add PCRE2_ASCII (RFC)

As suggested in PCRE2Project#185 and as done with Perl with the '/aa' modifier
it is preferably for performance/security[1] reasons to avoid
including in \d characters that are outside the commonly expected
digits.

Add that functionality with the foundations of what was suggested
in PCRE2Project#11

[1] https://perldoc.perl.org/perlre#/a-(and-/aa)

Author: carenas

doc/pcre2_compile.3

@@ -44,6 +44,7 @@ The option bits are:
   PCRE2_ALT_BSUX           Alternative handling of \eu, \eU, and \ex
   PCRE2_ALT_CIRCUMFLEX     Alternative handling of ^ in multiline mode
   PCRE2_ALT_VERBNAMES      Process backslashes in verb names
+  PCRE2_ASCII              Prefer ASCII in conflicting UTF classes
   PCRE2_AUTO_CALLOUT       Compile automatic callouts
   PCRE2_CASELESS           Do caseless matching
   PCRE2_DOLLAR_ENDONLY     $ not to match newline at end

doc/pcre2api.3

@@ -1446,6 +1446,12 @@ included in a name either as \e) or between \eQ and \eE. If the PCRE2_EXTENDED
 or PCRE2_EXTENDED_MORE option is set with PCRE2_ALT_VERBNAMES, unescaped
 whitespace in verb names is skipped and #-comments are recognized, exactly as
 in the rest of the pattern.
+.sp
+  PCRE2_ASCII
+.sp
+When PCRE2_UTF and PCRE2_UCP are both being used, some classes are changed in
+ways that conflict between UTF and ASCII characters. This option can be set
+to restrict \ed to only match the non UTF digits.
 .sp
   PCRE2_AUTO_CALLOUT
 .sp

doc/pcre2pattern.3

@@ -73,10 +73,11 @@ appearance in a pattern causes an error.
 .sp
 Another special sequence that may appear at the start of a pattern is (*UCP).
 This has the same effect as setting the PCRE2_UCP option: it causes sequences
-such as \ed and \ew to use Unicode properties to determine character types,
-instead of recognizing only characters with codes less than 256 via a lookup
-table. If also causes upper/lower casing operations to use Unicode properties
-for characters with code points greater than 127, even when UTF is not set.
+such as \ed (unless PCRE2_ASCII was set) and \ew to use Unicode properties
+to determine character types, instead of recognizing only characters with
+codes less than 256 via a lookup table. It also causes upper/lower casing
+operations to use Unicode properties for characters with code points greater
+than 127, even when UTF is not set.
 .P
 Some applications that allow their users to supply patterns may wish to
 restrict them for security reasons. If the PCRE2_NEVER_UCP option is passed to
@@ -670,7 +671,8 @@ determine character types, as follows:
   \ew  any character that matches \ep{L} or \ep{N}, plus underscore
 .sp
 The upper case escapes match the inverse sets of characters. Note that \ed
-matches only decimal digits, whereas \ew matches any Unicode digit, as well as
+matches only decimal digits and could be forced to match only the original
+set with PCRE2_ASCII, whereas \ew matches any Unicode digit, as well as
 any Unicode letter, and underscore. Note also that PCRE2_UCP affects \eb, and
 \eB because they are defined in terms of \ew and \eW. Matching these sequences
 is noticeably slower when PCRE2_UCP is set.

doc/pcre2syntax.3

@@ -101,7 +101,8 @@ or in the 16-bit and 32-bit libraries. However, if locale-specific matching is
 happening, \es and \ew may also match characters with code points in the range
 128-255. If the PCRE2_UCP option is set, the behaviour of these escape
 sequences is changed to use Unicode properties and they match many more
-characters.
+characters. Alternatively if the PCRE2_ASCII option is also set \ed original
+definition is preserved.
 .P
 Property descriptions in \ep and \eP are matched caselessly; hyphens,
 underscores, and white space are ignored, in accordance with Unicode's "loose

src/pcre2.h.in

@@ -143,6 +143,7 @@ D   is inspected during pcre2_dfa_match() execution
 #define PCRE2_EXTENDED_MORE       0x01000000u  /* C       */
 #define PCRE2_LITERAL             0x02000000u  /* C       */
 #define PCRE2_MATCH_INVALID_UTF   0x04000000u  /*   J M D */
+#define PCRE2_ASCII               0x08000000u  /* C       */
 
 /* An additional compile options word is available in the compile context. */
 

src/pcre2_compile.c

@@ -776,7 +776,7 @@ are allowed. */
    PCRE2_EXTENDED|PCRE2_EXTENDED_MORE|PCRE2_MATCH_UNSET_BACKREF| \
    PCRE2_MULTILINE|PCRE2_NEVER_BACKSLASH_C|PCRE2_NEVER_UCP| \
    PCRE2_NEVER_UTF|PCRE2_NO_AUTO_CAPTURE|PCRE2_NO_AUTO_POSSESS| \
-   PCRE2_NO_DOTSTAR_ANCHOR|PCRE2_UCP|PCRE2_UNGREEDY)
+   PCRE2_NO_DOTSTAR_ANCHOR|PCRE2_UCP|PCRE2_UNGREEDY|PCRE2_ASCII)
 
 #define PUBLIC_LITERAL_COMPILE_EXTRA_OPTIONS \
    (PCRE2_EXTRA_MATCH_LINE|PCRE2_EXTRA_MATCH_WORD)
@@ -3124,14 +3124,17 @@ while (ptr < ptrend)
         }
       else
         {
-        *parsed_pattern++ = META_ESCAPE +
-          ((escape == ESC_d || escape == ESC_s || escape == ESC_w)?
-            ESC_p : ESC_P);
+        if ((options & PCRE2_ASCII) == 0)
+          *parsed_pattern++ = META_ESCAPE +
+            ((escape == ESC_s || escape == ESC_w)? ESC_p : ESC_P);
+        else
+          *parsed_pattern++ = META_ESCAPE + escape;
         switch(escape)
           {
           case ESC_d:
           case ESC_D:
-          *parsed_pattern++ = (PT_PC << 16) | ucp_Nd;
+          if ((options & PCRE2_ASCII) == 0)
+            *parsed_pattern++ = (PT_PC << 16) | ucp_Nd;
           break;
 
           case ESC_s:
@@ -3671,14 +3674,17 @@ while (ptr < ptrend)
             }
           else
             {
-            *parsed_pattern++ = META_ESCAPE +
-              ((escape == ESC_d || escape == ESC_s || escape == ESC_w)?
-                ESC_p : ESC_P);
+            if ((options & PCRE2_ASCII) == 0)
+              *parsed_pattern++ = META_ESCAPE +
+                ((escape == ESC_s || escape == ESC_w)? ESC_p : ESC_P);
+            else
+              *parsed_pattern++ = META_ESCAPE + escape;
             switch(escape)
               {
               case ESC_d:
               case ESC_D:
-              *parsed_pattern++ = (PT_PC << 16) | ucp_Nd;
+              if ((options & PCRE2_ASCII) == 0)
+                *parsed_pattern++ = (PT_PC << 16) | ucp_Nd;
               break;
 
               case ESC_s:

src/pcre2test.c

@@ -640,6 +640,7 @@ static modstruct modlist[] = {
   { "alt_verbnames",               MOD_PAT,  MOD_OPT, PCRE2_ALT_VERBNAMES,        PO(options) },
   { "altglobal",                   MOD_PND,  MOD_CTL, CTL_ALTGLOBAL,              PO(control) },
   { "anchored",                    MOD_PD,   MOD_OPT, PCRE2_ANCHORED,             PD(options) },
+  { "ascii",                       MOD_PATP, MOD_OPT, PCRE2_ASCII,                PO(options) },
   { "auto_callout",                MOD_PAT,  MOD_OPT, PCRE2_AUTO_CALLOUT,         PO(options) },
   { "bad_escape_is_literal",       MOD_CTC,  MOD_OPT, PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL, CO(extra_options) },
   { "bincode",                     MOD_PAT,  MOD_CTL, CTL_BINCODE,                PO(control) },
@@ -762,8 +763,8 @@ static modstruct modlist[] = {
 /* Controls and options that are supported for use with the POSIX interface. */
 
 #define POSIX_SUPPORTED_COMPILE_OPTIONS ( \
-  PCRE2_CASELESS|PCRE2_DOTALL|PCRE2_LITERAL|PCRE2_MULTILINE|PCRE2_UCP| \
-  PCRE2_UTF|PCRE2_UNGREEDY)
+  PCRE2_ASCII|PCRE2_CASELESS|PCRE2_DOTALL|PCRE2_LITERAL|PCRE2_MULTILINE| \
+  PCRE2_UCP| PCRE2_UTF|PCRE2_UNGREEDY)
 
 #define POSIX_SUPPORTED_COMPILE_EXTRA_OPTIONS (0)
 
@@ -4202,12 +4203,13 @@ static void
 show_compile_options(uint32_t options, const char *before, const char *after)
 {
 if (options == 0) fprintf(outfile, "%s <none>%s", before, after);
-else fprintf(outfile, "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
+else fprintf(outfile, "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
   before,
   ((options & PCRE2_ALT_BSUX) != 0)? " alt_bsux" : "",
   ((options & PCRE2_ALT_CIRCUMFLEX) != 0)? " alt_circumflex" : "",
   ((options & PCRE2_ALT_VERBNAMES) != 0)? " alt_verbnames" : "",
   ((options & PCRE2_ALLOW_EMPTY_CLASS) != 0)? " allow_empty_class" : "",
+  ((options & PCRE2_ASCII) != 0)? " ascii" : "",
   ((options & PCRE2_ANCHORED) != 0)? " anchored" : "",
   ((options & PCRE2_AUTO_CALLOUT) != 0)? " auto_callout" : "",
   ((options & PCRE2_CASELESS) != 0)? " caseless" : "",