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1 nigel 41 The pcretest program
2     --------------------
3    
4     This program is intended for testing PCRE, but it can also be used for
5     experimenting with regular expressions.
6    
7     If it is given two filename arguments, it reads from the first and writes to
8     the second. If it is given only one filename argument, it reads from that file
9     and writes to stdout. Otherwise, it reads from stdin and writes to stdout, and
10 nigel 43 prompts for each line of input, using "re>" to prompt for regular expressions,
11     and "data>" to prompt for data lines.
12 nigel 41
13     The program handles any number of sets of input on a single input file. Each
14     set starts with a regular expression, and continues with any number of data
15     lines to be matched against the pattern. An empty line signals the end of the
16 nigel 43 data lines, at which point a new regular expression is read. The regular
17     expressions are given enclosed in any non-alphameric delimiters other than
18     backslash, for example
19 nigel 41
20     /(a|bc)x+yz/
21    
22     White space before the initial delimiter is ignored. A regular expression may
23     be continued over several input lines, in which case the newline characters are
24 nigel 43 included within it. See the test input files in the testdata directory for many
25     examples. It is possible to include the delimiter within the pattern by
26     escaping it, for example
27 nigel 41
28     /abc\/def/
29    
30     If you do so, the escape and the delimiter form part of the pattern, but since
31     delimiters are always non-alphameric, this does not affect its interpretation.
32     If the terminating delimiter is immediately followed by a backslash, for
33     example,
34    
35     /abc/\
36    
37     then a backslash is added to the end of the pattern. This is done to provide a
38     way of testing the error condition that arises if a pattern finishes with a
39     backslash, because
40    
41     /abc\/
42    
43     is interpreted as the first line of a pattern that starts with "abc/", causing
44     pcretest to read the next line as a continuation of the regular expression.
45    
46 nigel 49
47     PATTERN MODIFIERS
48     -----------------
49    
50 nigel 41 The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,
51     PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For
52     example:
53    
54     /caseless/i
55    
56     These modifier letters have the same effect as they do in Perl. There are
57     others which set PCRE options that do not correspond to anything in Perl: /A,
58     /E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.
59    
60     Searching for all possible matches within each subject string can be requested
61     by the /g or /G modifier. After finding a match, PCRE is called again to search
62     the remainder of the subject string. The difference between /g and /G is that
63     the former uses the startoffset argument to pcre_exec() to start searching at
64     a new point within the entire string (which is in effect what Perl does),
65     whereas the latter passes over a shortened substring. This makes a difference
66     to the matching process if the pattern begins with a lookbehind assertion
67     (including \b or \B).
68    
69     If any call to pcre_exec() in a /g or /G sequence matches an empty string, the
70 nigel 47 next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED flags set in order
71     to search for another, non-empty, match at the same point. If this second match
72     fails, the start offset is advanced by one, and the normal match is retried.
73     This imitates the way Perl handles such cases when using the /g modifier or the
74     split() function.
75 nigel 41
76     There are a number of other modifiers for controlling the way pcretest
77     operates.
78    
79     The /+ modifier requests that as well as outputting the substring that matched
80     the entire pattern, pcretest should in addition output the remainder of the
81     subject string. This is useful for tests where the subject contains multiple
82     copies of the same substring.
83    
84     The /L modifier must be followed directly by the name of a locale, for example,
85    
86     /pattern/Lfr
87    
88     For this reason, it must be the last modifier letter. The given locale is set,
89     pcre_maketables() is called to build a set of character tables for the locale,
90     and this is then passed to pcre_compile() when compiling the regular
91     expression. Without an /L modifier, NULL is passed as the tables pointer; that
92     is, /L applies only to the expression on which it appears.
93    
94     The /I modifier requests that pcretest output information about the compiled
95     expression (whether it is anchored, has a fixed first character, and so on). It
96 nigel 43 does this by calling pcre_fullinfo() after compiling an expression, and
97     outputting the information it gets back. If the pattern is studied, the results
98     of that are also output.
99 nigel 41
100     The /D modifier is a PCRE debugging feature, which also assumes /I. It causes
101     the internal form of compiled regular expressions to be output after
102     compilation.
103    
104     The /S modifier causes pcre_study() to be called after the expression has been
105     compiled, and the results used when the expression is matched.
106    
107     The /M modifier causes the size of memory block used to hold the compiled
108     pattern to be output.
109    
110 nigel 49 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API rather
111     than its native API. When this is done, all other modifiers except /i, /m, and
112     /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is set if /m
113     is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always, and
114     PCRE_DOTALL unless REG_NEWLINE is set.
115 nigel 41
116 nigel 49 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option set.
117     This turns on the (currently incomplete) support for UTF-8 character handling
118     in PCRE, provided that it was compiled with this support enabled. This modifier
119     also causes any non-printing characters in output strings to be printed using
120     the \x{hh...} notation if they are valid UTF-8 sequences.
121    
122    
123     DATA LINES
124     ----------
125    
126 nigel 41 Before each data line is passed to pcre_exec(), leading and trailing whitespace
127     is removed, and it is then scanned for \ escapes. The following are recognized:
128    
129 nigel 49 \a alarm (= BEL)
130     \b backspace
131     \e escape
132     \f formfeed
133     \n newline
134     \r carriage return
135     \t tab
136     \v vertical tab
137     \nnn octal character (up to 3 octal digits)
138     \xhh hexadecimal character (up to 2 hex digits)
139     \x{hh...} hexadecimal UTF-8 character
140 nigel 41
141 nigel 49 \A pass the PCRE_ANCHORED option to pcre_exec()
142     \B pass the PCRE_NOTBOL option to pcre_exec()
143     \Cdd call pcre_copy_substring() for substring dd after a successful
144     match (any decimal number less than 32)
145     \Gdd call pcre_get_substring() for substring dd after a successful
146     match (any decimal number less than 32)
147     \L call pcre_get_substringlist() after a successful match
148     \N pass the PCRE_NOTEMPTY option to pcre_exec()
149     \Odd set the size of the output vector passed to pcre_exec() to dd
150     (any number of decimal digits)
151     \Z pass the PCRE_NOTEOL option to pcre_exec()
152 nigel 41
153     A backslash followed by anything else just escapes the anything else. If the
154     very last character is a backslash, it is ignored. This gives a way of passing
155     an empty line as data, since a real empty line terminates the data input.
156    
157     If /P was present on the regex, causing the POSIX wrapper API to be used, only
158     \B, and \Z have any effect, causing REG_NOTBOL and REG_NOTEOL to be passed to
159     regexec() respectively.
160    
161 nigel 49 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
162     of the /8 modifier on the pattern. It is recognized always. There may be any
163     number of hexadecimal digits inside the braces. The result is from one to six
164     bytes, encoded according to the UTF-8 rules.
165    
166    
167     OUTPUT FROM PCRETEST
168     --------------------
169    
170 nigel 41 When a match succeeds, pcretest outputs the list of captured substrings that
171     pcre_exec() returns, starting with number 0 for the string that matched the
172     whole pattern. Here is an example of an interactive pcretest run.
173    
174     $ pcretest
175     PCRE version 2.06 08-Jun-1999
176    
177     re> /^abc(\d+)/
178     data> abc123
179     0: abc123
180     1: 123
181     data> xyz
182     No match
183    
184     If the strings contain any non-printing characters, they are output as \0x
185 nigel 49 escapes, or as \x{...} escapes if the /8 modifier was present on the pattern.
186     If the pattern has the /+ modifier, then the output for substring 0 is followed
187     by the the rest of the subject string, identified by "0+" like this:
188 nigel 41
189     re> /cat/+
190     data> cataract
191     0: cat
192     0+ aract
193    
194     If the pattern has the /g or /G modifier, the results of successive matching
195     attempts are output in sequence, like this:
196    
197     re> /\Bi(\w\w)/g
198     data> Mississippi
199     0: iss
200     1: ss
201     0: iss
202     1: ss
203     0: ipp
204     1: pp
205    
206     "No match" is output only if the first match attempt fails.
207    
208     If any of \C, \G, or \L are present in a data line that is successfully
209     matched, the substrings extracted by the convenience functions are output with
210     C, G, or L after the string number instead of a colon. This is in addition to
211     the normal full list. The string length (that is, the return from the
212     extraction function) is given in parentheses after each string for \C and \G.
213    
214     Note that while patterns can be continued over several lines (a plain ">"
215     prompt is used for continuations), data lines may not. However newlines can be
216     included in data by means of the \n escape.
217    
218 nigel 49
219     COMMAND LINE OPTIONS
220     --------------------
221    
222 nigel 41 If the -p option is given to pcretest, it is equivalent to adding /P to each
223     regular expression: the POSIX wrapper API is used to call PCRE. None of the
224     following flags has any effect in this case.
225    
226     If the option -d is given to pcretest, it is equivalent to adding /D to each
227     regular expression: the internal form is output after compilation.
228    
229     If the option -i is given to pcretest, it is equivalent to adding /I to each
230     regular expression: information about the compiled pattern is given after
231     compilation.
232    
233     If the option -m is given to pcretest, it outputs the size of each compiled
234     pattern after it has been compiled. It is equivalent to adding /M to each
235     regular expression. For compatibility with earlier versions of pcretest, -s is
236     a synonym for -m.
237    
238     If the -t option is given, each compile, study, and match is run 20000 times
239     while being timed, and the resulting time per compile or match is output in
240 nigel 49 milliseconds. Do not set -t with -m, because you will then get the size output
241 nigel 41 20000 times and the timing will be distorted. If you want to change the number
242     of repetitions used for timing, edit the definition of LOOPREPEAT at the top of
243     pcretest.c
244    
245     Philip Hazel <ph10@cam.ac.uk>
246 nigel 49 August 2000

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