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-rw-r--r--common/maps/params.go96
-rw-r--r--common/maps/params_test.go45
2 files changed, 141 insertions, 0 deletions
diff --git a/common/maps/params.go b/common/maps/params.go
new file mode 100644
index 000000000..0b81057b1
--- /dev/null
+++ b/common/maps/params.go
@@ -0,0 +1,96 @@
+// Copyright 2019 The Hugo Authors. All rights reserved.
+//
+// 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 maps
+
+import (
+ "strings"
+
+ "github.com/pkg/errors"
+
+ "github.com/spf13/cast"
+)
+
+// GetNestedParam gets the first match of the keyStr in the candidates given.
+// It will first try the exact match and then try to find it as a nested map value,
+// using the given separator, e.g. "mymap.name".
+// It assumes that all the maps given have lower cased keys.
+func GetNestedParam(keyStr, separator string, candidates ...map[string]interface{}) (interface{}, error) {
+ keyStr = strings.ToLower(keyStr)
+
+ lookupFn := func(key string) interface{} {
+ for _, m := range candidates {
+ if v, ok := m[key]; ok {
+ return v
+ }
+ }
+
+ return nil
+ }
+
+ v, _, _, err := GetNestedParamFn(keyStr, separator, lookupFn)
+ return v, err
+}
+
+func GetNestedParamFn(keyStr, separator string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
+ result, _ := traverseDirectParams(keyStr, lookupFn)
+ if result != nil {
+ return result, keyStr, nil, nil
+ }
+
+ keySegments := strings.Split(keyStr, separator)
+ if len(keySegments) == 1 {
+ return nil, keyStr, nil, nil
+ }
+
+ return traverseNestedParams(keySegments, lookupFn)
+}
+
+func traverseDirectParams(keyStr string, lookupFn func(key string) interface{}) (interface{}, error) {
+ return lookupFn(keyStr), nil
+}
+
+func traverseNestedParams(keySegments []string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
+ firstKey, rest := keySegments[0], keySegments[1:]
+ result := lookupFn(firstKey)
+ if result == nil || len(rest) == 0 {
+ return result, firstKey, nil, nil
+ }
+
+ switch m := result.(type) {
+ case map[string]interface{}:
+ v, key, owner := traverseParams(rest, m)
+ return v, key, owner, nil
+ default:
+ return nil, "", nil, errors.Errorf("unsupported Params type: %T", result)
+ }
+}
+
+func traverseParams(keys []string, m map[string]interface{}) (interface{}, string, map[string]interface{}) {
+ // Shift first element off.
+ firstKey, rest := keys[0], keys[1:]
+ result := m[firstKey]
+
+ // No point in continuing here.
+ if result == nil {
+ return result, "", nil
+ }
+
+ if len(rest) == 0 {
+ // That was the last key.
+ return result, firstKey, m
+ }
+
+ // That was not the last key.
+ return traverseParams(rest, cast.ToStringMap(result))
+}
diff --git a/common/maps/params_test.go b/common/maps/params_test.go
new file mode 100644
index 000000000..89b149617
--- /dev/null
+++ b/common/maps/params_test.go
@@ -0,0 +1,45 @@
+// Copyright 2019 The Hugo Authors. All rights reserved.
+//
+// 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 maps
+
+import (
+ "testing"
+
+ "github.com/stretchr/testify/require"
+)
+
+func TestGetNestedParam(t *testing.T) {
+
+ m := map[string]interface{}{
+ "first": 1,
+ "with_underscore": 2,
+ "nested": map[string]interface{}{
+ "color": "blue",
+ },
+ }
+
+ assert := require.New(t)
+
+ must := func(keyStr, separator string, candidates ...map[string]interface{}) interface{} {
+ v, err := GetNestedParam(keyStr, separator, candidates...)
+ assert.NoError(err)
+ return v
+ }
+
+ assert.Equal(1, must("first", "_", m))
+ assert.Equal(1, must("First", "_", m))
+ assert.Equal(2, must("with_underscore", "_", m))
+ assert.Equal("blue", must("nested_color", "_", m))
+
+}