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tpl/collections: Add collections.SymDiff

Fixes #5410
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bep committed Nov 6, 2018
1 parent b8b8436 commit 488776b6498d1377718133d42daa87ce1236215d
@@ -33,23 +33,9 @@ func (ns *Namespace) Complement(seqs ...interface{}) (interface{}, error) {
universe := seqs[len(seqs)-1]
as := seqs[:len(seqs)-1]
aset := make(map[interface{}]struct{})
for _, av := range as {
v := reflect.ValueOf(av)
switch v.Kind() {
case reflect.Array, reflect.Slice:
for i := 0; i < v.Len(); i++ {
ev, _ := indirectInterface(v.Index(i))
if !ev.Type().Comparable() {
return nil, errors.New("elements in complement must be comparable")
}
aset[normalize(ev)] = struct{}{}
}
default:
return nil, fmt.Errorf("arguments to complement must be slices or arrays")
}
aset, err := collectIdentities(as...)
if err != nil {
return nil, err
}
v := reflect.ValueOf(universe)
View
@@ -46,6 +46,13 @@ func init() {
},
)
ns.AddMethodMapping(ctx.SymDiff,
[]string{"symdiff"},
[][2]string{
{`{{ slice 1 2 3 | symdiff (slice 3 4) }}`, `[1 2 4]`},
},
)
ns.AddMethodMapping(ctx.Delimit,
[]string{"delimit"},
[][2]string{
@@ -14,10 +14,11 @@
package collections
import (
"errors"
"fmt"
"reflect"
"time"
"github.com/pkg/errors"
)
var (
@@ -59,6 +60,47 @@ func normalize(v reflect.Value) interface{} {
return v.Interface()
}
// collects identities from the slices in seqs into a set. Numeric values are normalized,
// pointers unwrapped.
func collectIdentities(seqs ...interface{}) (map[interface{}]bool, error) {
seen := make(map[interface{}]bool)
for _, seq := range seqs {
v := reflect.ValueOf(seq)
switch v.Kind() {
case reflect.Array, reflect.Slice:
for i := 0; i < v.Len(); i++ {
ev, _ := indirectInterface(v.Index(i))
if !ev.Type().Comparable() {
return nil, errors.New("elements must be comparable")
}
seen[normalize(ev)] = true
}
default:
return nil, fmt.Errorf("arguments must be slices or arrays")
}
}
return seen, nil
}
// We have some different numeric and string types that we try to behave like
// they were the same.
func convertValue(v reflect.Value, to reflect.Type) (reflect.Value, error) {
if v.Type().AssignableTo(to) {
return v, nil
}
switch kind := to.Kind(); {
case kind == reflect.String:
s, err := toString(v)
return reflect.ValueOf(s), err
case isNumber(kind):
return convertNumber(v, kind)
default:
return reflect.Value{}, errors.Errorf("%s is not assignable to %s", v.Type(), to)
}
}
// There are potential overflows in this function, but the downconversion of
// int64 etc. into int8 etc. is coming from the synthetic unit tests for Union etc.
// TODO(bep) We should consider normalizing the slices to int64 etc.
View
@@ -0,0 +1,71 @@
// Copyright 2018 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 (
"fmt"
"reflect"
"github.com/pkg/errors"
)
// SymDiff returns the symmetric difference of s1 and s2.
// Arguments must be either a slice or an array of comparable types.
func (ns *Namespace) SymDiff(s2, s1 interface{}) (interface{}, error) {
ids1, err := collectIdentities(s1)
if err != nil {
return nil, err
}
ids2, err := collectIdentities(s2)
if err != nil {
return nil, err
}
var slice reflect.Value
var sliceElemType reflect.Type
for i, s := range []interface{}{s1, s2} {
v := reflect.ValueOf(s)
switch v.Kind() {
case reflect.Array, reflect.Slice:
if i == 0 {
sliceType := v.Type()
sliceElemType = sliceType.Elem()
slice = reflect.MakeSlice(sliceType, 0, 0)
}
for i := 0; i < v.Len(); i++ {
ev, _ := indirectInterface(v.Index(i))
if !ev.Type().Comparable() {
return nil, errors.New("symdiff: elements must be comparable")
}
key := normalize(ev)
// Append if the key is not in their intersection.
if ids1[key] != ids2[key] {
v, err := convertValue(ev, sliceElemType)
if err != nil {
return nil, errors.WithMessage(err, "symdiff: failed to convert value")
}
slice = reflect.Append(slice, v)
}
}
default:
return nil, fmt.Errorf("arguments to symdiff must be slices or arrays")
}
}
return slice.Interface(), nil
}
@@ -0,0 +1,80 @@
// Copyright 2018 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 (
"fmt"
"reflect"
"testing"
"github.com/gohugoio/hugo/deps"
"github.com/stretchr/testify/require"
)
func TestSymDiff(t *testing.T) {
t.Parallel()
assert := require.New(t)
ns := New(&deps.Deps{})
s1 := []TstX{TstX{A: "a"}, TstX{A: "b"}}
s2 := []TstX{TstX{A: "a"}, TstX{A: "e"}}
xa, xd := &TstX{A: "a"}, &TstX{A: "d"}
sp1 := []*TstX{xa, &TstX{A: "b"}, xd, &TstX{A: "e"}}
sp2 := []*TstX{&TstX{A: "b"}, &TstX{A: "e"}}
for i, test := range []struct {
s1 interface{}
s2 interface{}
expected interface{}
}{
{[]string{"a", "x", "b", "c"}, []string{"a", "b", "y", "c"}, []string{"x", "y"}},
{[]string{"a", "b", "c"}, []string{"a", "b", "c"}, []string{}},
{[]interface{}{"a", "b", nil}, []interface{}{"a"}, []interface{}{"b", nil}},
{[]int{1, 2, 3}, []int{3, 4}, []int{1, 2, 4}},
{[]int{1, 2, 3}, []int64{3, 4}, []int{1, 2, 4}},
{s1, s2, []TstX{TstX{A: "b"}, TstX{A: "e"}}},
{sp1, sp2, []*TstX{xa, xd}},
// Errors
{"error", "error", false},
{[]int{1, 2, 3}, []string{"3", "4"}, false},
} {
errMsg := fmt.Sprintf("[%d]", i)
result, err := ns.SymDiff(test.s2, test.s1)
if b, ok := test.expected.(bool); ok && !b {
require.Error(t, err, errMsg)
continue
}
require.NoError(t, err, errMsg)
if !reflect.DeepEqual(test.expected, result) {
t.Fatalf("%s got\n%T: %v\nexpected\n%T: %v", errMsg, result, result, test.expected, test.expected)
}
}
_, err := ns.Complement()
assert.Error(err)
_, err = ns.Complement([]string{"a", "b"})
assert.Error(err)
}

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