97 lines
2.8 KiB
Go
97 lines
2.8 KiB
Go
// Copyright 2019 The Hugo Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package maps
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import (
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"strings"
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"github.com/pkg/errors"
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"github.com/spf13/cast"
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)
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// GetNestedParam gets the first match of the keyStr in the candidates given.
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// It will first try the exact match and then try to find it as a nested map value,
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// using the given separator, e.g. "mymap.name".
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// It assumes that all the maps given have lower cased keys.
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func GetNestedParam(keyStr, separator string, candidates ...map[string]interface{}) (interface{}, error) {
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keyStr = strings.ToLower(keyStr)
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lookupFn := func(key string) interface{} {
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for _, m := range candidates {
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if v, ok := m[key]; ok {
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return v
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}
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}
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return nil
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}
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v, _, _, err := GetNestedParamFn(keyStr, separator, lookupFn)
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return v, err
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}
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func GetNestedParamFn(keyStr, separator string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
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result, _ := traverseDirectParams(keyStr, lookupFn)
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if result != nil {
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return result, keyStr, nil, nil
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}
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keySegments := strings.Split(keyStr, separator)
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if len(keySegments) == 1 {
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return nil, keyStr, nil, nil
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}
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return traverseNestedParams(keySegments, lookupFn)
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}
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func traverseDirectParams(keyStr string, lookupFn func(key string) interface{}) (interface{}, error) {
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return lookupFn(keyStr), nil
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}
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func traverseNestedParams(keySegments []string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
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firstKey, rest := keySegments[0], keySegments[1:]
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result := lookupFn(firstKey)
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if result == nil || len(rest) == 0 {
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return result, firstKey, nil, nil
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}
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switch m := result.(type) {
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case map[string]interface{}:
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v, key, owner := traverseParams(rest, m)
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return v, key, owner, nil
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default:
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return nil, "", nil, errors.Errorf("unsupported Params type: %T", result)
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}
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}
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func traverseParams(keys []string, m map[string]interface{}) (interface{}, string, map[string]interface{}) {
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// Shift first element off.
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firstKey, rest := keys[0], keys[1:]
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result := m[firstKey]
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// No point in continuing here.
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if result == nil {
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return result, "", nil
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}
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if len(rest) == 0 {
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// That was the last key.
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return result, firstKey, m
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}
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// That was not the last key.
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return traverseParams(rest, cast.ToStringMap(result))
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}
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