[TASK] TRK-4879 Move package set from trk-publisher-api (#39)

Author: Skandalik

.gitignore

@@ -1 +1,2 @@
-.idea
+.idea
+.DS_Store

gofp/setx/product.go

@@ -0,0 +1,132 @@
+package setx
+
+import (
+	"cmp"
+	"fmt"
+
+	"github.com/msales/gox/gofp"
+)
+
+type Product[Value cmp.Ordered] struct {
+	Result[Value]
+	immutable bool
+}
+
+func NewProduct[Value cmp.Ordered]() Product[Value] {
+	return Product[Value]{
+		Result: Result[Value]{
+			Operator: All,
+			Values:   []Value{},
+		},
+	}
+}
+
+// Merge merges a condition to existing result - check package description for algorithm description
+func (r *Product[Value]) Merge(operator Operator, values ...Value) (MergeResult, error) {
+	if r.immutable {
+		return Immutable, nil
+	}
+
+	switch operator {
+	case All:
+		return r.mergeAll(values)
+	case None:
+		return r.mergeNone(values)
+	case In:
+		return r.mergeIn(values)
+	case NotIn:
+		return r.mergeNotIn(values)
+	default:
+		return Error, fmt.Errorf("unknown operator")
+	}
+}
+
+func (r *Product[Value]) mergeNone(values []Value) (MergeResult, error) {
+	if len(values) > 0 {
+		return Error, fmt.Errorf("cannot merge any values when using none operator")
+	}
+	return r.makeImmutable()
+}
+
+func (r *Product[Value]) mergeAll(values []Value) (MergeResult, error) {
+	if len(values) > 0 {
+		return Error, fmt.Errorf("cannot merge any values when using all operator")
+	}
+	// ToDo: implement when needed - the case we have will never use this
+	return r.makeImmutable()
+}
+
+func (r *Product[Value]) mergeIn(values []Value) (MergeResult, error) {
+	switch r.Operator {
+	case In:
+		// operator was IN and merging IN => IN
+		// so the resulting list is just an intersection of both
+		r.Result.intersect(values...)
+		if len(r.Values) == 0 {
+			return r.makeImmutable()
+		}
+		return Continue, nil
+	case NotIn:
+		// operator was NOT_IN and merging IN => IN
+		r.Values = r.mergeInNotIn(r.Values, values)
+		r.Operator = In
+		if len(r.Values) == 0 {
+			// If resulting set is empty (IN is completely contained in NOT IN condition)
+			// then this pair of conditions makes the result always false, so NONE and immutable.
+			return r.makeImmutable()
+		}
+		return Continue, nil
+	case All:
+		// if the result is mutable and operator is ALL, this means it was not used yet
+		// with first usage, operator and values are set
+		r.Operator = In
+		r.Values = values
+		return Continue, nil
+	default:
+		return Error, fmt.Errorf("unknown operator in result")
+	}
+}
+
+func (r *Product[Value]) mergeNotIn(values []Value) (MergeResult, error) {
+	switch r.Operator {
+	case In:
+		// operator was IN and merging NOT IN => IN
+		r.Values = r.mergeInNotIn(values, r.Values)
+		// the operator was already IN
+		if len(r.Values) == 0 {
+			// If resulting set is empty (IN is completely contained in NOT IN condition)
+			// then this pair of conditions makes the result always false, so NONE and immutable.
+			return r.makeImmutable()
+		}
+		return Continue, nil
+	case NotIn:
+		// operator was NOT IN and merging NOT IN => NOT IN
+		// Result is a sum of both sets.
+		r.Result.merge(values...)
+		return Continue, nil
+	case All:
+		// if the result is mutable and operator is ALL, this means it was not used yet
+		// with first usage, operator and values are set
+		r.Operator = NotIn
+		r.Values = values
+		return Continue, nil
+	default:
+		return Error, fmt.Errorf("unknown operator in result")
+	}
+}
+
+// makeImmutable changes the result to immutable with all possible values.
+// Once this state is reached it can't be changed.
+// If conditions so far make the result completely open, no other condition can narrow it anymore
+// because all conditions are connected with OR. ANY OR SOMETHING => ANY.
+func (r *Product[Value]) makeImmutable() (MergeResult, error) {
+	r.Values = []Value{}
+	r.immutable = true
+	r.Operator = None
+	return Immutable, nil
+}
+
+func (r *Product[Value]) mergeInNotIn(inValues, notInValues []Value) []Value {
+	diff := gofp.DiffRight(inValues, notInValues)
+	return diff
+}