1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 **********************************************************************
5 *   Copyright (c) 2001-2016, International Business Machines
6 *   Corporation and others.  All Rights Reserved.
7 **********************************************************************
8 *   Date        Name        Description
9 *   11/19/2001  aliu        Creation.
10 **********************************************************************
11 */
12 
13 #include "unicode/uchar.h"
14 #include "unicode/utf16.h"
15 #include "patternprops.h"
16 #include "util.h"
17 
18 U_NAMESPACE_BEGIN
19 
20 /**
21  * Parse an integer at pos, either of the form \d+ or of the form
22  * 0x[0-9A-Fa-f]+ or 0[0-7]+, that is, in standard decimal, hex,
23  * or octal format.
24  * @param pos INPUT-OUTPUT parameter.  On input, the first
25  * character to parse.  On output, the character after the last
26  * parsed character.
27  */
parseInteger(const UnicodeString & rule,int32_t & pos,int32_t limit)28 int32_t ICU_Utility::parseInteger(const UnicodeString& rule, int32_t& pos, int32_t limit) {
29     int32_t count = 0;
30     int32_t value = 0;
31     int32_t p = pos;
32     int8_t radix = 10;
33 
34     if (p < limit && rule.charAt(p) == 48 /*0*/) {
35         if (p+1 < limit && (rule.charAt(p+1) == 0x78 /*x*/ || rule.charAt(p+1) == 0x58 /*X*/)) {
36             p += 2;
37             radix = 16;
38         }
39         else {
40             p++;
41             count = 1;
42             radix = 8;
43         }
44     }
45 
46     while (p < limit) {
47         int32_t d = u_digit(rule.charAt(p++), radix);
48         if (d < 0) {
49             --p;
50             break;
51         }
52         ++count;
53         int32_t v = (value * radix) + d;
54         if (v <= value) {
55             // If there are too many input digits, at some point
56             // the value will go negative, e.g., if we have seen
57             // "0x8000000" already and there is another '0', when
58             // we parse the next 0 the value will go negative.
59             return 0;
60         }
61         value = v;
62     }
63     if (count > 0) {
64         pos = p;
65     }
66     return value;
67 }
68 
69 /**
70  * Parse a pattern string starting at offset pos.  Keywords are
71  * matched case-insensitively.  Spaces may be skipped and may be
72  * optional or required.  Integer values may be parsed, and if
73  * they are, they will be returned in the given array.  If
74  * successful, the offset of the next non-space character is
75  * returned.  On failure, -1 is returned.
76  * @param pattern must only contain lowercase characters, which
77  * will match their uppercase equivalents as well.  A space
78  * character matches one or more required spaces.  A '~' character
79  * matches zero or more optional spaces.  A '#' character matches
80  * an integer and stores it in parsedInts, which the caller must
81  * ensure has enough capacity.
82  * @param parsedInts array to receive parsed integers.  Caller
83  * must ensure that parsedInts.length is >= the number of '#'
84  * signs in 'pattern'.
85  * @return the position after the last character parsed, or -1 if
86  * the parse failed
87  */
parsePattern(const UnicodeString & rule,int32_t pos,int32_t limit,const UnicodeString & pattern,int32_t * parsedInts)88 int32_t ICU_Utility::parsePattern(const UnicodeString& rule, int32_t pos, int32_t limit,
89                               const UnicodeString& pattern, int32_t* parsedInts) {
90     // TODO Update this to handle surrogates
91     int32_t p;
92     int32_t intCount = 0; // number of integers parsed
93     for (int32_t i=0; i<pattern.length(); ++i) {
94         UChar cpat = pattern.charAt(i);
95         UChar c;
96         switch (cpat) {
97         case 32 /*' '*/:
98             if (pos >= limit) {
99                 return -1;
100             }
101             c = rule.charAt(pos++);
102             if (!PatternProps::isWhiteSpace(c)) {
103                 return -1;
104             }
105             // FALL THROUGH to skipWhitespace
106             U_FALLTHROUGH;
107         case 126 /*'~'*/:
108             pos = skipWhitespace(rule, pos);
109             break;
110         case 35 /*'#'*/:
111             p = pos;
112             parsedInts[intCount++] = parseInteger(rule, p, limit);
113             if (p == pos) {
114                 // Syntax error; failed to parse integer
115                 return -1;
116             }
117             pos = p;
118             break;
119         default:
120             if (pos >= limit) {
121                 return -1;
122             }
123             c = (UChar) u_tolower(rule.charAt(pos++));
124             if (c != cpat) {
125                 return -1;
126             }
127             break;
128         }
129     }
130     return pos;
131 }
132 
133 /**
134  * Parse a Unicode identifier from the given string at the given
135  * position.  Return the identifier, or an empty string if there
136  * is no identifier.
137  * @param str the string to parse
138  * @param pos INPUT-OUPUT parameter.  On INPUT, pos is the
139  * first character to examine.  It must be less than str.length(),
140  * and it must not point to a whitespace character.  That is, must
141  * have pos < str.length().  On
142  * OUTPUT, the position after the last parsed character.
143  * @return the Unicode identifier, or an empty string if there is
144  * no valid identifier at pos.
145  */
parseUnicodeIdentifier(const UnicodeString & str,int32_t & pos)146 UnicodeString ICU_Utility::parseUnicodeIdentifier(const UnicodeString& str, int32_t& pos) {
147     // assert(pos < str.length());
148     UnicodeString buf;
149     int p = pos;
150     while (p < str.length()) {
151         UChar32 ch = str.char32At(p);
152         if (buf.length() == 0) {
153             if (u_isIDStart(ch)) {
154                 buf.append(ch);
155             } else {
156                 buf.truncate(0);
157                 return buf;
158             }
159         } else {
160             if (u_isIDPart(ch)) {
161                 buf.append(ch);
162             } else {
163                 break;
164             }
165         }
166         p += U16_LENGTH(ch);
167     }
168     pos = p;
169     return buf;
170 }
171 
172 /**
173  * Parse an unsigned 31-bit integer at the given offset.  Use
174  * UCharacter.digit() to parse individual characters into digits.
175  * @param text the text to be parsed
176  * @param pos INPUT-OUTPUT parameter.  On entry, pos[0] is the
177  * offset within text at which to start parsing; it should point
178  * to a valid digit.  On exit, pos[0] is the offset after the last
179  * parsed character.  If the parse failed, it will be unchanged on
180  * exit.  Must be >= 0 on entry.
181  * @param radix the radix in which to parse; must be >= 2 and <=
182  * 36.
183  * @return a non-negative parsed number, or -1 upon parse failure.
184  * Parse fails if there are no digits, that is, if pos[0] does not
185  * point to a valid digit on entry, or if the number to be parsed
186  * does not fit into a 31-bit unsigned integer.
187  */
parseNumber(const UnicodeString & text,int32_t & pos,int8_t radix)188 int32_t ICU_Utility::parseNumber(const UnicodeString& text,
189                                  int32_t& pos, int8_t radix) {
190     // assert(pos[0] >= 0);
191     // assert(radix >= 2);
192     // assert(radix <= 36);
193     int32_t n = 0;
194     int32_t p = pos;
195     while (p < text.length()) {
196         UChar32 ch = text.char32At(p);
197         int32_t d = u_digit(ch, radix);
198         if (d < 0) {
199             break;
200         }
201         n = radix*n + d;
202         // ASSUME that when a 32-bit integer overflows it becomes
203         // negative.  E.g., 214748364 * 10 + 8 => negative value.
204         if (n < 0) {
205             return -1;
206         }
207         ++p;
208     }
209     if (p == pos) {
210         return -1;
211     }
212     pos = p;
213     return n;
214 }
215 
216 U_NAMESPACE_END
217 
218