hugo

Fork of github.com/gohugoio/hugo with reverse pagination support

git clone git://git.shimmy1996.com/hugo.git

merge.go (3311B)

    1 // Copyright 2019 The Hugo Authors. All rights reserved.
    2 //
    3 // Licensed under the Apache License, Version 2.0 (the "License");
    4 // you may not use this file except in compliance with the License.
    5 // You may obtain a copy of the License at
    6 // http://www.apache.org/licenses/LICENSE-2.0
    7 //
    8 // Unless required by applicable law or agreed to in writing, software
    9 // distributed under the License is distributed on an "AS IS" BASIS,
   10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   11 // See the License for the specific language governing permissions and
   12 // limitations under the License.
   13 
   14 package collections
   15 
   16 import (
   17 	"fmt"
   18 	"reflect"
   19 	"strings"
   20 
   21 	"github.com/gohugoio/hugo/common/hreflect"
   22 	"github.com/gohugoio/hugo/common/maps"
   23 
   24 	"errors"
   25 )
   26 
   27 // Merge creates a copy of the final parameter and merges the preceding
   28 // parameters into it in reverse order.
   29 // Currently only maps are supported. Key handling is case insensitive.
   30 func (ns *Namespace) Merge(params ...any) (any, error) {
   31 	if len(params) < 2 {
   32 		return nil, errors.New("merge requires at least two parameters")
   33 	}
   34 
   35 	var err error
   36 	result := params[len(params)-1]
   37 
   38 	for i := len(params) - 2; i >= 0; i-- {
   39 		result, err = ns.merge(params[i], result)
   40 		if err != nil {
   41 			return nil, err
   42 		}
   43 	}
   44 
   45 	return result, nil
   46 }
   47 
   48 // merge creates a copy of dst and merges src into it.
   49 func (ns *Namespace) merge(src, dst any) (any, error) {
   50 	vdst, vsrc := reflect.ValueOf(dst), reflect.ValueOf(src)
   51 
   52 	if vdst.Kind() != reflect.Map {
   53 		return nil, fmt.Errorf("destination must be a map, got %T", dst)
   54 	}
   55 
   56 	if !hreflect.IsTruthfulValue(vsrc) {
   57 		return dst, nil
   58 	}
   59 
   60 	if vsrc.Kind() != reflect.Map {
   61 		return nil, fmt.Errorf("source must be a map, got %T", src)
   62 	}
   63 
   64 	if vsrc.Type().Key() != vdst.Type().Key() {
   65 		return nil, fmt.Errorf("incompatible map types, got %T to %T", src, dst)
   66 	}
   67 
   68 	return mergeMap(vdst, vsrc).Interface(), nil
   69 }
   70 
   71 func caseInsensitiveLookup(m, k reflect.Value) (reflect.Value, bool) {
   72 	if m.Type().Key().Kind() != reflect.String || k.Kind() != reflect.String {
   73 		// Fall back to direct lookup.
   74 		v := m.MapIndex(k)
   75 		return v, hreflect.IsTruthfulValue(v)
   76 	}
   77 
   78 	for _, key := range m.MapKeys() {
   79 		if strings.EqualFold(k.String(), key.String()) {
   80 			return m.MapIndex(key), true
   81 		}
   82 	}
   83 
   84 	return reflect.Value{}, false
   85 }
   86 
   87 func mergeMap(dst, src reflect.Value) reflect.Value {
   88 	out := reflect.MakeMap(dst.Type())
   89 
   90 	// If the destination is Params, we must lower case all keys.
   91 	_, lowerCase := dst.Interface().(maps.Params)
   92 
   93 	// Copy the destination map.
   94 	for _, key := range dst.MapKeys() {
   95 		v := dst.MapIndex(key)
   96 		out.SetMapIndex(key, v)
   97 	}
   98 
   99 	// Add all keys in src not already in destination.
  100 	// Maps of the same type will be merged.
  101 	for _, key := range src.MapKeys() {
  102 		sv := src.MapIndex(key)
  103 		dv, found := caseInsensitiveLookup(dst, key)
  104 
  105 		if found {
  106 			// If both are the same map key type, merge.
  107 			dve := dv.Elem()
  108 			if dve.Kind() == reflect.Map {
  109 				sve := sv.Elem()
  110 				if sve.Kind() != reflect.Map {
  111 					continue
  112 				}
  113 
  114 				if dve.Type().Key() == sve.Type().Key() {
  115 					out.SetMapIndex(key, mergeMap(dve, sve))
  116 				}
  117 			}
  118 		} else {
  119 			if lowerCase && key.Kind() == reflect.String {
  120 				key = reflect.ValueOf(strings.ToLower(key.String()))
  121 			}
  122 			out.SetMapIndex(key, sv)
  123 		}
  124 	}
  125 
  126 	return out
  127 }