icuSources/i18n/string_segment.h

   1 // © 2018 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3
   4 #include "unicode/utypes.h"
   5
   6 #if !UCONFIG_NO_FORMATTING
   7 #ifndef __NUMPARSE_STRINGSEGMENT_H__
   8 #define __NUMPARSE_STRINGSEGMENT_H__
   9
  10 #include "unicode/unistr.h"
  11 #include "unicode/uniset.h"
  12
  13 U_NAMESPACE_BEGIN
  14
  15
  16 /**
  17  * A mutable UnicodeString wrapper with a variable offset and length and
  18  * support for case folding. The charAt, length, and subSequence methods all
  19  * operate relative to the fixed offset into the UnicodeString.
  20  *
  21  * Intended to be useful for parsing.
  22  *
  23  * CAUTION: Since this class is mutable, it must not be used anywhere that an
  24  * immutable object is required, like in a cache or as the key of a hash map.
  25  *
  26  * @author sffc (Shane Carr)
  27  */
  28 // Exported as U_I18N_API for tests
  29 class U_I18N_API StringSegment : public UMemory {
  30   public:
  31     StringSegment(const UnicodeString& str, bool ignoreCase);
  32
  33     int32_t getOffset() const;
  34
  35     void setOffset(int32_t start);
  36
  37     /**
  38      * Equivalent to <code>setOffset(getOffset()+delta)</code>.
  39      *
  40      * <p>
  41      * This method is usually called by a Matcher to register that a char was consumed. If the char is
  42      * strong (it usually is, except for things like whitespace), follow this with a call to
  43      * {@link ParsedNumber#setCharsConsumed}. For more information on strong chars, see that method.
  44      */
  45     void adjustOffset(int32_t delta);
  46
  47     /**
  48      * Adjusts the offset by the width of the current code point, either 1 or 2 chars.
  49      */
  50     void adjustOffsetByCodePoint();
  51
  52     void setLength(int32_t length);
  53
  54     void resetLength();
  55
  56     int32_t length() const;
  57
  58     char16_t charAt(int32_t index) const;
  59
  60     UChar32 codePointAt(int32_t index) const;
  61
  62     UnicodeString toUnicodeString() const;
  63
  64     const UnicodeString toTempUnicodeString() const;
  65
  66     /**
  67      * Returns the first code point in the string segment, or -1 if the string starts with an invalid
  68      * code point.
  69      *
  70      * <p>
  71      * <strong>Important:</strong> Most of the time, you should use {@link #startsWith}, which handles case
  72      * folding logic, instead of this method.
  73      */
  74     UChar32 getCodePoint() const;
  75
  76     /**
  77      * Returns true if the first code point of this StringSegment equals the given code point.
  78      *
  79      * <p>
  80      * This method will perform case folding if case folding is enabled for the parser.
  81      */
  82     bool startsWith(UChar32 otherCp) const;
  83
  84     /**
  85      * Returns true if the first code point of this StringSegment is in the given UnicodeSet.
  86      */
  87     bool startsWith(const UnicodeSet& uniset) const;
  88
  89     /**
  90      * Returns true if there is at least one code point of overlap between this StringSegment and the
  91      * given UnicodeString.
  92      */
  93     bool startsWith(const UnicodeString& other) const;
  94
  95     /**
  96      * Returns the length of the prefix shared by this StringSegment and the given UnicodeString. For
  97      * example, if this string segment is "aab", and the char sequence is "aac", this method returns 2,
  98      * since the first 2 characters are the same.
  99      *
 100      * <p>
 101      * This method only returns offsets along code point boundaries.
 102      *
 103      * <p>
 104      * This method will perform case folding if case folding was enabled in the constructor.
 105      *
 106      * <p>
 107      * IMPORTANT: The given UnicodeString must not be empty! It is the caller's responsibility to check.
 108      */
 109     int32_t getCommonPrefixLength(const UnicodeString& other);
 110
 111     /**
 112      * Like {@link #getCommonPrefixLength}, but never performs case folding, even if case folding is
 113      * enabled for the parser.
 114      */
 115     int32_t getCaseSensitivePrefixLength(const UnicodeString& other);
 116
 117     bool operator==(const UnicodeString& other) const;
 118
 119   private:
 120     const UnicodeString& fStr;
 121     int32_t fStart;
 122     int32_t fEnd;
 123     bool fFoldCase;
 124
 125     int32_t getPrefixLengthInternal(const UnicodeString& other, bool foldCase);
 126
 127     static bool codePointsEqual(UChar32 cp1, UChar32 cp2, bool foldCase);
 128 };
 129
 130
 131 U_NAMESPACE_END
 132
 133 #endif //__NUMPARSE_STRINGSEGMENT_H__
 134 #endif /* #if !UCONFIG_NO_FORMATTING */