Added files.

acl.go

@@ -0,0 +1,104 @@
+package imap
+
+import (
+	"fmt"
+	"strings"
+)
+
+// IMAP4 ACL extension (RFC 2086)
+
+// Right describes a set of operations controlled by the IMAP ACL extension.
+type Right byte
+
+const (
+	// Standard rights
+	RightLookup     = Right('l') // mailbox is visible to LIST/LSUB commands
+	RightRead       = Right('r') // SELECT the mailbox, perform CHECK, FETCH, PARTIAL, SEARCH, COPY from mailbox
+	RightSeen       = Right('s') // keep seen/unseen information across sessions (STORE SEEN flag)
+	RightWrite      = Right('w') // STORE flags other than SEEN and DELETED
+	RightInsert     = Right('i') // perform APPEND, COPY into mailbox
+	RightPost       = Right('p') // send mail to submission address for mailbox, not enforced by IMAP4 itself
+	RightCreate     = Right('c') // CREATE new sub-mailboxes in any implementation-defined hierarchy
+	RightDelete     = Right('d') // STORE DELETED flag, perform EXPUNGE
+	RightAdminister = Right('a') // perform SETACL
+)
+
+// RightSetAll contains all standard rights.
+var RightSetAll = RightSet("lrswipcda")
+
+// RightsIdentifier is an ACL identifier.
+type RightsIdentifier string
+
+// RightsIdentifierAnyone is the universal identity (matches everyone).
+const RightsIdentifierAnyone = RightsIdentifier("anyone")
+
+// NewRightsIdentifierUsername returns a rights identifier referring to a
+// username, checking for reserved values.
+func NewRightsIdentifierUsername(username string) (RightsIdentifier, error) {
+	if username == string(RightsIdentifierAnyone) || strings.HasPrefix(username, "-") {
+		return "", fmt.Errorf("imap: reserved rights identifier")
+	}
+	return RightsIdentifier(username), nil
+}
+
+// RightModification indicates how to mutate a right set.
+type RightModification byte
+
+const (
+	RightModificationReplace = RightModification(0)
+	RightModificationAdd     = RightModification('+')
+	RightModificationRemove  = RightModification('-')
+)
+
+// A RightSet is a set of rights.
+type RightSet []Right
+
+// String returns a string representation of the right set.
+func (r RightSet) String() string {
+	return string(r)
+}
+
+// Add returns a new right set containing rights from both sets.
+func (r RightSet) Add(rights RightSet) RightSet {
+	newRights := make(RightSet, len(r), len(r)+len(rights))
+	copy(newRights, r)
+
+	for _, right := range rights {
+		if !strings.ContainsRune(string(r), rune(right)) {
+			newRights = append(newRights, right)
+		}
+	}
+
+	return newRights
+}
+
+// Remove returns a new right set containing all rights in r except these in
+// the provided set.
+func (r RightSet) Remove(rights RightSet) RightSet {
+	newRights := make(RightSet, 0, len(r))
+
+	for _, right := range r {
+		if !strings.ContainsRune(string(rights), rune(right)) {
+			newRights = append(newRights, right)
+		}
+	}
+
+	return newRights
+}
+
+// Equal returns true if both right sets contain exactly the same rights.
+func (rs1 RightSet) Equal(rs2 RightSet) bool {
+	for _, r := range rs1 {
+		if !strings.ContainsRune(string(rs2), rune(r)) {
+			return false
+		}
+	}
+
+	for _, r := range rs2 {
+		if !strings.ContainsRune(string(rs1), rune(r)) {
+			return false
+		}
+	}
+
+	return true
+}