Annotation of gforth/regexp.fs, revision 1.15

1.1       pazsan      1: \ Regexp compile
                      2: 
1.13      anton       3: \ Copyright (C) 2005,2006,2007,2008 Free Software Foundation, Inc.
1.3       anton       4: 
                      5: \ This file is part of Gforth.
                      6: 
                      7: \ Gforth is free software; you can redistribute it and/or
                      8: \ modify it under the terms of the GNU General Public License
1.10      anton       9: \ as published by the Free Software Foundation, either version 3
1.3       anton      10: \ of the License, or (at your option) any later version.
                     11: 
                     12: \ This program is distributed in the hope that it will be useful,
                     13: \ but WITHOUT ANY WARRANTY; without even the implied warranty of
                     14: \ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                     15: \ GNU General Public License for more details.
                     16: 
                     17: \ You should have received a copy of the GNU General Public License
1.10      anton      18: \ along with this program. If not, see http://www.gnu.org/licenses/.
1.3       anton      19: 
1.1       pazsan     20: \ The idea of the parser is the following:
                     21: \ As long as there's a match, continue
                     22: \ On a mismatch, LEAVE.
                     23: \ Insert appropriate control structures on alternative branches
                     24: \ Keep the old pointer (backtracking) on the stack
                     25: \ I try to keep the syntax as close to a real regexp system as possible
                     26: \ All regexp stuff is compiled into one function as forward branching
                     27: \ state machine
                     28: 
1.2       pazsan     29: \ special control structure
1.1       pazsan     30: 
1.8       pazsan     31: : FORK ( compilation -- orig ; run-time f -- ) \ gforth
                     32:     \G AHEAD-like control structure: calls the code after JOIN.
1.1       pazsan     33:     POSTPONE call >mark ; immediate restrict
1.8       pazsan     34: : JOIN ( orig -- ) \ gforth
                     35:     \G THEN-like control structure for FORK
                     36:     postpone THEN ; immediate restrict
1.1       pazsan     37: 
                     38: \ Charclasses
                     39: 
                     40: : +bit ( addr n -- )  + 1 swap c! ;
                     41: : -bit ( addr n -- )  + 0 swap c! ;
                     42: : @+ ( addr -- n addr' )  dup @ swap cell+ ;
                     43: 
                     44: 0 Value cur-class
1.8       pazsan     45: : charclass ( -- ) \ regexp-cg
                     46:     \G Create a charclass
                     47:     Create here dup to cur-class $100 dup allot erase ;
                     48: : +char ( char -- ) \ regexp-cg
                     49:     \G add a char to the current charclass
                     50:     cur-class swap +bit ;
                     51: : -char ( char -- ) \ regexp-cg
                     52:     \G remove a char from the current charclass
                     53:     cur-class swap -bit ;
                     54: : ..char ( start end -- ) \ regexp-cg
                     55:     \G add a range of chars to the current charclass
                     56:     1+ swap ?DO  I +char  LOOP ;
1.1       pazsan     57: : or! ( n addr -- )  dup @ rot or swap ! ;
                     58: : and! ( n addr -- )  dup @ rot and swap ! ;
1.8       pazsan     59: : +class ( class -- ) \ regexp-cg
                     60:     \G union of charclass @var{class} and the current charclass
                     61:     $100 0 ?DO  @+ swap
                     62:     cur-class I + or!  cell +LOOP  drop ;
                     63: : -class ( class -- ) \ regexp-cg
                     64:     \G subtract the charclass @var{class} from the current charclass
                     65:     $100 0 ?DO  @+ swap invert
                     66:     cur-class I + and!  cell +LOOP  drop ;
1.1       pazsan     67: 
                     68: : char? ( addr class -- addr' flag )
                     69:     >r count r> + c@ ;
                     70: 
                     71: \ Charclass tests
                     72: 
1.8       pazsan     73: : c? ( addr class -- ) \ regexp-pattern
                     74:     \G check @var{addr} for membership in charclass @var{class}
                     75:     ]] char? 0= ?LEAVE [[ ; immediate
                     76: : -c? ( addr class -- ) \ regexp-pattern
                     77:     \G check @var{addr} for not membership in charclass @var{class}
                     78:     ]] char?    ?LEAVE [[ ; immediate
1.1       pazsan     79: 
                     80: charclass digit  '0 '9 ..char
                     81: charclass blanks 0 bl ..char
                     82: \ bl +char #tab +char #cr +char #lf +char ctrl L +char
                     83: charclass letter 'a 'z ..char 'A 'Z ..char
                     84: charclass any    0 $FF ..char #lf -char
                     85: 
1.8       pazsan     86: : \d ( addr -- addr' ) \ regexp-pattern
                     87:     \G check for digit
                     88:     ]] digit c?        [[ ; immediate
                     89: : \s ( addr -- addr' ) \ regexp-pattern
                     90:     \G check for blanks
                     91:     ]] blanks c?       [[ ; immediate
                     92: : .? ( addr -- addr' ) \ regexp-pattern
                     93:     \G check for any single charachter
                     94:     ]] any c?          [[ ; immediate
                     95: : -\d ( addr -- addr' ) \ regexp-pattern
                     96:     \G check for not digit
                     97:     ]] digit -c?       [[ ; immediate
                     98: : -\s ( addr -- addr' ) \ regexp-pattern
                     99:     \G check for not blank
                    100:     ]] blanks -c?      [[ ; immediate
                    101: : ` ( "char" -- ) \ regexp-pattern
                    102:     \G check for particular char
1.1       pazsan    103:     ]] count [[  char ]] Literal <> ?LEAVE [[ ;  immediate
                    104: 
                    105: \ A word for string comparison
                    106: 
                    107: : $= ( addr1 addr2 u -- f )  tuck compare ;
                    108: : ,=" ( addr u -- ) tuck ]] dup SLiteral $= ?LEAVE Literal + noop [[ ;
1.8       pazsan    109: : =" ( <string>" -- ) \ regexp-pattern
                    110:     \G check for string
                    111:     '" parse ,=" ; immediate
1.1       pazsan    112: 
                    113: \ loop stack
                    114: 
                    115: Variable loops  $40 3 * cells allot
                    116: : 3@ ( addr -- a b c )  dup >r 2 cells + @ r> 2@ ;
                    117: : 3! ( a b c addr -- )  dup >r 2! r> 2 cells + ! ;
                    118: : loops> ( -- addr ) -3 loops +!  loops @+ swap cells + 3@ ;
                    119: : >loops ( addr -- ) loops @+ swap cells + 3! 3 loops +! ;
                    120: : BEGIN, ( -- )  ]] BEGIN [[ >loops ;
                    121: : DONE, ( -- )  loops @ IF  loops> ]] DONE [[ THEN ]] noop [[ ;
                    122: 
                    123: \ variables
                    124: 
                    125: Variable vars   &18 cells allot
                    126: Variable varstack 9 cells allot
                    127: Variable varsmax
                    128: : >var ( -- addr ) vars @+ swap 2* cells +
                    129:     vars @ varstack @+ swap cells + !
                    130:     1 vars +! 1 varstack +! ;
                    131: : var> ( -- addr ) -1 varstack +!
                    132:     varstack @+ swap cells + @
                    133:     1+ 2* cells vars + ;
                    134: 
                    135: \ start end
                    136: 
                    137: 0 Value end$
                    138: 0 Value start$
                    139: : !end ( addr u -- addr )  over + to end$ dup to start$ ;
1.12      pazsan    140: : end-rex? ( addr -- addr flag ) dup end$ u< ;
                    141: : start-rex? ( addr -- addr flag ) dup start$ u> ;
1.1       pazsan    142: : ?end ( addr -- addr ) ]] dup end$ u> ?LEAVE [[ ; immediate
                    143: 
                    144: \ start and end
                    145: 
1.8       pazsan    146: : \^ ( addr -- addr ) \ regexp-pattern
                    147:     \G check for string start
1.12      pazsan    148:     ]] start-rex? ?LEAVE [[ ; immediate
1.8       pazsan    149: : \$ ( addr -- addr ) \ regexp-pattern
                    150:     \G check for string end
1.12      pazsan    151:     ]] end-rex? ?LEAVE [[ ; immediate
1.1       pazsan    152: 
                    153: \ regexp block
                    154: 
                    155: \ FORK/JOIN are like AHEAD THEN, but producing a call on AHEAD
                    156: \ instead of a jump.
                    157: 
1.8       pazsan    158: : (( ( addr u -- ) \ regexp-pattern
                    159:     \G start regexp block
                    160:     vars off varsmax off loops off
1.1       pazsan    161:     ]] FORK  AHEAD BUT JOIN !end [[ BEGIN, ; immediate
1.8       pazsan    162: : )) ( -- addr f ) \ regexp-pattern
                    163:     \G end regexp block
1.1       pazsan    164:     ]] ?end drop true EXIT [[
                    165:     DONE, ]] drop false EXIT THEN [[ ; immediate
                    166: 
                    167: \ greedy loops
                    168: 
                    169: \ Idea: scan as many characters as possible, try the rest of the pattern
                    170: \ and then back off one pattern at a time
                    171: 
                    172: : drops ( n -- ) 1+ cells sp@ + sp! ;
                    173: 
1.8       pazsan    174: : {** ( addr -- addr addr ) \ regexp-pattern
                    175:     \G greedy zero-or-more pattern
1.1       pazsan    176:     0 ]] Literal >r BEGIN dup [[ BEGIN, ; immediate
1.8       pazsan    177: ' {** Alias {++ ( addr -- addr addr ) \ regexp-pattern
                    178:     \G greedy one-or-more pattern
                    179:     immediate
                    180: : n*} ( sys n -- ) \ regexp-pattern
                    181:     \G At least @var{n} pattern
1.12      pazsan    182:     >r ]] r> 1+ >r end-rex? 0= UNTIL dup [[ DONE, ]] drop [[
1.1       pazsan    183:     r@ IF r@ ]] r@ Literal u< IF  r> 1+ drops false  EXIT  THEN [[ THEN
                    184:     r@ ]] r> 1+ Literal U+DO FORK BUT [[
                    185:     ]] IF  I' I - [[ r@ 1- ]] Literal + drops true UNLOOP EXIT  THEN  LOOP [[
                    186:     r@ IF  r@ ]] Literal drops [[ THEN
                    187:     rdrop ]] false  EXIT  JOIN [[ ; immediate
1.8       pazsan    188: : **} ( sys -- ) \ regexp-pattern
                    189:     \G end of greedy zero-or-more pattern
                    190:     0 postpone n*} ; immediate
                    191: : ++} ( sys -- ) \ regexp-pattern
                    192:     \G end of greedy zero-or-more pattern
                    193:     1 postpone n*} ; immediate
1.1       pazsan    194: 
                    195: \ non-greedy loops
                    196: 
                    197: \ Idea: Try to match rest of the regexp, and if that fails, try match
                    198: \ first expr and then try again rest of regexp.
                    199: 
1.8       pazsan    200: : {+ ( addr -- addr addr ) \ regexp-pattern
                    201:     \G non-greedy one-or-more pattern
1.1       pazsan    202:     ]] BEGIN  [[ BEGIN, ; immediate
1.8       pazsan    203: : {* ( addr -- addr addr ) \ regexp-pattern
                    204:     \G non-greedy zero-or-more pattern
1.1       pazsan    205:     ]] {+ dup FORK BUT  IF  drop true  EXIT THEN [[ ; immediate
1.8       pazsan    206: : *} ( addr addr' -- addr' ) \ regexp-pattern
                    207:     \G end of non-greedy zero-or-more pattern
1.1       pazsan    208:     ]] dup end$ u>  UNTIL [[
                    209:     DONE, ]] drop false  EXIT  JOIN [[ ; immediate
1.8       pazsan    210: : +} ( addr addr' -- addr' ) \ regexp-pattern
                    211:     \G end of non-greedy one-or-more pattern
1.1       pazsan    212:     ]] dup FORK BUT  IF  drop true  EXIT [[
                    213:     DONE, ]] drop false  EXIT  THEN *} [[ ; immediate
                    214: 
1.8       pazsan    215: : // ( -- ) \ regexp-pattern
                    216:     \G search for string
                    217:     ]] {* 1+ *} [[ ; immediate
1.1       pazsan    218: 
                    219: \ alternatives
                    220: 
                    221: \ idea: try to match one alternative and then the rest of regexp.
                    222: \ if that fails, jump back to second alternative
                    223: 
                    224: : THENs ( sys -- )  BEGIN  dup  WHILE  ]] THEN [[  REPEAT  drop ;
                    225: 
1.8       pazsan    226: : {{ ( addr -- addr addr ) \ regexp-pattern
                    227:     \G Start of alternatives
                    228:     0 ]] dup BEGIN [[  vars @ ; immediate
                    229: : || ( addr addr -- addr addr ) \ regexp-pattern
                    230:     \G separator between alternatives
                    231:     vars @ varsmax @ max varsmax !
1.1       pazsan    232:     ]] nip AHEAD [[ >r >r >r vars !
                    233:     ]] DONE drop dup [[ r> r> r> ]] BEGIN [[ vars @ ; immediate
1.8       pazsan    234: : }} ( addr addr -- addr addr ) \ regexp-pattern
                    235:     \G end of alternatives
                    236:     vars @ varsmax @ max vars !
1.1       pazsan    237:     ]] nip AHEAD [[ >r >r >r drop
                    238:     ]] DONE drop LEAVE [[ r> r> r> THENs ; immediate
                    239: 
                    240: \ match variables
                    241: 
1.8       pazsan    242: : \( ( addr -- addr ) \ regexp-pattern
                    243:     \G start of matching variable; variables are referred as \\1--9
                    244:     ]] dup [[
1.1       pazsan    245:     >var ]] ALiteral ! [[ ; immediate
1.8       pazsan    246: : \) ( addr -- addr ) \ regexp-pattern
                    247:     \G end of matching variable
                    248:     ]] dup [[
1.1       pazsan    249:     var> ]] ALiteral ! [[ ; immediate
1.8       pazsan    250: : \0 ( -- addr u ) \ regexp-pattern
                    251:     \G the whole string
                    252:     start$ end$ over - ;
1.1       pazsan    253: : \: ( i -- )
                    254:     Create 2* 1+ cells vars + ,
                    255:   DOES> ( -- addr u ) @ 2@ tuck - ;
                    256: : \:s ( n -- ) 0 ?DO  I \:  LOOP ;
                    257: 9 \:s \1 \2 \3 \4 \5 \6 \7 \8 \9
1.6       pazsan    258: 
                    259: \ replacements, needs string.fs
                    260: 
                    261: require string.fs
                    262: 
                    263: 0 Value >>ptr
                    264: 0 Value <<ptr
                    265: Variable >>string
1.8       pazsan    266: : >>  ( addr -- addr ) \ regexp-replace
                    267:     \G Start replace pattern region
                    268:     dup to >>ptr ;
                    269: : << ( run-addr addr u -- run-addr ) \ regexp-replace
                    270:     \G Replace string from start of replace pattern region with
                    271:     \G @var{addr} @var{u}
1.6       pazsan    272:     <<ptr 0= IF  start$ to <<ptr  THEN
                    273:     >>string @ 0= IF  s" " >>string $!  THEN
                    274:     <<ptr >>ptr over - >>string $+!
                    275:     >>string $+! dup to <<ptr ;
1.8       pazsan    276: : <<" ( "string<">" -- ) \ regexp-replace
                    277:     \G Replace string from start of replace pattern region with
                    278:     \G @var{string}
                    279:     '" parse postpone SLiteral postpone << ; immediate
1.6       pazsan    280: : >>string@ ( -- addr u )
                    281:     >>string $@ >>string off
                    282:     0 to >>ptr  0 to <<ptr ;
                    283: : >>next ( -- addr u ) <<ptr end$ over - ;
1.14      pazsan    284: : >>rest ( -- ) >>next >>string $+! ;
                    285: : s// ( addr u -- ptr )
1.8       pazsan    286:     \G start search/replace loop
1.14      pazsan    287:     ]] (( // >> [[ ; immediate
1.15    ! pazsan    288: : //o ( ptr addr u -- addr' u' )
1.14      pazsan    289:     \G end search/replace single loop
                    290:     ]] << )) drop >>rest >>string@ [[ ; immediate
                    291: : //g ( ptr addr u -- addr' u' )
                    292:     \G end search/replace all loop
                    293:     ]] << LEAVE )) drop >>string@ [[ ; immediate

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