ARROW-17588: [Go] Casting to binary-like types (apache#14027)

Authored-by: Matt Topol <zotthewizard@gmail.com> Signed-off-by: Matt Topol <zotthewizard@gmail.com>
zagto · Oct 7, 2022 · 329a56d · 329a56d
1 parent 74df9f7
commit 329a56d
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Showing 11 changed files with 849 additions and 25 deletions.
diff --git a/go/arrow/array/string.go b/go/arrow/array/string.go
@@ -482,9 +482,17 @@ func (b *LargeStringBuilder) UnmarshalJSON(data []byte) error {
 	return b.unmarshal(dec)
 }
 
+type StringLikeBuilder interface {
+	Builder
+	Append(string)
+	ReserveData(int)
+}
+
 var (
-	_ arrow.Array = (*String)(nil)
-	_ arrow.Array = (*LargeString)(nil)
-	_ Builder     = (*StringBuilder)(nil)
-	_ Builder     = (*LargeStringBuilder)(nil)
+	_ arrow.Array       = (*String)(nil)
+	_ arrow.Array       = (*LargeString)(nil)
+	_ Builder           = (*StringBuilder)(nil)
+	_ Builder           = (*LargeStringBuilder)(nil)
+	_ StringLikeBuilder = (*StringBuilder)(nil)
+	_ StringLikeBuilder = (*LargeStringBuilder)(nil)
 )
diff --git a/go/arrow/compute/cast.go b/go/arrow/compute/cast.go
@@ -163,6 +163,7 @@ func initCastTable() {
 	castTable = make(map[arrow.Type]*castFunction)
 	addCastFuncs(getBooleanCasts())
 	addCastFuncs(getNumericCasts())
+	addCastFuncs(getBinaryLikeCasts())
 	addCastFuncs(getTemporalCasts())
 }
 
@@ -273,6 +274,27 @@ func getNumericCasts() []*castFunction {
 	return out
 }
 
+func getBinaryLikeCasts() []*castFunction {
+	out := make([]*castFunction, 0)
+
+	addFn := func(name string, ty arrow.Type, kns []exec.ScalarKernel) {
+		fn := newCastFunction(name, ty)
+		for _, k := range kns {
+			if err := fn.AddTypeCast(k.Signature.InputTypes[0].MatchID(), k); err != nil {
+				panic(err)
+			}
+		}
+		out = append(out, fn)
+	}
+
+	addFn("cast_binary", arrow.BINARY, kernels.GetToBinaryKernels(arrow.BinaryTypes.Binary))
+	addFn("cast_large_binary", arrow.LARGE_BINARY, kernels.GetToBinaryKernels(arrow.BinaryTypes.LargeBinary))
+	addFn("cast_string", arrow.STRING, kernels.GetToBinaryKernels(arrow.BinaryTypes.String))
+	addFn("cast_large_string", arrow.LARGE_STRING, kernels.GetToBinaryKernels(arrow.BinaryTypes.LargeString))
+	addFn("cast_fixed_sized_binary", arrow.FIXED_SIZE_BINARY, kernels.GetFsbCastKernels())
+	return out
+}
+
 // CastDatum is a convenience function for casting a Datum to another type.
 // It is equivalent to calling CallFunction(ctx, "cast", opts, Datum) and
 // should work for Scalar, Array or ChunkedArray Datums.