feat(bun): generate native Go array slices for PostgreSQL array columns

Bun's pgdialect scans/appends native slices directly, so array columns
(text[], integer[], uuid[], ...) always generate as plain []string,
[]int32, etc. with an explicit "array" bun tag, regardless of --types
(sqltypes/stdlib/baselib). The SqlXxxArray wrapper types are no longer
used for Bun array columns (gorm is unaffected and keeps using them).

Adds --array-nullable pointer_slice to represent nullable array columns
as *[]T instead of []T, so callers can distinguish SQL NULL (nil) from
'{}' (pointer to an empty slice). Verified end-to-end against a live
PostgreSQL instance for NULL/{}/populated arrays in every --types mode.

Closes #13

vendor/github.com/uptrace/bun/dialect/pgdialect/range.go

@@ -0,0 +1,217 @@
+package pgdialect
+
+import (
+	"bytes"
+	"database/sql"
+	"fmt"
+	"time"
+
+	"github.com/uptrace/bun/internal"
+	"github.com/uptrace/bun/schema"
+)
+
+type Range[T any] struct {
+	Lower, Upper           T
+	LowerBound, UpperBound RangeBound
+}
+
+type MultiRange[T any] []Range[T]
+
+type RangeBound byte
+
+const (
+	// RangeBoundUnset indicates that no bound is set.
+	// This usually means the range is uninitialized or unspecified.
+	RangeBoundUnset RangeBound = 0x0
+	// RangeBoundEmpty is a special marker for an empty range.
+	// This is NOT a valid PostgreSQL bound character, but is used internally
+	// to represent a range that contains no values.
+	RangeBoundEmpty RangeBound = 'E'
+
+	RangeBoundInclusiveLeft  RangeBound = '['
+	RangeBoundInclusiveRight RangeBound = ']'
+	RangeBoundExclusiveLeft  RangeBound = '('
+	RangeBoundExclusiveRight RangeBound = ')'
+)
+
+type RangeOption[T any] func(*Range[T])
+
+func NewRange[T any](lower, upper T) Range[T] {
+	r := Range[T]{
+		Lower:      lower,
+		Upper:      upper,
+		LowerBound: RangeBoundInclusiveLeft,
+		UpperBound: RangeBoundExclusiveRight,
+	}
+	return r
+}
+
+func NewEmptyRange[T any]() Range[T] {
+	return Range[T]{LowerBound: RangeBoundEmpty, UpperBound: RangeBoundEmpty}
+}
+
+func (r *Range[T]) IsZero() bool {
+	// NOTE: r.LowerBound represent
+	return r == nil || r.LowerBound == 0
+}
+
+func (r Range[T]) IsEmpty() bool {
+	return r.LowerBound == RangeBoundEmpty
+}
+
+var _ sql.Scanner = (*Range[any])(nil)
+
+func (r *Range[T]) Scan(raw any) (err error) {
+	var src []byte
+	switch v := raw.(type) {
+	case []byte:
+		src = v
+	case string:
+		src = []byte(v)
+	case nil:
+		return nil
+	default:
+		return fmt.Errorf("pgdialect: Range can't scan %T", raw)
+	}
+
+	src = bytes.TrimSpace(src)
+	if len(src) == 0 {
+		return nil
+	}
+
+	if string(src) == "empty" {
+		r.LowerBound, r.UpperBound = RangeBoundEmpty, RangeBoundEmpty
+		return nil
+	}
+
+	switch src[0] {
+	case byte(RangeBoundInclusiveLeft), byte(RangeBoundExclusiveLeft):
+		r.LowerBound = RangeBound(src[0])
+	default:
+		return fmt.Errorf("unexpected lower bound: %s", string(src[:1]))
+	}
+	switch src[len(src)-1] {
+	case byte(RangeBoundInclusiveRight), byte(RangeBoundExclusiveRight):
+		r.UpperBound = RangeBound(src[len(src)-1])
+	default:
+		return fmt.Errorf("unexpected upper bound: %s", string(src[len(src)-1:]))
+	}
+
+	src = src[1 : len(src)-1]
+
+	ind := bytes.IndexByte(src, ',')
+	if ind == -1 {
+		return fmt.Errorf("invalid range: wanted comma, got %s", string(src))
+	}
+	left, right := src[:ind], src[ind+1:]
+
+	if len(left) > 0 {
+		_, err := scanElem(&r.Lower, left)
+		if err != nil {
+			return err
+		}
+	} else {
+		r.LowerBound = RangeBoundUnset
+	}
+
+	if len(right) > 0 {
+		_, err = scanElem(&r.Upper, right)
+		if err != nil {
+			return err
+		}
+	} else {
+		r.UpperBound = RangeBoundUnset
+	}
+
+	return nil
+}
+
+var _ schema.QueryAppender = (*Range[any])(nil)
+
+func (r Range[T]) AppendQuery(_ schema.QueryGen, buf []byte) ([]byte, error) {
+	buf = append(buf, '\'')
+	buf = appendRange(buf, r)
+	buf = append(buf, '\'')
+	return buf, nil
+}
+
+func appendRange[T any](buf []byte, r Range[T]) []byte {
+	if r.IsEmpty() {
+		buf = append(buf, []byte("empty")...)
+		return buf
+	}
+
+	if r.LowerBound == RangeBoundUnset {
+		// NOTE from pg's document:
+		// > Specifying a missing bound as inclusive is automatically converted to exclusive, e.g., [,] is converted to (,).
+		buf = append(buf, byte(RangeBoundExclusiveLeft))
+	} else {
+		buf = append(buf, byte(r.LowerBound))
+		buf = appendElem(buf, r.Lower)
+	}
+	buf = append(buf, ',')
+	if r.UpperBound == RangeBoundUnset {
+		buf = append(buf, byte(RangeBoundExclusiveRight))
+	} else {
+		buf = appendElem(buf, r.Upper)
+		buf = append(buf, byte(r.UpperBound))
+	}
+	return buf
+}
+
+func (m *MultiRange[T]) Len() int {
+	if m == nil {
+		return 0
+	}
+	return len(([]Range[T])(*m))
+}
+
+func (m *MultiRange[T]) IsZero() bool {
+	return m.Len() == 0
+}
+
+func (m MultiRange[T]) AppendQuery(_ schema.QueryGen, buf []byte) ([]byte, error) {
+	if m == nil {
+		return append(buf, []byte("'{}'")...), nil
+	}
+	rs := ([]Range[T])(m)
+	buf = append(buf, '\'', '{')
+	for _, r := range rs {
+		buf = appendRange(buf, r)
+		buf = append(buf, ',')
+	}
+	if len(rs) > 0 {
+		buf[len(buf)-1] = '}'
+	} else {
+		buf = append(buf, '}')
+	}
+	buf = append(buf, '\'')
+	return buf, nil
+}
+
+func scanElem(ptr any, src []byte) ([]byte, error) {
+	// NOTE: for daterange, pg return 2024-12-01, for tzrange, pg return "2024-12-01 12:00:00"
+	if len(src) >= 2 && src[0] == '"' {
+		src = src[1 : len(src)-1]
+	}
+
+	switch ptr := ptr.(type) {
+	case *time.Time:
+		tm, err := internal.ParseTime(internal.String(src))
+		if err != nil {
+			return nil, err
+		}
+		*ptr = tm
+
+		return src, nil
+
+	case sql.Scanner:
+		if err := ptr.Scan(src); err != nil {
+			return nil, err
+		}
+		return src, nil
+
+	default:
+		panic(fmt.Errorf("unsupported range type: %T", ptr))
+	}
+}