Decompose makeGetIndexFunction.

index.js

@@ -33,44 +33,7 @@ function encode(value) {
 
 function toTable(value) {
  var values = [];
- var indexMap = typeof Map === "function" && new Map;
-
- function getIndex(value) {
- switch (typeof value) {
- case "undefined":
- return UNDEFINED_INDEX;
-
- case "number":
- if (isNaN(value)) {
- return NAN_INDEX;
- }
-
- if (! isFinite(value)) {
- return value < 0 ? NEG_INF_INDEX : POS_INF_INDEX;
- }
-
- // fall through...
- }
-
- var index;
-
- if (indexMap) {
- // If we have Map, use it instead of values.indexOf to accelerate
- // object lookups.
- index = indexMap.get(value);
- if (typeof index === "undefined") {
- index = values.push(value) - 1;
- indexMap.set(value, index);
- }
- } else {
- index = values.indexOf(value);
- if (index < 0) {
- index = values.push(value) - 1;
- }
- }
-
- return index;
- }
+ var getIndex = makeGetIndexFunction(values);
 
  function copy(value) {
  var result = value;
@@ -150,6 +113,47 @@ function isPlainObject(value) {
  return false;
 }
 
+function makeGetIndexFunction(values) {
+ var indexMap = typeof Map === "function" && new Map;
+
+ return function getIndex(value) {
+ switch (typeof value) {
+ case "undefined":
+ return UNDEFINED_INDEX;
+
+ case "number":
+ if (isNaN(value)) {
+ return NAN_INDEX;
+ }
+
+ if (! isFinite(value)) {
+ return value < 0 ? NEG_INF_INDEX : POS_INF_INDEX;
+ }
+
+ // fall through...
+ }
+
+ var index;
+
+ if (indexMap) {
+ // If we have Map, use it instead of values.indexOf to accelerate
+ // object lookups.
+ index = indexMap.get(value);
+ if (typeof index === "undefined") {
+ index = values.push(value) - 1;
+ indexMap.set(value, index);
+ }
+ } else {
+ index = values.indexOf(value);
+ if (index < 0) {
+ index = values.push(value) - 1;
+ }
+ }
+
+ return index;
+ };
+}
+
 exports.decode = exports.parse =
 function decode(encoding) {
  return fromTable(JSON.parse(encoding));