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diff --git a/include/oox/mathml/importutils.hxx b/include/oox/mathml/importutils.hxx
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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+#ifndef INCLUDED_OOX_MATHML_IMPORTUTILS_HXX
+#define INCLUDED_OOX_MATHML_IMPORTUTILS_HXX
+
+#include <map>
+#include <string_view>
+#include <vector>
+
+#include <com/sun/star/uno/Reference.hxx>
+#include <oox/dllapi.h>
+#include <oox/token/tokens.hxx>
+#include <rtl/ustring.hxx>
+#include <sal/types.h>
+
+namespace com::sun::star
+{
+namespace xml::sax
+{
+class XFastAttributeList;
+}
+}
+
+namespace oox::formulaimport
+{
+// used to differentiate between tags that opening or closing
+const int TAG_OPENING = 1 << 29;
+const int TAG_CLOSING = 1 << 30;
+
+// you probably want to #define these to something shorter in the .cxx file,
+// but they must be done as macros, otherwise they wouldn't be usable for case values,
+// and macros cannot be namespaced
+#define XML_STREAM_OPENING(token) (TAG_OPENING | token)
+#define XML_STREAM_CLOSING(token) (TAG_CLOSING | token)
+
+/**
+ Class for storing a stream of xml tokens.
+
+ A part of an XML file can be parsed and stored in this stream, from which it can be read
+ as if parsed linearly. The purpose of this class is to allow simpler handling of XML
+ files, unlike the usual LO way of using callbacks, context handlers and similar needlessly
+ complicated stuff (YMMV).
+
+ The advantages of this approach is easy to read and debug code (as it is just functions
+ reading tokens one by one and calling other functions, compared to having to use callbacks
+ and temporary storage). The disadvantage is that the XML structure needs to be handled
+ manually by the code.
+
+ Note that tag identifiers are simply int values and the API does not care besides matching
+ their values to XML stream contents and requiring that the values are not as high as TAG_OPENING.
+ Be prepared for the fact that some of the functions may throw exceptions if the input
+ stream does not match the required token (TBD).
+
+ The API tries to make the common idioms as simple as possible, see the following examples.
+
+ Parse <tagone attr="value"><tagtwo>text</tagtwo></tagone> , where tagtwo is optional:
+ @code
+XmlStream::Tag tagoneTag = stream.ensureOpeningTag( tagone );
+if( attributeTag.hasAttribute( attr ))
+    ... = attributeTag.attribute( attr, defaultValueOfTheRightType );
+if( XmlStream::Tag tagtwoTag = stream.checkOpeningTag( tagtwo ))
+{
+    ... = tagtwoTag.text;
+    stream.ensureClosingTag( tagtwo );
+}
+stream.ensureClosingTag( tagone );
+ @endcode
+
+ Parse an element that may contain several sub-elements of different types in random order:
+ @code
+stream.ensureOpeningTag( element );
+while( !stream.atEnd() && stream.currentToken() != CLOSING( element ))
+    {
+    switch( stream.currentToken())
+    {
+        case OPENING( subelement1 ):
+            handleSubElement1();
+            break;
+        case OPENING( subelement2 ):
+            ... process subelement2;
+            break;
+        default:
+            stream.handleUnexpectedTag();
+            break;
+    }
+stream.ensureClosingTag( element );
+ @endcode
+
+ If there may not be a zero number of sub-elements, use a helper bool variable or use a do-while loop.
+
+ Parse an element that may contain an unknown number of sub-elements of the same type:
+ @code
+stream.ensureOpeningTag( element );
+while( !stream.atEnd() && stream.findTag( OPENING( subelement )))
+    {
+    handleSubelement();
+    }
+stream.ensureClosingTag( element );
+ @endcode
+
+ If there may not be a zero number of sub-elements, use a helper bool variable or use a do-while loop.
+
+ @since 3.5
+*/
+class OOX_DLLPUBLIC XmlStream
+{
+public:
+    XmlStream();
+    /**
+     Structure representing a list of attributes.
+    */
+    // One could theoretically use oox::AttributeList, but that complains if the passed reference is empty,
+    // which would be complicated to avoid here. Also, parsers apparently reuse the same instance of XFastAttributeList,
+    // which means using oox::AttributeList would make them all point to the one instance.
+    struct OOX_DLLPUBLIC AttributeList
+    {
+        OUString& operator[](int token);
+        OUString attribute(int token, const OUString& def) const;
+        bool attribute(int token, bool def) const;
+        sal_Unicode attribute(int token, sal_Unicode def) const;
+        // when adding more attribute() overloads, add also to XmlStream itself
+    protected:
+        std::map<int, OUString> attrs;
+    };
+    /**
+     Structure representing a tag, including its attributes and content text immediately following it.
+    */
+    struct OOX_DLLPUBLIC Tag
+    {
+        Tag(int token = XML_TOKEN_INVALID,
+            const css::uno::Reference<css::xml::sax::XFastAttributeList>& attributes
+            = css::uno::Reference<css::xml::sax::XFastAttributeList>());
+        Tag(int token, const AttributeList& attribs);
+        int token; ///< tag type, or XML_TOKEN_INVALID
+        AttributeList attributes;
+        OUString text;
+        /**
+         This function returns value of the given attribute, or the passed default value if not found.
+         The type of the default value selects the return type (OUString here).
+        */
+        OUString attribute(int token, const OUString& def = OUString()) const;
+        /**
+         @overload
+        */
+        bool attribute(int token, bool def) const;
+        /**
+         @overload
+        */
+        sal_Unicode attribute(int token, sal_Unicode def) const;
+        // when adding more attribute() overloads, add also to XmlStream::AttributeList and inline below
+        /**
+         Converts to true if the tag has a valid token, false otherwise. Allows simple
+         usage in if(), for example 'if( XmlStream::Tag foo = stream.checkOpeningTag( footoken ))'.
+        */
+        operator bool() const;
+    };
+    /**
+     @return true if current position is at the end of the XML stream
+    */
+    bool atEnd() const;
+    /**
+     @return data about the current tag
+    */
+    Tag currentTag() const;
+    /**
+     @return the token for the current tag
+    */
+    int currentToken() const;
+    /**
+     Moves position to the next tag.
+    */
+    void moveToNextTag();
+    /**
+     Ensures that an opening tag with the given token is read. If the current tag does not match,
+     writes out a warning and tries to recover by skipping tags until found (or until the current element would end).
+     If found, the position in the stream is afterwards moved to the next tag.
+     @return the matching found opening tag, or empty tag if not found
+    */
+    Tag ensureOpeningTag(int token);
+    /**
+     Tries to find an opening tag with the given token. Works similarly like ensureOpeningTag(),
+     but if a matching tag is not found, the position in the stream is not altered. The primary
+     use of this function is to check for optional elements.
+     @return the matching found opening tag, or empty tag if not found
+    */
+    Tag checkOpeningTag(int token);
+    /**
+     Ensures that a closing tag with the given token is read. Like ensureOpeningTag(),
+     if not, writes out a warning and tries to recover by skipping tags until found (or until the current element would end).
+     If found, the position in the stream is afterwards moved to the next tag.
+    */
+    void ensureClosingTag(int token);
+    /**
+     Tries to find the given token, until either found (returns true) or end of current element.
+     Position in the stream is set to make the tag current (i.e. it will be the next one read).
+    */
+    bool findTag(int token);
+    /**
+     Handle the current (unexpected) tag.
+    */
+    void handleUnexpectedTag();
+
+protected:
+    Tag checkTag(int token, bool optional);
+    bool findTagInternal(int token, bool silent);
+    void skipElementInternal(int token, bool silent);
+    std::vector<Tag> tags;
+    unsigned int pos;
+};
+
+/**
+ This class is used for creating XmlStream.
+
+ Simply use this class and then pass it as XmlStream to the consumer.
+
+ @since 3.5.0
+*/
+class OOX_DLLPUBLIC XmlStreamBuilder : public XmlStream
+{
+public:
+    void appendOpeningTag(int token,
+                          const css::uno::Reference<css::xml::sax::XFastAttributeList>& attributes
+                          = css::uno::Reference<css::xml::sax::XFastAttributeList>());
+    void appendOpeningTag(int token, const AttributeList& attribs);
+    void appendClosingTag(int token);
+    // appends the characters after the last appended token
+    void appendCharacters(std::u16string_view characters);
+};
+
+inline OUString XmlStream::Tag::attribute(int t, const OUString& def) const
+{
+    return attributes.attribute(t, def);
+}
+
+inline bool XmlStream::Tag::attribute(int t, bool def) const
+{
+    return attributes.attribute(t, def);
+}
+
+inline sal_Unicode XmlStream::Tag::attribute(int t, sal_Unicode def) const
+{
+    return attributes.attribute(t, def);
+}
+
+} // namespace
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */