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tpl/collections: Add collections.Complement

Fixes #5400
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bep committed Nov 5, 2018
1 parent 47506d1 commit 42d8dfc8c88af03ea926a59bc2332acc70cca5f6
Showing with 181 additions and 0 deletions.
  1. +72 −0 tpl/collections/complement.go
  2. +84 −0 tpl/collections/complement_test.go
  3. +7 −0 tpl/collections/init.go
  4. +18 −0 tpl/collections/reflect_helpers.go
@@ -0,0 +1,72 @@
// 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 (
"errors"
"fmt"
"reflect"
)
// Complement gives the elements in the last element of seqs that are not in
// any of the others.
// All elements of seqs must be slices or arrays of comparable types.
//
// The reasoning behind this rather clumsy API is so we can do this in the templates:
// {{ $c := .Pages | complement $last4 }}
func (ns *Namespace) Complement(seqs ...interface{}) (interface{}, error) {
if len(seqs) < 2 {
return nil, errors.New("complement needs at least two arguments")
}
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")
}
}
v := reflect.ValueOf(universe)
switch v.Kind() {
case reflect.Array, reflect.Slice:
sl := reflect.MakeSlice(v.Type(), 0, 0)
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")
}
if _, found := aset[normalize(ev)]; !found {
sl = reflect.Append(sl, ev)
}
}
return sl.Interface(), nil
default:
return nil, fmt.Errorf("arguments to complement must be slices or arrays")
}
}
@@ -0,0 +1,84 @@
// 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 TestComplement(t *testing.T) {
t.Parallel()
assert := require.New(t)
ns := New(&deps.Deps{})
s1 := []TstX{TstX{A: "a"}, TstX{A: "b"}, TstX{A: "d"}, TstX{A: "e"}}
s2 := []TstX{TstX{A: "b"}, 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 {
s interface{}
t []interface{}
expected interface{}
}{
{[]string{"a", "b", "c"}, []interface{}{[]string{"c", "d"}}, []string{"a", "b"}},
{[]string{"a", "b", "c"}, []interface{}{[]string{"c", "d"}, []string{"a", "b"}}, []string{}},
{[]interface{}{"a", "b", nil}, []interface{}{[]string{"a", "d"}}, []interface{}{"b", nil}},
{[]int{1, 2, 3, 4, 5}, []interface{}{[]int{1, 3}, []string{"a", "b"}, []int{1, 2}}, []int{4, 5}},
{[]int{1, 2, 3, 4, 5}, []interface{}{[]int64{1, 3}}, []int{2, 4, 5}},
{s1, []interface{}{s2}, []TstX{TstX{A: "a"}, TstX{A: "d"}}},
{sp1, []interface{}{sp2}, []*TstX{xa, xd}},
// Errors
{[]string{"a", "b", "c"}, []interface{}{"error"}, false},
{"error", []interface{}{[]string{"c", "d"}, []string{"a", "b"}}, false},
{[]string{"a", "b", "c"}, []interface{}{[][]string{[]string{"c", "d"}}}, false},
{[]interface{}{[][]string{[]string{"c", "d"}}}, []interface{}{[]string{"c", "d"}, []string{"a", "b"}}, false},
} {
errMsg := fmt.Sprintf("[%d]", i)
args := append(test.t, test.s)
result, err := ns.Complement(args...)
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)
}
View
@@ -39,6 +39,13 @@ func init() {
[][2]string{},
)
ns.AddMethodMapping(ctx.Complement,
[]string{"complement"},
[][2]string{
{`{{ slice "a" "b" "c" "d" "e" "f" | complement (slice "b" "c") (slice "d" "e") }}`, `[a f]`},
},
)
ns.AddMethodMapping(ctx.Delimit,
[]string{"delimit"},
[][2]string{
@@ -41,6 +41,24 @@ func numberToFloat(v reflect.Value) (float64, error) {
}
}
// normalizes different numeric types to make them comparable.
// If not, any pointer will be unwrapped.
func normalize(v reflect.Value) interface{} {
k := v.Kind()
switch {
case isNumber(k):
f, err := numberToFloat(v)
if err == nil {
return f
}
case k == reflect.Ptr:
v = v.Elem()
}
return v.Interface()
}
// 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.

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