1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
// Copyright 2017 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"
"github.com/spf13/cast"
"github.com/gohugoio/hugo/common/maps"
)
// Index returns the result of indexing its first argument by the following
// arguments. Thus "index x 1 2 3" is, in Go syntax, x[1][2][3]. Each
// indexed item must be a map, slice, or array.
//
// Adapted from Go stdlib src/text/template/funcs.go.
//
// We deviate from the stdlib mostly because of https://github.com/golang/go/issues/14751.
func (ns *Namespace) Index(item any, args ...any) (any, error) {
v, err := ns.doIndex(item, args...)
if err != nil {
return nil, fmt.Errorf("index of type %T with args %v failed: %s", item, args, err)
}
return v, nil
}
func (ns *Namespace) doIndex(item any, args ...any) (any, error) {
// TODO(moorereason): merge upstream changes.
v := reflect.ValueOf(item)
if !v.IsValid() {
// See issue 10489
// This used to be an error.
return nil, nil
}
var indices []any
if len(args) == 1 {
v := reflect.ValueOf(args[0])
if v.Kind() == reflect.Slice {
for i := 0; i < v.Len(); i++ {
indices = append(indices, v.Index(i).Interface())
}
} else {
indices = append(indices, args[0])
}
} else {
indices = args
}
lowerm, ok := item.(maps.Params)
if ok {
return lowerm.GetNested(cast.ToStringSlice(indices)...), nil
}
for _, i := range indices {
index := reflect.ValueOf(i)
var isNil bool
if v, isNil = indirect(v); isNil {
// See issue 10489
// This used to be an error.
return nil, nil
}
switch v.Kind() {
case reflect.Array, reflect.Slice, reflect.String:
var x int64
switch index.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
x = index.Int()
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
x = int64(index.Uint())
case reflect.Invalid:
return nil, errors.New("cannot index slice/array with nil")
default:
return nil, fmt.Errorf("cannot index slice/array with type %s", index.Type())
}
if x < 0 || x >= int64(v.Len()) {
// We deviate from stdlib here. Don't return an error if the
// index is out of range.
return nil, nil
}
v = v.Index(int(x))
case reflect.Map:
index, err := prepareArg(index, v.Type().Key())
if err != nil {
return nil, err
}
if x := v.MapIndex(index); x.IsValid() {
v = x
} else {
v = reflect.Zero(v.Type().Elem())
}
case reflect.Invalid:
// the loop holds invariant: v.IsValid()
panic("unreachable")
default:
return nil, fmt.Errorf("can't index item of type %s", v.Type())
}
}
return v.Interface(), nil
}
// prepareArg checks if value can be used as an argument of type argType, and
// converts an invalid value to appropriate zero if possible.
//
// Copied from Go stdlib src/text/template/funcs.go.
func prepareArg(value reflect.Value, argType reflect.Type) (reflect.Value, error) {
if !value.IsValid() {
if !canBeNil(argType) {
return reflect.Value{}, fmt.Errorf("value is nil; should be of type %s", argType)
}
value = reflect.Zero(argType)
}
if !value.Type().AssignableTo(argType) {
return reflect.Value{}, fmt.Errorf("value has type %s; should be %s", value.Type(), argType)
}
return value, nil
}
// canBeNil reports whether an untyped nil can be assigned to the type. See reflect.Zero.
//
// Copied from Go stdlib src/text/template/exec.go.
func canBeNil(typ reflect.Type) bool {
switch typ.Kind() {
case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
return true
}
return false
}
|
