Optimize swap, removing the need to move field state to a temporary field.

Author: huan086

src/swap.js

@@ -1,10 +1,6 @@
 // @flow
 import type { MutableState, Mutator, Tools } from 'final-form'
-import moveFieldState from './moveFieldState'
-import moveFields from './moveFields';
-import restoreFunctions from './restoreFunctions';
-
-const TMP: string = 'tmp'
+import copyField from './copyField'
 
 const swap: Mutator<any> = (
   [name, indexA, indexB]: any[],
@@ -22,19 +18,26 @@ const swap: Mutator<any> = (
     return copy
   })
 
-  //make a copy of a state for further functions restore
-  const backupState = { ...state, fields: { ...state.fields } }
-
   // swap all field state that begin with "name[indexA]" with that under "name[indexB]"
   const aPrefix = `${name}[${indexA}]`
   const bPrefix = `${name}[${indexB}]`
-  const tmpPrefix = `${name}[${TMP}]`
-
-  moveFields(name, aPrefix, TMP, state)
-  moveFields(name, bPrefix, indexA, state)
-  moveFields(name, tmpPrefix, indexB, state)
+  const newFields = {}
+  Object.keys(state.fields).forEach(key => {
+    if (key.substring(0, aPrefix.length) === aPrefix) {
+      const suffix = key.substring(aPrefix.length)
+      const newKey = bPrefix + suffix
+      copyField(state.fields, key, newFields, newKey)
+    } else if (key.substring(0, bPrefix.length) === bPrefix) {
+      const suffix = key.substring(bPrefix.length)
+      const newKey = aPrefix + suffix
+      copyField(state.fields, key, newFields, newKey)
+    } else {
+      // Keep this field that does not match the name
+      newFields[key] = state.fields[key]
+    }
+  })
 
-  restoreFunctions(state, backupState)
+  state.fields = newFields
 }
 
 export default swap

src/swap.test.js

@@ -93,10 +93,10 @@ describe('swap', () => {
         }
       },
       fields: {
-        'foo[0]': {
-          name: 'foo[0]',
-          touched: false,
-          error: 'Error C',
+        'foo[2]': {
+          name: 'foo[2]',
+          touched: true,
+          error: 'Error A',
           lastFieldState: undefined
         },
         'foo[1]': {
@@ -105,10 +105,10 @@ describe('swap', () => {
           error: 'Error B',
           lastFieldState: 'anything' // unchanged
         },
-        'foo[2]': {
-          name: 'foo[2]',
-          touched: true,
-          error: 'Error A',
+        'foo[0]': {
+          name: 'foo[0]',
+          touched: false,
+          error: 'Error C',
           lastFieldState: undefined
         },
         'foo[3]': {
@@ -215,22 +215,22 @@ describe('swap', () => {
         }
       },
       fields: {
-        'foo[0].dog': {
-          name: 'foo[0].dog',
+        'foo[2].dog': {
+          name: 'foo[2].dog',
           touched: true,
-          error: 'Error C Dog',
+          error: 'Error A Dog',
           lastFieldState: undefined
         },
-        'foo[0].cat': {
-          name: 'foo[0].cat',
+        'foo[2].cat': {
+          name: 'foo[2].cat',
           touched: false,
-          error: 'Error C Cat',
+          error: 'Error A Cat',
           lastFieldState: undefined
         },
-        'foo[0].axe': {
-          name: 'foo[0].axe',
+        'foo[2].rock': {
+          name: 'foo[2].rock',
           touched: false,
-          error: 'Error C Axe',
+          error: 'Error A Rock',
           lastFieldState: undefined
         },
         'foo[1].dog': {
@@ -245,22 +245,22 @@ describe('swap', () => {
           error: 'Error B Cat',
           lastFieldState: 'anything' // unchanged
         },
-        'foo[2].dog': {
-          name: 'foo[2].dog',
+        'foo[0].dog': {
+          name: 'foo[0].dog',
           touched: true,
-          error: 'Error A Dog',
+          error: 'Error C Dog',
           lastFieldState: undefined
         },
-        'foo[2].cat': {
-          name: 'foo[2].cat',
+        'foo[0].cat': {
+          name: 'foo[0].cat',
           touched: false,
-          error: 'Error A Cat',
+          error: 'Error C Cat',
           lastFieldState: undefined
         },
-        'foo[2].rock': {
-          name: 'foo[2].rock',
+        'foo[0].axe': {
+          name: 'foo[0].axe',
           touched: false,
-          error: 'Error A Rock',
+          error: 'Error C Axe',
           lastFieldState: undefined
         },
         'foo[3].dog': {