122 lines
2.5 KiB
Go
122 lines
2.5 KiB
Go
package jsoninfo
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import (
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"reflect"
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"strings"
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"unicode"
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"unicode/utf8"
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)
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// FieldInfo contains information about JSON serialization of a field.
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type FieldInfo struct {
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MultipleFields bool // Whether multiple Go fields share this JSON name
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HasJSONTag bool
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TypeIsMarshaller bool
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TypeIsUnmarshaller bool
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JSONOmitEmpty bool
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JSONString bool
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Index []int
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Type reflect.Type
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JSONName string
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}
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func AppendFields(fields []FieldInfo, parentIndex []int, t reflect.Type) []FieldInfo {
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// For each field
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numField := t.NumField()
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iteration:
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for i := 0; i < numField; i++ {
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f := t.Field(i)
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index := make([]int, 0, len(parentIndex)+1)
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index = append(index, parentIndex...)
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index = append(index, i)
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// See whether this is an embedded field
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if f.Anonymous {
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if f.Tag.Get("json") == "-" {
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continue
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}
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fields = AppendFields(fields, index, f.Type)
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continue iteration
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}
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// Ignore certain types
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switch f.Type.Kind() {
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case reflect.Func, reflect.Chan:
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continue iteration
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}
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// Is it a private (lowercase) field?
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firstRune, _ := utf8.DecodeRuneInString(f.Name)
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if unicode.IsLower(firstRune) {
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continue iteration
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}
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// Declare a field
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field := FieldInfo{
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Index: index,
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Type: f.Type,
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JSONName: f.Name,
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}
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// Read "json" tag
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jsonTag := f.Tag.Get("json")
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// Read our custom "multijson" tag that
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// allows multiple fields with the same name.
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if v := f.Tag.Get("multijson"); len(v) > 0 {
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field.MultipleFields = true
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jsonTag = v
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}
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// Handle "-"
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if jsonTag == "-" {
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continue
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}
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// Parse the tag
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if len(jsonTag) > 0 {
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field.HasJSONTag = true
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for i, part := range strings.Split(jsonTag, ",") {
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if i == 0 {
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if len(part) > 0 {
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field.JSONName = part
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}
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} else {
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switch part {
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case "omitempty":
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field.JSONOmitEmpty = true
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case "string":
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field.JSONString = true
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}
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}
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}
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}
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if _, ok := field.Type.MethodByName("MarshalJSON"); ok {
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field.TypeIsMarshaller = true
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}
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if _, ok := field.Type.MethodByName("UnmarshalJSON"); ok {
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field.TypeIsUnmarshaller = true
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}
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// Field is done
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fields = append(fields, field)
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}
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return fields
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}
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type sortableFieldInfos []FieldInfo
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func (list sortableFieldInfos) Len() int {
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return len(list)
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}
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func (list sortableFieldInfos) Less(i, j int) bool {
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return list[i].JSONName < list[j].JSONName
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}
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func (list sortableFieldInfos) Swap(i, j int) {
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a, b := list[i], list[j]
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list[i], list[j] = b, a
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}
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