Add convert_to_base_64 function to convert string integer to magnitudes

Author: sahmad98

CMakeLists.txt

@@ -49,6 +49,10 @@ add_executable(Functions.Random.Test
         test/functions/random.test.cpp)
 target_link_libraries(Functions.Random.Test TestRunner)
 
+add_executable(Utility.Helper.Test
+        test/functions/utility.test.cpp)
+target_link_libraries(Utility.Helper.Test TestRunner)
+
 # Operators:
 add_executable(Operators.ArithmeticAssignment.Test
         test/operators/arithmetic_assignment.test.cpp)

include/constructors/constructors.hpp

@@ -53,12 +53,7 @@ BigInt::BigInt(const std::string& num) {
     if (num[0] == '+' or num[0] == '-') {     // check for sign
         std::string num_magnitude = num.substr(1);
         if (is_valid_number(num_magnitude)) {
-            /*
-                TODO
-                ----
-                magnitude = convert_to_base_2_to_the_64(num_magnitude);
-            */
-            magnitude = {0};
+            magnitude = convert_to_base_64(num_magnitude);
             is_negative = num[0] == '-';
         }
         else {
@@ -67,12 +62,8 @@ BigInt::BigInt(const std::string& num) {
     }
     else {      // if no sign is specified
         if (is_valid_number(num)) {
-            /*
-                TODO
-                ----
-                magnitude = convert_to_base_2_to_the_64(num_magnitude);
-            */
-            magnitude = {0};
+            std::string num_magnitude(num);
+            magnitude = convert_to_base_64(num_magnitude);
             is_negative = false;    // positive by default
         }
         else {

include/functions/utility.hpp

@@ -110,4 +110,30 @@ bool is_power_of_10(const std::string& num){
     return true;    // first digit is 1 and the following digits are all 0
 }
 
+
+/*
+    conver_to_base_64
+    ----------------------
+    Converts a string represented BigInt into the Base64 magnitudes
+*/
+
+std::vector<unsigned long long> convert_to_base_64(std::string& num) {
+    std::vector<unsigned long long> magnitude;
+    auto start_it = num.size() - 1; // Starting from Backward direction
+    auto stop_it = num.size();
+    uint64_t component = 0;
+    while(start_it != -1) {
+        try {
+            std::string num_slice = num.substr(start_it, stop_it);
+            component = std::stoull(num_slice);
+        } catch (std::out_of_range& e) { //Using out_of_range to determine overflow
+            magnitude.push_back(component);
+            stop_it = start_it + 1;
+        }
+        --start_it;
+    }
+    magnitude.push_back(component);
+    return magnitude;
+}
+
 #endif  // BIG_INT_UTILITY_FUNCTIONS_HPP

test/functions/utility.test.cpp

@@ -0,0 +1,25 @@
+#include <string>
+#include <vector>
+
+#include "functions/utility.hpp"
+
+#include "third_party/catch.hpp"
+
+TEST_CASE("Conversion to Base64 magnitudes from String", "[Utility][Helper][Base64]") {
+    std::string num = "481482486096808911670147153572883801";
+    // Magnitude should be {11670147153572883801, 4814824860968089}
+    auto magnitude = convert_to_base_64(num);
+    REQUIRE(magnitude.size() == 2);
+    REQUIRE(magnitude[0] == uint64_t(11670147153572883801));
+    REQUIRE(magnitude[1] == uint64_t(4814824860968089));
+
+    num = "1";
+    magnitude = convert_to_base_64(num);
+    REQUIRE(magnitude.size() == 1);
+    REQUIRE(magnitude[0] == uint64_t(1));
+
+    num = "";
+    magnitude = convert_to_base_64(num);
+    REQUIRE(magnitude.size() == 1);
+    REQUIRE(magnitude[0] == uint64_t(0));
+}