Editorial: Move regulating and balancing logic into ISODateSurpasses

Author: sffc

spec/calendar.html

@@ -563,34 +563,26 @@ <h1>
           1. Let _years_ be 0.
           1. If _largestUnit_ is ~year~, then
             1. Let _candidateYears_ be _sign_.
-            1. Repeat, while ISODateSurpasses(_sign_, _one_.[[Year]] + _candidateYears_, _one_.[[Month]], _one_.[[Day]], _two_) is *false*,
+            1. Repeat, while ISODateSurpasses(_sign_, _one_, _two_, _candidateYears_, 0, 0, 0) is *false*,
               1. Set _years_ to _candidateYears_.
               1. Set _candidateYears_ to _candidateYears_ + _sign_.
           1. Let _months_ be 0.
           1. If _largestUnit_ is ~year~ or _largestUnit_ is ~month~, then
             1. Let _candidateMonths_ be _sign_.
-            1. Let _intermediate_ be BalanceISOYearMonth(_one_.[[Year]] + _years_, _one_.[[Month]] + _candidateMonths_).
-            1. Repeat, while ISODateSurpasses(_sign_, _intermediate_.[[Year]], _intermediate_.[[Month]], _one_.[[Day]], _two_) is *false*,
+            1. Repeat, while ISODateSurpasses(_sign_, _one_, _two_, _years_, _candidateMonths_, 0, 0) is *false*,
               1. Set _months_ to _candidateMonths_.
               1. Set _candidateMonths_ to _candidateMonths_ + _sign_.
-              1. Set _intermediate_ to BalanceISOYearMonth(_intermediate_.[[Year]], _intermediate_.[[Month]] + _sign_).
-          1. Set _intermediate_ to BalanceISOYearMonth(_one_.[[Year]] + _years_, _one_.[[Month]] + _months_).
-          1. Let _constrained_ be ! RegulateISODate(_intermediate_.[[Year]], _intermediate_.[[Month]], _one_.[[Day]], ~constrain~).
           1. Let _weeks_ be 0.
           1. If _largestUnit_ is ~week~, then
             1. Let _candidateWeeks_ be _sign_.
-            1. Set _intermediate_ to BalanceISODate(_constrained_.[[Year]], _constrained_.[[Month]], _constrained_.[[Day]] + 7 × _candidateWeeks_).
-            1. Repeat, while ISODateSurpasses(_sign_, _intermediate_.[[Year]], _intermediate_.[[Month]], _intermediate_.[[Day]], _two_) is *false*,
+            1. Repeat, while ISODateSurpasses(_sign_, _one_, _two_, _years_, _months_, _candidateWeeks_, 0) is *false*,
               1. Set _weeks_ to _candidateWeeks_.
               1. Set _candidateWeeks_ to _candidateWeeks_ + sign.
-              1. Set _intermediate_ to BalanceISODate(_intermediate_.[[Year]], _intermediate_.[[Month]], _intermediate_.[[Day]] + 7 × _sign_).
           1. Let _days_ be 0.
           1. Let _candidateDays_ be _sign_.
-          1. Set _intermediate_ to BalanceISODate(_constrained_.[[Year]], _constrained_.[[Month]], _constrained_.[[Day]] + 7 × _weeks_ + _candidateDays_).
-          1. Repeat, while ISODateSurpasses(_sign_, _intermediate_.[[Year]], _intermediate_.[[Month]], _intermediate_.[[Day]], _two_) is *false*,
+          1. Repeat, while ISODateSurpasses(_sign_, _one_, _two_, _years_, _months_, _weeks_, _candidateDays_) is *false*,
             1. Set _days_ to _candidateDays_.
             1. Set _candidateDays_ to _candidateDays_ + _sign_.
-            1. Set _intermediate_ to BalanceISODate(_intermediate_.[[Year]], _intermediate_.[[Month]], _intermediate_.[[Day]] + _sign_).
           1. Return ! CreateDateDurationRecord(_years_, _months_, _weeks_, _days_).
         1. Return NonISODateUntil(_calendar_, _one_, _two_, _largestUnit_).
       </emu-alg>

spec/plaindate.html

@@ -694,21 +694,34 @@ <h1>
       <h1>
         ISODateSurpasses (
           _sign_: -1 or 1,
-          _y1_: an integer,
-          _m1_: an integer,
-          _d1_: an integer,
+          _baseDate_: an ISO Date Record,
           _isoDate2_: an ISO Date Record,
+          _years_: an integer,
+          _months_: an integer,
+          _weeks_: an integer,
+          _days_: an integer,
         ): a Boolean
       </h1>
       <dl class="header">
         <dt>description</dt>
         <dd>
-          The return value indicates whether the date denoted by _y1_, _m1_, _d1_ surpasses that denoted by _isoDate2_ in the direction denoted by _sign_.
-          The former date does not have to exist.
+          The return value indicates whether the date _isoDate1_, the result of adding the duration denoted by _years_, _months_, _weeks_, and _days_ to _baseDate_, surpasses _isoDate2_ in the direction denoted by _sign_.
+          If _weeks_ and _days_ are both zero, then _isoDate1_ need not exist (for example, it could be February 30).
           Note that this operation is specific to date difference calculations and is not the same as CompareISODate.
         </dd>
       </dl>
       <emu-alg>
+        1. Let _yearMonth_ be BalanceISOYearMonth(_baseDate_.[[Year]] + _years_, _baseDate_.[[Month]] + _months_).
+        1. If _weeks_ is not 0 or _days_ is not 0, then
+          1. Let _regulatedDate_ be ! RegulateISODate(_yearMonth_.[[Year]], _yearMonth_.[[Month]], _baseDate_.[[Day]], ~constrain~).
+          1. Let _balancedDate_ be BalanceISODate(_regulatedDate_.[[Year]], _regulatedDate_.[[Month]], _regulatedDate_.[[Day]] + 7 * _weeks_ + _days_).
+          1. Let _y1_ be _balancedDate_.[[Year]].
+          1. Let _m1_ be _balancedDate_.[[Month]].
+          1. Let _d1_ be _balancedDate_.[[Day]].
+        1. Else,
+          1. Let _y1_ be _yearMonth_.[[Year]].
+          1. Let _m1_ be _yearMonth_.[[Month]].
+          1. Let _d1_ be _baseDate_.[[Day]].
         1. If _y1_ ≠ _isoDate2_.[[Year]], then
           1. If _sign_ × (_y1_ - _isoDate2_.[[Year]]) > 0, return *true*.
         1. Else if _m1_ ≠ _isoDate2_.[[Month]], then