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node_modules/validator/es/lib/util/algorithms.js

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+/**
+ * Algorithmic validation functions
+ * May be used as is or implemented in the workflow of other validators.
+ */
+
+/*
+ * ISO 7064 validation function
+ * Called with a string of numbers (incl. check digit)
+ * to validate according to ISO 7064 (MOD 11, 10).
+ */
+export function iso7064Check(str) {
+  var checkvalue = 10;
+  for (var i = 0; i < str.length - 1; i++) {
+    checkvalue = (parseInt(str[i], 10) + checkvalue) % 10 === 0 ? 10 * 2 % 11 : (parseInt(str[i], 10) + checkvalue) % 10 * 2 % 11;
+  }
+  checkvalue = checkvalue === 1 ? 0 : 11 - checkvalue;
+  return checkvalue === parseInt(str[10], 10);
+}
+
+/*
+ * Luhn (mod 10) validation function
+ * Called with a string of numbers (incl. check digit)
+ * to validate according to the Luhn algorithm.
+ */
+export function luhnCheck(str) {
+  var checksum = 0;
+  var second = false;
+  for (var i = str.length - 1; i >= 0; i--) {
+    if (second) {
+      var product = parseInt(str[i], 10) * 2;
+      if (product > 9) {
+        // sum digits of product and add to checksum
+        checksum += product.toString().split('').map(function (a) {
+          return parseInt(a, 10);
+        }).reduce(function (a, b) {
+          return a + b;
+        }, 0);
+      } else {
+        checksum += product;
+      }
+    } else {
+      checksum += parseInt(str[i], 10);
+    }
+    second = !second;
+  }
+  return checksum % 10 === 0;
+}
+
+/*
+ * Reverse TIN multiplication and summation helper function
+ * Called with an array of single-digit integers and a base multiplier
+ * to calculate the sum of the digits multiplied in reverse.
+ * Normally used in variations of MOD 11 algorithmic checks.
+ */
+export function reverseMultiplyAndSum(digits, base) {
+  var total = 0;
+  for (var i = 0; i < digits.length; i++) {
+    total += digits[i] * (base - i);
+  }
+  return total;
+}
+
+/*
+ * Verhoeff validation helper function
+ * Called with a string of numbers
+ * to validate according to the Verhoeff algorithm.
+ */
+export function verhoeffCheck(str) {
+  var d_table = [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [1, 2, 3, 4, 0, 6, 7, 8, 9, 5], [2, 3, 4, 0, 1, 7, 8, 9, 5, 6], [3, 4, 0, 1, 2, 8, 9, 5, 6, 7], [4, 0, 1, 2, 3, 9, 5, 6, 7, 8], [5, 9, 8, 7, 6, 0, 4, 3, 2, 1], [6, 5, 9, 8, 7, 1, 0, 4, 3, 2], [7, 6, 5, 9, 8, 2, 1, 0, 4, 3], [8, 7, 6, 5, 9, 3, 2, 1, 0, 4], [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]];
+  var p_table = [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [1, 5, 7, 6, 2, 8, 3, 0, 9, 4], [5, 8, 0, 3, 7, 9, 6, 1, 4, 2], [8, 9, 1, 6, 0, 4, 3, 5, 2, 7], [9, 4, 5, 3, 1, 2, 6, 8, 7, 0], [4, 2, 8, 6, 5, 7, 3, 9, 0, 1], [2, 7, 9, 3, 8, 0, 6, 4, 1, 5], [7, 0, 4, 6, 9, 1, 3, 2, 5, 8]];
+
+  // Copy (to prevent replacement) and reverse
+  var str_copy = str.split('').reverse().join('');
+  var checksum = 0;
+  for (var i = 0; i < str_copy.length; i++) {
+    checksum = d_table[checksum][p_table[i % 8][parseInt(str_copy[i], 10)]];
+  }
+  return checksum === 0;
+}