1 files changed, 145 insertions, 0 deletions
diff --git a/intl/icu/source/i18n/string_segment.cpp b/intl/icu/source/i18n/string_segment.cpp
new file mode 100644
index 0000000000..2ddb738f4d
--- /dev/null
+++ b/intl/icu/source/i18n/string_segment.cpp
@@ -0,0 +1,145 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_FORMATTING
+
+// Allow implicit conversion from char16_t* to UnicodeString for this file:
+// Helpful in toString methods and elsewhere.
+#define UNISTR_FROM_STRING_EXPLICIT
+
+#include "numparse_types.h"
+#include "string_segment.h"
+#include "putilimp.h"
+#include "unicode/utf16.h"
+#include "unicode/uniset.h"
+
+U_NAMESPACE_BEGIN
+
+
+StringSegment::StringSegment(const UnicodeString& str, bool ignoreCase)
+        : fStr(str), fStart(0), fEnd(str.length()),
+          fFoldCase(ignoreCase) {}
+
+int32_t StringSegment::getOffset() const {
+    return fStart;
+}
+
+void StringSegment::setOffset(int32_t start) {
+    fStart = start;
+}
+
+void StringSegment::adjustOffset(int32_t delta) {
+    fStart += delta;
+}
+
+void StringSegment::adjustOffsetByCodePoint() {
+    fStart += U16_LENGTH(getCodePoint());
+}
+
+void StringSegment::setLength(int32_t length) {
+    fEnd = fStart + length;
+}
+
+void StringSegment::resetLength() {
+    fEnd = fStr.length();
+}
+
+int32_t StringSegment::length() const {
+    return fEnd - fStart;
+}
+
+char16_t StringSegment::charAt(int32_t index) const {
+    return fStr.charAt(index + fStart);
+}
+
+UChar32 StringSegment::codePointAt(int32_t index) const {
+    return fStr.char32At(index + fStart);
+}
+
+UnicodeString StringSegment::toUnicodeString() const {
+    return UnicodeString(fStr.getBuffer() + fStart, fEnd - fStart);
+}
+
+const UnicodeString StringSegment::toTempUnicodeString() const {
+    // Use the readonly-aliasing constructor for efficiency.
+    return UnicodeString(false, fStr.getBuffer() + fStart, fEnd - fStart);
+}
+
+UChar32 StringSegment::getCodePoint() const {
+    char16_t lead = fStr.charAt(fStart);
+    if (U16_IS_LEAD(lead) && fStart + 1 < fEnd) {
+        return fStr.char32At(fStart);
+    } else if (U16_IS_SURROGATE(lead)) {
+        return -1;
+    } else {
+        return lead;
+    }
+}
+
+bool StringSegment::startsWith(UChar32 otherCp) const {
+    return codePointsEqual(getCodePoint(), otherCp, fFoldCase);
+}
+
+bool StringSegment::startsWith(const UnicodeSet& uniset) const {
+    // TODO: Move UnicodeSet case-folding logic here.
+    // TODO: Handle string matches here instead of separately.
+    UChar32 cp = getCodePoint();
+    if (cp == -1) {
+        return false;
+    }
+    return uniset.contains(cp);
+}
+
+bool StringSegment::startsWith(const UnicodeString& other) const {
+    if (other.isBogus() || other.length() == 0 || length() == 0) {
+        return false;
+    }
+    int cp1 = getCodePoint();
+    int cp2 = other.char32At(0);
+    return codePointsEqual(cp1, cp2, fFoldCase);
+}
+
+int32_t StringSegment::getCommonPrefixLength(const UnicodeString& other) {
+    return getPrefixLengthInternal(other, fFoldCase);
+}
+
+int32_t StringSegment::getCaseSensitivePrefixLength(const UnicodeString& other) {
+    return getPrefixLengthInternal(other, false);
+}
+
+int32_t StringSegment::getPrefixLengthInternal(const UnicodeString& other, bool foldCase) {
+    U_ASSERT(other.length() > 0);
+    int32_t offset = 0;
+    for (; offset < uprv_min(length(), other.length());) {
+        // TODO: case-fold code points, not chars
+        char16_t c1 = charAt(offset);
+        char16_t c2 = other.charAt(offset);
+        if (!codePointsEqual(c1, c2, foldCase)) {
+            break;
+        }
+        offset++;
+    }
+    return offset;
+}
+
+bool StringSegment::codePointsEqual(UChar32 cp1, UChar32 cp2, bool foldCase) {
+    if (cp1 == cp2) {
+        return true;
+    }
+    if (!foldCase) {
+        return false;
+    }
+    cp1 = u_foldCase(cp1, true);
+    cp2 = u_foldCase(cp2, true);
+    return cp1 == cp2;
+}
+
+bool StringSegment::operator==(const UnicodeString& other) const {
+    return toTempUnicodeString() == other;
+}
+
+
+U_NAMESPACE_END
+#endif /* #if !UCONFIG_NO_FORMATTING */