Refactor foreachApplyUtf to remove duplicate array literal logic

compiler/src/dmd/dinterpret.d

@@ -7270,6 +7270,33 @@ private Expression interpret_aaApply(UnionExp* pue, InterState* istate, Expressi
  return eresult;
 }
 
+/// Returns: equivalent `StringExp` from `ArrayLiteralExp ale` containing only `IntegerExp` elements
+StringExp arrayLiteralToString(ArrayLiteralExp ale)
+{
+ const len = ale.elements ? ale.elements.length : 0;
+ const size = ale.type.nextOf().size();
+
+ StringExp impl(T)()
+ {
+ T[] result = new T[len];
+ foreach (i; 0 .. len)
+ result[i] = cast(T) (*ale.elements)[i].isIntegerExp().getInteger();
+ return new StringExp(ale.loc, result[], len, cast(ubyte) size);
+ }
+
+ switch (size)
+ {
+ case 1:
+ return impl!char();
+ case 2:
+ return impl!wchar();
+ case 4:
+ return impl!dchar();
+ default:
+ assert(0);
+ }
+}
+
 /* Decoding UTF strings for foreach loops. Duplicates the functionality of
  * the twelve _aApplyXXn functions in aApply.d in the runtime.
  */
@@ -7306,8 +7333,10 @@ private Expression foreachApplyUtf(UnionExp* pue, InterState* istate, Expression
  str = resolveSlice(str, &strTmp);
 
  auto se = str.isStringExp();
- auto ale = str.isArrayLiteralExp();
- if (!se && !ale)
+ if (auto ale = str.isArrayLiteralExp())
+ se = arrayLiteralToString(ale);
+
+ if (!se)
  {
  error(str.loc, "CTFE internal error: cannot foreach `%s`", str.toChars());
  return CTFEExp.cantexp;
@@ -7316,7 +7345,7 @@ private Expression foreachApplyUtf(UnionExp* pue, InterState* istate, Expression
 
  Expression eresult = null; // ded-store to prevent spurious warning
 
- // Buffers for encoding; also used for decoding array literals
+ // Buffers for encoding
  char[4] utf8buf = void;
  wchar[2] utf16buf = void;
 
@@ -7330,90 +7359,11 @@ private Expression foreachApplyUtf(UnionExp* pue, InterState* istate, Expression
  dchar rawvalue; // Holds the decoded dchar
  size_t currentIndex = indx; // The index of the decoded character
 
- if (ale)
- {
- // If it is an array literal, copy the code points into the buffer
- size_t buflen = 1; // #code points in the buffer
- size_t n = 1; // #code points in this char
- size_t sz = cast(size_t)ale.type.nextOf().size();
-
- switch (sz)
- {
- case 1:
- if (rvs)
- {
- // find the start of the string
- --indx;
- buflen = 1;
- while (indx > 0 && buflen < 4)
- {
- Expression r = (*ale.elements)[indx];
- char x = cast(char)r.isIntegerExp().getInteger();
- if ((x & 0xC0) != 0x80)
- break;
- --indx;
- ++buflen;
- }
- }
- else
- buflen = (indx + 4 > len) ? len - indx : 4;
- for (size_t i = 0; i < buflen; ++i)
- {
- Expression r = (*ale.elements)[indx + i];
- utf8buf[i] = cast(char)r.isIntegerExp().getInteger();
- }
- n = 0;
- errmsg = utf_decodeChar(utf8buf[0 .. buflen], n, rawvalue);
- break;
-
- case 2:
- if (rvs)
- {
- // find the start of the string
- --indx;
- buflen = 1;
- Expression r = (*ale.elements)[indx];
- ushort x = cast(ushort)r.isIntegerExp().getInteger();
- if (indx > 0 && x >= 0xDC00 && x <= 0xDFFF)
- {
- --indx;
- ++buflen;
- }
- }
- else
- buflen = (indx + 2 > len) ? len - indx : 2;
- for (size_t i = 0; i < buflen; ++i)
- {
- Expression r = (*ale.elements)[indx + i];
- utf16buf[i] = cast(ushort)r.isIntegerExp().getInteger();
- }
- n = 0;
- errmsg = utf_decodeWchar(utf16buf[0 .. buflen], n, rawvalue);
- break;
-
- case 4:
- {
- if (rvs)
- --indx;
- Expression r = (*ale.elements)[indx];
- rawvalue = cast(dchar)r.isIntegerExp().getInteger();
- n = 1;
- }
- break;
+ // String literals
+ size_t saveindx; // used for reverse iteration
 
- default:
- assert(0);
- }
- if (!rvs)
- indx += n;
- }
- else
+ switch (se.sz)
  {
- // String literals
- size_t saveindx; // used for reverse iteration
-
- switch (se.sz)
- {
  case 1:
  {
  if (rvs)
@@ -7457,8 +7407,8 @@ private Expression foreachApplyUtf(UnionExp* pue, InterState* istate, Expression
 
  default:
  assert(0);
- }
  }
+
  if (errmsg)
  {
  error(deleg.loc, "`%.*s`", cast(int)errmsg.length, errmsg.ptr);