From 6522ab1e4e8756a509788300d8a1e497e48fbd6a Mon Sep 17 00:00:00 2001
From: benibus <bpharks@gmx.com>
Date: Wed, 14 Jun 2023 14:50:15 -0400
Subject: [PATCH] Implement LogicalType class

---
 cpp/src/parquet/types.cc | 26 ++++++++++++++++++++++++++
 cpp/src/parquet/types.h  | 13 +++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/cpp/src/parquet/types.cc b/cpp/src/parquet/types.cc
index 28f472aaf9dd8..6e838356c94dc 100644
--- a/cpp/src/parquet/types.cc
+++ b/cpp/src/parquet/types.cc
@@ -435,6 +435,8 @@ std::shared_ptr<const LogicalType> LogicalType::FromThrift(
     return BSONLogicalType::Make();
   } else if (type.__isset.UUID) {
     return UUIDLogicalType::Make();
+  } else if (type.__isset.FLOAT16) {
+    return Float16LogicalType::Make();
   } else {
     throw ParquetException("Metadata contains Thrift LogicalType that is not recognized");
   }
@@ -488,6 +490,10 @@ std::shared_ptr<const LogicalType> LogicalType::BSON() { return BSONLogicalType:
 
 std::shared_ptr<const LogicalType> LogicalType::UUID() { return UUIDLogicalType::Make(); }
 
+std::shared_ptr<const LogicalType> LogicalType::Float16() {
+  return Float16LogicalType::Make();
+}
+
 std::shared_ptr<const LogicalType> LogicalType::None() { return NoLogicalType::Make(); }
 
 /*
@@ -569,6 +575,7 @@ class LogicalType::Impl {
   class JSON;
   class BSON;
   class UUID;
+  class Float16;
   class No;
   class Undefined;
 
@@ -638,6 +645,9 @@ bool LogicalType::is_null() const { return impl_->type() == LogicalType::Type::N
 bool LogicalType::is_JSON() const { return impl_->type() == LogicalType::Type::JSON; }
 bool LogicalType::is_BSON() const { return impl_->type() == LogicalType::Type::BSON; }
 bool LogicalType::is_UUID() const { return impl_->type() == LogicalType::Type::UUID; }
+bool LogicalType::is_float16() const {
+  return impl_->type() == LogicalType::Type::FLOAT16;
+}
 bool LogicalType::is_none() const { return impl_->type() == LogicalType::Type::NONE; }
 bool LogicalType::is_valid() const {
   return impl_->type() != LogicalType::Type::UNDEFINED;
@@ -1551,6 +1561,22 @@ class LogicalType::Impl::UUID final : public LogicalType::Impl::Incompatible,
 
 GENERATE_MAKE(UUID)
 
+class LogicalType::Impl::Float16 final : public LogicalType::Impl::Incompatible,
+                                         public LogicalType::Impl::TypeLengthApplicable {
+ public:
+  friend class Float16LogicalType;
+
+  OVERRIDE_TOSTRING(Float16)
+  OVERRIDE_TOTHRIFT(Float16Type, FLOAT16)
+
+ private:
+  Float16()
+      : LogicalType::Impl(LogicalType::Type::FLOAT16, SortOrder::SIGNED),
+        LogicalType::Impl::TypeLengthApplicable(parquet::Type::FIXED_LEN_BYTE_ARRAY, 2) {}
+};
+
+GENERATE_MAKE(Float16)
+
 class LogicalType::Impl::No final : public LogicalType::Impl::SimpleCompatible,
                                     public LogicalType::Impl::UniversalApplicable {
  public:
diff --git a/cpp/src/parquet/types.h b/cpp/src/parquet/types.h
index d4d6a73f147fc..d07ad6246a853 100644
--- a/cpp/src/parquet/types.h
+++ b/cpp/src/parquet/types.h
@@ -159,6 +159,7 @@ class PARQUET_EXPORT LogicalType {
       JSON,
       BSON,
       UUID,
+      FLOAT16,
       NONE  // Not a real logical type; should always be last element
     };
   };
@@ -212,6 +213,7 @@ class PARQUET_EXPORT LogicalType {
   static std::shared_ptr<const LogicalType> JSON();
   static std::shared_ptr<const LogicalType> BSON();
   static std::shared_ptr<const LogicalType> UUID();
+  static std::shared_ptr<const LogicalType> Float16();
 
   /// \brief Create a placeholder for when no logical type is specified
   static std::shared_ptr<const LogicalType> None();
@@ -265,6 +267,7 @@ class PARQUET_EXPORT LogicalType {
   bool is_JSON() const;
   bool is_BSON() const;
   bool is_UUID() const;
+  bool is_float16() const;
   bool is_none() const;
   /// \brief Return true if this logical type is of a known type.
   bool is_valid() const;
@@ -435,6 +438,16 @@ class PARQUET_EXPORT UUIDLogicalType : public LogicalType {
   UUIDLogicalType() = default;
 };
 
+/// \brief Allowed for physical type FIXED_LEN_BYTE_ARRAY with length 2,
+/// must encode raw FLOAT16 bytes.
+class PARQUET_EXPORT Float16LogicalType : public LogicalType {
+ public:
+  static std::shared_ptr<const LogicalType> Make();
+
+ private:
+  Float16LogicalType() = default;
+};
+
 /// \brief Allowed for any physical type.
 class PARQUET_EXPORT NoLogicalType : public LogicalType {
  public: