->aux) == attr_Only) &&
+		    (flags & MARKUP))
+		    element_close(ho, "strong");
+
+	break;
+    }
+}
+
+static void html_codepara(htmloutput *ho, word *words)
+{
+    element_open(ho, "pre");
+    element_open(ho, "code");
+    for (; words; words = words->next) if (words->type == word_WeakCode) {
+	char *open_tag;
+	wchar_t *t, *e;
+
+	t = words->text;
+	if (words->next && words->next->type == word_Emph) {
+	    e = words->next->text;
+	    words = words->next;
+	} else
+	    e = NULL;
+
+	while (e && *e && *t) {
+	    int n;
+	    int ec = *e;
+
+	    for (n = 0; t[n] && e[n] && e[n] == ec; n++);
+
+	    open_tag = NULL;
+	    if (ec == 'i')
+		open_tag = "em";
+	    else if (ec == 'b')
+		open_tag = "b";
+	    if (open_tag)
+		element_open(ho, open_tag);
+
+	    html_text_limit(ho, t, n);
+
+	    if (open_tag)
+		element_close(ho, open_tag);
+
+	    t += n;
+	    e += n;
+	}
+	html_text(ho, t);
+	html_nl(ho);
+    }
+    element_close(ho, "code");
+    element_close(ho, "pre");
+}
+
+static void html_charset_cleanup(htmloutput *ho)
+{
+    char outbuf[256];
+    int bytes;
+
+    bytes = charset_from_unicode(NULL, NULL, outbuf, lenof(outbuf),
+				 ho->charset, &ho->cstate, NULL);
+    if (ho->fp && bytes > 0)
+	fwrite(outbuf, 1, bytes, ho->fp);
+}
+
+static void return_mostly_to_neutral(htmloutput *ho)
+{
+    if (ho->fp) {
+	if (ho->state == HO_IN_EMPTY_TAG && is_xhtml(ho->ver)) {
+	    fprintf(ho->fp, " />");
+	} else if (ho->state == HO_IN_EMPTY_TAG || ho->state == HO_IN_TAG) {
+	    fprintf(ho->fp, ">");
+	}
+    }
+
+    ho->state = HO_NEUTRAL;
+}
+
+static void return_to_neutral(htmloutput *ho)
+{
+    if (ho->state == HO_IN_TEXT) {
+	html_charset_cleanup(ho);
+    }
+
+    return_mostly_to_neutral(ho);
+}
+
+static void element_open(htmloutput *ho, char const *name)
+{
+    return_to_neutral(ho);
+    if (ho->fp)
+	fprintf(ho->fp, "<%s", name);
+    ho->state = HO_IN_TAG;
+}
+
+static void element_close(htmloutput *ho, char const *name)
+{
+    return_to_neutral(ho);
+    if (ho->fp)
+	fprintf(ho->fp, "</%s>", name);
+    ho->state = HO_NEUTRAL;
+}
+
+static void element_empty(htmloutput *ho, char const *name)
+{
+    return_to_neutral(ho);
+    if (ho->fp)
+	fprintf(ho->fp, "<%s", name);
+    ho->state = HO_IN_EMPTY_TAG;
+}
+
+static void html_nl(htmloutput *ho)
+{
+    return_to_neutral(ho);
+    if (ho->fp)
+	fputc('\n', ho->fp);
+}
+
+static void html_raw(htmloutput *ho, char *text)
+{
+    return_to_neutral(ho);
+    if (ho->fp)
+	fputs(text, ho->fp);
+}
+
+static void html_raw_as_attr(htmloutput *ho, char *text)
+{
+    assert(ho->state == HO_IN_TAG || ho->state == HO_IN_EMPTY_TAG);
+    if (ho->fp) {
+	fputc(' ', ho->fp);
+	fputs(text, ho->fp);
+    }
+}
+
+static void element_attr(htmloutput *ho, char const *name, char const *value)
+{
+    html_charset_cleanup(ho);
+    assert(ho->state == HO_IN_TAG || ho->state == HO_IN_EMPTY_TAG);
+    if (ho->fp)
+	fprintf(ho->fp, " %s=\"%s\"", name, value);
+}
+
+static void element_attr_w(htmloutput *ho, char const *name,
+			   wchar_t const *value)
+{
+    html_charset_cleanup(ho);
+    if (ho->fp)
+	fprintf(ho->fp, " %s=\"", name);
+    html_text_limit_internal(ho, value, 0, TRUE, FALSE);
+    html_charset_cleanup(ho);
+    if (ho->fp)
+	fputc('"', ho->fp);
+}
+
+static void html_text(htmloutput *ho, wchar_t const *text)
+{
+    return_mostly_to_neutral(ho);
+    html_text_limit_internal(ho, text, 0, FALSE, FALSE);
+}
+
+static void html_text_nbsp(htmloutput *ho, wchar_t const *text)
+{
+    return_mostly_to_neutral(ho);
+    html_text_limit_internal(ho, text, 0, FALSE, TRUE);
+}
+
+static void html_text_limit(htmloutput *ho, wchar_t const *text, int maxlen)
+{
+    return_mostly_to_neutral(ho);
+    html_text_limit_internal(ho, text, maxlen, FALSE, FALSE);
+}
+
+static void html_text_limit_internal(htmloutput *ho, wchar_t const *text,
+				     int maxlen, int quote_quotes, int nbsp)
+{
+    int textlen = ustrlen(text);
+    char outbuf[256];
+    int bytes, err;
+
+    if (ho->hackflags & (HO_HACK_QUOTEQUOTES | HO_HACK_OMITQUOTES))
+	quote_quotes = TRUE;	       /* override the input value */
+
+    if (maxlen > 0 && textlen > maxlen)
+	textlen = maxlen;
+    if (ho->hacklimit >= 0) {
+	if (textlen > ho->hacklimit)
+	    textlen = ho->hacklimit;
+	ho->hacklimit -= textlen;
+    }
+
+    while (textlen > 0) {
+	/* Scan ahead for characters we really can't display in HTML. */
+	int lenbefore, lenafter;
+	for (lenbefore = 0; lenbefore < textlen; lenbefore++)
+	    if (text[lenbefore] == L'<' ||
+		text[lenbefore] == L'>' ||
+		text[lenbefore] == L'&' ||
+		(text[lenbefore] == L'"' && quote_quotes) ||
+		(text[lenbefore] == L' ' && nbsp))
+		break;
+	lenafter = lenbefore;
+	bytes = charset_from_unicode(&text, &lenafter, outbuf, lenof(outbuf),
+				     ho->charset, &ho->cstate, &err);
+	textlen -= (lenbefore - lenafter);
+	if (bytes > 0 && ho->fp)
+	    fwrite(outbuf, 1, bytes, ho->fp);
+	if (err) {
+	    /*
+	     * We have encountered a character that cannot be
+	     * displayed in the selected output charset. Therefore,
+	     * we use an HTML numeric entity reference.
+	     */
+	    assert(textlen > 0);
+	    if (ho->fp)
+		fprintf(ho->fp, "&#%ld;", (long int)*text);
+	    text++, textlen--;
+	} else if (lenafter == 0 && textlen > 0) {
+	    /*
+	     * We have encountered a character which is special to
+	     * HTML.
+	     */
+	    if (ho->fp) {
+		if (*text == L'"' && (ho->hackflags & HO_HACK_OMITQUOTES)) {
+		    fputc('\'', ho->fp);
+		} else if (ho->hackflags & HO_HACK_QUOTENOTHING) {
+		    fputc(*text, ho->fp);
+		} else {
+		    if (*text == L'<')
+			fprintf(ho->fp, "&lt;");
+		    else if (*text == L'>')
+			fprintf(ho->fp, "&gt;");
+		    else if (*text == L'&')
+			fprintf(ho->fp, "&amp;");
+		    else if (*text == L'"')
+			fprintf(ho->fp, "&quot;");
+		    else if (*text == L' ') {
+			assert(nbsp);
+			fprintf(ho->fp, "&nbsp;");
+		    } else
+			assert(!"Can't happen");
+		}
+	    }
+	    text++, textlen--;
+	}
+    }
+}
+
+static void cleanup(htmloutput *ho)
+{
+    return_to_neutral(ho);
+    if (ho->fp)
+	fclose(ho->fp);
+}
+
+static void html_href(htmloutput *ho, htmlfile *thisfile,
+		      htmlfile *targetfile, char *targetfrag)
+{
+    rdstringc rs = { 0, 0, NULL };
+    char *url;
+
+    if (targetfile != thisfile)
+	rdaddsc(&rs, targetfile->filename);
+    if (targetfrag) {
+	rdaddc(&rs, '#');
+	rdaddsc(&rs, targetfrag);
+    }
+    url = rs.text;
+
+    element_open(ho, "a");
+    element_attr(ho, "href", url);
+    sfree(url);
+}
+
+static void html_fragment(htmloutput *ho, char const *fragment)
+{
+    element_open(ho, "a");
+    element_attr(ho, "name", fragment);
+    if (is_xhtml(ho->ver))
+	element_attr(ho, "id", fragment);
+    element_close(ho, "a");
+}
+
+static char *html_format(paragraph *p, char *template_string)
+{
+    char *c, *t;
+    word *w;
+    wchar_t *ws, wsbuf[2];
+    rdstringc rs = { 0, 0, NULL };
+
+    t = template_string;
+    while (*t) {
+	if (*t == '%' && t[1]) {
+	    int fmt;
+
+	    t++;
+	    fmt = *t++;
+
+	    if (fmt == '%') {
+		rdaddc(&rs, fmt);
+		continue;
+	    }
+
+	    w = NULL;
+	    ws = NULL;
+
+	    if (p->kwtext && fmt == 'n')
+		w = p->kwtext;
+	    else if (p->kwtext2 && fmt == 'b') {
+		/*
+		 * HTML fragment names must start with a letter, so
+		 * simply `1.2.3' is not adequate. In this case I'm
+		 * going to cheat slightly by prepending the first
+		 * character of the first word of kwtext, so that
+		 * we get `C1' for chapter 1, `S2.3' for section
+		 * 2.3 etc.
+		 */
+		if (p->kwtext && p->kwtext->text[0]) {
+		    ws = wsbuf;
+		    wsbuf[1] = '\0';
+		    wsbuf[0] = p->kwtext->text[0];
+		}
+		w = p->kwtext2;
+	    } else if (p->keyword && *p->keyword && fmt == 'k')
+		ws = p->keyword;
+	    else
+		/* %N comes here; also failure cases of other fmts */
+		w = p->words;
+
+	    if (ws) {
+		c = utoa_dup(ws, CS_ASCII);
+		rdaddsc(&rs,c);
+		sfree(c);
+	    }
+
+	    while (w) {
+		if (removeattr(w->type) == word_Normal) {
+		    c = utoa_dup(w->text, CS_ASCII);
+		    rdaddsc(&rs,c);
+		    sfree(c);
+		}
+		w = w->next;
+	    }
+	} else {
+	    rdaddc(&rs, *t++);
+	}
+    }
+
+    return rdtrimc(&rs);
+}
+
+static char *html_sanitise_fragment(htmlfilelist *files, htmlfile *file,
+				    char *text)
+{
+    /*
+     * The HTML 4 spec's strictest definition of fragment names (<a
+     * name> and "id" attributes) says that they `must begin with a
+     * letter and may be followed by any number of letters, digits,
+     * hyphens, underscores, colons, and periods'.
+     * 
+     * So here we unceremoniously rip out any characters not
+     * conforming to this limitation.
+     */
+    char *p = text, *q = text;
+
+    while (*p && !((*p>='A' && *p<='Z') || (*p>='a' && *p<='z')))
+	p++;
+    if ((*q++ = *p++) != '\0') {
+	while (*p) {
+	    if ((*p>='A' && *p<='Z') ||
+		(*p>='a' && *p<='z') ||
+		(*p>='0' && *p<='9') ||
+		*p=='-' || *p=='_' || *p==':' || *p=='.')
+		*q++ = *p;
+	    p++;
+	}
+
+	*q = '\0';
+    }
+
+    /* If there's nothing left, make something valid up */
+    if (!*text) {
+	static const char anonfrag[] = "anon";
+	text = sresize(text, lenof(anonfrag), char);
+	strcpy(text, anonfrag);
+    }
+
+    /*
+     * Now we check for clashes with other fragment names, and
+     * adjust this one if necessary by appending a hyphen followed
+     * by a number.
+     */
+    {
+	htmlfragment *frag = snew(htmlfragment);
+	int len = 0;		       /* >0 indicates we have resized */
+	int suffix = 1;
+
+	frag->file = file;
+	frag->fragment = text;
+
+	while (add234(files->frags, frag) != frag) {
+	    if (!len) {
+		len = strlen(text);
+		frag->fragment = text = sresize(text, len+20, char);
+	    }
+
+	    sprintf(text + len, "-%d", ++suffix);
+	}
+    }
+
+    return text;
+}
+
+static char *html_sanitise_filename(htmlfilelist *files, char *text)
+{
+    /*
+     * Unceremoniously rip out any character that might cause
+     * difficulty in some filesystem or another, or be otherwise
+     * inconvenient.
+     * 
+     * That doesn't leave much punctuation. I permit alphanumerics
+     * and +-.=_ only.
+     */
+    char *p = text, *q = text;
+
+    while (*p) {
+	if ((*p>='A' && *p<='Z') ||
+	    (*p>='a' && *p<='z') ||
+	    (*p>='0' && *p<='9') ||
+	    *p=='-' || *p=='_' || *p=='+' || *p=='.' || *p=='=')
+	    *q++ = *p;
+	p++;
+    }
+    *q = '\0';
+
+    /* If there's nothing left, make something valid up */
+    if (!*text) {
+	static const char anonfrag[] = "anon.html";
+	text = sresize(text, lenof(anonfrag), char);
+	strcpy(text, anonfrag);
+    }
+
+    /*
+     * Now we check for clashes with other filenames, and adjust
+     * this one if necessary by appending a hyphen followed by a
+     * number just before the file extension (if any).
+     */
+    {
+	int len, extpos;
+	int suffix = 1;
+
+	p = NULL;
+
+	while (find234(files->files, text, NULL)) {
+	    if (!p) {
+		len = strlen(text);
+		p = text;
+		text = snewn(len+20, char);
+
+		for (extpos = len; extpos > 0 && p[extpos-1] != '.'; extpos--);
+		if (extpos > 0)
+		    extpos--;
+		else
+		    extpos = len;
+	    }
+
+	    sprintf(text, "%.*s-%d%s", extpos, p, ++suffix, p+extpos);
+	}
+
+	if (p)
+	    sfree(p);
+    }
+
+    return text;
+}
+
+static void html_contents_entry(htmloutput *ho, int depth, htmlsect *s,
+				htmlfile *thisfile, keywordlist *keywords,
+				htmlconfig *cfg)
+{
+    if (ho->contents_level >= depth && ho->contents_level > 0) {
+	element_close(ho, "li");
+	html_nl(ho);
+    }
+
+    while (ho->contents_level > depth) {
+	element_close(ho, "ul");
+	ho->contents_level--;
+	if (ho->contents_level > 0) {
+	    element_close(ho, "li");
+	}
+	html_nl(ho);
+    }
+
+    while (ho->contents_level < depth) {
+	html_nl(ho);
+	element_open(ho, "ul");
+	html_nl(ho);
+	ho->contents_level++;
+    }
+
+    if (!s)
+	return;
+
+    element_open(ho, "li");
+    html_href(ho, thisfile, s->file, s->fragments[0]);
+    html_section_title(ho, s, thisfile, keywords, cfg, FALSE);
+    element_close(ho, "a");
+    /* <li> will be closed by a later invocation */
+}
+
+static void html_section_title(htmloutput *ho, htmlsect *s, htmlfile *thisfile,
+			       keywordlist *keywords, htmlconfig *cfg,
+			       int real)
+{
+    if (s->title) {
+	sectlevel *sl;
+	word *number;
+	int depth = heading_depth(s->title);
+
+	if (depth < 0)
+	    sl = NULL;
+	else if (depth == 0)
+	    sl = &cfg->achapter;
+	else if (depth <= cfg->nasect)
+	    sl = &cfg->asect[depth-1];
+	else
+	    sl = &cfg->asect[cfg->nasect-1];
+
+	if (!sl)
+	    number = NULL;
+	else if (sl->just_numbers)
+	    number = s->title->kwtext2;
+	else
+	    number = s->title->kwtext;
+
+	if (number) {
+	    html_words(ho, number, MARKUP,
+		       thisfile, keywords, cfg);
+	    html_text(ho, sl->number_suffix);
+	}
+
+	html_words(ho, s->title->words, real ? ALL : MARKUP,
+		   thisfile, keywords, cfg);
+    } else {
+	assert(s->type != NORMAL);
+	/*
+	 * If we're printing the full document title for _real_ and
+	 * there isn't one, we don't want to print `Preamble' at
+	 * the top of what ought to just be some text. If we need
+	 * it in any other context such as TOCs, we need to print
+	 * `Preamble'.
+	 */
+	if (s->type == TOP && !real)
+	    html_text(ho, cfg->preamble_text);
+	else if (s->type == INDEX)
+	    html_text(ho, cfg->index_text);
+    }
+}