feat: expose the identification source in mx::api

src/include/mx/api/ScoreData.h

@@ -66,6 +66,11 @@ class ScoreData
     // The <rights> type attribute for `copyright` (above).
     std::optional<std::string> copyrightType;
 
+    // Where the music came from: the edition, manuscript, or other publication this score was
+    // made from. This is MusicXML's <source> element. It names the origin of the music, not of
+    // the file. Leave it empty when the score does not name one.
+    std::optional<std::string> source;
+
     EncodingData encoding;
     std::vector<PageTextData> pageTextItems;
 
@@ -118,6 +123,7 @@ MXAPI_EQUALS_MEMBER(arranger)
 MXAPI_EQUALS_MEMBER(publisher)
 MXAPI_EQUALS_MEMBER(copyright)
 MXAPI_EQUALS_MEMBER(copyrightType)
+MXAPI_EQUALS_MEMBER(source)
 MXAPI_EQUALS_MEMBER(encoding)
 MXAPI_EQUALS_MEMBER(pageTextItems)
 MXAPI_EQUALS_MEMBER(pageImageItems)

src/private/mx/api/ScoreData.cpp

@@ -14,7 +14,7 @@ namespace api
 ScoreData::ScoreData()
     : musicXmlVersion{api::MusicXmlVersion::unspecified}, declaredMusicXmlVersion{}, musicXmlType{"partwise"},
       workTitle{}, workNumber{}, movementTitle{}, movementNumber{}, composer{}, lyricist{}, copyright{},
-      copyrightType{"copyright"}, encoding{}, pageTextItems{}, defaults{}, parts{}, partGroups{},
+      copyrightType{"copyright"}, source{}, encoding{}, pageTextItems{}, defaults{}, parts{}, partGroups{},
       ticksPerQuarter{DEFAULT_TICKS_PER_QUARTER}
 {
 }

src/private/mx/impl/ScoreReader.cpp

@@ -234,6 +234,8 @@ api::ScoreData ScoreReader::getScoreData() const
                 myOutScoreData.copyrightType = std::nullopt;
             }
         }
+        myOutScoreData.source = ident.source();
+
         api::EncodingData encodingData;
 
         if (ident.encoding().has_value())

src/private/mx/impl/ScoreWriter.cpp

@@ -144,6 +144,12 @@ core::ScorePartwise ScoreWriter::getScorePartwise() const
         hasIdentification = true;
     }
 
+    if (myScoreData.source.has_value())
+    {
+        identification.setSource(myScoreData.source);
+        hasIdentification = true;
+    }
+
     if (hasIdentification)
     {
         header.setIdentification(identification);

src/private/mxtest/api/IdentificationSourceApiTest.cpp

@@ -0,0 +1,69 @@
+// MusicXML Class Library
+// Copyright (c) by Matthew James Briggs
+// Distributed under the MIT License
+
+#include "mxtest/control/CompileControl.h"
+#ifdef MX_COMPILE_API_TESTS
+
+#include "cpul/cpulTestHarness.h"
+#include "mx/api/DocumentManager.h"
+#include "mxtest/api/RoundTrip.h"
+#include "mxtest/api/TestHelpers.h"
+
+using namespace std;
+using namespace mx::api;
+using namespace mxtest;
+
+// An otherwise empty one-part score, so the only thing under test is the header.
+ScoreData identificationSourceMakeScore()
+{
+    ScoreData score;
+    score.parts.emplace_back();
+    score.parts.back().uniqueId = "P1";
+    score.parts.back().measures.emplace_back();
+    score.parts.back().measures.back().staves.emplace_back();
+    return score;
+}
+
+TEST(sourceSurvivesRoundTrip, IdentificationSource)
+{
+    auto score = identificationSourceMakeScore();
+    score.source = "Bach-Gesellschaft Ausgabe, Band 3";
+
+    const auto out = roundTrip(score);
+    REQUIRE(out.source.has_value());
+    CHECK_EQUAL("Bach-Gesellschaft Ausgabe, Band 3", *out.source);
+}
+
+TEST(sourceWritesTheMusicXmlElement, IdentificationSource)
+{
+    auto score = identificationSourceMakeScore();
+    score.source = "Urtext";
+
+    const auto xml = toXml(score);
+    CHECK(xml.find("<source>Urtext</source>") != std::string::npos);
+}
+
+TEST(anEmptySourceWritesNothing, IdentificationSource)
+{
+    const auto score = identificationSourceMakeScore();
+    const auto xml = toXml(score);
+    CHECK(xml.find("<source>") == std::string::npos);
+
+    const auto out = roundTrip(score);
+    CHECK(!out.source.has_value());
+}
+
+// MusicXML allows <source></source>, which says the score named a source and left it blank.
+// That is a different fact from saying nothing at all, so both have to survive the round trip.
+TEST(aBlankSourceIsNotTheSameAsNoSource, IdentificationSource)
+{
+    auto score = identificationSourceMakeScore();
+    score.source = "";
+
+    const auto out = roundTrip(score);
+    REQUIRE(out.source.has_value());
+    CHECK_EQUAL("", *out.source);
+}
+
+#endif

src/private/mxtest/api/roundtrip-baseline.txt

@@ -686,3 +686,12 @@ foundsuite/Invention_6.xml
 foundsuite/Invention_7.xml
 foundsuite/Invention_8.xml
 foundsuite/Invention_9.xml
+
+# Unblocked by ScoreData::source: <identification>/<source> names the edition or
+# manuscript a score was made from, and the api had nowhere to keep it, so the
+# element was dropped on write.
+musetrainer/Canon_in_D_easy.xml
+musetrainer/Carol_of_the_Bells_easy_piano.xml
+musetrainer/Lacrimosa_-_Requiem.xml
+musetrainer/Prelude_I_in_C_major_BWV_846_-_Well_Tempered_Clavier_First_Book.xml
+synthetic/source.3.0.xml