regguts.h

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/*
 * Internal interface definitions, etc., for the reg package
 *
 * Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.
 *
 * Development of this software was funded, in part, by Cray Research Inc.,
 * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
 * Corporation, none of whom are responsible for the results.  The author
 * thanks all of them.
 *
 * Redistribution and use in source and binary forms -- with or without
 * modification -- are permitted for any purpose, provided that
 * redistributions in source form retain this entire copyright notice and
 * indicate the origin and nature of any modifications.
 *
 * I'd appreciate being given credit for this package in the documentation
 * of software which uses it, but that is not a requirement.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * src/include/regex/regguts.h
 */



/*
 * Environmental customization.  It should not (I hope) be necessary to
 * alter the file you are now reading -- regcustom.h should handle it all,
 * given care here and elsewhere.
 */
#include "regcustom.h"



/*
 * Things that regcustom.h might override.
 */

/* assertions */
#ifndef assert
#ifndef REG_DEBUG
#define  NDEBUG                 /* no assertions */
#endif
#include <assert.h>
#endif

/* voids */
#ifndef DISCARD
#define DISCARD void            /* for throwing values away */
#endif
#ifndef VS
#define VS(x)   ((void *)(x))   /* cast something to generic ptr */
#endif

/* function-pointer declarator */
#ifndef FUNCPTR
#define FUNCPTR(name, args) (*(name)) args
#endif

/* memory allocation */
#ifndef MALLOC
#define MALLOC(n)   malloc(n)
#endif
#ifndef REALLOC
#define REALLOC(p, n)   realloc(VS(p), n)
#endif
#ifndef FREE
#define FREE(p)     free(VS(p))
#endif

/* want size of a char in bits, and max value in bounded quantifiers */
#ifndef CHAR_BIT
#include <limits.h>
#endif
#ifndef _POSIX2_RE_DUP_MAX
#define _POSIX2_RE_DUP_MAX  255 /* normally from <limits.h> */
#endif



/*
 * misc
 */

#define NOTREACHED  0
#define xxx     1

#define DUPMAX  _POSIX2_RE_DUP_MAX
#define INFINITY    (DUPMAX+1)

#define REMAGIC 0xfed7          /* magic number for main struct */



/*
 * debugging facilities
 */
#ifdef REG_DEBUG
/* FDEBUG does finite-state tracing */
#define FDEBUG(arglist) { if (v->eflags&REG_FTRACE) printf arglist; }
/* MDEBUG does higher-level tracing */
#define MDEBUG(arglist) { if (v->eflags&REG_MTRACE) printf arglist; }
#else
#define FDEBUG(arglist) {}
#define MDEBUG(arglist) {}
#endif



/*
 * bitmap manipulation
 */
#define UBITS   (CHAR_BIT * sizeof(unsigned))
#define BSET(uv, sn)    ((uv)[(sn)/UBITS] |= (unsigned)1 << ((sn)%UBITS))
#define ISBSET(uv, sn)  ((uv)[(sn)/UBITS] & ((unsigned)1 << ((sn)%UBITS)))



/*
 * We dissect a chr into byts for colormap table indexing.  Here we define
 * a byt, which will be the same as a byte on most machines...  The exact
 * size of a byt is not critical, but about 8 bits is good, and extraction
 * of 8-bit chunks is sometimes especially fast.
 */
#ifndef BYTBITS
#define BYTBITS 8               /* bits in a byt */
#endif
#define BYTTAB  (1<<BYTBITS)    /* size of table with one entry per byt value */
#define BYTMASK (BYTTAB-1)      /* bit mask for byt */
#define NBYTS   ((CHRBITS+BYTBITS-1)/BYTBITS)
/* the definition of GETCOLOR(), below, assumes NBYTS <= 4 */



/*
 * As soon as possible, we map chrs into equivalence classes -- "colors" --
 * which are of much more manageable number.
 */
typedef short color;            /* colors of characters */
typedef int pcolor;             /* what color promotes to */

#define MAX_COLOR   32767       /* max color (must fit in 'color' datatype) */
#define COLORLESS   (-1)        /* impossible color */
#define WHITE       0           /* default color, parent of all others */



/*
 * A colormap is a tree -- more precisely, a DAG -- indexed at each level
 * by a byt of the chr, to map the chr to a color efficiently.  Because
 * lower sections of the tree can be shared, it can exploit the usual
 * sparseness of such a mapping table.  The tree is always NBYTS levels
 * deep (in the past it was shallower during construction but was "filled"
 * to full depth at the end of that); areas that are unaltered as yet point
 * to "fill blocks" which are entirely WHITE in color.
 */

/* the tree itself */
struct colors
{
    color       ccolor[BYTTAB];
};
struct ptrs
{
    union tree *pptr[BYTTAB];
};
union tree
{
    struct colors colors;
    struct ptrs ptrs;
};

#define tcolor  colors.ccolor
#define tptr    ptrs.pptr

/*
 * Per-color data structure for the compile-time color machinery
 *
 * If "sub" is not NOSUB then it is the number of the color's current
 * subcolor, i.e. we are in process of dividing this color (character
 * equivalence class) into two colors.  See src/backend/regex/README for
 * discussion of subcolors.
 *
 * Currently-unused colors have the FREECOL bit set and are linked into a
 * freelist using their "sub" fields, but only if their color numbers are
 * less than colormap.max.  Any array entries beyond "max" are just garbage.
 */
struct colordesc
{
    uchr        nchrs;          /* number of chars of this color */
    color       sub;            /* open subcolor, if any; or free-chain ptr */
#define  NOSUB   COLORLESS      /* value of "sub" when no open subcolor */
    struct arc *arcs;           /* chain of all arcs of this color */
    chr         firstchr;       /* char first assigned to this color */
    int         flags;          /* bit values defined next */
#define  FREECOL 01             /* currently free */
#define  PSEUDO  02             /* pseudocolor, no real chars */
#define  UNUSEDCOLOR(cd) ((cd)->flags & FREECOL)
    union tree *block;          /* block of solid color, if any */
};

/*
 * The color map itself
 *
 * Much of the data in the colormap struct is only used at compile time.
 * However, the bulk of the space usage is in the "tree" structure, so it's
 * not clear that there's much point in converting the rest to a more compact
 * form when compilation is finished.
 */
struct colormap
{
    int         magic;
#define  CMMAGIC 0x876
    struct vars *v;             /* for compile error reporting */
    size_t      ncds;           /* allocated length of colordescs array */
    size_t      max;            /* highest color number currently in use */
    color       free;           /* beginning of free chain (if non-0) */
    struct colordesc *cd;       /* pointer to array of colordescs */
#define  CDEND(cm)   (&(cm)->cd[(cm)->max + 1])
    /* If we need up to NINLINECDS, we store them here to save a malloc */
#define  NINLINECDS  ((size_t)10)
    struct colordesc cdspace[NINLINECDS];
    union tree  tree[NBYTS];    /* tree top, plus lower-level fill blocks */
};

/* optimization magic to do fast chr->color mapping */
#define B0(c)   ((c) & BYTMASK)
#define B1(c)   (((c)>>BYTBITS) & BYTMASK)
#define B2(c)   (((c)>>(2*BYTBITS)) & BYTMASK)
#define B3(c)   (((c)>>(3*BYTBITS)) & BYTMASK)
#if NBYTS == 1
#define GETCOLOR(cm, c) ((cm)->tree->tcolor[B0(c)])
#endif
/* beware, for NBYTS>1, GETCOLOR() is unsafe -- 2nd arg used repeatedly */
#if NBYTS == 2
#define GETCOLOR(cm, c) ((cm)->tree->tptr[B1(c)]->tcolor[B0(c)])
#endif
#if NBYTS == 4
#define GETCOLOR(cm, c) ((cm)->tree->tptr[B3(c)]->tptr[B2(c)]->tptr[B1(c)]->tcolor[B0(c)])
#endif


/*
 * Interface definitions for locale-interface functions in regc_locale.c.
 */

/*
 * Representation of a set of characters.  chrs[] represents individual
 * code points, ranges[] represents ranges in the form min..max inclusive.
 *
 * Note that in cvecs gotten from newcvec() and intended to be freed by
 * freecvec(), both arrays of chrs are after the end of the struct, not
 * separately malloc'd; so chrspace and rangespace are effectively immutable.
 */
struct cvec
{
    int         nchrs;          /* number of chrs */
    int         chrspace;       /* number of chrs allocated in chrs[] */
    chr        *chrs;           /* pointer to vector of chrs */
    int         nranges;        /* number of ranges (chr pairs) */
    int         rangespace;     /* number of ranges allocated in ranges[] */
    chr        *ranges;         /* pointer to vector of chr pairs */
};


/*
 * definitions for NFA internal representation
 *
 * Having a "from" pointer within each arc may seem redundant, but it
 * saves a lot of hassle.
 */
struct state;

struct arc
{
    int         type;           /* 0 if free, else an NFA arc type code */
    color       co;
    struct state *from;         /* where it's from (and contained within) */
    struct state *to;           /* where it's to */
    struct arc *outchain;       /* link in *from's outs chain or free chain */
#define  freechain   outchain
    struct arc *inchain;        /* link in *to's ins chain */
    struct arc *colorchain;     /* link in color's arc chain */
    struct arc *colorchainRev;  /* back-link in color's arc chain */
};

struct arcbatch
{                               /* for bulk allocation of arcs */
    struct arcbatch *next;
#define  ABSIZE  10
    struct arc  a[ABSIZE];
};

struct state
{
    int         no;
#define  FREESTATE   (-1)
    char        flag;           /* marks special states */
    int         nins;           /* number of inarcs */
    struct arc *ins;            /* chain of inarcs */
    int         nouts;          /* number of outarcs */
    struct arc *outs;           /* chain of outarcs */
    struct arc *free;           /* chain of free arcs */
    struct state *tmp;          /* temporary for traversal algorithms */
    struct state *next;         /* chain for traversing all */
    struct state *prev;         /* back chain */
    struct arcbatch oas;        /* first arcbatch, avoid malloc in easy case */
    int         noas;           /* number of arcs used in first arcbatch */
};

struct nfa
{
    struct state *pre;          /* pre-initial state */
    struct state *init;         /* initial state */
    struct state *final;        /* final state */
    struct state *post;         /* post-final state */
    int         nstates;        /* for numbering states */
    struct state *states;       /* state-chain header */
    struct state *slast;        /* tail of the chain */
    struct state *free;         /* free list */
    struct colormap *cm;        /* the color map */
    color       bos[2];         /* colors, if any, assigned to BOS and BOL */
    color       eos[2];         /* colors, if any, assigned to EOS and EOL */
    size_t      size;           /* Current NFA size; differs from nstates as
                                 * it also counts the number of states created
                                 * by children of this state. */
    struct vars *v;             /* simplifies compile error reporting */
    struct nfa *parent;         /* parent NFA, if any */
};



/*
 * definitions for compacted NFA
 *
 * The main space savings in a compacted NFA is from making the arcs as small
 * as possible.  We store only the transition color and next-state number for
 * each arc.  The list of out arcs for each state is an array beginning at
 * cnfa.states[statenumber], and terminated by a dummy carc struct with
 * co == COLORLESS.
 *
 * The non-dummy carc structs are of two types: plain arcs and LACON arcs.
 * Plain arcs just store the transition color number as "co".  LACON arcs
 * store the lookahead constraint number plus cnfa.ncolors as "co".  LACON
 * arcs can be distinguished from plain by testing for co >= cnfa.ncolors.
 */
struct carc
{
    color       co;             /* COLORLESS is list terminator */
    int         to;             /* next-state number */
};

struct cnfa
{
    int         nstates;        /* number of states */
    int         ncolors;        /* number of colors (max color in use + 1) */
    int         flags;
#define  HASLACONS  01          /* uses lookahead constraints */
    int         pre;            /* setup state number */
    int         post;           /* teardown state number */
    color       bos[2];         /* colors, if any, assigned to BOS and BOL */
    color       eos[2];         /* colors, if any, assigned to EOS and EOL */
    char       *stflags;        /* vector of per-state flags bytes */
#define  CNFA_NOPROGRESS    01  /* flag bit for a no-progress state */
    struct carc **states;       /* vector of pointers to outarc lists */
    /* states[n] are pointers into a single malloc'd array of arcs */
    struct carc *arcs;          /* the area for the lists */
};

#define ZAPCNFA(cnfa)   ((cnfa).nstates = 0)
#define NULLCNFA(cnfa)  ((cnfa).nstates == 0)

/*
 * Used to limit the maximum NFA size to something sane. [Tcl Bug 1810264]
 */
#ifndef REG_MAX_STATES
#define REG_MAX_STATES  100000
#endif

/*
 * subexpression tree
 *
 * "op" is one of:
 *      '='  plain regex without interesting substructure (implemented as DFA)
 *      'b'  back-reference (has no substructure either)
 *      '('  capture node: captures the match of its single child
 *      '.'  concatenation: matches a match for left, then a match for right
 *      '|'  alternation: matches a match for left or a match for right
 *      '*'  iteration: matches some number of matches of its single child
 *
 * Note: the right child of an alternation must be another alternation or
 * NULL; hence, an N-way branch requires N alternation nodes, not N-1 as you
 * might expect.  This could stand to be changed.  Actually I'd rather see
 * a single alternation node with N children, but that will take revising
 * the representation of struct subre.
 *
 * Note: when a backref is directly quantified, we stick the min/max counts
 * into the backref rather than plastering an iteration node on top.  This is
 * for efficiency: there is no need to search for possible division points.
 */
struct subre
{
    char        op;             /* see type codes above */
    char        flags;
#define  LONGER  01             /* prefers longer match */
#define  SHORTER 02             /* prefers shorter match */
#define  MIXED   04             /* mixed preference below */
#define  CAP 010                /* capturing parens below */
#define  BACKR   020            /* back reference below */
#define  INUSE   0100           /* in use in final tree */
#define  LOCAL   03             /* bits which may not propagate up */
#define  LMIX(f) ((f)<<2)       /* LONGER -> MIXED */
#define  SMIX(f) ((f)<<1)       /* SHORTER -> MIXED */
#define  UP(f)   (((f)&~LOCAL) | (LMIX(f) & SMIX(f) & MIXED))
#define  MESSY(f)    ((f)&(MIXED|CAP|BACKR))
#define  PREF(f) ((f)&LOCAL)
#define  PREF2(f1, f2)   ((PREF(f1) != 0) ? PREF(f1) : PREF(f2))
#define  COMBINE(f1, f2) (UP((f1)|(f2)) | PREF2(f1, f2))
    short       id;             /* ID of subre (1..ntree-1) */
    int         subno;          /* subexpression number (for 'b' and '(') */
    short       min;            /* min repetitions for iteration or backref */
    short       max;            /* max repetitions for iteration or backref */
    struct subre *left;         /* left child, if any (also freelist chain) */
    struct subre *right;        /* right child, if any */
    struct state *begin;        /* outarcs from here... */
    struct state *end;          /* ...ending in inarcs here */
    struct cnfa cnfa;           /* compacted NFA, if any */
    struct subre *chain;        /* for bookkeeping and error cleanup */
};



/*
 * table of function pointers for generic manipulation functions
 * A regex_t's re_fns points to one of these.
 */
struct fns
{
    void        FUNCPTR(free, (regex_t *));
};



/*
 * the insides of a regex_t, hidden behind a void *
 */
struct guts
{
    int         magic;
#define  GUTSMAGIC   0xfed9
    int         cflags;         /* copy of compile flags */
    long        info;           /* copy of re_info */
    size_t      nsub;           /* copy of re_nsub */
    struct subre *tree;
    struct cnfa search;         /* for fast preliminary search */
    int         ntree;          /* number of subre's, less one */
    struct colormap cmap;
    int         FUNCPTR(compare, (const chr *, const chr *, size_t));
    struct subre *lacons;       /* lookahead-constraint vector */
    int         nlacons;        /* size of lacons */
};