1 files changed, 132 insertions, 0 deletions
diff --git a/intl/components/src/ListFormat.cpp b/intl/components/src/ListFormat.cpp
new file mode 100644
index 0000000000..6d1e10826a
--- /dev/null
+++ b/intl/components/src/ListFormat.cpp
@@ -0,0 +1,132 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "mozilla/intl/ListFormat.h"
+
+#include "ScopedICUObject.h"
+
+namespace mozilla::intl {
+
+/*static*/ Result<UniquePtr<ListFormat>, ICUError> ListFormat::TryCreate(
+    mozilla::Span<const char> aLocale, const Options& aOptions) {
+  UListFormatterType utype = ToUListFormatterType(aOptions.mType);
+  UListFormatterWidth uwidth = ToUListFormatterWidth(aOptions.mStyle);
+
+  UErrorCode status = U_ZERO_ERROR;
+  UListFormatter* fmt =
+      ulistfmt_openForType(IcuLocale(aLocale), utype, uwidth, &status);
+  if (U_FAILURE(status)) {
+    return Err(ICUError::InternalError);
+  }
+
+  return UniquePtr<ListFormat>(new ListFormat(fmt));
+}
+
+ListFormat::~ListFormat() {
+  if (mListFormatter) {
+    ulistfmt_close(mListFormatter.GetMut());
+  }
+}
+
+/* static */ UListFormatterType ListFormat::ToUListFormatterType(Type type) {
+  switch (type) {
+    case Type::Conjunction:
+      return ULISTFMT_TYPE_AND;
+    case Type::Disjunction:
+      return ULISTFMT_TYPE_OR;
+    case Type::Unit:
+      return ULISTFMT_TYPE_UNITS;
+  }
+  MOZ_ASSERT_UNREACHABLE();
+  return ULISTFMT_TYPE_AND;
+}
+
+/* static */ UListFormatterWidth ListFormat::ToUListFormatterWidth(
+    Style style) {
+  switch (style) {
+    case Style::Long:
+      return ULISTFMT_WIDTH_WIDE;
+    case Style::Short:
+      return ULISTFMT_WIDTH_SHORT;
+    case Style::Narrow:
+      return ULISTFMT_WIDTH_NARROW;
+  }
+  MOZ_ASSERT_UNREACHABLE();
+  return ULISTFMT_WIDTH_WIDE;
+}
+
+ICUResult ListFormat::FormattedToParts(const UFormattedValue* formattedValue,
+                                       size_t formattedSize,
+                                       PartVector& parts) {
+  size_t lastEndIndex = 0;
+
+  auto AppendPart = [&](PartType type, size_t endIndex) {
+    if (!parts.emplaceBack(type, endIndex)) {
+      return false;
+    }
+
+    lastEndIndex = endIndex;
+    return true;
+  };
+
+  UErrorCode status = U_ZERO_ERROR;
+  UConstrainedFieldPosition* fpos = ucfpos_open(&status);
+  if (U_FAILURE(status)) {
+    return Err(ICUError::InternalError);
+  }
+  ScopedICUObject<UConstrainedFieldPosition, ucfpos_close> toCloseFpos(fpos);
+
+  // We're only interested in ULISTFMT_ELEMENT_FIELD fields.
+  ucfpos_constrainField(fpos, UFIELD_CATEGORY_LIST, ULISTFMT_ELEMENT_FIELD,
+                        &status);
+  if (U_FAILURE(status)) {
+    return Err(ICUError::InternalError);
+  }
+
+  while (true) {
+    bool hasMore = ufmtval_nextPosition(formattedValue, fpos, &status);
+    if (U_FAILURE(status)) {
+      return Err(ICUError::InternalError);
+    }
+    if (!hasMore) {
+      break;
+    }
+
+    int32_t beginIndexInt, endIndexInt;
+    ucfpos_getIndexes(fpos, &beginIndexInt, &endIndexInt, &status);
+    if (U_FAILURE(status)) {
+      return Err(ICUError::InternalError);
+    }
+
+    MOZ_ASSERT(beginIndexInt <= endIndexInt,
+               "field iterator returning invalid range");
+
+    size_t beginIndex = AssertedCast<size_t>(beginIndexInt);
+    size_t endIndex = AssertedCast<size_t>(endIndexInt);
+
+    // Indices are guaranteed to be returned in order (from left to right).
+    MOZ_ASSERT(lastEndIndex <= beginIndex,
+               "field iteration didn't return fields in order start to "
+               "finish as expected");
+
+    if (lastEndIndex < beginIndex) {
+      if (!AppendPart(PartType::Literal, beginIndex)) {
+        return Err(ICUError::InternalError);
+      }
+    }
+
+    if (!AppendPart(PartType::Element, endIndex)) {
+      return Err(ICUError::InternalError);
+    }
+  }
+
+  // Append any final literal.
+  if (lastEndIndex < formattedSize) {
+    if (!AppendPart(PartType::Literal, formattedSize)) {
+      return Err(ICUError::InternalError);
+    }
+  }
+
+  return Ok();
+}
+}  // namespace mozilla::intl