From 9dc458f5725536ca11da1e60d5580635509d59b7 Mon Sep 17 00:00:00 2001
From: Martchus <martchus@gmx.net>
Date: Mon, 26 Jun 2017 23:44:14 +0200
Subject: [PATCH] WIP: Allow conversion of TagValue to any number

---
 tagvalue.cpp | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 tagvalue.h   |  7 +++--
 2 files changed, 81 insertions(+), 4 deletions(-)

diff --git a/tagvalue.cpp b/tagvalue.cpp
index 9dc6eb6..33a7467 100644
--- a/tagvalue.cpp
+++ b/tagvalue.cpp
@@ -177,6 +177,7 @@ int32 TagValue::toInteger() const
                 ensureHostByteOrder(u16str, m_encoding);
                 return ConversionUtilities::stringToNumber<int32>(u16str);
             }
+            break;
         case TagDataType::Integer:
         case TagDataType::PositionInSet:
         case TagDataType::StandardGenreIndex:
@@ -192,6 +193,59 @@ int32 TagValue::toInteger() const
     return 0;
 }
 
+/*!
+ * \brief Converts the value of the current TagValue object to its equivalent integer representation.
+ * \tparam Specifies the integer type to convert to.
+ * \remarks Precision loss or overflow might occur if \a NumberType isn't suitable to hold the assigned
+ *          number.
+ * \throws Throws ConversionException on failure.
+ */
+template<typename NumberType>
+NumberType TagValue::toNumber() const
+{
+    if(!isEmpty()) {
+        switch(m_type) {
+        case TagDataType::Text:
+            switch(m_encoding) {
+            case TagTextEncoding::Unspecified:
+            case TagTextEncoding::Latin1:
+            case TagTextEncoding::Utf8:
+                return ConversionUtilities::bufferToNumber<NumberType>(m_ptr.get(), m_size);
+            case TagTextEncoding::Utf16LittleEndian:
+            case TagTextEncoding::Utf16BigEndian:
+                u16string u16str(reinterpret_cast<char16_t *>(m_ptr.get()), m_size / 2);
+                ensureHostByteOrder(u16str, m_encoding);
+                return ConversionUtilities::stringToNumber<NumberType>(u16str);
+            }
+            break;
+        case TagDataType::Integer:
+        case TagDataType::PositionInSet:
+        case TagDataType::StandardGenreIndex:
+            if(m_size == sizeof(int32)) {
+                return static_cast<NumberType>(*reinterpret_cast<int32 *>(m_ptr.get()));
+            } else(m_size == sizeof(int64)) {
+                // maybe support assignment of 64-bit int in the future
+                return static_cast<NumberType>(*reinterpret_cast<int64 *>(m_ptr.get()));
+            } else {
+                throw ConversionException("Can not convert assigned data to integer because the data size is not appropriate.");
+            }
+            break;
+        case TagDataType::Float:
+            if(m_size == sizeof(float)) {
+                return static_cast<NumberType>(*reinterpret_cast<float *>(m_ptr.get()));
+            } else if(m_size == sizeof(double)) {
+                return static_cast<NumberType>(*reinterpret_cast<double *>(m_ptr.get()));
+            } else {
+                throw ConversionException("Can not convert assigned float to integer because the data size is not appropriate.");
+            }
+            break;
+        default:
+            throw ConversionException("Can not convert binary data/picture/time span/date time to integer.");
+        }
+    }
+    return 0;
+}
+
 /*!
  * \brief Converts the value of the current TagValue object to its equivalent
  *        standard genre index.
@@ -283,7 +337,17 @@ TimeSpan TagValue::toTimeSpan() const
     if(!isEmpty()) {
         switch(m_type) {
         case TagDataType::Text:
-            return TimeSpan::fromString(string(m_ptr.get(), m_size));
+            switch(m_encoding) {
+            case TagTextEncoding::Unspecified:
+            case TagTextEncoding::Latin1:
+            case TagTextEncoding::Utf8:
+                return TimeSpan::fromString(string(m_ptr.get(), m_size));
+            case TagTextEncoding::Utf16LittleEndian:
+                return TimeSpan::fromString(convertUtf16LEToUtf8(m_ptr.get(), m_size));
+            case TagTextEncoding::Utf16BigEndian:
+                return TimeSpan::fromString(convertUtf16BEToUtf8(m_ptr.get(), m_size));
+            }
+            break;
         case TagDataType::Integer:
         case TagDataType::TimeSpan:
             switch(m_size) {
@@ -311,7 +375,17 @@ DateTime TagValue::toDateTime() const
     if(!isEmpty()) {
         switch(m_type) {
         case TagDataType::Text:
-            return DateTime::fromString(string(m_ptr.get(), m_size));
+            switch(m_encoding) {
+            case TagTextEncoding::Unspecified:
+            case TagTextEncoding::Latin1:
+            case TagTextEncoding::Utf8:
+                return DateTime::fromString(string(m_ptr.get(), m_size));
+            case TagTextEncoding::Utf16LittleEndian:
+                return DateTime::fromString(convertUtf16LEToUtf8(m_ptr.get(), m_size));
+            case TagTextEncoding::Utf16BigEndian:
+                return DateTime::fromString(convertUtf16BEToUtf8(m_ptr.get(), m_size));
+            }
+            break;
         case TagDataType::Integer:
         case TagDataType::DateTime:
             if(m_size == sizeof(int32)) {
diff --git a/tagvalue.h b/tagvalue.h
index 7e2c539..4f1d6f5 100644
--- a/tagvalue.h
+++ b/tagvalue.h
@@ -51,14 +51,15 @@ inline int characterSize(TagTextEncoding encoding) {
 enum class TagDataType : unsigned int
 {
     Text, /**< text/string */
-    Integer, /**< integer */
+    Integer, /**< integer, up to 64-bit */
     PositionInSet, /**< position in set, see Media::PositionInSet */
     StandardGenreIndex, /**< pre-defined genre name denoted by numerical code */
     TimeSpan, /**< time span, see ChronoUtils::TimeSpan */
     DateTime, /**< date time, see ChronoUtils::DateTime */
     Picture, /**< picture file */
     Binary, /**< unspecified binary data */
-    Undefined /**< undefined/invalid data type */
+    Undefined, /**< undefined/invalid data type */
+    Float, /**< IEEE float, 32- or 64-bit */
 };
 
 class TAG_PARSER_EXPORT TagValue
@@ -95,6 +96,8 @@ public:
     std::u16string toWString(TagTextEncoding encoding = TagTextEncoding::Unspecified) const;
     void toWString(std::u16string &result, TagTextEncoding encoding = TagTextEncoding::Unspecified) const;
     int32 toInteger() const;
+    template<typename NumberType>
+    NumberType toNumber() const;
     int toStandardGenreIndex() const;
     PositionInSet toPositionInSet() const;
     ChronoUtilities::TimeSpan toTimeSpan() const;