smarter path splitter for replacements

api/internal/utils/pathsplitter.go

@@ -5,18 +5,50 @@ package utils
 
 import "strings"
 
-// PathSplitter splits a slash delimited string, permitting escaped slashes.
-func PathSplitter(path string) []string {
-	ps := strings.Split(path, "/")
+// TODO: Move these to kyaml
+
+// PathSplitter splits a delimited string, permitting escaped delimiters.
+func PathSplitter(path string, delimiter string) []string {
+	ps := strings.Split(path, delimiter)
 	var res []string
 	res = append(res, ps[0])
 	for i := 1; i < len(ps); i++ {
 		last := len(res) - 1
 		if strings.HasSuffix(res[last], `\`) {
-			res[last] = strings.TrimSuffix(res[last], `\`) + "/" + ps[i]
+			res[last] = strings.TrimSuffix(res[last], `\`) + delimiter + ps[i]
 		} else {
 			res = append(res, ps[i])
 		}
 	}
 	return res
 }
+
+// SmarterPathSplitter splits a path, retaining bracketed list entry identifiers.
+// E.g. [name=com.foo.someapp] survives as one thing after splitting
+// "spec.template.spec.containers.[name=com.foo.someapp].image"
+// See kyaml/yaml/match.go for use of list entry identifiers.
+// This function uses `PathSplitter`, so it respects list entry identifiers
+// and escaped delimiters.
+func SmarterPathSplitter(path string, delimiter string) []string {
+	var result []string
+	split := PathSplitter(path, delimiter)
+
+	for i := 0; i < len(split); i++ {
+		elem := split[i]
+		if strings.HasPrefix(elem, "[") && !strings.HasSuffix(elem, "]") {
+			// continue until we find the matching "]"
+			bracketed := []string{elem}
+			for i < len(split)-1 {
+				i++
+				bracketed = append(bracketed, split[i])
+				if strings.HasSuffix(split[i], "]") {
+					break
+				}
+			}
+			result = append(result, strings.Join(bracketed, delimiter))
+		} else {
+			result = append(result, elem)
+		}
+	}
+	return result
+}

api/internal/utils/pathsplitter_test.go

@@ -44,6 +44,47 @@ func TestPathSplitter(t *testing.T) {
 				"nginx.ingress.kubernetes.io/auth-secret"},
 		},
 	} {
-		assert.Equal(t, tc.exp, PathSplitter(tc.path))
+		assert.Equal(t, tc.exp, PathSplitter(tc.path, "/"))
+	}
+}
+
+func TestSmarterPathSplitter(t *testing.T) {
+	testCases := map[string]struct {
+		input    string
+		expected []string
+	}{
+		"simple": {
+			input:    "spec.replicas",
+			expected: []string{"spec", "replicas"},
+		},
+		"sequence": {
+			input:    "spec.data.[name=first].key",
+			expected: []string{"spec", "data", "[name=first]", "key"},
+		},
+		"key, value with . prefix": {
+			input:    "spec.data.[.name=.first].key",
+			expected: []string{"spec", "data", "[.name=.first]", "key"},
+		},
+		"key, value with . suffix": {
+			input:    "spec.data.[name.=first.].key",
+			expected: []string{"spec", "data", "[name.=first.]", "key"},
+		},
+		"multiple '.' in value": {
+			input:    "spec.data.[name=f.i.r.s.t.].key",
+			expected: []string{"spec", "data", "[name=f.i.r.s.t.]", "key"},
+		},
+		"with escaped delimiter": {
+			input:    `spec\.replicas`,
+			expected: []string{`spec.replicas`},
+		},
+		"unmatched bracket": {
+			input:    "spec.data.[name=f.i.[r.s.t..key",
+			expected: []string{"spec", "data", "[name=f.i.[r.s.t..key"},
+		},
+	}
+	for tn, tc := range testCases {
+		t.Run(tn, func(t *testing.T) {
+			assert.Equal(t, tc.expected, SmarterPathSplitter(tc.input, "."))
+		})
 	}
 }