dialect/sql: support capturing predicates in selectors

This allows custom predicates mutating the root querying and still respect the AND/OR/NOT semantics

dialect/sql/builder.go

@@ -2146,6 +2146,7 @@ type Selector struct {
 	selection []selection
 	from      []TableView
 	joins     []join
+	collected [][]*Predicate
 	where     *Predicate
 	or        bool
 	not       bool
@@ -2385,8 +2386,35 @@ func (s *Selector) Offset(offset int) *Selector {
 	return s
 }
 
+// CollectPredicates indicates the appended predicated should be collected
+// and not appended to the `WHERE` clause.
+func (s *Selector) CollectPredicates() *Selector {
+	s.collected = append(s.collected, []*Predicate{})
+	return s
+}
+
+// CollectedPredicates returns the collected predicates.
+func (s *Selector) CollectedPredicates() []*Predicate {
+	if len(s.collected) == 0 {
+		return nil
+	}
+	return s.collected[len(s.collected)-1]
+}
+
+// UncollectedPredicates stop collecting predicates.
+func (s *Selector) UncollectedPredicates() *Selector {
+	if len(s.collected) > 0 {
+		s.collected = s.collected[:len(s.collected)-1]
+	}
+	return s
+}
+
 // Where sets or appends the given predicate to the statement.
 func (s *Selector) Where(p *Predicate) *Selector {
+	if len(s.collected) > 0 {
+		s.collected[len(s.collected)-1] = append(s.collected[len(s.collected)-1], p)
+		return s
+	}
 	if s.not {
 		p = Not(p)
 		s.not = false

dialect/sql/sql.go

@@ -170,6 +170,63 @@ func FieldContainsFold(name string, substr string) func(*Selector) {
 	}
 }
 
+// AndPredicates returns a new predicate for joining multiple generated predicates with AND between them.
+func AndPredicates[P ~func(*Selector)](predicates ...P) func(*Selector) {
+	return func(s *Selector) {
+		s.CollectPredicates()
+		for _, p := range predicates {
+			p(s)
+		}
+		collected := s.CollectedPredicates()
+		s.UncollectedPredicates()
+		switch len(collected) {
+		case 0:
+		case 1:
+			s.Where(collected[0])
+		default:
+			s.Where(And(collected...))
+		}
+	}
+}
+
+// OrPredicates returns a new predicate for joining multiple generated predicates with OR between them.
+func OrPredicates[P ~func(*Selector)](predicates ...P) func(*Selector) {
+	return func(s *Selector) {
+		s.CollectPredicates()
+		for _, p := range predicates {
+			p(s)
+		}
+		collected := s.CollectedPredicates()
+		s.UncollectedPredicates()
+		switch len(collected) {
+		case 0:
+		case 1:
+			s.Where(collected[0])
+		default:
+			s.Where(Or(collected...))
+		}
+	}
+}
+
+// NotPredicates wraps the generated predicates with NOT. For example, NOT(P), NOT((P1 AND P2)).
+func NotPredicates[P ~func(*Selector)](predicates ...P) func(*Selector) {
+	return func(s *Selector) {
+		s.CollectPredicates()
+		for _, p := range predicates {
+			p(s)
+		}
+		collected := s.CollectedPredicates()
+		s.UncollectedPredicates()
+		switch len(collected) {
+		case 0:
+		case 1:
+			s.Where(Not(collected[0]))
+		default:
+			s.Where(Not(And(collected...)))
+		}
+	}
+}
+
 // ColumnCheck is a function that verifies whether the
 // specified column exists within the given table.
 type ColumnCheck func(table, column string) error