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 */
135