diff options
Diffstat (limited to 'src/include/regex/regguts.h')
| -rw-r--r-- | src/include/regex/regguts.h | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/src/include/regex/regguts.h b/src/include/regex/regguts.h index 0a616562d03..6d391083194 100644 --- a/src/include/regex/regguts.h +++ b/src/include/regex/regguts.h @@ -130,11 +130,16 @@ /* * As soon as possible, we map chrs into equivalence classes -- "colors" -- * which are of much more manageable number. + * + * To further reduce the number of arcs in NFAs and DFAs, we also have a + * special RAINBOW "color" that can be assigned to an arc. This is not a + * real color, in that it has no entry in color maps. */ typedef short color; /* colors of characters */ #define MAX_COLOR 32767 /* max color (must fit in 'color' datatype) */ #define COLORLESS (-1) /* impossible color */ +#define RAINBOW (-2) /* represents all colors except pseudocolors */ #define WHITE 0 /* default color, parent of all others */ /* Note: various places in the code know that WHITE is zero */ @@ -276,7 +281,7 @@ struct state; struct arc { int type; /* 0 if free, else an NFA arc type code */ - color co; + color co; /* color the arc matches (possibly RAINBOW) */ 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 */ @@ -284,6 +289,7 @@ struct arc #define freechain outchain /* we do not maintain "freechainRev" */ struct arc *inchain; /* link in *to's ins chain */ struct arc *inchainRev; /* back-link in *to's ins chain */ + /* these fields are not used when co == RAINBOW: */ struct arc *colorchain; /* link in color's arc chain */ struct arc *colorchainRev; /* back-link in color's arc chain */ }; @@ -344,6 +350,9 @@ struct nfa * Plain arcs just store the transition color number as "co". LACON arcs * store the lookaround constraint number plus cnfa.ncolors as "co". LACON * arcs can be distinguished from plain by testing for co >= cnfa.ncolors. + * + * Note that in a plain arc, "co" can be RAINBOW; since that's negative, + * it doesn't break the rule about how to recognize LACON arcs. */ struct carc { |