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27af91438b
Create src/backend/regex/README to hold an implementation overview of the regex package, and fill it in with some preliminary notes about the code's DFA/NFA processing and colormap management. Much more to do there of course. Also, improve some code comments around the colormap and cvec code. No functional changes except to add one missing assert.
137 lines
3.9 KiB
C
137 lines
3.9 KiB
C
/*
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* Utility functions for handling cvecs
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* This file is #included by regcomp.c.
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*
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* Copyright (c) 1998, 1999 Henry Spencer. All rights reserved.
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*
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* Development of this software was funded, in part, by Cray Research Inc.,
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* UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
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* Corporation, none of whom are responsible for the results. The author
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* thanks all of them.
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*
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* Redistribution and use in source and binary forms -- with or without
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* modification -- are permitted for any purpose, provided that
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* redistributions in source form retain this entire copyright notice and
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* indicate the origin and nature of any modifications.
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*
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* I'd appreciate being given credit for this package in the documentation
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* of software which uses it, but that is not a requirement.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* src/backend/regex/regc_cvec.c
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*
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*/
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/*
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* Notes:
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* Only (selected) functions in _this_ file should treat chr* as non-constant.
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*/
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/*
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* newcvec - allocate a new cvec
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*/
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static struct cvec *
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newcvec(int nchrs, /* to hold this many chrs... */
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int nranges) /* ... and this many ranges */
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{
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size_t nc = (size_t) nchrs + (size_t) nranges * 2;
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size_t n = sizeof(struct cvec) + nc * sizeof(chr);
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struct cvec *cv = (struct cvec *) MALLOC(n);
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if (cv == NULL)
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return NULL;
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cv->chrspace = nchrs;
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cv->chrs = (chr *) (((char *) cv) + sizeof(struct cvec));
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cv->ranges = cv->chrs + nchrs;
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cv->rangespace = nranges;
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return clearcvec(cv);
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}
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/*
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* clearcvec - clear a possibly-new cvec
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* Returns pointer as convenience.
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*/
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static struct cvec *
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clearcvec(struct cvec * cv)
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{
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assert(cv != NULL);
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cv->nchrs = 0;
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cv->nranges = 0;
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return cv;
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}
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/*
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* addchr - add a chr to a cvec
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*/
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static void
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addchr(struct cvec * cv, /* character vector */
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chr c) /* character to add */
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{
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assert(cv->nchrs < cv->chrspace);
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cv->chrs[cv->nchrs++] = (chr) c;
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}
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/*
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* addrange - add a range to a cvec
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*/
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static void
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addrange(struct cvec * cv, /* character vector */
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chr from, /* first character of range */
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chr to) /* last character of range */
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{
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assert(cv->nranges < cv->rangespace);
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cv->ranges[cv->nranges * 2] = (chr) from;
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cv->ranges[cv->nranges * 2 + 1] = (chr) to;
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cv->nranges++;
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}
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/*
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* getcvec - get a transient cvec, initialized to empty
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*
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* The returned cvec is valid only until the next call of getcvec, which
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* typically will recycle the space. Callers should *not* free the cvec
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* explicitly; it will be cleaned up when the struct vars is destroyed.
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*
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* This is typically used while interpreting bracket expressions. In that
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* usage the cvec is only needed momentarily until we build arcs from it,
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* so transientness is a convenient behavior.
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*/
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static struct cvec *
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getcvec(struct vars * v, /* context */
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int nchrs, /* to hold this many chrs... */
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int nranges) /* ... and this many ranges */
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{
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/* recycle existing transient cvec if large enough */
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if (v->cv != NULL && nchrs <= v->cv->chrspace &&
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nranges <= v->cv->rangespace)
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return clearcvec(v->cv);
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/* nope, make a new one */
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if (v->cv != NULL)
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freecvec(v->cv);
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v->cv = newcvec(nchrs, nranges);
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if (v->cv == NULL)
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ERR(REG_ESPACE);
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return v->cv;
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}
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/*
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* freecvec - free a cvec
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*/
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static void
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freecvec(struct cvec * cv)
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{
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FREE(cv);
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}
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