init: pristine aerc 0.20.0 source

worker/lib/headers.go

@@ -0,0 +1,29 @@
+package lib
+
+import (
+	"strings"
+
+	"github.com/emersion/go-message/mail"
+)
+
+// LimitHeaders returns a new Header with the specified headers included or
+// excluded
+func LimitHeaders(hdr *mail.Header, fields []string, exclude bool) *mail.Header {
+	fieldMap := make(map[string]struct{}, len(fields))
+	for _, f := range fields {
+		fieldMap[strings.ToLower(f)] = struct{}{}
+	}
+	nh := &mail.Header{}
+	curFields := hdr.Fields()
+	for curFields.Next() {
+		key := strings.ToLower(curFields.Key())
+		_, present := fieldMap[key]
+		// XOR exclude and present. When they are equal, it means we
+		// should not add the header to the new header struct
+		if exclude == present {
+			continue
+		}
+		nh.Add(key, curFields.Value())
+	}
+	return nh
+}