Merge pull request #16 from jf-tech/fqdn_with_esc

Adding `BuildFQDNWithEsc` and `LastNameletOfFQDNWithEsc`

Author: jf-tech

strs/strs.go

@@ -54,9 +54,11 @@ func CopyStrPtr(sp *string) *string {
 const (
 	// FQDNDelimiter is the default FQDN delimiter.
 	FQDNDelimiter = "."
+	// FQDNEsc is the default escape char for FQDN. Esc is used for escaping "." and itself.
+	FQDNEsc = "%"
 )
 
-// BuildFQDN builds an FQDN from a slice of namelet strings.
+// BuildFQDN builds an FQDN (dot delimited) from a slice of namelet strings.
 func BuildFQDN(namelets ...string) string {
 	return BuildFQDN2(FQDNDelimiter, namelets...)
 }
@@ -66,9 +68,22 @@ func BuildFQDN2(delimiter string, namelets ...string) string {
 	return strings.Join(namelets, delimiter)
 }
 
+var fqdnEscReplacer = strings.NewReplacer(".", "%.", "%", "%%")
+
+// BuildFQDNWithEsc builds an FQDN (dot delimited) from a slice of namelet strings with proper escaping.
+// e.g. If namelets are 'a.b', 'c%d', it will return 'a%.b.c%%d'.
+// Note this function isn't optimized for alloc/perf.
+func BuildFQDNWithEsc(namelets ...string) string {
+	return strings.Join(
+		NoErrMapSlice(namelets, func(s string) string {
+			return fqdnEscReplacer.Replace(s)
+		}),
+		FQDNDelimiter)
+}
+
 // LastNameletOfFQDN returns the last namelet of an FQDN delimited by default
 // delimiter. If there is no delimiter in the FQDN, then the FQDN itself is
-// // returned.
+// returned.
 func LastNameletOfFQDN(fqdn string) string {
 	return LastNameletOfFQDN2(FQDNDelimiter, fqdn)
 }
@@ -84,6 +99,15 @@ func LastNameletOfFQDN2(delimiter, fqdn string) string {
 	return fqdn[index+1:]
 }
 
+// LastNameletOfFQDNWithEsc returns the last namelet of an FQDN delimited by default
+// delimiter, with escaping considered. If there is no delimiter in the FQDN, then the
+// FQDN itself is returned.
+// Note this function isn't optimized for alloc/perf.
+func LastNameletOfFQDNWithEsc(fqdn string) string {
+	namelets := SplitWithEsc(fqdn, FQDNDelimiter, FQDNEsc)
+	return Unescape(namelets[len(namelets)-1], FQDNEsc)
+}
+
 // CopySlice copies a string slice. The returned slice is guaranteed to be a different
 // slice (thus the name Copy) so modifying the src from the caller side won't affect
 // the returned slice.

strs/strs_test.go

@@ -109,6 +109,39 @@ func TestBuildFQDN(t *testing.T) {
 	}
 }
 
+func TestBuildFQDNWithEsc(t *testing.T) {
+	for _, test := range []struct {
+		name     string
+		namelets []string
+		expected string
+	}{
+		{
+			name:     "nil",
+			namelets: nil,
+			expected: "",
+		},
+		{
+			name:     "empty",
+			namelets: []string{},
+			expected: "",
+		},
+		{
+			name:     "single with space, dot, and percent",
+			namelets: []string{"o n%.e"},
+			expected: "o n%%%.e",
+		},
+		{
+			name:     "multiple",
+			namelets: []string{"o n%.e", ".", "%three%"},
+			expected: "o n%%%.e.%..%%three%%",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			assert.Equal(t, test.expected, BuildFQDNWithEsc(test.namelets...))
+		})
+	}
+}
+
 func TestLastNameletOfFQDN(t *testing.T) {
 	for _, test := range []struct {
 		name     string
@@ -147,6 +180,49 @@ func TestLastNameletOfFQDN(t *testing.T) {
 	}
 }
 
+func TestLastNameletOfFQDNWithEsc(t *testing.T) {
+	for _, test := range []struct {
+		name     string
+		fqdn     string
+		expected string
+	}{
+		{
+			name:     "empty",
+			fqdn:     "",
+			expected: "",
+		},
+		{
+			name:     "no delimiter, no esc",
+			fqdn:     "abc",
+			expected: "abc",
+		},
+		{
+			name:     "no delimiter, with esc",
+			fqdn:     "%.a%b%%c",
+			expected: ".ab%c",
+		},
+		{
+			name:     "delimiter at beginning",
+			fqdn:     ".a%.bc",
+			expected: "a.bc",
+		},
+		{
+			name:     "delimiter at the end",
+			fqdn:     "a%%bc.",
+			expected: "",
+		},
+		{
+			name:     "fqdn",
+			fqdn:     "o n%%%.e.%..%%three%%",
+			expected: "%three%",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			assert.Equal(t, test.expected, LastNameletOfFQDNWithEsc(test.fqdn))
+		})
+	}
+}
+
 func TestCopySlice(t *testing.T) {
 	for _, test := range []struct {
 		name           string