From 7692eec9af1a62d40fc9c01b5afac30b58e2a73b Mon Sep 17 00:00:00 2001
From: Martchus <martchus@gmx.net>
Date: Sat, 30 Jan 2021 19:12:04 +0100
Subject: [PATCH] Make it easier to customize getting internal values

---
 fieldbasedtag.h  | 18 +++++++++++++++---
 id3/id3v2tag.cpp | 20 ++++++++------------
 id3/id3v2tag.h   |  2 +-
 3 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/fieldbasedtag.h b/fieldbasedtag.h
index 7d5ac04..cbda291 100644
--- a/fieldbasedtag.h
+++ b/fieldbasedtag.h
@@ -68,6 +68,7 @@ protected:
     using CRTPBase = FieldMapBasedTag<ImplementationType>;
 
     const TagValue &internallyGetValue(const IdentifierType &id) const;
+    void internallyGetValuesFromField(const FieldType &field, std::vector<const TagValue *> &values) const;
     std::vector<const TagValue *> internallyGetValues(const IdentifierType &id) const;
     bool internallySetValue(const IdentifierType &id, const TagValue &value);
     bool internallySetValues(const IdentifierType &id, const std::vector<TagValue> &values);
@@ -126,6 +127,19 @@ template <class ImplementationType> const TagValue &FieldMapBasedTag<Implementat
     return i != m_fields.end() ? i->second.value() : TagValue::empty();
 }
 
+/*!
+ * \brief Default way to gather values from a field in internallyGetValues().
+ * \remarks Shadow in subclass to provide custom implementation.
+ */
+template <class ImplementationType>
+void FieldMapBasedTag<ImplementationType>::internallyGetValuesFromField(
+    const FieldMapBasedTag<ImplementationType>::FieldType &field, std::vector<const TagValue *> &values) const
+{
+    if (!field.value().isEmpty()) {
+        values.emplace_back(&field.value());
+    }
+}
+
 /*!
  * \brief Default implementation for values().
  * \remarks Shadow in subclass to provide custom implementation.
@@ -136,9 +150,7 @@ std::vector<const TagValue *> FieldMapBasedTag<ImplementationType>::internallyGe
     auto range = m_fields.equal_range(id);
     std::vector<const TagValue *> values;
     for (auto i = range.first; i != range.second; ++i) {
-        if (!i->second.value().isEmpty()) {
-            values.push_back(&i->second.value());
-        }
+        static_cast<const ImplementationType *>(this)->internallyGetValuesFromField(i->second, values);
     }
     return values;
 }
diff --git a/id3/id3v2tag.cpp b/id3/id3v2tag.cpp
index 64ff563..7065d86 100644
--- a/id3/id3v2tag.cpp
+++ b/id3/id3v2tag.cpp
@@ -68,22 +68,18 @@ void Id3v2Tag::ensureTextValuesAreProperlyEncoded()
 }
 
 /*!
- * \brief Works like the default implementation but adds additional values as well.
+ * \brief Adds additional values as well.
  */
-std::vector<const TagValue *> Id3v2Tag::internallyGetValues(const IdentifierType &id) const
+void Id3v2Tag::internallyGetValuesFromField(const Id3v2Tag::FieldType &field, std::vector<const TagValue *> &values) const
 {
-    auto range = fields().equal_range(id);
-    std::vector<const TagValue *> values;
-    for (auto i = range.first; i != range.second; ++i) {
-        const auto &frame(i->second);
-        if (!frame.value().isEmpty()) {
-            values.push_back(&frame.value());
-        }
-        for (const auto &value : frame.additionalValues()) {
-            values.push_back(&value);
+    if (!field.value().isEmpty()) {
+        values.emplace_back(&field.value());
+    }
+    for (const auto &value : field.additionalValues()) {
+        if (!value.isEmpty()) {
+            values.emplace_back(&value);
         }
     }
-    return values;
 }
 
 /*!
diff --git a/id3/id3v2tag.h b/id3/id3v2tag.h
index d4a35d9..01aa883 100644
--- a/id3/id3v2tag.h
+++ b/id3/id3v2tag.h
@@ -95,7 +95,7 @@ protected:
     IdentifierType internallyGetFieldId(KnownField field) const;
     KnownField internallyGetKnownField(const IdentifierType &id) const;
     TagDataType internallyGetProposedDataType(const std::uint32_t &id) const;
-    std::vector<const TagValue *> internallyGetValues(const IdentifierType &id) const;
+    void internallyGetValuesFromField(const FieldType &field, std::vector<const TagValue *> &values) const;
     bool internallySetValues(const IdentifierType &id, const std::vector<TagValue> &values);
 
 private: