[IMP] web: add math_utils to core

math_utils is a small library that exports two
functions:

    - cartesian: allows to compute the cartesian
                products of any numbers of arrays
                while preserving the internal
                structures of their elements.
    - sections: returns an array with all
                the initial sections of the
                array passed as parameter.

1 files changed, 73 insertions, 0 deletions

diff --git a/addons/web/static/src/js/core/math_utils.js b/addons/web/static/src/js/core/math_utils.js
new file mode 100644
index 00000000000..0eeb631125b
--- /dev/null
+++ b/addons/web/static/src/js/core/math_utils.js
@@ -0,0 +1,73 @@
+odoo.define('web.mathUtils', function () {
+"use strict";
+
+/**
+ * Same values returned as those returned by cartesian function for case n = 0
+ * and n > 1. For n = 1, brackets are put around the unique parameter elements.
+ *
+ * @returns {Array}
+ */
+function _cartesian() {
+    var args = Array.prototype.slice.call(arguments);
+    if (args.length === 0) {
+        return [undefined];
+    }
+    var firstArray = args[0].map(function (elem) {
+        return [elem];
+    });
+    if (args.length === 1) {
+        return firstArray;
+    }
+    var productOfOtherArrays = _cartesian.apply(null, args.slice(1));
+    var result = firstArray.reduce(
+        function (acc, elem) {
+            return acc.concat(productOfOtherArrays.map(function (tuple) {
+                return elem.concat(tuple);
+            }));
+        },
+        []
+    );
+    return result;
+}
+
+/**
+ * Returns the product of any number n of arrays.
+ * The internal structures of their elements is preserved.
+ * For n = 1, no brackets are put around the unique parameter elements
+ * For n = 0, the singleton [undefined] is returned since it is the unit
+ * of the cartesian product (up to isomorphism).
+ *
+ * @returns {Array}
+ */
+function cartesian() {
+    var args = Array.prototype.slice.call(arguments);
+    if (args.length === 0) {
+        return [undefined];
+    } else if (args.length === 1) {
+        return args[0];
+    } else {
+        return _cartesian.apply(null, args);
+    }
+}
+
+/**
+ * Returns all initial sections of a given array, e.g. for [1, 2] the array
+ * [[], [1], [1, 2]] is returned.
+ *
+ * @param {Array} array
+ * @returns {Array[]}
+ */
+function sections(array) {
+    var sections = [];
+    for (var i = 0; i < array.length + 1; i++) {
+        sections.push(array.slice(0, i));
+    }
+    return sections;
+}
+
+return {
+    cartesian: cartesian,
+    sections: sections,
+};
+
+});