Merge pull request #1045 from go-kivik/MangoSplitKeys

x/mango: Split JSON keys more intelligently

x/mango/selector.go

@@ -130,7 +130,7 @@ func (f *fieldNode) Match(doc interface{}) bool {
 	val := doc
 
 	// Traverse nested fields (e.g. "foo.bar.baz")
-	segments := strings.Split(f.field, ".")
+	segments := SplitKeys(f.field)
 	for _, segment := range segments {
 		m, ok := val.(map[string]interface{})
 		if !ok {
@@ -371,3 +371,33 @@ func cmpSelectors(a, b Node) int {
 	}
 	return 0
 }
+
+// SplitKeys splits a field into its component keys. For example,
+// "foo.bar" is split into `["foo", "bar"]`. Escaped dots are not treated
+// as separators, so `"foo\\.bar"` becomes `["foo.bar"]`.
+func SplitKeys(field string) []string {
+	var escaped bool
+	result := []string{}
+	word := make([]byte, 0, len(field))
+	for _, ch := range field {
+		if escaped {
+			word = append(word, byte(ch))
+			escaped = false
+			continue
+		}
+		if ch == '\\' {
+			escaped = true
+			continue
+		}
+		if ch == '.' {
+			result = append(result, string(word))
+			word = word[:0]
+			continue
+		}
+		word = append(word, byte(ch))
+	}
+	if escaped {
+		word = append(word, '\\')
+	}
+	return append(result, string(word))
+}

x/mango/selector_test.go

@@ -0,0 +1,64 @@
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+
+package mango
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestSplitKeys(t *testing.T) {
+	tests := []struct {
+		input string
+		want  []string
+	}{
+		{
+			input: "foo.bar.baz",
+			want:  []string{"foo", "bar", "baz"},
+		},
+		{
+			input: "foo",
+			want:  []string{"foo"},
+		},
+		{
+			input: "",
+			want:  []string{""},
+		},
+		{
+			input: "foo\\.bar",
+			want:  []string{"foo.bar"},
+		},
+		{
+			input: "foo\\\\.bar",
+			want:  []string{"foo\\", "bar"},
+		},
+		{
+			input: "foo\\",
+			want:  []string{"foo\\"},
+		},
+		{
+			input: "foo.",
+			want:  []string{"foo", ""},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			got := SplitKeys(tt.input)
+			if d := cmp.Diff(tt.want, got); d != "" {
+				t.Errorf("unexpected keys (-want, +got): %s", d)
+			}
+		})
+	}
+}