Data commit

Task/Range-expansion/JavaScript/range-expansion-2.js

@@ -0,0 +1,39 @@
+(function (strTest) {
+    'use strict';
+
+    // s -> [n]
+    function expansion(strExpr) {
+
+        // concat map yields flattened output list
+        return [].concat.apply([], strExpr.split(',')
+            .map(function (x) {
+                return x.split('-')
+                    .reduce(function (a, s, i, l) {
+
+                        // negative (after item 0) if preceded by an empty string
+                        // (i.e. a hyphen-split artefact, otherwise ignored)
+                        return s.length ? i ? a.concat(
+                            parseInt(l[i - 1].length ? s :
+                                '-' + s, 10)
+                        ) : [+s] : a;
+                    }, []);
+
+                // two-number lists are interpreted as ranges
+            })
+            .map(function (r) {
+                return r.length > 1 ? range.apply(null, r) : r;
+            }));
+    }
+
+
+    // [m..n]
+    function range(m, n) {
+        return Array.apply(null, Array(n - m + 1))
+            .map(function (x, i) {
+                return m + i;
+            });
+    }
+
+    return expansion(strTest);
+
+})('-6,-3--1,3-5,7-11,14,15,17-20');