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Fix bug when \K is used in a lookbehind in a substitute pattern.

This commit is contained in:
Philip.Hazel 2018-06-22 16:29:56 +00:00
parent 9de1a271a0
commit 89c2a02027
7 changed files with 249 additions and 221 deletions
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16
doc/html/pcre2api.html
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@ -2569,7 +2569,7 @@ calls to <b>pcre2_match()</b> if you are making repeated calls to find other
matches in the same subject string.
</P>
<P>
WARNING: When PCRE2_NO_UTF_CHECK is set, the effect of passing an invalid
<b>Warning:</b> When PCRE2_NO_UTF_CHECK is set, the effect of passing an invalid
string as a subject, or an invalid value of <i>startoffset</i>, is undefined.
Your program may crash or loop indefinitely.
<pre>
@ -2776,6 +2776,15 @@ branch of the group, but it is not on the matching path. On the other hand,
when this pattern fails to match "bx", the returned name is B.
</P>
<P>
<b>Warning:</b> By default, certain start-of-match optimizations are used to
give a fast "no match" result in some situations. For example, if the anchoring
is removed from the pattern above, there is an initial check for the presence
of "c" in the subject before running the matching engine. This check fails for
"bx", causing a match failure without seeing any marks. You can disable the
start-of-match optimizations by setting the PCRE2_NO_START_OPTIMIZE option for
<b>pcre2_compile()</b> or starting the pattern with (*NO_START_OPT).
</P>
<P>
After a successful match, a partial match, or one of the invalid UTF errors
(for example, PCRE2_ERROR_UTF8_ERR5), <b>pcre2_get_startchar()</b> can be
called. After a successful or partial match it returns the code unit offset of
@ -3330,7 +3339,8 @@ replacement string, with more particular errors being PCRE2_ERROR_BADREPESCAPE
(invalid escape sequence), PCRE2_ERROR_REPMISSINGBRACE (closing curly bracket
not found), PCRE2_ERROR_BADSUBSTITUTION (syntax error in extended group
substitution), and PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before
it started, which can happen if \K is used in an assertion).
it started or the match started earlier than the current position in the
subject, which can happen if \K is used in an assertion).
</P>
<P>
As for all PCRE2 errors, a text message that describes the error can be
@ -3604,7 +3614,7 @@ Cambridge, England.
</P>
<br><a name="SEC42" href="#TOC1">REVISION</a><br>
<P>
Last updated: 27 April 2018
Last updated: 22 June 2018
<br>
Copyright &copy; 1997-2018 University of Cambridge.
<br>

420
doc/pcre2.txt
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@ -2519,7 +2519,7 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION
second and subsequent calls to pcre2_match() if you are making repeated
calls to find other matches in the same subject string.
WARNING: When PCRE2_NO_UTF_CHECK is set, the effect of passing an
Warning: When PCRE2_NO_UTF_CHECK is set, the effect of passing an
invalid string as a subject, or an invalid value of startoffset, is
undefined. Your program may crash or loop indefinitely.
@ -2704,30 +2704,39 @@ OTHER INFORMATION ABOUT A MATCH
the other hand, when this pattern fails to match "bx", the returned
name is B.
After a successful match, a partial match, or one of the invalid UTF
errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
Warning: By default, certain start-of-match optimizations are used to
give a fast "no match" result in some situations. For example, if the
anchoring is removed from the pattern above, there is an initial check
for the presence of "c" in the subject before running the matching
engine. This check fails for "bx", causing a match failure without see-
ing any marks. You can disable the start-of-match optimizations by set-
ting the PCRE2_NO_START_OPTIMIZE option for pcre2_compile() or starting
the pattern with (*NO_START_OPT).
After a successful match, a partial match, or one of the invalid UTF
errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
be called. After a successful or partial match it returns the code unit
offset of the character at which the match started. For a non-partial
match, this can be different to the value of ovector[0] if the pattern
contains the \K escape sequence. After a partial match, however, this
value is always the same as ovector[0] because \K does not affect the
offset of the character at which the match started. For a non-partial
match, this can be different to the value of ovector[0] if the pattern
contains the \K escape sequence. After a partial match, however, this
value is always the same as ovector[0] because \K does not affect the
result of a partial match.
After a UTF check failure, pcre2_get_startchar() can be used to obtain
After a UTF check failure, pcre2_get_startchar() can be used to obtain
the code unit offset of the invalid UTF character. Details are given in
the pcre2unicode page.
ERROR RETURNS FROM pcre2_match()
If pcre2_match() fails, it returns a negative number. This can be con-
verted to a text string by calling the pcre2_get_error_message() func-
tion (see "Obtaining a textual error message" below). Negative error
codes are also returned by other functions, and are documented with
them. The codes are given names in the header file. If UTF checking is
If pcre2_match() fails, it returns a negative number. This can be con-
verted to a text string by calling the pcre2_get_error_message() func-
tion (see "Obtaining a textual error message" below). Negative error
codes are also returned by other functions, and are documented with
them. The codes are given names in the header file. If UTF checking is
in force and an invalid UTF subject string is detected, one of a number
of UTF-specific negative error codes is returned. Details are given in
the pcre2unicode page. The following are the other errors that may be
of UTF-specific negative error codes is returned. Details are given in
the pcre2unicode page. The following are the other errors that may be
returned by pcre2_match():
PCRE2_ERROR_NOMATCH
@ -2736,20 +2745,20 @@ ERROR RETURNS FROM pcre2_match()
PCRE2_ERROR_PARTIAL
The subject string did not match, but it did match partially. See the
The subject string did not match, but it did match partially. See the
pcre2partial documentation for details of partial matching.
PCRE2_ERROR_BADMAGIC
PCRE2 stores a 4-byte "magic number" at the start of the compiled code,
to catch the case when it is passed a junk pointer. This is the error
to catch the case when it is passed a junk pointer. This is the error
that is returned when the magic number is not present.
PCRE2_ERROR_BADMODE
This error is given when a compiled pattern is passed to a function in
a library of a different code unit width, for example, a pattern com-
piled by the 8-bit library is passed to a 16-bit or 32-bit library
This error is given when a compiled pattern is passed to a function in
a library of a different code unit width, for example, a pattern com-
piled by the 8-bit library is passed to a 16-bit or 32-bit library
function.
PCRE2_ERROR_BADOFFSET
@ -2763,15 +2772,15 @@ ERROR RETURNS FROM pcre2_match()
PCRE2_ERROR_BADUTFOFFSET
The UTF code unit sequence that was passed as a subject was checked and
found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
value of startoffset did not point to the beginning of a UTF character
found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
value of startoffset did not point to the beginning of a UTF character
or the end of the subject.
PCRE2_ERROR_CALLOUT
This error is never generated by pcre2_match() itself. It is provided
for use by callout functions that want to cause pcre2_match() or
pcre2_callout_enumerate() to return a distinctive error code. See the
This error is never generated by pcre2_match() itself. It is provided
for use by callout functions that want to cause pcre2_match() or
pcre2_callout_enumerate() to return a distinctive error code. See the
pcre2callout documentation for details.
PCRE2_ERROR_DEPTHLIMIT
@ -2784,14 +2793,14 @@ ERROR RETURNS FROM pcre2_match()
PCRE2_ERROR_INTERNAL
An unexpected internal error has occurred. This error could be caused
An unexpected internal error has occurred. This error could be caused
by a bug in PCRE2 or by overwriting of the compiled pattern.
PCRE2_ERROR_JIT_STACKLIMIT
This error is returned when a pattern that was successfully studied
using JIT is being matched, but the memory available for the just-in-
time processing stack is not large enough. See the pcre2jit documenta-
This error is returned when a pattern that was successfully studied
using JIT is being matched, but the memory available for the just-in-
time processing stack is not large enough. See the pcre2jit documenta-
tion for more details.
PCRE2_ERROR_MATCHLIMIT
@ -2800,10 +2809,10 @@ ERROR RETURNS FROM pcre2_match()
PCRE2_ERROR_NOMEMORY
If a pattern contains many nested backtracking points, heap memory is
used to remember them. This error is given when the memory allocation
function (default or custom) fails. Note that a different error,
PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
If a pattern contains many nested backtracking points, heap memory is
used to remember them. This error is given when the memory allocation
function (default or custom) fails. Note that a different error,
PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
the heap limit.
PCRE2_ERROR_NULL
@ -2812,12 +2821,12 @@ ERROR RETURNS FROM pcre2_match()
PCRE2_ERROR_RECURSELOOP
This error is returned when pcre2_match() detects a recursion loop
within the pattern. Specifically, it means that either the whole pat-
This error is returned when pcre2_match() detects a recursion loop
within the pattern. Specifically, it means that either the whole pat-
tern or a subpattern has been called recursively for the second time at
the same position in the subject string. Some simple patterns that
might do this are detected and faulted at compile time, but more com-
plicated cases, in particular mutual recursions between two different
the same position in the subject string. Some simple patterns that
might do this are detected and faulted at compile time, but more com-
plicated cases, in particular mutual recursions between two different
subpatterns, cannot be detected until matching is attempted.
@ -2826,20 +2835,20 @@ OBTAINING A TEXTUAL ERROR MESSAGE
int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer,
PCRE2_SIZE bufflen);
A text message for an error code from any PCRE2 function (compile,
match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
sage(). The code is passed as the first argument, with the remaining
two arguments specifying a code unit buffer and its length in code
units, into which the text message is placed. The message is returned
in code units of the appropriate width for the library that is being
A text message for an error code from any PCRE2 function (compile,
match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
sage(). The code is passed as the first argument, with the remaining
two arguments specifying a code unit buffer and its length in code
units, into which the text message is placed. The message is returned
in code units of the appropriate width for the library that is being
used.
The returned message is terminated with a trailing zero, and the func-
tion returns the number of code units used, excluding the trailing
The returned message is terminated with a trailing zero, and the func-
tion returns the number of code units used, excluding the trailing
zero. If the error number is unknown, the negative error code
PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes-
sage is truncated (but still with a trailing zero), and the negative
error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are
PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes-
sage is truncated (but still with a trailing zero), and the negative
error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are
very long; a buffer size of 120 code units is ample.
@ -2858,39 +2867,39 @@ EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
void pcre2_substring_free(PCRE2_UCHAR *buffer);
Captured substrings can be accessed directly by using the ovector as
Captured substrings can be accessed directly by using the ovector as
described above. For convenience, auxiliary functions are provided for
extracting captured substrings as new, separate, zero-terminated
extracting captured substrings as new, separate, zero-terminated
strings. A substring that contains a binary zero is correctly extracted
and has a further zero added on the end, but the result is not, of
and has a further zero added on the end, but the result is not, of
course, a C string.
The functions in this section identify substrings by number. The number
zero refers to the entire matched substring, with higher numbers refer-
ring to substrings captured by parenthesized groups. After a partial
match, only substring zero is available. An attempt to extract any
other substring gives the error PCRE2_ERROR_PARTIAL. The next section
ring to substrings captured by parenthesized groups. After a partial
match, only substring zero is available. An attempt to extract any
other substring gives the error PCRE2_ERROR_PARTIAL. The next section
describes similar functions for extracting captured substrings by name.
If a pattern uses the \K escape sequence within a positive assertion,
If a pattern uses the \K escape sequence within a positive assertion,
the reported start of a successful match can be greater than the end of
the match. For example, if the pattern (?=ab\K) is matched against
"ab", the start and end offset values for the match are 2 and 0. In
this situation, calling these functions with a zero substring number
the match. For example, if the pattern (?=ab\K) is matched against
"ab", the start and end offset values for the match are 2 and 0. In
this situation, calling these functions with a zero substring number
extracts a zero-length empty string.
You can find the length in code units of a captured substring without
extracting it by calling pcre2_substring_length_bynumber(). The first
argument is a pointer to the match data block, the second is the group
number, and the third is a pointer to a variable into which the length
is placed. If you just want to know whether or not the substring has
You can find the length in code units of a captured substring without
extracting it by calling pcre2_substring_length_bynumber(). The first
argument is a pointer to the match data block, the second is the group
number, and the third is a pointer to a variable into which the length
is placed. If you just want to know whether or not the substring has
been captured, you can pass the third argument as NULL.
The pcre2_substring_copy_bynumber() function copies a captured sub-
string into a supplied buffer, whereas pcre2_substring_get_bynumber()
copies it into new memory, obtained using the same memory allocation
function that was used for the match data block. The first two argu-
ments of these functions are a pointer to the match data block and a
The pcre2_substring_copy_bynumber() function copies a captured sub-
string into a supplied buffer, whereas pcre2_substring_get_bynumber()
copies it into new memory, obtained using the same memory allocation
function that was used for the match data block. The first two argu-
ments of these functions are a pointer to the match data block and a
capturing group number.
The final arguments of pcre2_substring_copy_bynumber() are a pointer to
@ -2899,25 +2908,25 @@ EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
for the extracted substring, excluding the terminating zero.
For pcre2_substring_get_bynumber() the third and fourth arguments point
to variables that are updated with a pointer to the new memory and the
number of code units that comprise the substring, again excluding the
terminating zero. When the substring is no longer needed, the memory
to variables that are updated with a pointer to the new memory and the
number of code units that comprise the substring, again excluding the
terminating zero. When the substring is no longer needed, the memory
should be freed by calling pcre2_substring_free().
The return value from all these functions is zero for success, or a
negative error code. If the pattern match failed, the match failure
code is returned. If a substring number greater than zero is used
after a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
The return value from all these functions is zero for success, or a
negative error code. If the pattern match failed, the match failure
code is returned. If a substring number greater than zero is used
after a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
error codes are:
PCRE2_ERROR_NOMEMORY
The buffer was too small for pcre2_substring_copy_bynumber(), or the
The buffer was too small for pcre2_substring_copy_bynumber(), or the
attempt to get memory failed for pcre2_substring_get_bynumber().
PCRE2_ERROR_NOSUBSTRING
There is no substring with that number in the pattern, that is, the
There is no substring with that number in the pattern, that is, the
number is greater than the number of capturing parentheses.
PCRE2_ERROR_UNAVAILABLE
@ -2928,8 +2937,8 @@ EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
PCRE2_ERROR_UNSET
The substring did not participate in the match. For example, if the
pattern is (abc)|(def) and the subject is "def", and the ovector con-
The substring did not participate in the match. For example, if the
pattern is (abc)|(def) and the subject is "def", and the ovector con-
tains at least two capturing slots, substring number 1 is unset.
@ -2940,32 +2949,32 @@ EXTRACTING A LIST OF ALL CAPTURED SUBSTRINGS
void pcre2_substring_list_free(PCRE2_SPTR *list);
The pcre2_substring_list_get() function extracts all available sub-
strings and builds a list of pointers to them. It also (optionally)
builds a second list that contains their lengths (in code units),
The pcre2_substring_list_get() function extracts all available sub-
strings and builds a list of pointers to them. It also (optionally)
builds a second list that contains their lengths (in code units),
excluding a terminating zero that is added to each of them. All this is
done in a single block of memory that is obtained using the same memory
allocation function that was used to get the match data block.
This function must be called only after a successful match. If called
This function must be called only after a successful match. If called
after a partial match, the error code PCRE2_ERROR_PARTIAL is returned.
The address of the memory block is returned via listptr, which is also
The address of the memory block is returned via listptr, which is also
the start of the list of string pointers. The end of the list is marked
by a NULL pointer. The address of the list of lengths is returned via
lengthsptr. If your strings do not contain binary zeros and you do not
by a NULL pointer. The address of the list of lengths is returned via
lengthsptr. If your strings do not contain binary zeros and you do not
therefore need the lengths, you may supply NULL as the lengthsptr argu-
ment to disable the creation of a list of lengths. The yield of the
function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
ory block could not be obtained. When the list is no longer needed, it
ment to disable the creation of a list of lengths. The yield of the
function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
ory block could not be obtained. When the list is no longer needed, it
should be freed by calling pcre2_substring_list_free().
If this function encounters a substring that is unset, which can happen
when capturing subpattern number n+1 matches some part of the subject,
but subpattern n has not been used at all, it returns an empty string.
This can be distinguished from a genuine zero-length substring by
when capturing subpattern number n+1 matches some part of the subject,
but subpattern n has not been used at all, it returns an empty string.
This can be distinguished from a genuine zero-length substring by
inspecting the appropriate offset in the ovector, which contain
PCRE2_UNSET for unset substrings, or by calling pcre2_sub-
PCRE2_UNSET for unset substrings, or by calling pcre2_sub-
string_length_bynumber().
@ -2985,39 +2994,39 @@ EXTRACTING CAPTURED SUBSTRINGS BY NAME
void pcre2_substring_free(PCRE2_UCHAR *buffer);
To extract a substring by name, you first have to find associated num-
To extract a substring by name, you first have to find associated num-
ber. For example, for this pattern:
(a+)b(?<xxx>\d+)...
the number of the subpattern called "xxx" is 2. If the name is known to
be unique (PCRE2_DUPNAMES was not set), you can find the number from
be unique (PCRE2_DUPNAMES was not set), you can find the number from
the name by calling pcre2_substring_number_from_name(). The first argu-
ment is the compiled pattern, and the second is the name. The yield of
ment is the compiled pattern, and the second is the name. The yield of
the function is the subpattern number, PCRE2_ERROR_NOSUBSTRING if there
is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if
there is more than one subpattern of that name. Given the number, you
can extract the substring directly from the ovector, or use one of the
is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if
there is more than one subpattern of that name. Given the number, you
can extract the substring directly from the ovector, or use one of the
"bynumber" functions described above.
For convenience, there are also "byname" functions that correspond to
the "bynumber" functions, the only difference being that the second
argument is a name instead of a number. If PCRE2_DUPNAMES is set and
For convenience, there are also "byname" functions that correspond to
the "bynumber" functions, the only difference being that the second
argument is a name instead of a number. If PCRE2_DUPNAMES is set and
there are duplicate names, these functions scan all the groups with the
given name, and return the first named string that is set.
If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
returned. If all groups with the name have numbers that are greater
than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is
returned. If there is at least one group with a slot in the ovector,
If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
returned. If all groups with the name have numbers that are greater
than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is
returned. If there is at least one group with a slot in the ovector,
but no group is found to be set, PCRE2_ERROR_UNSET is returned.
Warning: If the pattern uses the (?| feature to set up multiple subpat-
terns with the same number, as described in the section on duplicate
subpattern numbers in the pcre2pattern page, you cannot use names to
distinguish the different subpatterns, because names are not included
in the compiled code. The matching process uses only numbers. For this
reason, the use of different names for subpatterns of the same number
terns with the same number, as described in the section on duplicate
subpattern numbers in the pcre2pattern page, you cannot use names to
distinguish the different subpatterns, because names are not included
in the compiled code. The matching process uses only numbers. For this
reason, the use of different names for subpatterns of the same number
causes an error at compile time.
@ -3030,80 +3039,80 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
PCRE2_SIZE rlength, PCRE2_UCHAR *outputbufferP,
PCRE2_SIZE *outlengthptr);
This function calls pcre2_match() and then makes a copy of the subject
string in outputbuffer, replacing the part that was matched with the
replacement string, whose length is supplied in rlength. This can be
This function calls pcre2_match() and then makes a copy of the subject
string in outputbuffer, replacing the part that was matched with the
replacement string, whose length is supplied in rlength. This can be
given as PCRE2_ZERO_TERMINATED for a zero-terminated string. Matches in
which a \K item in a lookahead in the pattern causes the match to end
which a \K item in a lookahead in the pattern causes the match to end
before it starts are not supported, and give rise to an error return.
The first seven arguments of pcre2_substitute() are the same as for
The first seven arguments of pcre2_substitute() are the same as for
pcre2_match(), except that the partial matching options are not permit-
ted, and match_data may be passed as NULL, in which case a match data
block is obtained and freed within this function, using memory manage-
ment functions from the match context, if provided, or else those that
ted, and match_data may be passed as NULL, in which case a match data
block is obtained and freed within this function, using memory manage-
ment functions from the match context, if provided, or else those that
were used to allocate memory for the compiled code.
The outlengthptr argument must point to a variable that contains the
length, in code units, of the output buffer. If the function is suc-
cessful, the value is updated to contain the length of the new string,
The outlengthptr argument must point to a variable that contains the
length, in code units, of the output buffer. If the function is suc-
cessful, the value is updated to contain the length of the new string,
excluding the trailing zero that is automatically added.
If the function is not successful, the value set via outlengthptr
depends on the type of error. For syntax errors in the replacement
string, the value is the offset in the replacement string where the
error was detected. For other errors, the value is PCRE2_UNSET by
default. This includes the case of the output buffer being too small,
unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which
case the value is the minimum length needed, including space for the
trailing zero. Note that in order to compute the required length,
pcre2_substitute() has to simulate all the matching and copying,
If the function is not successful, the value set via outlengthptr
depends on the type of error. For syntax errors in the replacement
string, the value is the offset in the replacement string where the
error was detected. For other errors, the value is PCRE2_UNSET by
default. This includes the case of the output buffer being too small,
unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which
case the value is the minimum length needed, including space for the
trailing zero. Note that in order to compute the required length,
pcre2_substitute() has to simulate all the matching and copying,
instead of giving an error return as soon as the buffer overflows. Note
also that the length is in code units, not bytes.
In the replacement string, which is interpreted as a UTF string in UTF
mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK
In the replacement string, which is interpreted as a UTF string in UTF
mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK
option is set, a dollar character is an escape character that can spec-
ify the insertion of characters from capturing groups or (*MARK),
(*PRUNE), or (*THEN) items in the pattern. The following forms are
ify the insertion of characters from capturing groups or (*MARK),
(*PRUNE), or (*THEN) items in the pattern. The following forms are
always recognized:
$$ insert a dollar character
$<n> or ${<n>} insert the contents of group <n>
$*MARK or ${*MARK} insert a (*MARK), (*PRUNE), or (*THEN) name
Either a group number or a group name can be given for <n>. Curly
brackets are required only if the following character would be inter-
Either a group number or a group name can be given for <n>. Curly
brackets are required only if the following character would be inter-
preted as part of the number or name. The number may be zero to include
the entire matched string. For example, if the pattern a(b)c is
matched with "=abc=" and the replacement string "+$1$0$1+", the result
the entire matched string. For example, if the pattern a(b)c is
matched with "=abc=" and the replacement string "+$1$0$1+", the result
is "=+babcb+=".
$*MARK inserts the name from the last encountered (*MARK), (*PRUNE), or
(*THEN) on the matching path that has a name. (*MARK) must always
include a name, but (*PRUNE) and (*THEN) need not. For example, in the
case of (*MARK:A)(*PRUNE) the name inserted is "A", but for
(*MARK:A)(*PRUNE:B) the relevant name is "B". This facility can be
used to perform simple simultaneous substitutions, as this pcre2test
(*THEN) on the matching path that has a name. (*MARK) must always
include a name, but (*PRUNE) and (*THEN) need not. For example, in the
case of (*MARK:A)(*PRUNE) the name inserted is "A", but for
(*MARK:A)(*PRUNE:B) the relevant name is "B". This facility can be
used to perform simple simultaneous substitutions, as this pcre2test
example shows:
/(*MARK:pear)apple|(*MARK:orange)lemon/g,replace=${*MARK}
apple lemon
2: pear orange
As well as the usual options for pcre2_match(), a number of additional
As well as the usual options for pcre2_match(), a number of additional
options can be set in the options argument of pcre2_substitute().
PCRE2_SUBSTITUTE_GLOBAL causes the function to iterate over the subject
string, replacing every matching substring. If this option is not set,
only the first matching substring is replaced. The search for matches
takes place in the original subject string (that is, previous replace-
ments do not affect it). Iteration is implemented by advancing the
startoffset value for each search, which is always passed the entire
string, replacing every matching substring. If this option is not set,
only the first matching substring is replaced. The search for matches
takes place in the original subject string (that is, previous replace-
ments do not affect it). Iteration is implemented by advancing the
startoffset value for each search, which is always passed the entire
subject string. If an offset limit is set in the match context, search-
ing stops when that limit is reached.
You can restrict the effect of a global substitution to a portion of
You can restrict the effect of a global substitution to a portion of
the subject string by setting either or both of startoffset and an off-
set limit. Here is a pcre2test example:
@ -3111,87 +3120,87 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
ABC ABC ABC ABC\=offset=3,offset_limit=12
2: ABC A!C A!C ABC
When continuing with global substitutions after matching a substring
When continuing with global substitutions after matching a substring
with zero length, an attempt to find a non-empty match at the same off-
set is performed. If this is not successful, the offset is advanced by
one character except when CRLF is a valid newline sequence and the next
two characters are CR, LF. In this case, the offset is advanced by two
two characters are CR, LF. In this case, the offset is advanced by two
characters.
PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
buffer is too small. The default action is to return PCRE2_ERROR_NOMEM-
ORY immediately. If this option is set, however, pcre2_substitute()
ORY immediately. If this option is set, however, pcre2_substitute()
continues to go through the motions of matching and substituting (with-
out, of course, writing anything) in order to compute the size of buf-
fer that is needed. This value is passed back via the outlengthptr
variable, with the result of the function still being
out, of course, writing anything) in order to compute the size of buf-
fer that is needed. This value is passed back via the outlengthptr
variable, with the result of the function still being
PCRE2_ERROR_NOMEMORY.
Passing a buffer size of zero is a permitted way of finding out how
much memory is needed for given substitution. However, this does mean
Passing a buffer size of zero is a permitted way of finding out how
much memory is needed for given substitution. However, this does mean
that the entire operation is carried out twice. Depending on the appli-
cation, it may be more efficient to allocate a large buffer and free
the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
cation, it may be more efficient to allocate a large buffer and free
the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
FLOW_LENGTH.
PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capturing groups
that do not appear in the pattern to be treated as unset groups. This
option should be used with care, because it means that a typo in a
group name or number no longer causes the PCRE2_ERROR_NOSUBSTRING
PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capturing groups
that do not appear in the pattern to be treated as unset groups. This
option should be used with care, because it means that a typo in a
group name or number no longer causes the PCRE2_ERROR_NOSUBSTRING
error.
PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capturing groups (including
PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capturing groups (including
unknown groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be
treated as empty strings when inserted as described above. If this
option is not set, an attempt to insert an unset group causes the
PCRE2_ERROR_UNSET error. This option does not influence the extended
treated as empty strings when inserted as described above. If this
option is not set, an attempt to insert an unset group causes the
PCRE2_ERROR_UNSET error. This option does not influence the extended
substitution syntax described below.
PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
replacement string. Without this option, only the dollar character is
special, and only the group insertion forms listed above are valid.
PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
replacement string. Without this option, only the dollar character is
special, and only the group insertion forms listed above are valid.
When PCRE2_SUBSTITUTE_EXTENDED is set, two things change:
Firstly, backslash in a replacement string is interpreted as an escape
Firstly, backslash in a replacement string is interpreted as an escape
character. The usual forms such as \n or \x{ddd} can be used to specify
particular character codes, and backslash followed by any non-alphanu-
meric character quotes that character. Extended quoting can be coded
particular character codes, and backslash followed by any non-alphanu-
meric character quotes that character. Extended quoting can be coded
using \Q...\E, exactly as in pattern strings.
There are also four escape sequences for forcing the case of inserted
letters. The insertion mechanism has three states: no case forcing,
There are also four escape sequences for forcing the case of inserted
letters. The insertion mechanism has three states: no case forcing,
force upper case, and force lower case. The escape sequences change the
current state: \U and \L change to upper or lower case forcing, respec-
tively, and \E (when not terminating a \Q quoted sequence) reverts to
no case forcing. The sequences \u and \l force the next character (if
it is a letter) to upper or lower case, respectively, and then the
tively, and \E (when not terminating a \Q quoted sequence) reverts to
no case forcing. The sequences \u and \l force the next character (if
it is a letter) to upper or lower case, respectively, and then the
state automatically reverts to no case forcing. Case forcing applies to
all inserted characters, including those from captured groups and let-
ters within \Q...\E quoted sequences.
Note that case forcing sequences such as \U...\E do not nest. For exam-
ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
\E has no effect.
The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
flexibility to group substitution. The syntax is similar to that used
The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
flexibility to group substitution. The syntax is similar to that used
by Bash:
${<n>:-<string>}
${<n>:+<string1>:<string2>}
As before, <n> may be a group number or a name. The first form speci-
fies a default value. If group <n> is set, its value is inserted; if
not, <string> is expanded and the result inserted. The second form
specifies strings that are expanded and inserted when group <n> is set
or unset, respectively. The first form is just a convenient shorthand
As before, <n> may be a group number or a name. The first form speci-
fies a default value. If group <n> is set, its value is inserted; if
not, <string> is expanded and the result inserted. The second form
specifies strings that are expanded and inserted when group <n> is set
or unset, respectively. The first form is just a convenient shorthand
for
${<n>:+${<n>}:<string>}
Backslash can be used to escape colons and closing curly brackets in
the replacement strings. A change of the case forcing state within a
replacement string remains in force afterwards, as shown in this
Backslash can be used to escape colons and closing curly brackets in
the replacement strings. A change of the case forcing state within a
replacement string remains in force afterwards, as shown in this
pcre2test example:
/(some)?(body)/substitute_extended,replace=${1:+\U:\L}HeLLo
@ -3200,37 +3209,38 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
somebody
1: HELLO
The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause
The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause
unknown groups in the extended syntax forms to be treated as unset.
If successful, pcre2_substitute() returns the number of replacements
If successful, pcre2_substitute() returns the number of replacements
that were made. This may be zero if no matches were found, and is never
greater than 1 unless PCRE2_SUBSTITUTE_GLOBAL is set.
In the event of an error, a negative error code is returned. Except for
PCRE2_ERROR_NOMATCH (which is never returned), errors from
PCRE2_ERROR_NOMATCH (which is never returned), errors from
pcre2_match() are passed straight back.
PCRE2_ERROR_NOSUBSTRING is returned for a non-existent substring inser-
tion, unless PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set.
PCRE2_ERROR_UNSET is returned for an unset substring insertion (includ-
ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
when the simple (non-extended) syntax is used and PCRE2_SUBSTI-
TUTE_UNSET_EMPTY is not set.
PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big
PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big
enough. If the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set, the size
of buffer that is needed is returned via outlengthptr. Note that this
of buffer that is needed is returned via outlengthptr. Note that this
does not happen by default.
PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
the replacement string, with more particular errors being
PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP-
MISSINGBRACE (closing curly bracket not found), PCRE2_ERROR_BADSUBSTI-
PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP-
MISSINGBRACE (closing curly bracket not found), PCRE2_ERROR_BADSUBSTI-
TUTION (syntax error in extended group substitution), and
PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before it started,
PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before it started
or the match started earlier than the current position in the subject,
which can happen if \K is used in an assertion).
As for all PCRE2 errors, a text message that describes the error can be
@ -3484,7 +3494,7 @@ AUTHOR
REVISION
Last updated: 27 April 2018
Last updated: 22 June 2018
Copyright (c) 1997-2018 University of Cambridge.
------------------------------------------------------------------------------

7
doc/pcre2api.3
View File

@ -1,4 +1,4 @@
.TH PCRE2API 3 "18 June 2018" "PCRE2 10.32"
.TH PCRE2API 3 "22 June 2018" "PCRE2 10.32"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.sp
@ -3328,7 +3328,8 @@ replacement string, with more particular errors being PCRE2_ERROR_BADREPESCAPE
(invalid escape sequence), PCRE2_ERROR_REPMISSINGBRACE (closing curly bracket
not found), PCRE2_ERROR_BADSUBSTITUTION (syntax error in extended group
substitution), and PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before
it started, which can happen if \eK is used in an assertion).
it started or the match started earlier than the current position in the
subject, which can happen if \eK is used in an assertion).
.P
As for all PCRE2 errors, a text message that describes the error can be
obtained by calling the \fBpcre2_get_error_message()\fP function (see
@ -3621,6 +3622,6 @@ Cambridge, England.
.rs
.sp
.nf
Last updated: 18 June 2018
Last updated: 22 June 2018
Copyright (c) 1997-2018 University of Cambridge.
.fi

2
src/pcre2_error.c
View File

@ -255,7 +255,7 @@ static const unsigned char match_error_texts[] =
"expected closing curly bracket in replacement string\0"
"bad substitution in replacement string\0"
/* 60 */
"match with end before start is not supported\0"
"match with end before start or start moved backwards is not supported\0"
"too many replacements (more than INT_MAX)\0"
"bad serialized data\0"
"heap limit exceeded\0"

4
src/pcre2_substitute.c
View File

@ -361,9 +361,9 @@ do
}
/* Handle a successful match. Matches that use \K to end before they start
are not supported. */
or start before the current point in the subject are not supported. */
if (ovector[1] < ovector[0])
if (ovector[1] < ovector[0] || ovector[0] < start_offset)
{
rc = PCRE2_ERROR_BADSUBSPATTERN;
goto EXIT;

3
testdata/testinput2 vendored
View File

@ -4644,6 +4644,9 @@ B)x/alt_verbnames,mark
/(?=a\K)/replace=z
BaCaD
/(?<=\K.)/g,replace=-
ab
/(?'abcdefghijklmnopqrstuvwxyzABCDEFG'toolong)/
/(?'abcdefghijklmnopqrstuvwxyzABCDEF'justright)/

6
testdata/testoutput2 vendored
View File

@ -14899,7 +14899,11 @@ Subject length lower bound = 1
/(?=a\K)/replace=z
BaCaD
Failed: error -60: match with end before start is not supported
Failed: error -60: match with end before start or start moved backwards is not supported
/(?<=\K.)/g,replace=-
ab
Failed: error -60: match with end before start or start moved backwards is not supported
/(?'abcdefghijklmnopqrstuvwxyzABCDEFG'toolong)/
Failed: error 148 at offset 36: subpattern name is too long (maximum 32 characters)