tpl/collections: Add Merge function

Merges two maps recursively and returns a new one. Merge is case-insensitive.

Fixes #5992

diff --git a/tpl/collections/init.go b/tpl/collections/init.go
index 8dbef75c996ac10ba53d23449f143f71806ce2ea..17ca16543fd756ed09b6c7648d2ab7c588154ea0 100644 (file)
--- a/tpl/collections/init.go
+++ b/tpl/collections/init.go
@@ -183,6 +183,16 @@ func init() {
                        },
                )
 
+               ns.AddMethodMapping(ctx.Merge,
+                       []string{"merge"},
+                       [][2]string{
+                               {`{{ dict "title" "Hugo Rocks!" | collections.Merge (dict "title" "Default Title" "description" "Yes, Hugo Rocks!") | sort }}`,
+                                       `[Yes, Hugo Rocks! Hugo Rocks!]`},
+                               {`{{  merge (dict "title" "Default Title" "description" "Yes, Hugo Rocks!") (dict "title" "Hugo Rocks!") | sort }}`,
+                                       `[Yes, Hugo Rocks! Hugo Rocks!]`},
+                       },
+               )
+
                return ns
 
        }

diff --git a/tpl/collections/merge.go b/tpl/collections/merge.go
new file mode 100644 (file)
index 0000000..6916d07
--- /dev/null
+++ b/tpl/collections/merge.go
@@ -0,0 +1,98 @@
+// 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 collections
+
+import (
+       "reflect"
+       "strings"
+
+       "github.com/gohugoio/hugo/common/hreflect"
+
+       "github.com/pkg/errors"
+)
+
+// Merge creates a copy of dst and merges src into it.
+// Currently only maps supported. Key handling is case insensitive.
+func (ns *Namespace) Merge(src, dst interface{}) (interface{}, error) {
+
+       vdst, vsrc := reflect.ValueOf(dst), reflect.ValueOf(src)
+
+       if vdst.Kind() != reflect.Map {
+               return nil, errors.Errorf("destination must be a map, got %T", dst)
+       }
+
+       if !hreflect.IsTruthfulValue(vsrc) {
+               return dst, nil
+       }
+
+       if vsrc.Kind() != reflect.Map {
+               return nil, errors.Errorf("source must be a map, got %T", src)
+       }
+
+       if vsrc.Type() != vdst.Type() {
+               return nil, errors.Errorf("incompatible map types, got %T to %T", src, dst)
+       }
+
+       return mergeMap(vdst, vsrc).Interface(), nil
+}
+
+func caseInsensitiveLookup(m, k reflect.Value) (reflect.Value, bool) {
+       if m.Type().Key().Kind() != reflect.String || k.Kind() != reflect.String {
+               // Fall back to direct lookup.
+               v := m.MapIndex(k)
+               return v, hreflect.IsTruthfulValue(v)
+       }
+
+       for _, key := range m.MapKeys() {
+               if strings.EqualFold(k.String(), key.String()) {
+                       return m.MapIndex(key), true
+               }
+
+       }
+
+       return reflect.Value{}, false
+}
+
+func mergeMap(dst, src reflect.Value) reflect.Value {
+
+       out := reflect.MakeMap(dst.Type())
+
+       // Copy the destination map.
+       for _, key := range dst.MapKeys() {
+               v := dst.MapIndex(key)
+               out.SetMapIndex(key, v)
+       }
+
+       // Add all keys in src not already in destination.
+       // Maps of the same type will be merged.
+       for _, key := range src.MapKeys() {
+               sv := src.MapIndex(key)
+               dv, found := caseInsensitiveLookup(dst, key)
+
+               if found {
+                       // If both are the same map type, merge.
+                       dve := dv.Elem()
+                       if dve.Kind() == reflect.Map {
+                               sve := sv.Elem()
+                               if dve.Type() == sve.Type() {
+                                       out.SetMapIndex(key, mergeMap(dve, sve))
+                               }
+                       }
+               } else {
+                       out.SetMapIndex(key, sv)
+               }
+       }
+
+       return out
+}

diff --git a/tpl/collections/merge_test.go b/tpl/collections/merge_test.go
new file mode 100644 (file)
index 0000000..9e34a6e
--- /dev/null
+++ b/tpl/collections/merge_test.go
@@ -0,0 +1,173 @@
+// 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 collections
+
+import (
+       "bytes"
+       "fmt"
+       "reflect"
+       "runtime"
+       "strings"
+       "testing"
+
+       "github.com/gohugoio/hugo/parser"
+
+       "github.com/gohugoio/hugo/parser/metadecoders"
+
+       "github.com/gohugoio/hugo/deps"
+       "github.com/stretchr/testify/require"
+)
+
+func TestMerge(t *testing.T) {
+
+       ns := New(&deps.Deps{})
+
+       simpleMap := map[string]interface{}{"a": 1, "b": 2}
+
+       for i, test := range []struct {
+               name   string
+               dst    interface{}
+               src    interface{}
+               expect interface{}
+               isErr  bool
+       }{
+               {
+                       "basic",
+                       map[string]interface{}{"a": 1, "b": 2},
+                       map[string]interface{}{"a": 42, "c": 3},
+                       map[string]interface{}{"a": 1, "b": 2, "c": 3}, false},
+               {
+                       "basic case insensitive",
+                       map[string]interface{}{"a": 1, "b": 2},
+                       map[string]interface{}{"A": 42, "c": 3},
+                       map[string]interface{}{"a": 1, "b": 2, "c": 3}, false},
+               {
+                       "nested",
+                       map[string]interface{}{"a": 1, "b": map[string]interface{}{"d": 1, "e": 2}},
+                       map[string]interface{}{"a": 42, "c": 3, "b": map[string]interface{}{"d": 55, "e": 66, "f": 3}},
+                       map[string]interface{}{"a": 1, "b": map[string]interface{}{"d": 1, "e": 2, "f": 3}, "c": 3}, false},
+               {"src nil", simpleMap, nil, simpleMap, false},
+               // Error cases.
+               {"dst not a map", "not a map", nil, nil, true},
+               {"src not a map", simpleMap, "not a map", nil, true},
+               {"diferent map typs", simpleMap, map[int]interface{}{32: "a"}, nil, true},
+               {"all nil", nil, nil, nil, true},
+       } {
+
+               test := test
+
+               t.Run(test.name, func(t *testing.T) {
+                       t.Parallel()
+                       errMsg := fmt.Sprintf("[%d] %v", i, test)
+
+                       assert := require.New(t)
+
+                       srcStr, dstStr := fmt.Sprint(test.src), fmt.Sprint(test.dst)
+
+                       result, err := ns.Merge(test.src, test.dst)
+
+                       if test.isErr {
+                               assert.Error(err, errMsg)
+                               return
+                       }
+
+                       assert.NoError(err, errMsg)
+                       assert.Equal(test.expect, result, errMsg)
+
+                       // map sort in fmt was fixed in go 1.12.
+                       if !strings.HasPrefix(runtime.Version(), "go1.11") {
+                               // Verify that the original maps are preserved.
+                               assert.Equal(srcStr, fmt.Sprint(test.src))
+                               assert.Equal(dstStr, fmt.Sprint(test.dst))
+                       }
+
+               })
+       }
+}
+
+func TestMergeDataFormats(t *testing.T) {
+       assert := require.New(t)
+       ns := New(&deps.Deps{})
+
+       toml1 := `
+V1 = "v1_1"
+
+[V2s]
+V21 = "v21_1"
+
+`
+
+       toml2 := `
+V1 = "v1_2"
+V2 = "v2_2"
+
+[V2s]
+V21 = "v21_2"
+V22 = "v22_2"
+
+`
+
+       meta1, err := metadecoders.Default.UnmarshalToMap([]byte(toml1), metadecoders.TOML)
+       assert.NoError(err)
+       meta2, err := metadecoders.Default.UnmarshalToMap([]byte(toml2), metadecoders.TOML)
+       assert.NoError(err)
+
+       for _, format := range []metadecoders.Format{metadecoders.JSON, metadecoders.YAML, metadecoders.TOML} {
+
+               var dataStr1, dataStr2 bytes.Buffer
+               err = parser.InterfaceToConfig(meta1, format, &dataStr1)
+               assert.NoError(err)
+               err = parser.InterfaceToConfig(meta2, format, &dataStr2)
+               assert.NoError(err)
+
+               dst, err := metadecoders.Default.UnmarshalToMap(dataStr1.Bytes(), format)
+               assert.NoError(err)
+               src, err := metadecoders.Default.UnmarshalToMap(dataStr2.Bytes(), format)
+               assert.NoError(err)
+
+               merged, err := ns.Merge(src, dst)
+               assert.NoError(err)
+
+               assert.Equal(map[string]interface{}{"V1": "v1_1", "V2": "v2_2", "V2s": map[string]interface{}{"V21": "v21_1", "V22": "v22_2"}}, merged)
+       }
+
+}
+
+func TestCaseInsensitiveMapLookup(t *testing.T) {
+       assert := require.New(t)
+
+       m1 := reflect.ValueOf(map[string]interface{}{
+               "a": 1,
+               "B": 2,
+       })
+
+       m2 := reflect.ValueOf(map[int]interface{}{
+               1: 1,
+               2: 2,
+       })
+
+       var found bool
+
+       a, found := caseInsensitiveLookup(m1, reflect.ValueOf("A"))
+       assert.True(found)
+       assert.Equal(1, a.Interface())
+
+       b, found := caseInsensitiveLookup(m1, reflect.ValueOf("b"))
+       assert.True(found)
+       assert.Equal(2, b.Interface())
+
+       two, found := caseInsensitiveLookup(m2, reflect.ValueOf(2))
+       assert.True(found)
+       assert.Equal(2, two.Interface())
+}