Fixing operator equals

src/bigdecimal.cpp

@@ -79,12 +79,12 @@ void bigdecimal::set_scale(int32_t nscale) {
 }
 
 void bigdecimal::rescale(int32_t nscale) {
-  int32_t const nsteps = add_scale(nscale);
-  if (steps_ > nsteps) {
-    data.erase(data.begin(), data.begin() + steps_ - nsteps);
+  auto const diff = steps_ - add_scale(nscale);
+  if (diff > 0) {
+    data.erase(data.begin(), data.begin() + diff);
     if (data.empty()) { data.push_back(0); }
-  } else if (steps_ < nsteps) {
-    data.insert(data.begin(), size_t(nsteps-steps_), 0);
+  } else if (diff < 0) {
+    data.insert(data.begin(), size_t(-diff), 0);
   }
   auto const idx = -nscale % SEG_DIGITS;
   if (scale() > nscale && nscale < 0 && idx) {
@@ -149,10 +149,21 @@ static bool all_zero(bigdecimal::data_type const & data, size_t from) {
   return true;
 }
 
+static int compare(bigdecimal::data_type const & ldata, bigdecimal::data_type const & rdata, size_t offset) {
+  auto cmp = detail::compare(ldata, rdata, offset);
+  if (cmp == 0) { return !all_zero(ldata, offset); }
+  return cmp;
+}
+
+static int compare(bigdecimal::data_type const & ldata, int32_t lsteps, bigdecimal::data_type const & rdata, int32_t rsteps) {
+  return lsteps < rsteps ?
+    compare(rdata, ldata, size_t(rsteps - lsteps))
+  : compare(ldata, rdata, size_t(lsteps - rsteps));
+}
+
 static bool is_one(bigdecimal::data_type const & data, int32_t scale) {
   static bigdecimal::data_type ONE = {1};
-  auto ms = mul_scale(scale);
-  return scale >= 0 && detail::compare(data, ONE, ms) == 0 && all_zero(data, ms);
+  return compare(data, add_scale(scale), ONE, 0) == 0;
 }
 
 bigdecimal & math::operator*=(bigdecimal & rhs, bigdecimal const & lhs) {
@@ -223,7 +234,7 @@ bigdecimal math::operator/(bigdecimal rhs, bigdecimal const & lhs) {
 }
 
 bool math::operator==(bigdecimal const & lhs, bigdecimal const & rhs) {
-  return lhs.is_negative == rhs.is_negative && detail::compare(lhs.data, rhs.data) == 0; // TODO
+  return lhs.is_negative == rhs.is_negative && compare(lhs.data, lhs.steps_, rhs.data, rhs.steps_) == 0;
 }
 
 bigdecimal const bigdecimal::ZERO{0}, bigdecimal::ONE{1}, bigdecimal::NEGATIVE_ONE{-1};