Make regular expression parse error messages easier to understand.

Subject: Re: enhanced(?) regex error messages
Message-Id: <200008050634.XAA20360@ventrue.yahoo.com>

p4raw-id: //depot/perl@6540

diff --git a/regcomp.c b/regcomp.c
index f092e7e..911ef1c 100644 (file)
--- a/regcomp.c
+++ b/regcomp.c
@@ -201,6 +201,30 @@ static scan_data_t zero_scan_data = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 #define CHR_SVLEN(sv) (UTF ? sv_len_utf8(sv) : SvCUR(sv))
 #define CHR_DIST(a,b) (UTF ? utf8_distance(a,b) : a - b)
 
+
+#define        vFAIL(m)                                                             \
+    STMT_START {                                                             \
+       if (!SIZE_ONLY)                                                      \
+           SAVEDESTRUCTOR_X(clear_re,(void*)PL_regcomp_rx);                 \
+       Perl_croak(aTHX_ "%s at {#} mark in regex m/%.*s{#}%s/", m,          \
+                  strlen(PL_regprecomp)-(PL_regxend - PL_regcomp_parse),    \
+                   PL_regprecomp,                                            \
+                   PL_regprecomp + strlen(PL_regprecomp)-(PL_regxend - PL_regcomp_parse));\
+    } STMT_END
+
+#define        vFAIL2(pat,m)                                                        \
+    STMT_START {                                                             \
+       if (!SIZE_ONLY)                                                      \
+           SAVEDESTRUCTOR_X(clear_re,(void*)PL_regcomp_rx);                 \
+                                                                             \
+       S_re_croak2(aTHX_ pat, " at {#} mark in regex m/%.*s{#}%s/: ", m,    \
+                  strlen(PL_regprecomp)-(PL_regxend - PL_regcomp_parse),    \
+                   PL_regprecomp,                                            \
+                   PL_regprecomp + strlen(PL_regprecomp)-(PL_regxend - PL_regcomp_parse));\
+    } STMT_END
+
+
+
 /* Allow for side effects in s */
 #define REGC(c,s) STMT_START { if (!SIZE_ONLY) *(s) = (c); else (s);} STMT_END
 
@@ -1193,10 +1217,10 @@ S_study_chunk(pTHX_ regnode **scanp, I32 *deltap, regnode *last, scan_data_t *da
            minnext = study_chunk(&nscan, &deltanext, last, &data_fake, f);
            if (scan->flags) {
                if (deltanext) {
-                   FAIL("variable length lookbehind not implemented");
+                   vFAIL("variable length lookbehind not implemented");
                }
                else if (minnext > U8_MAX) {
-                   FAIL2("lookbehind longer than %"UVuf" not implemented", (UV)U8_MAX);
+                   vFAIL2("lookbehind longer than %"UVuf" not implemented", (UV)U8_MAX);
                }
                scan->flags = minnext;
            }
@@ -1307,6 +1331,7 @@ Perl_reginitcolors(pTHX)
     PL_colorset = 1;
 }
 
+
 /*
  - pregcomp - compile a regular expression into internal code
  *
@@ -1726,7 +1751,7 @@ S_reg(pTHX_ I32 paren, I32 *flagp)
                break;
            case '$':
            case '@':
-               FAIL2("Sequence (?%c...) not implemented", (int)paren);
+               vFAIL2("Sequence (?%c...) not implemented", (int)paren);
                break;
            case '#':
                while (*PL_regcomp_parse && *PL_regcomp_parse != ')')
@@ -1825,7 +1850,7 @@ S_reg(pTHX_ I32 paren, I32 *flagp)
                        PL_regcomp_parse++;
                    ret = reganode(GROUPP, parno);
                    if ((c = *nextchar()) != ')')
-                       FAIL2("Switch (?(number%c not recognized", c);
+                       vFAIL2("Switch (?(number%c not recognized", c);
                  insert_if:
                    regtail(ret, reganode(IFTHEN, 0));
                    br = regbranch(&flags, 1);
@@ -1847,7 +1872,7 @@ S_reg(pTHX_ I32 paren, I32 *flagp)
                    else
                        lastbr = NULL;
                    if (c != ')')
-                       FAIL("Switch (?(condition)... contains too many branches");
+                       vFAIL("Switch (?(condition)... contains too many branches");
                    ender = reg_node(TAIL);
                    regtail(br, ender);
                    if (lastbr) {
@@ -1859,11 +1884,11 @@ S_reg(pTHX_ I32 paren, I32 *flagp)
                    return ret;
                }
                else {
-                   FAIL2("Unknown condition for (?(%.2s", PL_regcomp_parse);
+                   vFAIL2("Unknown condition for (?(%.2s", PL_regcomp_parse);
                }
            }
             case 0:
-                FAIL("Sequence (? incomplete");
+                vFAIL("Sequence (? incomplete");
                 break;
            default:
                --PL_regcomp_parse;
@@ -1887,7 +1912,7 @@ S_reg(pTHX_ I32 paren, I32 *flagp)
                }               
              unknown:
                if (*PL_regcomp_parse != ')')
-                   FAIL2("Sequence (?%c...) not recognized", *PL_regcomp_parse);
+                   vFAIL2("Sequence (?%c...) not recognized", *PL_regcomp_parse);
                nextchar();
                *flagp = TRYAGAIN;
                return NULL;
@@ -2132,7 +2157,7 @@ S_regpiece(pTHX_ I32 *flagp)
            if (!max && *maxpos != '0')
                max = REG_INFTY;                /* meaning "infinity" */
            else if (max >= REG_INFTY)
-               FAIL2("Quantifier in {,} bigger than %d", REG_INFTY - 1);
+               vFAIL2("Quantifier in {,} bigger than %d", REG_INFTY - 1);
            PL_regcomp_parse = next;
            nextchar();
 
@@ -2166,7 +2191,7 @@ S_regpiece(pTHX_ I32 *flagp)
            if (max > 0)
                *flagp |= HASWIDTH;
            if (max && max < min)
-               FAIL("Can't do {n,m} with n > m");
+               vFAIL("Can't do {n,m} with n > m");
            if (!SIZE_ONLY) {
                ARG1_SET(ret, min);
                ARG2_SET(ret, max);
@@ -2224,7 +2249,7 @@ S_regpiece(pTHX_ I32 *flagp)
        regtail(ret, ret + NODE_STEP_REGNODE);
     }
     if (ISMULT2(PL_regcomp_parse))
-       FAIL("nested *?+ in regexp");
+       vFAIL("nested quantifiers in regexp");
 
     return(ret);
 }
@@ -2319,7 +2344,7 @@ tryagain:
            *flagp |= TRYAGAIN;
            return NULL;
        }
-       FAIL2("internal urp in regexp at /%s/", PL_regcomp_parse);
+       vFAIL("internal urp");
                                /* Supposed to be caught earlier. */
        break;
     case '{':
@@ -2331,7 +2356,7 @@ tryagain:
     case '?':
     case '+':
     case '*':
-       FAIL("?+*{} follows nothing in regexp");
+       vFAIL("quantifier follows nothing in regexp");
        break;
     case '\\':
        switch (*++PL_regcomp_parse) {
@@ -2490,7 +2515,7 @@ tryagain:
                    goto defchar;
                else {
                    if (!SIZE_ONLY && num > PL_regcomp_rx->nparens)
-                       FAIL("reference to nonexistent group");
+                       vFAIL("reference to nonexistent group");
                    PL_regsawback = 1;
                    ret = reganode(FOLD
                                   ? (LOC ? REFFL : REFF)
@@ -2620,7 +2645,7 @@ tryagain:
                                p = e + 1;
                            }
                            else
-                               FAIL("Can't use \\x{} without 'use utf8' declaration");
+                               vFAIL("Can't use \\x{} without 'use utf8' declaration");
                        }
                        else {
                            numlen = 0;         /* disallow underscores */
@@ -2703,7 +2728,7 @@ tryagain:
            PL_regcomp_parse = p - 1;
            nextchar();
            if (len < 0)
-               FAIL("internal disaster in regexp");
+               vFAIL("internal disaster");
            if (len > 0)
                *flagp |= HASWIDTH;
            if (len == 1)
@@ -3239,7 +3264,7 @@ S_regclass(pTHX)
                    }
                    break;
                default:
-                   FAIL("invalid [::] class in regexp");
+                   vFAIL("invalid [::] class");
                    break;
                }
                if (LOC)