102 lines
1.9 KiB
Go
102 lines
1.9 KiB
Go
package stats
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import (
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"reflect"
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"strings"
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)
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type FlatMap map[string]interface{}
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func isEmptyValue(v reflect.Value) bool {
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return v.Interface() == reflect.Zero(v.Type()).Interface()
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}
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func keyForField(field reflect.StructField, v reflect.Value) (string, bool) {
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if tag := field.Tag.Get("json"); tag != "" {
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tokens := strings.SplitN(tag, ",", 2)
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name := tokens[0]
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opts := ""
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if len(tokens) > 1 {
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opts = tokens[1]
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}
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if name == "-" || strings.Contains(opts, "omitempty") && isEmptyValue(v) {
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return "", false
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} else if name != "" {
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return name, false
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}
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}
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if field.Anonymous {
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return "", true
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}
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return field.Name, false
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}
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func extractValue(val, fallback reflect.Value) reflect.Value {
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switch val.Kind() {
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case reflect.Struct:
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return val
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case reflect.Ptr:
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return extractValue(val.Elem(), fallback)
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case reflect.Interface:
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return extractValue(val.Elem(), fallback)
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default:
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return fallback
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}
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}
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func recursiveFlatten(val reflect.Value, prefix string, output FlatMap) int {
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valType := val.Type()
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added := 0
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for i := 0; i < val.NumField(); i++ {
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child := val.Field(i)
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childType := valType.Field(i)
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childPrefix := ""
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key, anonymous := keyForField(childType, child)
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if childType.PkgPath != "" || (key == "" && !anonymous) {
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continue
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}
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child = extractValue(child, child)
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if !anonymous {
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childPrefix = prefix + key + "."
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}
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if child.Kind() == reflect.Struct {
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childAdded := recursiveFlatten(child, childPrefix, output)
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if childAdded != 0 {
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added += childAdded
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continue
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}
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}
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output[prefix+key] = child.Addr().Interface()
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added++
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}
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return added
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}
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func flattenValue(val reflect.Value) FlatMap {
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if val.Kind() == reflect.Ptr {
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return flattenValue(val.Elem())
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}
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if val.Kind() != reflect.Struct {
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panic("must be called with a struct type")
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}
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m := FlatMap{}
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recursiveFlatten(val, "", m)
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return m
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}
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func Flatten(val interface{}) FlatMap {
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return flattenValue(reflect.ValueOf(val))
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}
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