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https://github.com/webern/mx

C++ binding for MusicXML.
https://github.com/webern/mx

c-plus-plus music music-notation musicxml xml xml-dom

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C++ binding for MusicXML.

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README 

        
MusicXML Class Library

======================



- Author: Matthew James Briggs

- License: MIT

- Version: 1.0

- Supported MusicXML Version: 3.0

- Language: C++17



-----------------------------------------



[![CircleCI](https://circleci.com/gh/webern/mx.svg?style=svg)](https://circleci.com/gh/webern/mx)



## Introduction



This project is a C++ library for working with MusicXML.



# Build



Building and running tests should be as simple as:



```

git clone https://github.com/webern/mx.git mx

mkdir build

cd build

cmake ../mx -DMX_BUILD_TESTS=on -DMX_BUILD_CORE_TESTS=off -DMX_BUILD_EXAMPLES=on

make -j6

./mxtest

```



### Cmake Options



There are three `cmake` options:



```

    -DMX_BUILD_TESTS=on

    -DMX_BUILD_CORE_TESTS=off

    -DMX_BUILD_EXAMPLES=on

```



The configuration shown above is the recommended configuration for development.

If you just need the lib then turn off all three of the `cmake` options.

The 'core tests' take a long time to compile.

You only need to run them if you make changes in the `mx::core` namespace.



### Build Tenets



* `mx` should not depend on any outside libraries (no deps).

* `mx` third-party code should be kept to a minimum.

* `mx` third-party code should be checked into the `mx` repo and compiled as part of the `mx` library.

* `mx` should not depened on any package manager, though it may be published into any package manager.



### Using `mx` in a Cmake Project



The following script demonstrates how you can start a new cmake project that uses `mx` by commiting its sourcecode into your project:



```sh

#!/bin/bash

se -eou pipefail



# this script demonstrates how to depend on mx by including it in your

# sourcecode tree.



# if given, the first argument is a path to directory where the new

# project will be created.

REPO="${1:-/tmp/$(uuidgen)}"

echo "Creating a new project in: ${REPO}"



# create a new git repository for your project

mkdir -p "${REPO}"

cd "${REPO}"

git init

# bring the mx sourcecode into your project into a temporary location

git clone https://github.com/webern/mx.git mxtemp



# copy only what we need.  all we need is the Sourcode directory, the

# cmake file, the license, and the .gitignore file (helpful since there

# is one generated file.)

mkdir mx

mv mxtemp/Sourcecode mx/Sourcecode

mv mxtemp/.gitignore mx/.gitignore

mv mxtemp/LICENSE.txt mx/LICENSE.txt

mv mxtemp/CMakeLists.txt mx/CMakeLists.txt

# we don't need the test code, either

rm -rf mx/Sourcecode/private/mxtest

rm -rf mxtemp



# commit the mx sourcecode to our project repo

git add --all && git commit -m'mx sourcecode'



# create a main.cpp file

cat <<- "EOF" > main.cpp

#include 

#include "mx/api/ScoreData.h"

#include "mx/api/DocumentManager.h"



int main () {

    using namespace mx::api;

    ScoreData score{};

    score.workTitle = "Hello World";

    NoteData note{};

    note.durationData.durationName = DurationName::quarter;

    note.pitchData.step = Step::d;

    VoiceData voiceData{};

    voiceData.notes.push_back(note);

    StaffData staff{};

    staff.voices[0] = voiceData;

    MeasureData measure{};

    measure.staves.push_back(staff);

    PartData part{};

    part.measures.push_back(measure);

    score.parts.push_back(part);

    auto& mgr = DocumentManager::getInstance();

    const auto id = mgr.createFromScore(score);

    mgr.writeToStream(id, std::cout);

    mgr.destroyDocument(id);

}

EOF



# create a cmake file

cat <<- "EOF" > CMakeLists.txt

cmake_minimum_required(VERSION 3.17)

project(my-musicxml-proj)

set(CMAKE_CXX_STANDARD 17)

set(CPP_VERSION 17)



add_executable(my-musicxml-proj main.cpp)

add_subdirectory(mx)

target_link_libraries(my-musicxml-proj mx)

target_include_directories(my-musicxml-proj PRIVATE mx/Sourcecode/include)

EOF



# create a .gitignore file to ignore a build directory

cat <<- "EOF" > .gitignore

build/

EOF



git add --all && git commit -m'musicxml hello world'



# create a build directory

mkdir build



# build your project

cd build

cmake .. && make -j10

# run your executable

./my-musicxml-proj

```



### Xcode Project



The Xcode project (checked-in to the repo) has targets for iOS and macOS frameworks and dylibs.

These are not specified in the cmake file.

Contributors are not required to keep the Xcode project up-to-date.

If you add, move or remove files from the codebase, it is likely that the Xcode CI run will fail.

This will not prevent a contribution from being merged, the maintainer will fix the project after-the-fact.



# Using `mx`



## API



The `mx::api` namespace is intended to be a simplified structural representation of MusicXML.

It should be more intuitive than manipulating the DOM representation directly.

In particular, voices and time positions are more explicitly managed.

Some complexities, on the other hand, are retained in `mx::api`, such as the need to manage beam starts and stops explicitly.



#### Writing MusicXML with `mx::api`



```C++

#include 

#include 

#include 

#include 



#include "mx/api/DocumentManager.h"

#include "mx/api/ScoreData.h"



// set this to 1 if you want to see the xml in your console

#define MX_WRITE_THIS_TO_THE_CONSOLE 0



int main(int argc, const char * argv[])

{

    using namespace mx::api;

    const auto qticks = 4;



    // create a score

    auto score = ScoreData{};

    score.workTitle = "Mx Example";

    score.composer = "Matthew James Briggs";

    score.copyright = "Copyright (c) 2019";

    score.ticksPerQuarter = qticks;



    // create a part

    score.parts.emplace_back( PartData{} );

    auto& part = score.parts.back();



    // give the part a name

    part.name = "Flute";

    part.abbreviation = "Fl.";

    part.displayName = "Flute";

    part.displayAbbreviation = "Fl.";



    // give the part an instrument

    part.instrumentData.soundID = SoundID::windFlutesFlute;

    part.instrumentData.midiData.channel = 1;

    part.instrumentData.midiData.program = 74;



    // add a measure

    part.measures.emplace_back( MeasureData{} );

    auto& measure = part.measures.back();

    measure.timeSignature.beats = 4;

    measure.timeSignature.beatType = 4;

    measure.timeSignature.isImplicit = false;



    // add a staff

    measure.staves.emplace_back( StaffData{} );

    auto& staff = measure.staves.back();



    // set the clef

    auto clef = ClefData{};

    clef.setTreble();

    staff.clefs.emplace_back( clef );



    // add a voice

    staff.voices[0] = VoiceData{};

    auto& voice = staff.voices.at( 0 );



    const auto quarter = qticks;

    const auto half = qticks * 2;

    const auto eighth = qticks / 2;



    // add a few notes

    auto currentTime = 0;

    auto note = NoteData{};

    note.pitchData.step = Step::d;

    note.pitchData.alter = 1;

    note.pitchData.octave = 5;

    note.pitchData.accidental = Accidental::sharp;

    note.durationData.durationName = DurationName::half;

    note.durationData.durationTimeTicks = half;

    note.tickTimePosition = currentTime;

    voice.notes.push_back( note );



    // advance our time

    currentTime += half;



    note.pitchData.step = Step::e;

    note.pitchData.alter = 0;

    note.pitchData.octave = 5;

    note.pitchData.accidental = Accidental::none;

    note.durationData.durationName = DurationName::eighth;

    note.durationData.durationTimeTicks = eighth;

    note.tickTimePosition = currentTime;

    // beams are handled explicitly in musicxml

    note.beams.push_back( Beam::begin ); // start an eighth-note beam

    voice.notes.push_back( note );

    currentTime += eighth;



    note.pitchData.step = Step::f;

    note.pitchData.alter = 0;

    note.pitchData.octave = 5;

    note.pitchData.accidental = Accidental::none;

    note.durationData.durationName = DurationName::eighth;

    note.tickTimePosition = currentTime;

    note.durationData.durationTimeTicks = eighth;

    note.beams.clear();

    note.beams.push_back( Beam::end ); // end the eighth-note beam

    voice.notes.push_back( note );

    currentTime += eighth;



    note.pitchData.step = Step::e;

    note.pitchData.alter = 0;

    note.pitchData.octave = 5;

    note.pitchData.accidental = Accidental::none;

    note.durationData.durationName = DurationName::quarter;

    note.durationData.durationTimeTicks = quarter;

    note.tickTimePosition = currentTime;

    note.beams.clear();

    voice.notes.push_back( note );



    // the document manager is the liaison between our score data and the MusicXML DOM.

    // it completely hides the MusicXML DOM from us when using mx::api

    auto& mgr = DocumentManager::getInstance();

    const auto documentID = mgr.createFromScore( score );



    // write to the console

    #if MX_WRITE_THIS_TO_THE_CONSOLE

    mgr.writeToStream( documentID, std::cout );

    std::cout << std::endl;

    #endif



    // write to a file

    mgr.writeToFile( documentID, "./example.musicxml" );



    // we need to explicitly delete the object held by the manager

    mgr.destroyDocument( documentID );



    return 0;

}

```



#### Reading MusicXML with `mx::api`



```C++

#include "mx/api/DocumentManager.h"

#include "mx/api/ScoreData.h"



#include 

#include 

#include 

#include 



#define MX_IS_A_SUCCESS 0

#define MX_IS_A_FAILURE 1



constexpr const char* const xml = R"(



  

    

      Music

    

  

  

    

      

        1

        

          0

        

        

        

          G

          2

        

      

      

        

          C

          4

        

        4

        whole

      

    

  



)";



int main(int argc, const char * argv[])

{

    using namespace mx::api;



    // create a reference to the singleton which holds documents in memory for us

    auto& mgr = DocumentManager::getInstance();



    // place the xml from above into a stream object

    std::istringstream istr{ xml };



    // ask the document manager to parse the xml into memory for us, returns a document ID.

    const auto documentID = mgr.createFromStream( istr );



    // get the structural representation of the score from the document manager

    const auto score = mgr.getData( documentID );



    // we need to explicitly destroy the document from memory

    mgr.destroyDocument(documentID);



    // make sure we have exactly one part

    if( score.parts.size() != 1 )

    {

        return MX_IS_A_FAILURE;

    }



    // drill down into the data structure to retrieve the note

    const auto& part = score.parts.at( 0 );

    const auto& measure = part.measures.at( 0 );

    const auto& staff = measure.staves.at( 0 );

    const auto& voice = staff.voices.at( 0 );

    const auto& note = voice.notes.at( 0 );



    if( note.durationData.durationName != DurationName::whole )

    {

        return MX_IS_A_FAILURE;

    }



    if( note.pitchData.step != Step::c )

    {

        return MX_IS_A_FAILURE;

    }



    return MX_IS_A_SUCCESS;

}

```



# Implementation Details



The MusicXML classes in `mx::core` are tightly bound to the `musicxml.xsd` specification.

MusicXML can be challenging to use and the `mx::core` class structure mirrors the complexity of the MusicXML specification.

A simplified representation is available in `mx::api`.

It is possible to work with a subset of MusicXML using only `mx::api`, without delving into `mx::core`.



##### Namespaces



```C++

using namespace mx::api;    // an easier interface for reading and writing MusicXML

using namespace mx::core;   // a direct representation of a musicxml document in C++ classes

using namespace mx::impl    // the logic that translates between mx::api and mx::core

using namespace mx::utility // a typical catch-all for generic stuff like logging macros

using namespace ezxml;      // generic serialization and deserialization of xml

```



##### `mx::api`



The `mx::api` namespace is a set of 'plain old data' structs that represent a simplified model of MusicXML.

For example, here is the `ScoreData.h`, which represents the top level of the object heirarchy:



```C++

class ScoreData

{

public:

    MusicXmlVersion musicXmlVersion;

    std::string musicXmlType;

    std::string workTitle;

    std::string workNumber;

    std::string movementTitle;

    std::string movementNumber;

    std::string composer;

    std::string lyricist;

    std::string arranger;

    std::string publisher;

    std::string copyright;

    EncodingData encoding;

    std::vector pageTextItems;

    DefaultsData defaults;

    std::vector parts;

    std::vector partGroups;

    int ticksPerQuarter;

    std::map layout;

};

```



`mx::api` and `mx::core` are kept completely separate.\

That is, `mx::api` data is serialized into `mx::core` data, which is then serialized into MusicXML.

The `mx::api` struct allow us to simplify things like specifying a note's tick time position, and allowing the serialization process to take care of details such as `` `` elements.



##### `mx::core`



The `mx::core` namespace contains the MusicXML representation objects such as elements and attributes.

`mx::core` was mostly generated from `musicxml.xsd` with plenty of intervention by hand.



###### XML Choices and Groups



In the `musicxml.xsd` there are many cases of `xs:choice` or `xs:group` being used.

These constructs are typically represented in the `mx::core` class structure the same way that they are found in the `musicxml.xsd` specification.

The interfaces in this namespace are relatively stable, however they are tightly bound to MusicXML's specification and thus they will change when it comes time to support a future version of MusicXML.



##### `mx::impl`



`mx::impl` is the translation layer between `mx::api` and `mx::core`.



##### `mx::utility`



This namespace is small.

It mostly contains macros and small, generic functions.



##### `ezxml`



The `ezxml` namespace contains generic XML DOM functionality.

Under the hood [pugixml](http://pugixml.org/) is being used.

See the XML DOM section for more information.

Note that, even though `ezxml` can stand alone as a useful abstraction, we build it as if it were entirely owned by the `mx` project.

Additionally, we check the `pugixml` library in and build it as if it were part of the `mx` project.

This is in keeping with the build tenets [above](#build-tenets)



##### Partwise vs. Timewise

There are two types of MusicXML documents, `partwise` and `timewise`.

A partwise document consists of a set of parts which contain measures.

A timewise document consists of a set of measures which contain parts.

Partwise is used more often by MusicXML applications while Timewise documents seem to be rare or even nonresistant.

Nonetheless *MusicXML Class Library* implements both Timewise and Partwise.

The class `mx::core::Document` can hold *either* a Partwise *or* a Timewise score.

Note that it actually holds both, but only one or the other is 'active' (this is similar to how `xsd` `choice` constructs are handled).

You can check the inner document type with the getChoice function.

You can convert between Partwise and Timewise with the convertContents function.



##### Elements

Each XML element is represented by a class which derives from ElementInterface.

Elements are created and used by way of shared pointers.

Each element comes with a set of using/typedef statements as well as a convenience function for making the shared pointers.



##### Shared Pointers

Many elements contain other elements.

When they do, these data members will also be shared pointers.

Get/set functions will allow access to the data members by accepting and returning shared pointers.

If you attempt to set a data member to a nullptr, the setter function will silently do nothing.

Thus we can be reasonably assured our objects will never return nullptr.



For example



```C++

std::shared_ptr foo; /* nullptr! */

bar->setFoo( foo );       /* no-op because you passed a nullptr */

auto x = bar->getFoo();   /* guaranteed not to be null */

x->somefuntion();         /* OK to dereference without checking for nullptr */

```



##### Optional Member Data

Many of the elements in MusicXML are optional.

In these cases there is a bool which indicates whether or not the element is present.

The bool serves as a flag indicating whether or not the optional element will be output when you stream out your MusicXML document.

The bool has no side-effect on the element who's presence/absence it represents.

So for example we may set some data:



```C++

foo->setValue( "hello" );

bar->setFoo( foo );

```



But in this example, if Foo is an optional member of Bar, then we must also set hasFoo to *true* or else foo will not be in the XML output.



```C++

bar->toStream(...); /* Foo is not in the output! */

bar->setHasFoo( true );

bar->toStream(...); /* Now we see hello in the output. */

```



Also note that setting HasFoo to *false* does not mean that Foo's value is gone.



```C++

bar->setHasFoo( false ); /* The XML document no longer has a Foo */

bar->getFoo()->getValue() == "hello"; /* True! The value still exists but is not present in the XML. */

```



##### Optional Member Data with Unbounded Occurrences

Sometimes an element may contain zero, one, or many occurrences of another element.

For example



```xml



```



In this case there will be a collection of Key objects and the getter/setters will look like this, where `KeySet` is a typedef of `std::vector`.



```C++

const KeySet& getKeySet() const;

void addKey( const KeyPtr& value );

void removeKey( const KeySetIterConst& value );

void clearKeySet();

KeyPtr getKey( const KeySetIterConst& setIterator ) const;

```



##### Required Member Data with Unbounded Occurrences

Sometimes an element is required, but you may optionally have more than one.

For example



```xml



```



In this case, minOccurs="1" (by default per XSD language rules).

The functions will look just like the previous example, but they will behave differently



```C++

const DirectionTypeSet& getDirectionTypeSet() const;

void addDirectionType( const DirectionTypePtr& value );

void removeDirectionType( const DirectionTypeSetIterConst& value );

void clearDirectionTypeSet();

DirectionTypePtr getDirectionType( const DirectionTypeSetIterConst& setIterator ) const;

```



When the containing element is constructed, a single DirectionType will be default constructed and pushed onto the vector.

Thus you will have one default constructed DirectionType in the set upon construction.



If you try to call removeDirectionType with only one DirectionType in the set (size==1) nothing will happen.

You will still have a single DirectionType in the collection.



When you call clearDirectionTypeSet vector.clear() will be called but it will follow up by pushing a default constructed DirectionType onto the vector so you will still have size==1.



As it turns out, this design choice tends to be annoying in practice.

On the upside, it does guarantee that your MusicXML document will be valid, even if you forget to add a required element.

The downside is that it means you have to deal with the fact that a default constructed element always exists in the set, so you must replace or remove the first element.

Furthermore, you cannot remove the existing element until another one has been added.

Here are the two patterns I have used for this (pseudocode).



**Pattern 1:** Replace the first element by dereferencing the begin() iterator:



```C++

bool isFirstAdded = false;

for( auto stuffElement : stuffElementsIWantToAdd )

{

    if( !isFirstAdded )

    {

        *( myElementIWantToAddThemTo->getStuffSet().begin() ) = stuffElement;

        isFirstAdded = true;

    }

    else

    {

        myElementIWantToAddThemTo->addStuff( stuffElement );

    }

}

```



**Pattern 2:** Remove the default element *After* adding a replacement:



```C++

bool isFirstAdded = false;

for( auto stuffElement : stuffIWantToAdd )

{

    myElementIWantToAddThemTo->addStuff( stuffElement );

    if( !isFirstAdded )

    {

        myElementIWantToAddThemTo->removeStuff( myElementIWantToAddThemTo->getStuffSet().cbegin() )

        isFirstAdded = true;

    }

}

```



Pattern 1 always works, even if you're not sure whether or not the `minOccurs="1"` or `"0"`.

Pattern 2 only works when `minOccurs="1"`.

There are no cases where `minOccurs` is greater than 1.



##### Member Data with Bounded maxOccurs

```xml



```

In this case if you call addBeam when there are already 8 beams in the vector, nothing will happen.



##### xs:groups

For an xs:group there is usually a single 'element' class which represents the group of elements.

For example this XSD snippet:



```xml



	

		

		

	



```



is represented by this class:



```C++

class EditorialGroup : public ElementInterface

{

public:

    EditorialGroup();



    /* ... other stuff ... */



    /* _________ Footnote minOccurs = 0, maxOccurs = 1 _________ */

    FootnotePtr getFootnote() const;

    void setFootnote( const FootnotePtr& value );

    bool getHasFootnote() const;

    void setHasFootnote( const bool value );



    /* _________ Level minOccurs = 0, maxOccurs = 1 _________ */

    LevelPtr getLevel() const;

    void setLevel( const LevelPtr& value );

    bool getHasLevel() const;

    void setHasLevel( const bool value );

    

    bool fromXElement( std::ostream& message, xml::XElement& xelement );



private:

    FootnotePtr myFootnote;

    bool myHasFootnote;

    LevelPtr myLevel;

    bool myHasLevel;

};

```



##### xs:choices



There are a few exceptions (mistakes) but for the most part, `xs:choice` constructs are represented by a class with a name ending in 'Choice'.

The element will have an enum named 'Choice' in the public scope of the class.

Each of the possible 'choices' will exist as data members of the class, but only one of them will be 'active' (was present in, or will be written to, XML).

For example, this xsd construct:



```xml



    

        

            The pre-bend element indicates that this is a pre-bend rather than a normal bend or a release.

        

    

    

        

            The release element indicates that this is a release rather than a normal bend or pre-bend.

        

    



```



Is represented by this class:



```C++

class BendChoice : public ElementInterface

{

public:

    enum class Choice

    {

        preBend = 1,

        release = 2

    };

    BendChoice();



	/* ... other stuff ... */

    

    BendChoice::Choice getChoice() const;

    void setChoice( BendChoice::Choice value );



    /* _________ PreBend minOccurs = 1, maxOccurs = 1 _________ */

    PreBendPtr getPreBend() const;

    void setPreBend( const PreBendPtr& value );



    /* _________ Release minOccurs = 1, maxOccurs = 1 _________ */

    ReleasePtr getRelease() const;

    void setRelease( const ReleasePtr& value );



    bool fromXElement( std::ostream& message, xml::XElement& xelement );



private:

    Choice myChoice;

    PreBendPtr myPreBend;

    ReleasePtr myRelease;

};

```



When `getChoice() == BendChoice::Choice::preBend` then we will see `` in the XML, but when `getChoice() == BendChoice::Choice::postBend` then we will see `` in the XML.



### XML DOM (::ezxml::)



Any XML document can be read and manipulated with the classes in the `::ezxml::` namespace.

Most notably, look at the following pure virtual interfaces XDoc, XElement, XAttribute.

Also look at the STL-compliant iterators XElementIterator and XAttributeIterator.



These interfaces are designed to wrap any underlying XML DOM software so that `mx::core` does not care or know about the XML DOM code.

A set of implementation classes wrapping pugixml are provided, but if you need to use, say Xerces or RapidXML, you can look at the PugiElement, PugiDoc, etc classes and wrap whatever library you need.



Here's how you can read a MusicXML document into `mx::core` classes by way of `::ezxml::`.



```C++

#include "mx/core/Document.h"

#include "mx/utility/Utility.h"

#include "functions.h"

#include "ezxml/XFactory.h"

#include "ezxml/XDoc.h"



#include 

#include 

#include 



int main(int argc, const char *argv[])

{

    // allocate the objects

    mx::core::DocumentPtr mxDoc = makeDocument();

    ::ezxml::::XDocPtr xmlDoc = ::ezxml::::XFactory::makeXDoc();

    

    // read a MusicXML file into the XML DOM structure

    xmlDoc->loadFile( "music.xml" );



    // create an ostream to receive any parsing messages

    std::stringstream parseMessages;

    

    // convert the XML DOM into MusicXML Classes

    bool isSuccess = mxDoc->fromXDoc( parseMessages, *xmlDoc );

    

    if( !isSuccess )

    {

        std::cout << "Parsing of the MusicXML document failed with the following message(s):" << std::endl;

        std::cout << parseMessages.str() << std::endl;

        return -1;

    }

    

    // maybe the document was timewise document. if so, convert it to partwise

    if( mxDoc->getChoice() == mx::core::DocumentChoice::timewise )

    {

        mxDoc->convertContents();

    }

    

    // get the root

    auto scorePartwise = mxDoc->getScorePartwise();

    

    // change the title

    scorePartwise->getScoreHeaderGroup()->setHasWork( true );

    scorePartwise->getScoreHeaderGroup()->getWork()->setHasWorkTitle( true );

    scorePartwise->getScoreHeaderGroup()->getWork()->getWorkTitle()->setValue( mx::core::XsString( "New Title" ) );

    

    // write it back out to disk

    mxDoc->toXDoc( *xmlDoc );

    xmlDoc->write( "newtitle.xml" );

    

    return 0;

}

```



### Hello World using mx::core

On the MusicXML home page there is an example of a "Hello World" simple MusicXML file.

Here is a main function that would output this "Hello World" MusicXML example to std::cout.



```C++

#include 

#include "DocumentPartwise.h"

#include "Elements.h"



using namespace mx::core;

using namespace std;



int main(int argc, const char * argv[])

{

    auto doc = makeDocumentPartwise();

    auto s = doc->getScorePartwise();

    s->getAttributes()->hasVersion = true;

    s->getAttributes()->version = XsToken( "3.0" );

    auto header = s->getScoreHeaderGroup();

    header->getPartList()->getScorePart()->getAttributes()->id = XsID( "P1" );

    header->getPartList()->getScorePart()->getPartName()->setValue( XsString( "Music" ) );

    auto part = *( s->getPartwisePartSet().cbegin() );

    part->getAttributes()->id = XsIDREF( "P1" );

    auto measure = *( part->getPartwiseMeasureSet().cbegin() );

    measure->getAttributes()->number = XsToken( "1" );

    auto propertiesChoice = makeMusicDataChoice();

    propertiesChoice->setChoice( MusicDataChoice::Choice::properties );

    auto properties = propertiesChoice->getProperties();

    properties->setHasDivisions( true );

    properties->getDivisions()->setValue( PositiveDivisionsValue( 1 ) );

    properties->addKey( makeKey() );

    auto time = makeTime();

    time->getTimeChoice()->setChoice( TimeChoice::Choice::timeSignature );

    time->getTimeChoice()->getTimeSignature()->getBeats()->setValue( XsString( "4" ) );

    time->getTimeChoice()->getTimeSignature()->getBeatType()->setValue( XsString( "4" ) );

    properties->addTime( time );

    auto clef = makeClef();

    clef->getSign()->setValue( ClefSign::g );

    clef->setHasLine( true );

    clef->getLine()->setValue( StaffLine( 2 ) );

    properties->addClef( clef );

    measure->getMusicDataGroup()->addMusicDataChoice( propertiesChoice );

    auto noteData = makeMusicDataChoice();

    noteData->setChoice( MusicDataChoice::Choice::note );

    noteData->getNote()->getNoteChoice()->setChoice( NoteChoice::Choice::normal );

    noteData->getNote()->getNoteChoice()->getNormalNoteGroup()->getFullNoteGroup()->getFullNoteTypeChoice()->setChoice( FullNoteTypeChoice::Choice::pitch );

    noteData->getNote()->getNoteChoice()->getNormalNoteGroup()->getFullNoteGroup()->getFullNoteTypeChoice()->getPitch()->getStep()->setValue( StepEnum::c );

    noteData->getNote()->getNoteChoice()->getNormalNoteGroup()->getFullNoteGroup()->getFullNoteTypeChoice()->getPitch()->getOctave()->setValue( OctaveValue( 4 ) );

    noteData->getNote()->getNoteChoice()->getNormalNoteGroup()->getDuration()->setValue( PositiveDivisionsValue( 4 ) );

    noteData->getNote()->getType()->setValue( NoteTypeValue::whole );

    measure->getMusicDataGroup()->addMusicDataChoice( noteData );

    

    doc->toStream( cout ); /* print Hello World MusicXML document to console */

    return 0;

}

```



### Unit Test Framework



An executable program named mxtest is also included in the project.

mxtest utilizes the Catch2 test framework.

The core tests are slow to compile, see the [`cmake` options](#cmake-options) section for more info on how to skip compilation of the tests.