imap: make SearchCriteria.Not a pointer

imapclient/search.go

@@ -182,9 +182,9 @@ func writeSearchKey(enc *imapwire.Encoder, criteria *imap.SearchCriteria) {
 		encodeItem("SMALLER").SP().Number64(criteria.Smaller)
 	}
 
-	for _, not := range criteria.Not {
+	if criteria.Not != nil {
 		encodeItem("NOT").SP()
-		writeSearchKey(enc, &not)
+		writeSearchKey(enc, criteria.Not)
 	}
 	for _, or := range criteria.Or {
 		encodeItem("OR").SP()
@@ -290,10 +290,8 @@ func searchCriteriaIsASCII(criteria *imap.SearchCriteria) bool {
 			return false
 		}
 	}
-	for _, not := range criteria.Not {
-		if !searchCriteriaIsASCII(&not) {
-			return false
-		}
+	if criteria.Not != nil && !searchCriteriaIsASCII(criteria.Not) {
+		return false
 	}
 	for _, or := range criteria.Or {
 		if !searchCriteriaIsASCII(&or[0]) || !searchCriteriaIsASCII(&or[1]) {

imapserver/imapmemserver/message.go

@@ -320,10 +320,8 @@ func (msg *message) search(seqNum uint32, criteria *imap.SearchCriteria) bool {
 		}
 	}
 
-	for _, not := range criteria.Not {
-		if msg.search(seqNum, &not) {
-			return false
-		}
+	if criteria.Not != nil && msg.search(seqNum, criteria.Not) {
+		return false
 	}
 	for _, or := range criteria.Or {
 		if !msg.search(seqNum, &or[0]) && !msg.search(seqNum, &or[1]) {

imapserver/search.go

@@ -284,7 +284,7 @@ func readSearchKeyWithAtom(criteria *imap.SearchCriteria, dec *imapwire.Decoder,
 		if err := readSearchKey(&not, dec); err != nil {
 			return nil
 		}
-		criteria.Not = append(criteria.Not, not)
+		criteria.And(&imap.SearchCriteria{Not: &not})
 	case "OR":
 		if !dec.ExpectSP() {
 			return dec.Err()

search.go

@@ -44,7 +44,7 @@ type SearchCriteria struct {
 	Larger  int64
 	Smaller int64
 
-	Not []SearchCriteria
+	Not *SearchCriteria
 	Or  [][2]SearchCriteria
 }
 
@@ -90,8 +90,10 @@ func (criteria *SearchCriteria) And(other *SearchCriteria) {
 		criteria.Smaller = other.Smaller
 	}
 
-	for _, not := range other.Not {
-		criteria.Not = append(criteria.Not, not)
+	if criteria.Not != nil && other.Not != nil {
+		criteria.Not.And(other.Not)
+	} else if other.Not != nil {
+		criteria.Not = other.Not
 	}
 	for _, or := range other.Or {
 		criteria.Or = append(criteria.Or, or)