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// mxj - A collection of map[string]interface{} and associated XML and JSON utilities.
// Copyright 2012-2014, 2018 Charles Banning. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file
// remap.go - build a new Map from the current Map based on keyOld:keyNew mapppings
// keys can use dot-notation, keyOld can use wildcard, '*'
//
// Computational strategy -
// Using the key path - []string - traverse a new map[string]interface{} and
// insert the oldVal as the newVal when we arrive at the end of the path.
// If the type at the end is nil, then that is newVal
// If the type at the end is a singleton (string, float64, bool) an array is created.
// If the type at the end is an array, newVal is just appended.
// If the type at the end is a map, it is inserted if possible or the map value
// is converted into an array if necessary.
package mxj
import (
"errors"
"strings"
)
// (Map)NewMap - create a new Map from data in the current Map.
// 'keypairs' are key mappings "oldKey:newKey" and specify that the current value of 'oldKey'
// should be the value for 'newKey' in the returned Map.
// - 'oldKey' supports dot-notation as described for (Map)ValuesForPath()
// - 'newKey' supports dot-notation but with no wildcards, '*', or indexed arrays
// - "oldKey" is shorthand for the keypair value "oldKey:oldKey"
// - "oldKey:" and ":newKey" are invalid keypair values
// - if 'oldKey' does not exist in the current Map, it is not written to the new Map.
// "null" is not supported unless it is the current Map.
// - see newmap_test.go for several syntax examples
// - mv.NewMap() == mxj.New()
//
// NOTE: "examples/partial.go" shows how to create arbitrary sub-docs of an XML doc.
func (mv Map) NewMap(keypairs ...string) (Map, error) {
n := make(map[string]interface{}, 0)
if len(keypairs) == 0 {
return n, nil
}
// loop through the pairs
var oldKey, newKey string
var path []string
for _, v := range keypairs {
if len(v) == 0 {
continue // just skip over empty keypair arguments
}
// initialize oldKey, newKey and check
vv := strings.Split(v, ":")
if len(vv) > 2 {
return n, errors.New("oldKey:newKey keypair value not valid - " + v)
}
if len(vv) == 1 {
oldKey, newKey = vv[0], vv[0]
} else {
oldKey, newKey = vv[0], vv[1]
}
strings.TrimSpace(oldKey)
strings.TrimSpace(newKey)
if i := strings.Index(newKey, "*"); i > -1 {
return n, errors.New("newKey value cannot contain wildcard character - " + v)
}
if i := strings.Index(newKey, "["); i > -1 {
return n, errors.New("newKey value cannot contain indexed arrays - " + v)
}
if oldKey == "" || newKey == "" {
return n, errors.New("oldKey or newKey is not specified - " + v)
}
// get oldKey value
oldVal, err := mv.ValuesForPath(oldKey)
if err != nil {
return n, err
}
if len(oldVal) == 0 {
continue // oldKey has no value, may not exist in mv
}
// break down path
path = strings.Split(newKey, ".")
if path[len(path)-1] == "" { // ignore a trailing dot in newKey spec
path = path[:len(path)-1]
}
addNewVal(&n, path, oldVal)
}
return n, nil
}
// navigate 'n' to end of path and add val
func addNewVal(n *map[string]interface{}, path []string, val []interface{}) {
// newVal - either singleton or array
var newVal interface{}
if len(val) == 1 {
newVal = val[0] // is type interface{}
} else {
newVal = interface{}(val)
}
// walk to the position of interest, create it if necessary
m := (*n) // initialize map walker
var k string // key for m
lp := len(path) - 1 // when to stop looking
for i := 0; i < len(path); i++ {
k = path[i]
if i == lp {
break
}
var nm map[string]interface{} // holds position of next-map
switch m[k].(type) {
case nil: // need a map for next node in path, so go there
nm = make(map[string]interface{}, 0)
m[k] = interface{}(nm)
m = m[k].(map[string]interface{})
case map[string]interface{}:
// OK - got somewhere to walk to, go there
m = m[k].(map[string]interface{})
case []interface{}:
// add a map and nm points to new map unless there's already
// a map in the array, then nm points there
// The placement of the next value in the array is dependent
// on the sequence of members - could land on a map or a nil
// value first. TODO: how to test this.
a := make([]interface{}, 0)
var foundmap bool
for _, vv := range m[k].([]interface{}) {
switch vv.(type) {
case nil: // doesn't appear that this occurs, need a test case
if foundmap { // use the first one in array
a = append(a, vv)
continue
}
nm = make(map[string]interface{}, 0)
a = append(a, interface{}(nm))
foundmap = true
case map[string]interface{}:
if foundmap { // use the first one in array
a = append(a, vv)
continue
}
nm = vv.(map[string]interface{})
a = append(a, vv)
foundmap = true
default:
a = append(a, vv)
}
}
// no map found in array
if !foundmap {
nm = make(map[string]interface{}, 0)
a = append(a, interface{}(nm))
}
m[k] = interface{}(a) // must insert in map
m = nm
default: // it's a string, float, bool, etc.
aa := make([]interface{}, 0)
nm = make(map[string]interface{}, 0)
aa = append(aa, m[k], nm)
m[k] = interface{}(aa)
m = nm
}
}
// value is nil, array or a singleton of some kind
// initially m.(type) == map[string]interface{}
v := m[k]
switch v.(type) {
case nil: // initialized
m[k] = newVal
case []interface{}:
a := m[k].([]interface{})
a = append(a, newVal)
m[k] = interface{}(a)
default: // v exists:string, float64, bool, map[string]interface, etc.
a := make([]interface{}, 0)
a = append(a, v, newVal)
m[k] = interface{}(a)
}
}
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