github.com/aclisp/heapster@v0.19.2-0.20160613100040-51756f899a96/Godeps/_workspace/src/k8s.io/kubernetes/pkg/util/json/json.go (about)

     1  /*
     2  Copyright 2015 The Kubernetes Authors All rights reserved.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package json
    18  
    19  import (
    20  	"bytes"
    21  	"encoding/json"
    22  	"io"
    23  )
    24  
    25  // NewEncoder delegates to json.NewEncoder
    26  // It is only here so this package can be a drop-in for common encoding/json uses
    27  func NewEncoder(w io.Writer) *json.Encoder {
    28  	return json.NewEncoder(w)
    29  }
    30  
    31  // Marshal delegates to json.Marshal
    32  // It is only here so this package can be a drop-in for common encoding/json uses
    33  func Marshal(v interface{}) ([]byte, error) {
    34  	return json.Marshal(v)
    35  }
    36  
    37  // Unmarshal unmarshals the given data
    38  // If v is a *map[string]interface{}, numbers are converted to int64 or float64
    39  func Unmarshal(data []byte, v interface{}) error {
    40  	switch v := v.(type) {
    41  	case *map[string]interface{}:
    42  		// Build a decoder from the given data
    43  		decoder := json.NewDecoder(bytes.NewBuffer(data))
    44  		// Preserve numbers, rather than casting to float64 automatically
    45  		decoder.UseNumber()
    46  		// Run the decode
    47  		if err := decoder.Decode(v); err != nil {
    48  			return err
    49  		}
    50  		// If the decode succeeds, post-process the map to convert json.Number objects to int64 or float64
    51  		return convertMapNumbers(*v)
    52  
    53  	default:
    54  		return json.Unmarshal(data, v)
    55  	}
    56  }
    57  
    58  // convertMapNumbers traverses the map, converting any json.Number values to int64 or float64.
    59  // values which are map[string]interface{} or []interface{} are recursively visited
    60  func convertMapNumbers(m map[string]interface{}) error {
    61  	var err error
    62  	for k, v := range m {
    63  		switch v := v.(type) {
    64  		case json.Number:
    65  			m[k], err = convertNumber(v)
    66  		case map[string]interface{}:
    67  			err = convertMapNumbers(v)
    68  		case []interface{}:
    69  			err = convertSliceNumbers(v)
    70  		}
    71  		if err != nil {
    72  			return err
    73  		}
    74  	}
    75  	return nil
    76  }
    77  
    78  // convertSliceNumbers traverses the slice, converting any json.Number values to int64 or float64.
    79  // values which are map[string]interface{} or []interface{} are recursively visited
    80  func convertSliceNumbers(s []interface{}) error {
    81  	var err error
    82  	for i, v := range s {
    83  		switch v := v.(type) {
    84  		case json.Number:
    85  			s[i], err = convertNumber(v)
    86  		case map[string]interface{}:
    87  			err = convertMapNumbers(v)
    88  		case []interface{}:
    89  			err = convertSliceNumbers(v)
    90  		}
    91  		if err != nil {
    92  			return err
    93  		}
    94  	}
    95  	return nil
    96  }
    97  
    98  // convertNumber converts a json.Number to an int64 or float64, or returns an error
    99  func convertNumber(n json.Number) (interface{}, error) {
   100  	// Attempt to convert to an int64 first
   101  	if i, err := n.Int64(); err == nil {
   102  		return i, nil
   103  	}
   104  	// Return a float64 (default json.Decode() behavior)
   105  	// An overflow will return an error
   106  	return n.Float64()
   107  }