1 files changed, 134 insertions, 0 deletions
diff --git a/intl/icu/source/i18n/string_segment.h b/intl/icu/source/i18n/string_segment.h
new file mode 100644
index 0000000000..b581f7e575
--- /dev/null
+++ b/intl/icu/source/i18n/string_segment.h
@@ -0,0 +1,134 @@
+// © 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
+#ifndef __NUMPARSE_STRINGSEGMENT_H__
+#define __NUMPARSE_STRINGSEGMENT_H__
+
+#include "unicode/unistr.h"
+#include "unicode/uniset.h"
+
+U_NAMESPACE_BEGIN
+
+
+/**
+ * A mutable UnicodeString wrapper with a variable offset and length and
+ * support for case folding. The charAt, length, and subSequence methods all
+ * operate relative to the fixed offset into the UnicodeString.
+ *
+ * Intended to be useful for parsing.
+ *
+ * CAUTION: Since this class is mutable, it must not be used anywhere that an
+ * immutable object is required, like in a cache or as the key of a hash map.
+ *
+ * @author sffc (Shane Carr)
+ */
+// Exported as U_I18N_API for tests
+class U_I18N_API StringSegment : public UMemory {
+  public:
+    StringSegment(const UnicodeString& str, bool ignoreCase);
+
+    int32_t getOffset() const;
+
+    void setOffset(int32_t start);
+
+    /**
+     * Equivalent to <code>setOffset(getOffset()+delta)</code>.
+     *
+     * <p>
+     * This method is usually called by a Matcher to register that a char was consumed. If the char is
+     * strong (it usually is, except for things like whitespace), follow this with a call to
+     * {@link ParsedNumber#setCharsConsumed}. For more information on strong chars, see that method.
+     */
+    void adjustOffset(int32_t delta);
+
+    /**
+     * Adjusts the offset by the width of the current code point, either 1 or 2 chars.
+     */
+    void adjustOffsetByCodePoint();
+
+    void setLength(int32_t length);
+
+    void resetLength();
+
+    int32_t length() const;
+
+    char16_t charAt(int32_t index) const;
+
+    UChar32 codePointAt(int32_t index) const;
+
+    UnicodeString toUnicodeString() const;
+
+    const UnicodeString toTempUnicodeString() const;
+
+    /**
+     * Returns the first code point in the string segment, or -1 if the string starts with an invalid
+     * code point.
+     *
+     * <p>
+     * <strong>Important:</strong> Most of the time, you should use {@link #startsWith}, which handles case
+     * folding logic, instead of this method.
+     */
+    UChar32 getCodePoint() const;
+
+    /**
+     * Returns true if the first code point of this StringSegment equals the given code point.
+     *
+     * <p>
+     * This method will perform case folding if case folding is enabled for the parser.
+     */
+    bool startsWith(UChar32 otherCp) const;
+
+    /**
+     * Returns true if the first code point of this StringSegment is in the given UnicodeSet.
+     */
+    bool startsWith(const UnicodeSet& uniset) const;
+
+    /**
+     * Returns true if there is at least one code point of overlap between this StringSegment and the
+     * given UnicodeString.
+     */
+    bool startsWith(const UnicodeString& other) const;
+
+    /**
+     * Returns the length of the prefix shared by this StringSegment and the given UnicodeString. For
+     * example, if this string segment is "aab", and the char sequence is "aac", this method returns 2,
+     * since the first 2 characters are the same.
+     *
+     * <p>
+     * This method only returns offsets along code point boundaries.
+     *
+     * <p>
+     * This method will perform case folding if case folding was enabled in the constructor.
+     *
+     * <p>
+     * IMPORTANT: The given UnicodeString must not be empty! It is the caller's responsibility to check.
+     */
+    int32_t getCommonPrefixLength(const UnicodeString& other);
+
+    /**
+     * Like {@link #getCommonPrefixLength}, but never performs case folding, even if case folding is
+     * enabled for the parser.
+     */
+    int32_t getCaseSensitivePrefixLength(const UnicodeString& other);
+
+    bool operator==(const UnicodeString& other) const;
+
+  private:
+    const UnicodeString& fStr;
+    int32_t fStart;
+    int32_t fEnd;
+    bool fFoldCase;
+
+    int32_t getPrefixLengthInternal(const UnicodeString& other, bool foldCase);
+
+    static bool codePointsEqual(UChar32 cp1, UChar32 cp2, bool foldCase);
+};
+
+
+U_NAMESPACE_END
+
+#endif //__NUMPARSE_STRINGSEGMENT_H__
+#endif /* #if !UCONFIG_NO_FORMATTING */