lyx_mirror/src/output_docbook.cpp

/**
 * \file output_docbook.cpp
 * This file is part of LyX, the document processor.
 * Licence details can be found in the file COPYING.
 *
 * \author Lars Gullik Bjønnes
 * \author José Matos
 *
 * Full author contact details are available in file CREDITS.
 */

#include <config.h>

#include "output_docbook.h"

#include "Buffer.h"
#include "buffer_funcs.h"
#include "BufferParams.h"
#include "Font.h"
#include "InsetList.h"
#include "Paragraph.h"
#include "ParagraphList.h"
#include "ParagraphParameters.h"
#include "xml.h"
#include "Text.h"
#include "TextClass.h"

#include "insets/InsetBibtex.h"
#include "insets/InsetBibitem.h"
#include "insets/InsetLabel.h"
#include "mathed/InsetMath.h"
#include "insets/InsetNote.h"

#include "support/debug.h"
#include "support/lassert.h"
#include "support/textutils.h"

#include <stack>
#include <iostream>
#include <algorithm>
#include <sstream>

using namespace std;
using namespace lyx::support;

namespace lyx {

namespace {

std::string fontToDocBookTag(xml::FontTypes type)
{
	switch (type) {
	case xml::FontTypes::FT_EMPH:
	case xml::FontTypes::FT_BOLD:
		return "emphasis";
	case xml::FontTypes::FT_NOUN:
		return "personname";
	case xml::FontTypes::FT_UBAR:
	case xml::FontTypes::FT_WAVE:
	case xml::FontTypes::FT_DBAR:
	case xml::FontTypes::FT_SOUT:
	case xml::FontTypes::FT_XOUT:
	case xml::FontTypes::FT_ITALIC:
	case xml::FontTypes::FT_UPRIGHT:
	case xml::FontTypes::FT_SLANTED:
	case xml::FontTypes::FT_SMALLCAPS:
	case xml::FontTypes::FT_ROMAN:
	case xml::FontTypes::FT_SANS:
		return "emphasis";
	case xml::FontTypes::FT_TYPE:
		return "code";
	case xml::FontTypes::FT_SIZE_TINY:
	case xml::FontTypes::FT_SIZE_SCRIPT:
	case xml::FontTypes::FT_SIZE_FOOTNOTE:
	case xml::FontTypes::FT_SIZE_SMALL:
	case xml::FontTypes::FT_SIZE_NORMAL:
	case xml::FontTypes::FT_SIZE_LARGE:
	case xml::FontTypes::FT_SIZE_LARGER:
	case xml::FontTypes::FT_SIZE_LARGEST:
	case xml::FontTypes::FT_SIZE_HUGE:
	case xml::FontTypes::FT_SIZE_HUGER:
	case xml::FontTypes::FT_SIZE_INCREASE:
	case xml::FontTypes::FT_SIZE_DECREASE:
		return "emphasis";
	default:
		return "";
	}
}


string fontToRole(xml::FontTypes type)
{
	// Specific fonts are achieved with roles. The only common ones are "" for basic emphasis,
	// and "bold"/"strong" for bold. With some specific options, other roles are copied into
	// HTML output (via the DocBook XSLT sheets); otherwise, if not recognised, they are just ignored.
	// Hence, it is not a problem to have many roles by default here.
	// See https://www.sourceware.org/ml/docbook/2003-05/msg00269.html
	switch (type) {
	case xml::FontTypes::FT_ITALIC:
	case xml::FontTypes::FT_EMPH:
		return "";
	case xml::FontTypes::FT_BOLD:
		return "bold";
	case xml::FontTypes::FT_NOUN: // Outputs a <person>
	case xml::FontTypes::FT_TYPE: // Outputs a <code>
		return "";
	case xml::FontTypes::FT_UBAR:
		return "underline";

	// All other roles are non-standard for DocBook.

	case xml::FontTypes::FT_WAVE:
		return "wave";
	case xml::FontTypes::FT_DBAR:
		return "dbar";
	case xml::FontTypes::FT_SOUT:
		return "sout";
	case xml::FontTypes::FT_XOUT:
		return "xout";
	case xml::FontTypes::FT_UPRIGHT:
		return "upright";
	case xml::FontTypes::FT_SLANTED:
		return "slanted";
	case xml::FontTypes::FT_SMALLCAPS:
		return "smallcaps";
	case xml::FontTypes::FT_ROMAN:
		return "roman";
	case xml::FontTypes::FT_SANS:
		return "sans";
	case xml::FontTypes::FT_SIZE_TINY:
		return "tiny";
	case xml::FontTypes::FT_SIZE_SCRIPT:
		return "size_script";
	case xml::FontTypes::FT_SIZE_FOOTNOTE:
		return "size_footnote";
	case xml::FontTypes::FT_SIZE_SMALL:
		return "size_small";
	case xml::FontTypes::FT_SIZE_NORMAL:
		return "size_normal";
	case xml::FontTypes::FT_SIZE_LARGE:
		return "size_large";
	case xml::FontTypes::FT_SIZE_LARGER:
		return "size_larger";
	case xml::FontTypes::FT_SIZE_LARGEST:
		return "size_largest";
	case xml::FontTypes::FT_SIZE_HUGE:
		return "size_huge";
	case xml::FontTypes::FT_SIZE_HUGER:
		return "size_huger";
	case xml::FontTypes::FT_SIZE_INCREASE:
		return "size_increase";
	case xml::FontTypes::FT_SIZE_DECREASE:
		return "size_decrease";
	default:
		return "";
	}
}


string fontToAttribute(xml::FontTypes type) {
	// If there is a role (i.e. nonstandard use of a tag), output the attribute. Otherwise, the sheer tag is sufficient
	// for the font.
	string role = fontToRole(type);
	if (!role.empty())
		return "role='" + role + "'";
	else
		return "";
}


// Higher-level convenience functions.

void openParTag(XMLStream & xs, const Paragraph * par, const Paragraph * prevpar, const OutputParams & runparams)
{
	if (par == prevpar)
		prevpar = nullptr;

	// If the previous paragraph is empty, don't consider it when opening wrappers.
	if (prevpar && prevpar->empty() && !prevpar->allowEmpty())
		prevpar = nullptr;

	// When should the wrapper be opened here? Only if the previous paragraph has the SAME wrapper tag
	// (usually, they won't have the same layout) and the CURRENT one allows merging.
	// The main use case is author information in several paragraphs: if the name of the author is the
	// first paragraph of an author, then merging with the previous tag does not make sense. Say the
	// next paragraph is the affiliation, then it should be output in the same <author> tag (different
	// layout, same wrapper tag).
	Layout const & lay = par->layout();
	bool openWrapper = lay.docbookwrappertag() != "NONE" && !runparams.docbook_ignore_wrapper;

	if (prevpar != nullptr && !runparams.docbook_ignore_wrapper) {
		Layout const & prevlay = prevpar->layout();
		if (prevlay.docbookwrappertag() != "NONE") {
			if (prevlay.docbookwrappertag() == lay.docbookwrappertag() &&
					prevlay.docbookwrapperattr() == lay.docbookwrapperattr())
				openWrapper = !lay.docbookwrappermergewithprevious();
			else
				openWrapper = true;
		}
	}

	// Main logic.
	if (openWrapper) {
		xml::openTag(xs, lay.docbookwrappertag(), lay.docbookwrapperattr(), lay.docbookwrappertagtype());

		if (lay.docbookgeneratetitle()) {
			docstring const label = par->params().labelString();

			xml::openTag(xs, "title", "", "paragraph");
			xs << (!label.empty() ? label : from_ascii("No title"));
			xml::closeTag(xs, "title", "paragraph");
		}
	}

	const string & tag = lay.docbooktag();
	if (tag != "NONE") {
		auto xmltag = xml::ParTag(tag, lay.docbookattr());
		if (!xs.isTagOpen(xmltag, 1)) { // Don't nest a paragraph directly in a paragraph.
			// TODO: required or not?
			// TODO: avoid creating a ParTag object just for this query...
			xml::openTag(xs, lay.docbooktag(), lay.docbookattr(), lay.docbooktagtype());
			xml::openTag(xs, lay.docbookinnertag(), lay.docbookinnerattr(), lay.docbookinnertagtype());
		}
	}

	xml::openTag(xs, lay.docbookitemwrappertag(), lay.docbookitemwrapperattr(), lay.docbookitemwrappertagtype());
	xml::openTag(xs, lay.docbookitemtag(), lay.docbookitemattr(), lay.docbookitemtagtype());
	xml::openTag(xs, lay.docbookiteminnertag(), lay.docbookiteminnerattr(), lay.docbookiteminnertagtype());
}


void closeParTag(XMLStream & xs, Paragraph const * par, Paragraph const * nextpar, const OutputParams & runparams)
{
	if (par == nextpar)
		nextpar = nullptr;

	// If the next paragraph is empty, don't consider it when closing wrappers.
	if (nextpar && nextpar->empty() && !nextpar->allowEmpty())
		nextpar = nullptr;

	// See comment in openParTag.
	Layout const & lay = par->layout();
	bool closeWrapper = lay.docbookwrappertag() != "NONE" && !runparams.docbook_ignore_wrapper;

	if (nextpar != nullptr && !runparams.docbook_ignore_wrapper) {
		Layout const & nextlay = nextpar->layout();
		if (nextlay.docbookwrappertag() != "NONE") {
			if (nextlay.docbookwrappertag() == lay.docbookwrappertag() &&
					nextlay.docbookwrapperattr() == lay.docbookwrapperattr())
				closeWrapper = !nextlay.docbookwrappermergewithprevious();
			else
				closeWrapper = true;
		}
	}

	// Main logic.
	xml::closeTag(xs, lay.docbookiteminnertag(), lay.docbookiteminnertagtype());
	xml::closeTag(xs, lay.docbookitemtag(), lay.docbookitemtagtype());
	xml::closeTag(xs, lay.docbookitemwrappertag(), lay.docbookitemwrappertagtype());
	xml::closeTag(xs, lay.docbookinnertag(), lay.docbookinnertagtype());
	xml::closeTag(xs, lay.docbooktag(), lay.docbooktagtype());
	if (closeWrapper)
		xml::closeTag(xs, lay.docbookwrappertag(), lay.docbookwrappertagtype());
}


void makeBibliography(
		Text const & text,
		Buffer const & buf,
		XMLStream & xs,
		OutputParams const & runparams,
		ParagraphList::const_iterator const & par)
{
	// If this is the first paragraph in a bibliography, open the bibliography tag.
	auto const * pbegin_before = text.paragraphs().getParagraphBefore(par);
	if (pbegin_before == nullptr || (pbegin_before && pbegin_before->layout().latextype != LATEX_BIB_ENVIRONMENT)) {
		xs << xml::StartTag("bibliography");
		xs << xml::CR();
	}

	// Start the precooked bibliography entry. This is very much like opening a paragraph tag.
	// Don't forget the citation ID!
	docstring attr;
	for (auto i = 0; i < par->size(); ++i) {
		Inset const *ip = par->getInset(i);
		if (!ip)
			continue;
		if (const auto * bibitem = dynamic_cast<const InsetBibitem*>(ip)) {
			auto id = xml::cleanID(bibitem->getParam("key"));
			attr = from_utf8("xml:id='") + id + from_utf8("'");
			break;
		}
	}
	xs << xml::StartTag(from_utf8("bibliomixed"), attr);

	// Generate the entry. Concatenate the different parts of the paragraph if any.
	auto const begin = text.paragraphs().begin();
	std::vector<docstring> pars_prepend;
	std::vector<docstring> pars;
	std::vector<docstring> pars_append;
	tie(pars_prepend, pars, pars_append) = par->simpleDocBookOnePar(buf, runparams, text.outerFont(std::distance(begin, par)), 0);

	for (auto & parXML : pars_prepend)
		xs << XMLStream::ESCAPE_NONE << parXML;
	for (auto & parXML : pars)
		xs << XMLStream::ESCAPE_NONE << parXML;
	for (auto & parXML : pars_append)
		xs << XMLStream::ESCAPE_NONE << parXML;

	// End the precooked bibliography entry.
	xs << xml::EndTag("bibliomixed");
	xs << xml::CR();

	// If this is the last paragraph in a bibliography, close the bibliography tag.
	auto const end = text.paragraphs().end();
	auto nextpar = par;
	++nextpar;
	bool endBibliography = nextpar == end || nextpar->layout().latextype != LATEX_BIB_ENVIRONMENT;

	if (endBibliography) {
		xs << xml::EndTag("bibliography");
		xs << xml::CR();
	}
}


void makeParagraph(
		Text const & text,
		Buffer const & buf,
		XMLStream & xs,
		OutputParams const & runparams,
		ParagraphList::const_iterator const & par)
{
	// Useful variables.
	auto const begin = text.paragraphs().begin();
	auto const end = text.paragraphs().end();
	auto prevpar = text.paragraphs().getParagraphBefore(par);

	// We want to open the paragraph tag if:
	//   (i) the current layout permits multiple paragraphs
	//  (ii) we are either not already inside a paragraph (HTMLIsBlock) OR
	//	   we are, but this is not the first paragraph
	//
	// But there is also a special case, and we first see whether we are in it.
	// We do not want to open the paragraph tag if this paragraph contains
	// only one item, and that item is "inline", i.e., not HTMLIsBlock (such
	// as a branch). On the other hand, if that single item has a font change
	// applied to it, then we still do need to open the paragraph.
	//
	// Obviously, this is very fragile. The main reason we need to do this is
	// because of branches, e.g., a branch that contains an entire new section.
	// We do not really want to wrap that whole thing in a <div>...</div>.
	bool special_case = false;
	Inset const *specinset = par->size() == 1 ? par->getInset(0) : nullptr;
	if (specinset && !specinset->getLayout().htmlisblock()) { // TODO: Convert htmlisblock to a DocBook parameter? docbooknotinpara should be enough in most cases.
		Layout const &style = par->layout();
		FontInfo const first_font = style.labeltype == LABEL_MANUAL ?
									style.labelfont : style.font;
		FontInfo const our_font =
				par->getFont(buf.masterBuffer()->params(), 0,
							 text.outerFont(std::distance(begin, par))).fontInfo();

		if (first_font == our_font)
			special_case = true;
	}

	size_t nInsets = std::distance(par->insetList().begin(), par->insetList().end());
	auto parSize = (size_t) par->size();

	// Plain layouts must be ignored.
	special_case |= buf.params().documentClass().isPlainLayout(par->layout()) && !runparams.docbook_force_pars;

	// Equations do not deserve their own paragraph (DocBook allows them outside paragraphs).
	// Exception: any case that generates an <inlineequation> must still get a paragraph to be valid.
	auto isEquationSpecialCase = [](InsetList::Element inset) {
		return inset.inset && inset.inset->asInsetMath() && inset.inset->asInsetMath()->getType() != hullSimple;
	};
	special_case |= nInsets == parSize && std::all_of(par->insetList().begin(), par->insetList().end(), isEquationSpecialCase);

	// Things that should not get into their own paragraph. (Only valid for DocBook.)
	static std::set<InsetCode> lyxCodeSpecialCases = {
			TABULAR_CODE,
			FLOAT_CODE,
			BIBTEX_CODE, // Bibliographies cannot be in paragraphs. Bibitems should still be handled as paragraphs,
			// though (see makeBibliography).
			ERT_CODE, // ERTs are in comments, not paragraphs.
			LISTINGS_CODE,
			BOX_CODE,
			INCLUDE_CODE,
			NOMENCL_PRINT_CODE,
			TOC_CODE, // To be ignored in DocBook, the processor afterwards should deal with ToCs.
			NOTE_CODE // Notes do not produce any output.
	};
	auto isLyxCodeSpecialCase = [](InsetList::Element inset) {
		return lyxCodeSpecialCases.find(inset.inset->lyxCode()) != lyxCodeSpecialCases.end();
	};
	special_case |= nInsets == parSize && std::all_of(par->insetList().begin(), par->insetList().end(), isLyxCodeSpecialCase);

	// Flex elements (InsetLayout) have their own parameter to control the special case.
	auto isFlexSpecialCase = [](InsetList::Element inset) {
		if (inset.inset->lyxCode() != FLEX_CODE)
			return false;

		// Standard condition: check the parameter.
		if (inset.inset->getLayout().docbooknotinpara())
			return true;

		// If the parameter is not set, maybe the flex inset only contains things that should match the standard
		// condition. In this case, isLyxCodeSpecialCase must also check for bibitems...
		auto isLyxCodeSpecialCase = [](InsetList::Element inset) {
			return lyxCodeSpecialCases.find(inset.inset->lyxCode()) != lyxCodeSpecialCases.end() ||
					inset.inset->lyxCode() == BIBITEM_CODE;
		};
		if (InsetText * text = inset.inset->asInsetText()) {
			for (auto const & par : text->paragraphs()) {
				size_t nInsets = std::distance(par.insetList().begin(), par.insetList().end());
				auto parSize = (size_t) par.size();

				if (nInsets == 1 && par.insetList().begin()->inset->lyxCode() == BIBITEM_CODE)
					return true;
				if (nInsets != parSize)
					return false;
				if (!std::all_of(par.insetList().begin(), par.insetList().end(), isLyxCodeSpecialCase))
					return false;
			}
			return true;
		}

		// No case matched: give up.
		return false;
	};
	special_case |= nInsets == parSize && std::all_of(par->insetList().begin(), par->insetList().end(), isFlexSpecialCase);

	// If the insets should be rendered as images, enter the special case.
	auto isRenderedAsImageSpecialCase = [](InsetList::Element inset) {
		return inset.inset && inset.inset->getLayout().docbookrenderasimage();
	};
	special_case |= nInsets == parSize && std::all_of(par->insetList().begin(), par->insetList().end(), isRenderedAsImageSpecialCase);

	// Open a paragraph if it is allowed, we are not already within a paragraph, and the insets in the paragraph do
	// not forbid paragraphs (aka special cases).
	bool const open_par = runparams.docbook_make_pars
						  && !runparams.docbook_in_par
						  && !special_case;

	// We want to issue the closing tag if either:
	//   (i)  We opened it, and either docbook_in_par is false,
	//		or we're not in the last paragraph, anyway.
	//   (ii) We didn't open it and docbook_in_par is true,
	//		but we are in the first par, and there is a next par.
	bool const close_par = open_par && !runparams.docbook_in_par;

	// Determine if this paragraph has some real content. Things like new pages are not caught
	// by Paragraph::empty(), even though they do not generate anything useful in DocBook.
	// Thus, remove all spaces (including new lines: \r, \n) before checking for emptiness.
	// std::all_of allows doing this check without having to copy the string.
	// Open and close tags around each contained paragraph.
	auto nextpar = par;
	++nextpar;

	std::vector<docstring> pars_prepend;
	std::vector<docstring> pars;
	std::vector<docstring> pars_append;
	tie(pars_prepend, pars, pars_append) = par->simpleDocBookOnePar(buf, runparams, text.outerFont(distance(begin, par)), 0, nextpar == end, special_case);

	for (docstring const & parXML : pars_prepend)
	    xs << XMLStream::ESCAPE_NONE << parXML;
	for (docstring const & parXML : pars) {
		if (!xml::isNotOnlySpace(parXML))
			continue;

		if (open_par)
			openParTag(xs, &*par, prevpar, runparams);

		xs << XMLStream::ESCAPE_NONE << parXML;

		if (close_par)
			closeParTag(xs, &*par, (nextpar != end) ? &*nextpar : nullptr, runparams);
	}
	for (docstring const & parXML : pars_append)
	    xs << XMLStream::ESCAPE_NONE << parXML;
}


void makeEnvironment(Text const &text,
					 Buffer const &buf,
                     XMLStream &xs,
                     OutputParams const &runparams,
                     ParagraphList::const_iterator const & par)
{
	// Useful variables.
	auto const end = text.paragraphs().end();
	auto nextpar = par;
	++nextpar;

	// Special cases for listing-like environments provided in layouts. This is quite ad-hoc, but provides a useful
	// default. This should not be used by too many environments (only LyX-Code right now).
	// This would be much simpler if LyX-Code was implemented as InsetListings...
	bool mimicListing = false;
	bool ignoreFonts = false;
	if (par->layout().docbooktag() == "programlisting") {
		mimicListing = true;
		ignoreFonts = true;
	}

	// Output the opening tag for this environment, but only if it has not been previously opened (condition
	// implemented in openParTag).
	auto prevpar = text.paragraphs().getParagraphBefore(par);
	openParTag(xs, &*par, prevpar, runparams);

	// Generate the contents of this environment. There is a special case if this is like some environment.
	Layout const & style = par->layout();
	if (style.latextype == LATEX_COMMAND) {
		// Nothing to do (otherwise, infinite loops).
	} else if (style.latextype == LATEX_ENVIRONMENT) {
		// Generate the paragraph, if need be.
		std::vector<docstring> pars_prepend;
        std::vector<docstring> pars;
        std::vector<docstring> pars_append;
        tie(pars_prepend, pars, pars_append) =
				par->simpleDocBookOnePar(buf, runparams, text.outerFont(std::distance(text.paragraphs().begin(), par)),
										 0, false, ignoreFonts);

        for (docstring const & parXML : pars_prepend)
            xs << XMLStream::ESCAPE_NONE << parXML;
		if (mimicListing) {
			auto p = pars.begin();
			while (p != pars.end()) {
				xml::openTag(xs, par->layout().docbookiteminnertag(), par->layout().docbookiteminnerattr(),
				             par->layout().docbookiteminnertagtype());
				xs << XMLStream::ESCAPE_NONE << *p;
				xml::closeTag(xs, par->layout().docbookiteminnertag(), par->layout().docbookiteminnertagtype());
				++p;

				// Insert a new line after each "paragraph" (i.e. line in the listing), except for the last one.
				// Otherwise, there would one more new line in the output than in the LyX document.
				if (p != pars.end())
					xs << xml::CR();
			}
		} else {
			for (auto const & p : pars) {
				xml::openTag(xs, par->layout().docbookiteminnertag(), par->layout().docbookiteminnerattr(),
				             par->layout().docbookiteminnertagtype());
				xs << XMLStream::ESCAPE_NONE << p;
				xml::closeTag(xs, par->layout().docbookiteminnertag(), par->layout().docbookiteminnertagtype());
			}
		}
        for (docstring const & parXML : pars_append)
            xs << XMLStream::ESCAPE_NONE << parXML;
	} else {
		makeAny(text, buf, xs, runparams, par);
	}

	// Close the environment.
	closeParTag(xs, &*par, (nextpar != end) ? &*nextpar : nullptr, runparams);
}


ParagraphList::const_iterator findEndOfEnvironment(
		ParagraphList::const_iterator const & pstart,
		ParagraphList::const_iterator const & pend)
{
	// Copy-paste from XHTML. Should be factored out at some point...
	ParagraphList::const_iterator p = pstart;
	Layout const & bstyle = p->layout();
	size_t const depth = p->params().depth();
	for (++p; p != pend; ++p) {
		Layout const & style = p->layout();
		// It shouldn't happen that e.g. a section command occurs inside
		// a quotation environment, at a higher depth, but as of 6/2009,
		// it can happen. We pretend that it's just at lowest depth.
		if (style.latextype == LATEX_COMMAND)
			return p;

		// If depth is down, we're done
		if (p->params().depth() < depth)
			return p;

		// If depth is up, we're not done
		if (p->params().depth() > depth)
			continue;

		// FIXME I am not sure about the first check.
		// Surely we *could* have different layouts that count as
		// LATEX_PARAGRAPH, right?
		if (style.latextype == LATEX_PARAGRAPH || style != bstyle)
			return p;
	}
	return pend;
}


ParagraphList::const_iterator makeListEnvironment(Text const &text,
												  Buffer const &buf,
		                                          XMLStream &xs,
		                                          OutputParams const &runparams,
		                                          ParagraphList::const_iterator const & begin)
{
	// Useful variables.
	auto par = begin;
	auto const end = text.paragraphs().end();
	auto const envend = findEndOfEnvironment(par, end);

	// Output the opening tag for this environment.
	Layout const & envstyle = par->layout();
	xml::openTag(xs, envstyle.docbookwrappertag(), envstyle.docbookwrapperattr(), envstyle.docbookwrappertagtype());
	xml::openTag(xs, envstyle.docbooktag(), envstyle.docbookattr(), envstyle.docbooktagtype());

	// Handle the content of the list environment, item by item.
	while (par != envend) {
		// Skip this paragraph if it is both empty and the last one (otherwise, there may be deeper paragraphs after).
		auto nextpar = par;
		++nextpar;
		if (par->empty() && nextpar == envend)
			break;

		// Open the item wrapper.
		Layout const & style = par->layout();
		xml::openTag(xs, style.docbookitemwrappertag(), style.docbookitemwrapperattr(),
		             style.docbookitemwrappertagtype());

		// Generate the label, if need be. If it is taken from the text, sep != 0 and corresponds to the first
		// character after the label.
		pos_type sep = 0;
		if (style.labeltype != LABEL_NO_LABEL && style.docbookitemlabeltag() != "NONE") {
			if (style.labeltype == LABEL_MANUAL) {
				// Only variablelist gets here (or similar items defined as an extension in the layout).
				xml::openTag(xs, style.docbookitemlabeltag(), style.docbookitemlabelattr(),
				             style.docbookitemlabeltagtype());
				sep = 1 + par->firstWordDocBook(xs, runparams);
				xml::closeTag(xs, style.docbookitemlabeltag(), style.docbookitemlabeltagtype());
			} else {
				// Usual cases: maybe there is something specified at the layout level. Highly unlikely, though.
				docstring const lbl = par->params().labelString();

				if (!lbl.empty()) {
					xml::openTag(xs, style.docbookitemlabeltag(), style.docbookitemlabelattr(),
					             style.docbookitemlabeltagtype());
					xs << lbl;
					xml::closeTag(xs, style.docbookitemlabeltag(), style.docbookitemlabeltagtype());
				}
			}
		}

		// Open the item (after the wrapper and the label).
		xml::openTag(xs, style.docbookitemtag(), style.docbookitemattr(), style.docbookitemtagtype());

		// Generate the content of the item.
		if (sep < par->size()) {
            std::vector<docstring> pars_prepend;
            std::vector<docstring> pars;
            std::vector<docstring> pars_append;
            tie(pars_prepend, pars, pars_append) = par->simpleDocBookOnePar(buf, runparams,
			                                     text.outerFont(std::distance(text.paragraphs().begin(), par)), sep);
            for (docstring const & parXML : pars_prepend)
                xs << XMLStream::ESCAPE_NONE << parXML;
			for (auto &p : pars) {
				xml::openTag(xs, par->layout().docbookiteminnertag(), par->layout().docbookiteminnerattr(),
				             par->layout().docbookiteminnertagtype());
				xs << XMLStream::ESCAPE_NONE << p;
				xml::closeTag(xs, par->layout().docbookiteminnertag(), par->layout().docbookiteminnertagtype());
			}
            for (docstring const & parXML : pars_append)
                xs << XMLStream::ESCAPE_NONE << parXML;
		} else {
			// DocBook doesn't like emptiness.
			xml::compTag(xs, par->layout().docbookiteminnertag(), par->layout().docbookiteminnerattr(),
			             par->layout().docbookiteminnertagtype());
		}

		// If the next item is deeper, it must go entirely within this item (do it recursively).
		// By construction, with findEndOfEnvironment, depth can only stay constant or increase, never decrease.
		depth_type currentDepth = par->getDepth();
		++par;
		while (par != envend && par->getDepth() != currentDepth)
			par = makeAny(text, buf, xs, runparams, par);
		// Usually, this loop only makes one iteration, except in complex scenarios, like an item with a paragraph,
		// a list, and another paragraph; or an item with two types of list (itemise then enumerate, for instance).

		// Close the item.
		xml::closeTag(xs, style.docbookitemtag(), style.docbookitemtagtype());
		xml::closeTag(xs, style.docbookitemwrappertag(), style.docbookitemwrappertagtype());
	}

	// Close this environment in exactly the same way as it was opened.
	xml::closeTag(xs, envstyle.docbooktag(), envstyle.docbooktagtype());
	xml::closeTag(xs, envstyle.docbookwrappertag(), envstyle.docbookwrappertagtype());

	return envend;
}


void makeCommand(
		Text const & text,
		Buffer const & buf,
		XMLStream & xs,
		OutputParams const & runparams,
		ParagraphList::const_iterator const & par)
{
	// Useful variables.
	// Unlike XHTML, no need for labels, as they are handled by DocBook tags.
	auto const begin = text.paragraphs().begin();
	auto const end = text.paragraphs().end();
	auto nextpar = par;
	++nextpar;

	// Generate this command.
	auto prevpar = text.paragraphs().getParagraphBefore(par);

    std::vector<docstring> pars_prepend;
    std::vector<docstring> pars;
    std::vector<docstring> pars_append;
    tie(pars_prepend, pars, pars_append) = par->simpleDocBookOnePar(buf, runparams,text.outerFont(distance(begin, par)));

    for (docstring const & parXML : pars_prepend)
        xs << XMLStream::ESCAPE_NONE << parXML;

    openParTag(xs, &*par, prevpar, runparams);
	for (auto & parXML : pars)
		// TODO: decide what to do with openParTag/closeParTag in new lines.
		xs << XMLStream::ESCAPE_NONE << parXML;
    closeParTag(xs, &*par, (nextpar != end) ? &*nextpar : nullptr, runparams);

    for (docstring const & parXML : pars_append)
        xs << XMLStream::ESCAPE_NONE << parXML;
}


bool isLayoutSectioning(Layout const & lay)
{
	if (lay.docbooksection()) // Special case: some DocBook styles must be handled as sections.
		return true;
	else if (lay.category() == from_utf8("Sectioning") || lay.docbooktag() == "section") // Generic case.
		return lay.toclevel != Layout::NOT_IN_TOC;
	return false;
}


bool isLayoutSectioningOrSimilar(Layout const & lay)
{
	return isLayoutSectioning(lay) || lay.docbooktag() == "bridgehead";
}


using DocBookDocumentSectioning = tuple<bool, pit_type>;


struct DocBookInfoTag
{
	const set<pit_type> shouldBeInInfo;
	const set<pit_type> mustBeInInfo; // With the notable exception of the abstract!
	const set<pit_type> abstract;
	const bool abstractLayout;
	pit_type bpit;
	pit_type epit;

	DocBookInfoTag(const set<pit_type> & shouldBeInInfo, const set<pit_type> & mustBeInInfo,
				   const set<pit_type> & abstract, bool abstractLayout, pit_type bpit, pit_type epit) :
				   shouldBeInInfo(shouldBeInInfo), mustBeInInfo(mustBeInInfo), abstract(abstract),
				   abstractLayout(abstractLayout), bpit(bpit), epit(epit) {}
};


DocBookDocumentSectioning hasDocumentSectioning(ParagraphList const &paragraphs, pit_type bpit, pit_type const epit) {
	bool documentHasSections = false;

	while (bpit < epit) {
		LASSERT(static_cast<size_t>(bpit) < paragraphs.size(), return make_tuple(documentHasSections, bpit));

		Layout const &style = paragraphs[bpit].layout();
		documentHasSections |= isLayoutSectioningOrSimilar(style);

		if (documentHasSections)
			break;
		bpit += 1;
	}
	// Paragraphs before the first section: [ runparams.par_begin ; eppit )

	return make_tuple(documentHasSections, bpit);
}


bool hasOnlyNotes(Paragraph const & par)
{
	// Precondition: the paragraph is not empty. Otherwise, the function will always return true...
	for (int i = 0; i < par.size(); ++i)
		// If you find something that is not an inset (like actual text) or an inset that is not a note,
		// return false.
		if (!par.isInset(i) || par.getInset(i)->lyxCode() != NOTE_CODE)
			return false;

	// An empty paragraph may still require some output.
	if (par.layout().docbooksection())
		return false;

	// There should be really no content here.
	return true;
}


DocBookInfoTag getParagraphsWithInfo(ParagraphList const &paragraphs,
									 pit_type bpit, pit_type const epit,
									 // Typically, bpit is the beginning of the document and epit the end of the
									 // document *or* the first section.
									 bool documentHasSections,
									 bool detectUnlayoutedAbstract
									 // Whether paragraphs with no specific layout should be detected as abstracts.
									 // For inner sections, an abstract should only be detected if it has a specific
									 // layout. For others, anything that might look like an abstract should be sought.
									 ) {
	set<pit_type> shouldBeInInfo;
	set<pit_type> mustBeInInfo;
	set<pit_type> abstractWithLayout;
	set<pit_type> abstractNoLayout;

	// Find the first nonempty paragraph by mutating bpit.
	while (bpit < epit) {
		Paragraph const &par = paragraphs[bpit];
		if (par.empty() || hasOnlyNotes(par))
			bpit += 1;
		else
			break;
	}

	// Traverse everything that might belong to <info>.
	bool hasAbstractLayout = false;
	static depth_type INVALID_DEPTH = 100000;
	depth_type abstractDepth = INVALID_DEPTH;
	pit_type cpit = bpit;
	for (; cpit < epit; ++cpit) {
		// Skip paragraphs that don't generate anything in DocBook.
		Paragraph const & par = paragraphs[cpit];
		Layout const &style = par.layout();
		if (hasOnlyNotes(par))
			continue;

		// There should never be any section here, except for the first paragraph (a title can be part of <info>).
		// (Just a sanity check: if this fails, this function could end up processing the whole document.)
		if (cpit != bpit && isLayoutSectioningOrSimilar(par.layout())) {
			LYXERR(Debug::OUTFILE, "Assertion failed: section found in potential <info> paragraphs.");
			break;
		}

		// If this is marked as an abstract by the layout, put it in the right set.
		if (style.docbookabstract()) {
			hasAbstractLayout = true;
			abstractDepth = par.getDepth();
			abstractWithLayout.emplace(cpit);
			continue;
		}

		// Deeper paragraphs following the abstract must still be considered as part of the abstract.
		// For instance, this includes lists. There should not be any other kind of paragraph in between.
		if (abstractDepth != INVALID_DEPTH && style.docbookininfo() == "never") {
			if (par.getDepth() > abstractDepth) {
				abstractWithLayout.emplace(cpit);
				continue;
			}
			if (par.getDepth() == abstractDepth) {
				// This is not an abstract paragraph and it should not either be considered as part
				// of it. It breaks the rule that abstract paragraphs must follow each other.
				abstractDepth = INVALID_DEPTH;
				break;
			}
		}

		// Based on layout information, store this paragraph in one set: should be in <info>, must be,
		// or abstract (either because of layout or of position).
		if (style.docbookininfo() == "always")
			mustBeInInfo.emplace(cpit);
		else if (style.docbookininfo() == "maybe")
			shouldBeInInfo.emplace(cpit);
		else if (documentHasSections && !hasAbstractLayout && detectUnlayoutedAbstract &&
				(style.docbooktag() == "NONE" || style.docbooktag() == "para") &&
				style.docbookwrappertag() == "NONE")
			// In this case, it is very likely that style.docbookininfo() == "never"! Be extra careful
			// about anything that gets caught here. For instance, don't ake into account
			abstractNoLayout.emplace(cpit);
		else // This should definitely not be in <info>.
			break;
	}
	// Now, cpit points to the first paragraph that no more has things that could go in <info>.
	// bpit is the beginning of the <info> part.

	return DocBookInfoTag(shouldBeInInfo, mustBeInInfo,
					      hasAbstractLayout ? abstractWithLayout : abstractNoLayout,
					      hasAbstractLayout, bpit, cpit);
}

} // end anonymous namespace


std::set<const Inset *> gatherInfo(ParagraphList::const_iterator par)
{
	// This function has a structure highly similar to makeAny and its friends. It's only made to be called on what
	// should become the document's <abstract>.
	std::set<const Inset *> values;

	// If this kind of layout should be ignored, already leave.
	if (par->layout().docbooktag() == "IGNORE")
		return values;

	// If this should go in info, mark it as such. Dive deep into the abstract, as it may hide many things that
	// DocBook doesn't want to be inside the abstract.
	for (pos_type i = 0; i < par->size(); ++i) {
		if (par->getInset(i) && par->getInset(i)->asInsetText()) {
			InsetText const *inset = par->getInset(i)->asInsetText();

			if (inset->getLayout().docbookininfo() != "never") {
				values.insert(inset);
			} else {
				auto subpar = inset->paragraphs().begin();
				while (subpar != inset->paragraphs().end()) {
					auto subinfos = gatherInfo(subpar);
					for (auto & subinfo: subinfos)
						values.insert(subinfo);
					++subpar;
				}
			}
		}
	}

	return values;
}


ParagraphList::const_iterator makeAny(Text const &text,
                                      Buffer const &buf,
                                      XMLStream &xs,
                                      OutputParams const &runparams,
                                      ParagraphList::const_iterator par)
{
	bool ignoreParagraph = false;

	// If this kind of layout should be ignored, already leave.
	ignoreParagraph |= par->layout().docbooktag() == "IGNORE";

	// For things that should go into <info>, check the variable rp.docbook_generate_info. This does not apply to the
	// abstract itself.
	bool isAbstract = par->layout().docbookabstract() || par->layout().docbooktag() == "abstract";
	ignoreParagraph |= !isAbstract && par->layout().docbookininfo() != "never" && !runparams.docbook_generate_info;

	// Switch on the type of paragraph to call the right handler.
	if (!ignoreParagraph) {
		switch (par->layout().latextype) {
		case LATEX_COMMAND:
			makeCommand(text, buf, xs, runparams, par);
			break;
		case LATEX_ENVIRONMENT:
			makeEnvironment(text, buf, xs, runparams, par);
			break;
		case LATEX_LIST_ENVIRONMENT:
		case LATEX_ITEM_ENVIRONMENT:
			// Only case when makeAny() might consume more than one paragraph.
			return makeListEnvironment(text, buf, xs, runparams, par);
		case LATEX_PARAGRAPH:
			makeParagraph(text, buf, xs, runparams, par);
			break;
		case LATEX_BIB_ENVIRONMENT:
			makeBibliography(text, buf, xs, runparams, par);
			break;
		}
	}

	// For cases that are not lists, the next paragraph to handle is the next one.
	++par;
	return par;
}


xml::FontTag docbookStartFontTag(xml::FontTypes type)
{
	return xml::FontTag(from_utf8(fontToDocBookTag(type)), from_utf8(fontToAttribute(type)), type);
}


xml::EndFontTag docbookEndFontTag(xml::FontTypes type)
{
	return xml::EndFontTag(from_utf8(fontToDocBookTag(type)), type);
}


void outputDocBookInfo(
		Text const & text,
		Buffer const & buf,
		XMLStream & xs,
		OutputParams const & runparams,
		ParagraphList const & paragraphs,
		DocBookInfoTag const & info)
{
	// Perform an additional check on the abstract. Sometimes, there are many paragraphs that should go
	// into the abstract, but none generates actual content. Thus, first generate to a temporary stream,
	// then only create the <abstract> tag if these paragraphs generate some content.
	// This check must be performed *before* a decision on whether or not to output <info> is made.
	bool hasAbstract = !info.abstract.empty();
	docstring abstract;
	set<const Inset *> infoInsets; // Paragraphs that should go into <info>, but are hidden in an <abstract>
	// paragraph. (This happens for quite a few layouts, unfortunately.)

	if (hasAbstract) {
		// Generate the abstract XML into a string before further checks.
		// Usually, makeAny only generates one paragraph at a time. However, for the specific case of lists, it might
		// generate more than one paragraph, as indicated in the return value.
		odocstringstream os2;
		XMLStream xs2(os2);

		auto rp = runparams;
		rp.docbook_generate_info = false;
		rp.docbook_ignore_wrapper = true;

		set<pit_type> doneParas; // Paragraphs that have already been converted (mostly to deal with lists).
		for (auto const & p : info.abstract) {
			if (doneParas.find(p) == doneParas.end()) {
				auto oldPar = paragraphs.iterator_at(p);
				auto newPar = makeAny(text, buf, xs2, rp, oldPar);

				// Find insets that should go outside the abstract.
				auto subinfos = gatherInfo(oldPar);
				for (auto & subinfo: subinfos)
					infoInsets.insert(subinfo);

				// Insert the indices of all the paragraphs that were just generated (typically, one).
				// **Make the hypothesis that, when an abstract has a list, all its items are consecutive.**
				// Otherwise, makeAny and makeListEnvironment would have to be adapted too.
				pit_type id = p;
				while (oldPar != newPar) {
					doneParas.emplace(id);
					++oldPar;
					++id;
				}
			}
		}

		// Actually output the abstract if there is something to do. Don't count line feeds, spaces, or comments
		// in this -- even though line feeds and spaces must be properly output if there is some abstract.
		abstract = os2.str();
		docstring cleaned = abstract;
		cleaned.erase(std::remove_if(cleaned.begin(), cleaned.end(), lyx::isSpace), cleaned.end());

		size_t beginComment;
		size_t endComment;
		while ((beginComment = cleaned.find(from_ascii("<!--"))) != lyx::docstring::npos) {
			if ((endComment = cleaned.find(from_ascii("-->"), beginComment)) != lyx::docstring::npos) {
				cleaned.erase(cleaned.begin() + beginComment, cleaned.begin() + endComment + 3);
			}
		}

		// Nothing? Then there is no abstract!
		if (cleaned.empty())
			hasAbstract = false;
	}

	// The abstract must go in <info>. Otherwise, decide whether to open <info> based on the layouts.
	bool needInfo = !info.mustBeInInfo.empty() || hasAbstract;

	// Start the <info> tag if required.
	if (needInfo) {
		xs.startDivision(false);
		xs << xml::StartTag("info");
		xs << xml::CR();
	}

	// Output the elements that should go in <info>.
	// - First, the title.
	for (auto pit : info.shouldBeInInfo) // Typically, the title: these elements are so important and ubiquitous
		// that mandating a wrapper like <info> would repel users. Thus, generate them first.
		makeAny(text, buf, xs, runparams, paragraphs.iterator_at(pit));
	// If there is no title, generate one (required for the document to be valid).
	// This code is called for the main document, for table cells, etc., so be precise in this condition.
	if (text.isMainText() && info.shouldBeInInfo.empty() && !runparams.inInclude) {
		xs << xml::StartTag("title");
		xs << "Untitled Document";
		xs << xml::EndTag("title");
		xs << xml::CR();
	}

	// - Then, other metadata.
	for (auto pit : info.mustBeInInfo)
		makeAny(text, buf, xs, runparams, paragraphs.iterator_at(pit));
	for (auto const * inset : infoInsets)
		inset->docbook(xs, runparams);

	// - Finally, always output the abstract as the last item of the <info>, as it requires special treatment
	// (especially if it contains several paragraphs that are empty).
	if (hasAbstract) {
		string tag = paragraphs[*info.abstract.begin()].layout().docbookforceabstracttag();
		if (tag == "NONE")
			tag = "abstract";

		if (!xs.isLastTagCR())
			xs << xml::CR();

		xs << xml::StartTag(tag);
		xs << xml::CR();
		xs << XMLStream::ESCAPE_NONE << abstract;
		xs << xml::EndTag(tag);
		xs << xml::CR();
	}

	// End the <info> tag if it was started.
	if (needInfo) {
		if (!xs.isLastTagCR())
			xs << xml::CR();

		xs << xml::EndTag("info");
		xs << xml::CR();
		xs.endDivision();
	}
}


void docbookSimpleAllParagraphs(
		Text const & text,
		Buffer const & buf,
		XMLStream & xs,
		OutputParams const & runparams)
{
	// Handle the given text, supposing it has no sections (i.e. a "simple" text). The input may vary in length
	// between a single paragraph to a whole document.
	pit_type const bpit = runparams.par_begin;
	pit_type const epit = runparams.par_end;
	ParagraphList const &paragraphs = text.paragraphs();

	// First, the <info> tag.
	DocBookInfoTag info = getParagraphsWithInfo(paragraphs, bpit, epit, false, true);
	outputDocBookInfo(text, buf, xs, runparams, paragraphs, info);

	// Then, the content. It starts where the <info> ends.
	auto par = paragraphs.iterator_at(info.epit);
	auto par_epit = paragraphs.iterator_at(epit);
	auto par_end = paragraphs.end();
	while (par != par_epit && par != par_end) {
		if (!hasOnlyNotes(*par))
			par = makeAny(text, buf, xs, runparams, par);
		else
			++par;
	}
}


void docbookParagraphs(Text const &text,
					   Buffer const &buf,
					   XMLStream &xs,
					   OutputParams const &runparams) {
	ParagraphList const &paragraphs = text.paragraphs();
	if (runparams.par_begin == runparams.par_end) {
		runparams.par_begin = 0;
		runparams.par_end = paragraphs.size();
	}
	pit_type bpit = runparams.par_begin;
	pit_type const epit = runparams.par_end;
	LASSERT(bpit < epit,
			{
				xs << XMLStream::ESCAPE_NONE << "<!-- DocBook output error! -->\n";
				return;
			});

	// Detect whether the document contains sections. If there are no sections, treatment is largely simplified.
	// In particular, there can't be an abstract, unless it is manually marked.
	bool documentHasSections;
	pit_type eppit;
	tie(documentHasSections, eppit) = hasDocumentSectioning(paragraphs, bpit, epit);

	// Deal with "simple" documents, i.e. those without sections.
	if (!documentHasSections) {
		docbookSimpleAllParagraphs(text, buf, xs, runparams);
		return;
	}

	// Output the first <info> tag (or just the title).
	DocBookInfoTag info = getParagraphsWithInfo(paragraphs, bpit, eppit, true, true);
	outputDocBookInfo(text, buf, xs, runparams, paragraphs, info);
	bpit = info.epit;

	// In the specific case of books, there must be parts or chapters. In some cases, star sections are used at the
	// beginning for many things like acknowledgements or licenses. DocBook has tags for many of these cases, but not
	// the LyX layouts... Gather everything in a <preface>, that's the closest in meaning.
	// This is only useful if the things after the <info> tag are not already parts or chapters!
	if (buf.params().documentClass().docbookroot() == "book") {
	    // Check the condition on the first few elements.
	    bool hasPreface = false;
	    pit_type pref_bpit = bpit;
	    pit_type pref_epit = bpit;

	    static const std::set<std::string> allowedElements = {
	            // List from https://tdg.docbook.org/tdg/5.2/book.html
	            "acknowledgements", "appendix", "article", "bibliography", "chapter", "colophon", "dedication",
	            "glossary", "index", "part", "preface", "reference", "toc"
	    };

	    for (; pref_epit < epit; ++pref_epit) {
            auto par = text.paragraphs().iterator_at(pref_epit);
            if (allowedElements.find(par->layout().docbooktag()) != allowedElements.end() ||
                    allowedElements.find(par->layout().docbooksectiontag()) != allowedElements.end())
                break;

            hasPreface = true;
	    }

	    // Output a preface if required. A title is needed for the document to be valid...
	    if (hasPreface) {
	        xs << xml::StartTag("preface");
	        xs << xml::CR();

	        xs << xml::StartTag("title");
	        xs << "Preface";
	        xs << xml::EndTag("title");
            xs << xml::CR();

            auto pref_par = text.paragraphs().iterator_at(pref_bpit);
            auto pref_end = text.paragraphs().iterator_at(pref_epit);
            while (pref_par != pref_end) {
                // Skip paragraphs not producing any output.
                if (hasOnlyNotes(*pref_par)) {
                    ++pref_par;
                    continue;
                }

                // TODO: must sections be handled here? If so, it might be useful to extract the corresponding loop
                // in the rest of this function to use the same here (and avoid copy-paste mistakes).
                pref_par = makeAny(text, buf, xs, runparams, pref_par);
            }

	        xs << xml::EndTag("preface");
            xs << xml::CR();

            // Skip what has just been generated in the preface.
            bpit = pref_epit;
	    }
	}

	std::stack<std::pair<int, string>> headerLevels; // Used to determine when to open/close sections: store the depth
	// of the section and the tag that was used to open it.

	// Then, iterate through the paragraphs of this document.
	auto par = text.paragraphs().iterator_at(bpit);
	auto end = text.paragraphs().iterator_at(epit);
	while (par != end) {
		// Skip paragraphs not producing any output.
		if (hasOnlyNotes(*par)) {
			++par;
			continue;
		}

		OutputParams ourparams = runparams;
		Layout const &style = par->layout();

		// Think about adding <section> and/or </section>s.
		if (isLayoutSectioning(style) || par->params().startOfAppendix()) {
			int level = style.toclevel;

			// Need to close a previous section if it has the same level or a higher one (close <section> if opening a
			// <h2> after a <h2>, <h3>, <h4>, <h5> or <h6>). More examples:
			//   - current: h2; back: h1; do not close any <section>
			//   - current: h1; back: h2; close two <section> (first the <h2>, then the <h1>, so a new <h1> can come)
			// Some layouts require that Layout::NOT_IN_TOC sections still cause closing of previous sections. This is
			// mostly to ensure that the section is positioned at a DocBook-compatible level (acknowledgements: cannot
			// be under a section!).
			while (!headerLevels.empty() && level <= headerLevels.top().first) {
				// Output the tag only if it corresponds to a legit section.
				int stackLevel = headerLevels.top().first;
				if (stackLevel != Layout::NOT_IN_TOC) {
					xs << xml::EndTag(headerLevels.top().second);
					xs << xml::CR();
				}
				headerLevels.pop();
			}

			// Open the new section: first push it onto the stack, then output it in DocBook.
			string sectionTag = (par->params().startOfAppendix()) ? "appendix" : style.docbooksectiontag();
			headerLevels.push(std::make_pair(level, sectionTag));

			// Some sectioning-like elements should not be output (such as FrontMatter).
			if (level != Layout::NOT_IN_TOC) {
				// Look for a label in the title, i.e. a InsetLabel as a child.
				docstring id = docstring();
				for (pos_type i = 0; i < par->size(); ++i) {
					Inset const *inset = par->getInset(i);
					if (inset) {
						if (auto label = dynamic_cast<InsetLabel const *>(inset)) {
							// Generate the attributes for the section if need be.
							id += "xml:id=\"" + xml::cleanID(label->screenLabel()) + "\"";

							// Don't output the ID as a DocBook <anchor>.
							ourparams.docbook_anchors_to_ignore.emplace(label->screenLabel());

							// Cannot have multiple IDs per tag. If there is another ID inset in the document, it will
							// be output as a DocBook anchor.
							break;
						}
					}
				}

				// Write the open tag for this section.
				docstring attrs;
				if (!id.empty())
					attrs = id;
				xs << xml::StartTag(sectionTag, attrs);
				xs << xml::CR();
			}
		}

		// Close all sections before the bibliography.
		// TODO: Only close all when the bibliography is at the end of the document? Or force to output the bibliography
		// at the end of the document? Or don't care (as allowed by DocBook)?
		if (!par->insetList().empty()) {
			Inset const *firstInset = par->getInset(0);
			if (firstInset && (firstInset->lyxCode() == BIBITEM_CODE || firstInset->lyxCode() == BIBTEX_CODE)) {
				while (!headerLevels.empty()) {
					// Don't close appendices before bibliographies.
					if (headerLevels.top().second == "appendix")
						break;

					// Pop the section from the stack.
					int level = headerLevels.top().first;
					docstring tag = from_utf8("</" + headerLevels.top().second + ">");
					headerLevels.pop();

					// Output the tag only if it corresponds to a legit section, as the rest of the code.
					if (level != Layout::NOT_IN_TOC) {
						xs << XMLStream::ESCAPE_NONE << tag;
						xs << xml::CR();
					}
				}
			}
		}

		// Generate the <info> tag if a section was just opened.
		// Some sections may require abstracts (mostly parts, in books: DocBookForceAbstractTag will not be NONE),
		// others can still have an abstract (it must be detected so that it can be output at the right place).
		// TODO: docbookforceabstracttag is a bit contrived here, but it does the job. Having another field just for
		// this would be cleaner, but that's just for <part> and <partintro>, so it's probably not worth the effort.
		if (isLayoutSectioning(style)) {
			// This abstract may be found between the next paragraph and the next title.
			pit_type cpit = std::distance(text.paragraphs().begin(), par);
			pit_type ppit = std::get<1>(hasDocumentSectioning(paragraphs, cpit + 1L, epit));

			// Generate this abstract (this code corresponds to parts of outputDocBookInfo).
			DocBookInfoTag secInfo = getParagraphsWithInfo(paragraphs, cpit, ppit, true,
												  style.docbookforceabstracttag() != "NONE");

			if (!secInfo.mustBeInInfo.empty() || !secInfo.shouldBeInInfo.empty() || !secInfo.abstract.empty()) {
				// Generate the <info>, if required. If DocBookForceAbstractTag != NONE, this abstract will not be in
				// <info>, unlike other ("standard") abstracts.
				bool hasStandardAbstract = !secInfo.abstract.empty() && style.docbookforceabstracttag() == "NONE";
				bool needInfo = !secInfo.mustBeInInfo.empty() || hasStandardAbstract;

				if (needInfo) {
					xs.startDivision(false);
					xs << xml::StartTag("info");
					xs << xml::CR();
				}

				// Output the elements that should go in <info>, before and after the abstract.
				for (auto pit : secInfo.shouldBeInInfo) // Typically, the title: these elements are so important and ubiquitous
					// that mandating a wrapper like <info> would repel users. Thus, generate them first.
					makeAny(text, buf, xs, ourparams, paragraphs.iterator_at(pit));
				for (auto pit : secInfo.mustBeInInfo)
					makeAny(text, buf, xs, ourparams, paragraphs.iterator_at(pit));

				// Deal with the abstract in <info> if it is standard (i.e. its tag is <abstract>).
				if (!secInfo.abstract.empty() && hasStandardAbstract) {
					if (!secInfo.abstractLayout) {
						xs << xml::StartTag("abstract");
						xs << xml::CR();
					}

					for (auto const &p : secInfo.abstract)
						makeAny(text, buf, xs, ourparams, paragraphs.iterator_at(p));

					if (!secInfo.abstractLayout) {
						xs << xml::EndTag("abstract");
						xs << xml::CR();
					}
				}

				// End the <info> tag if it was started.
				if (needInfo) {
					if (!xs.isLastTagCR())
						xs << xml::CR();

					xs << xml::EndTag("info");
					xs << xml::CR();
					xs.endDivision();
				}

				// Deal with the abstract outside <info> if it is not standard (i.e. its tag is layout-defined).
				if (!secInfo.abstract.empty() && !hasStandardAbstract) {
					// Assert: style.docbookforceabstracttag() != NONE.
					xs << xml::StartTag(style.docbookforceabstracttag());
					xs << xml::CR();
					for (auto const &p : secInfo.abstract)
						makeAny(text, buf, xs, ourparams, paragraphs.iterator_at(p));
					xs << xml::EndTag(style.docbookforceabstracttag());
					xs << xml::CR();
				}

				// Skip all the text that has just been generated.
				par = paragraphs.iterator_at(secInfo.epit);
			} else {
				// No <info> tag to generate, proceed as for normal paragraphs.
				par = makeAny(text, buf, xs, ourparams, par);
			}
		} else {
			// Generate this paragraph, as it has nothing special.
			par = makeAny(text, buf, xs, ourparams, par);
		}
	}

	// If need be, close <section>s, but only at the end of the document (otherwise, dealt with at the beginning
	// of the loop).
	while (!headerLevels.empty() && headerLevels.top().first > Layout::NOT_IN_TOC) {
		docstring tag = from_utf8("</" + headerLevels.top().second + ">");
		headerLevels.pop();
		xs << XMLStream::ESCAPE_NONE << tag;
		xs << xml::CR();
	}
}

} // namespace lyx