Create merge.ts

Author: wolfram77

src/merge.ts

@@ -0,0 +1,26 @@
+import min from './min';
+import type {compareFn, mapFn} from './_types';
+
+/**
+ * Merges values from sorted iterables.
+ * @param xs iterables
+ * @param fc compare function (a, b)
+ * @param fm map function (v, i, x)
+ */
+function merge<T, U=T>(xs: T[][], fc: compareFn<T|U>=null, fm: mapFn<T, T|U>=null): T[] {
+  var X = xs.length, a = [];
+  if(X===0) return a;
+  var is = new Array(X).fill(0);
+  var xs = xs.filter(x => x.length>0);
+  while(xs.length>0) {
+    for(var i=0, I=xs.length, vs=[]; i<I; i++)
+      vs[i] = xs[i][is[i]];
+    var i = min(vs, fc, fm)[0];
+    a.push(vs[i]);
+    if(++is[i]<xs[i].length) continue;
+    xs.splice(i, 1);
+    is.splice(i, 1);
+  }
+  return a;
+}
+export default merge;