zeroshade commented on code in PR #13136:
URL: https://github.com/apache/arrow/pull/13136#discussion_r886913269
##########
go/arrow/datatype.go:
##########
@@ -209,3 +210,77 @@ func timeUnitFingerprint(unit TimeUnit) rune {
return rune(0)
}
}
+
+// BufferKind describes the type of buffer expected when defining a layout
specification
+type BufferKind int8
+
+// The expected types of buffers
+const (
+ KindFixedWidth BufferKind = iota
+ KindVarWidth
+ KindBitmap
+ KindAlwaysNull
+)
+
+// BufferSpec provides a specification for the buffers of a particular datatype
+type BufferSpec struct {
+ Kind BufferKind
+ ByteWidth int // for KindFixedWidth
+}
+
+func (b BufferSpec) Equals(other BufferSpec) bool {
+ return b.Kind == other.Kind && (b.Kind != KindFixedWidth || b.ByteWidth
== other.ByteWidth)
+}
+
+// DataTypeLayout represents the physical layout of a datatype's buffers
including
+// the number of and types of those binary buffers. This will correspond
+// with the buffers in the ArrayData for an array of that type.
+type DataTypeLayout struct {
+ Buffers []BufferSpec
+ HasDict bool
+}
+
+func SpecFixedWidth(w int) BufferSpec { return BufferSpec{KindFixedWidth, w} }
+func SpecVariableWidth() BufferSpec { return BufferSpec{KindVarWidth, -1} }
+func SpecBitmap() BufferSpec { return BufferSpec{KindBitmap, -1} }
+func SpecAlwaysNull() BufferSpec { return BufferSpec{KindAlwaysNull, -1} }
+
+// IsInteger is a helper to return true if the type ID provided is one of the
+// integral types of uint or int with the varying sizes.
+func IsInteger(t Type) bool {
+ switch t {
+ case UINT8, INT8, UINT16, INT16, UINT32, INT32, UINT64, INT64:
+ return true
+ }
+ return false
+}
+
+// IsPrimitive returns true if the provided type ID represents a fixed width
Review Comment:
I mentioned this in my response
[here](https://github.com/apache/arrow/pull/13136/#discussion_r885716884) but
essentially the reason why this is `IsPrimitive` is because it returns true if
the type is a value with a bit-width that is interpretable as a single
"primitive" value in most languages (ie: an integer with a specific bit-width
or a float/double) as opposed to values like DECIMAL128 and the interval values
which are compound structures consisting of multiple primitive values despite
being a known fixed width (for example two 64-bit integers for DECIMAL). That's
why i don't think `IsKnownFixedWidth` works for this
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