( regex.tal ) ( ) ( compiles regex expression strings into regex nodes, then uses ) ( regex ndoes to match input strings. ) ( ) ( this currently only supports matching an entire string, as ) ( opposed to searching for a matching substring, or extracting ) ( matching subgroups. ) ( ) ( regex node types: ) ( ) ( NAME DESCRIPTION STRUCT ) ( empty matches empty string [ #01 next* ] ) ( dot matches any one char [ #02 next* ] ) ( lit matches one specific char (c) [ #03 c^ next* ] ) ( or matches either left or right [ #04 left* right* ] ) ( star matches expr zero-or-more times [ #05 r* next* ] ) ( (NOTE: r.expr.next must be r) ) ( ) ( `or` and `star` have the same structure and are handled by the ) ( same code (;do-or). however, the node types are kept different ) ( to make it clearer how to parse and assemble the nodes. ) ( ) ( concatenation isn't a node, it is implied by the *next addr. ) ( a next value of #0000 signals the end of the regex. ) ( ) ( in these docs str* is an address to a null-terminated string. ) ( regexes should not include nulls and cannot match them (other ) ( than the null which signals the end of a string). ) %null? { #00 EQU } %debug { #ff #0e DEO } %emit { #18 DEO } %space { #20 emit } %newline { #0a emit } |0100 ;test1 ;expr1 ;match JSR2 ;emit-byte JSR2 newline ;test2 ;expr1 ;match JSR2 ;emit-byte JSR2 newline ;test3 ;expr1 ;match JSR2 ;emit-byte JSR2 newline ;test4 ;expr1 ;match JSR2 ;emit-byte JSR2 newline ;test5 ;expr1 ;match JSR2 ;emit-byte JSR2 newline ;test6 ;expr1 ;match JSR2 ;emit-byte JSR2 newline ;test7 ;expr1 ;match JSR2 ;emit-byte JSR2 newline ;test8 ;expr1 ;match JSR2 ;emit-byte JSR2 newline BRK @match ( str* regex* -> bool^ ) ;reset-stack JSR2 ;loop JMP2 ( we don't use the return stack here since that ) ( complicates the back-tracking we need to do. ) ( ultimately this code will issue a JMP2r to ) ( return a boolean, which is where the stack ) ( effects signature comes from. ) @loop ( s* r* -> bool^ ) LDAk #01 EQU ;do-empty JCN2 LDAk #02 EQU ;do-dot JCN2 LDAk #03 EQU ;do-literal JCN2 LDAk #04 EQU ;do-or JCN2 LDAk #05 EQU ;do-or JCN2 ( same code as the or case ) #00 #00 DIV ( should not happen ) @goto-backtrack ( -> bool^ ) ;stack-exist JSR2 ,&has-stack JCN ( do we have stack? ) #00 JMP2r ( no, return false ) &has-stack ;pop JSR2 ;goto-next JMP2 ( yes, resume from the top ) @goto-next ( str* next* -> bool^ ) DUP2 #0000 GTH2 ,&has-next JCN POP2 LDA null? ,&end-of-string JCN ;goto-backtrack JMP2 &end-of-string #01 JMP2r &has-next ;loop JMP2 @do-empty ( str* regex* -> bool^ ) INC2 LDA2 ( load next ) ;goto-next JMP2 ( jump to next ) @do-dot ( str* regex* -> bool^ ) INC2 LDA2 STH2 ( load and stash next ) LDAk #00 NEQ ,&non-empty JCN ( is there a char? ) POP2r POP2 ;goto-backtrack JMP2 ( no, clear stacks and backtrack ) &non-empty INC2 STH2r ;goto-next JMP2 ( yes, inc s, restore and jump ) @do-literal ( str* regex* -> bool^ ) INC2 LDAk STH ( store c ) INC2 LDA2 STH2 ROTr ( store next, move c to top ) LDAk STHr EQU ,&matches JCN ( do we match this char? ) POP2r POP2 ;goto-backtrack JMP2 ( no, clear stacks and backtrack ) &matches INC2 STH2r ;goto-next JMP2 ( yes, inc s, restore and jump ) ( this also handles asteration, since it ends up having the same structure ) @do-or ( str* regex* -> bool^ ) INC2 OVR2 OVR2 #0002 ADD2 ( s r+1 s r+3 ) LDA2 ;push JSR2 ( save (s, right) in the stack for possible backtracking ) LDA2 ;loop JMP2 ( continue on left branch ) ( compile an expression string into a regex graph ) @compile ( expr* -> regex* ) ( corresponds to regex: a(b|c)d* ) ( accepts "ab" or "ac" followd by any number of d's ) @expr1 03 'a :x1 @x1 04 :x2 :x3 @x2 03 'b :x4 @x3 03 'c :x4 @x4 05 :x5 0000 @x5 03 'd :x4 @test1 "ab 00 ( yes ) @test2 "acdd 00 ( yes ) @test3 "add 00 ( no ) @test4 "abd 00 ( yes ) @test5 "acddddddddddd 00 ( yes ) @test6 "bd 00 ( no ) @test7 "z 00 ( no ) @test8 00 ( no ) @emit-short ( byte -- ) SWP ;emit-byte JSR2 ;emit-byte JSR2 JMP2r @emit-byte ( byte -- ) DUP #04 SFT ,&hex JSR #0f AND ,&hex JMP &hex #30 ADD DUP #39 GTH #27 MUL ADD emit JMP2r @emit3 ( addr* -> addr* ) DUP2 LDAk ;emit-byte JSR2 space INC2 LDA2 ;emit-short JSR2 newline JMP2r @emit4 ( addr* -> addr* ) DUP2 LDAk ;emit-byte JSR2 space INC2 LDAk ;emit-byte JSR2 space INC2 LDA2 ;emit-short JSR2 newline JMP2r @emit5 ( addr* -> addr* ) DUP2 LDAk ;emit-byte JSR2 space INC2 LDA2k ;emit-short JSR2 space #0002 ADD2 LDA2 ;emit-short JSR2 newline JMP2r @push ( str* regex* -> ) ;assert-avail JSR2 ( check for space ) ;stack-pos LDA2 #0002 ADD2 STA2 ( cell[2:3] <- regex ) ;stack-pos LDA2 STA2 ( cell[0:1] <- str ) ;stack-pos LDA2 #0004 ADD2 ;stack-pos STA2 ( pos += 4 ) JMP2r @pop ( -> str* regex* ) ;stack-pos LDA2 ( load stack-pos ) #0002 SUB2 LDA2k STH2 ( pop and stash regex ) #0002 SUB2 LDA2k STH2 ( pop and stash str ) ;stack-pos STA2 ( save new stack-pos ) STH2r STH2r ( restore str and regex ) JMP2r @reset-stack ( -> ) ;stack-bot ;stack-pos STA2 JMP2r ( pos <- 0 ) @stack-avail ( -> bool^ ) ;stack-pos LDA2 ;stack-top LTH2 JMP2r @stack-exist ( -> bool^ ) ;stack-pos LDA2 ;stack-bot GTH2 JMP2r @assert-avail ( -> ) ;stack-avail JSR2 ,&ok JCN #00 #00 DIV &ok JMP2r @emit-stack ( -> ) space LIT 'n emit space ;stack-pos LDA2 ;stack-bot SUB2 #0004 DIV2 ;emit-short JSR2 newline ;stack-bot &loop DUP2 ;stack-pos LDA2 LTH2 ,&ok JCN POP2 JMP2r &ok space space LDA2k ;emit-short JSR2 #0002 ADD2 DUP2 LDA2 space ;emit-short JSR2 newline #0002 ADD2 ,&loop JMP @stack-pos :stack-bot ( the next position to insert at ) @stack-bot $1000 @stack-top ( holds 1024 steps (4096 bytes) ) @reset-arena ( -> ) ;arena-bot ;arena-pos STA2 JMP2r @alloc ( size^ -> addr* ) #00 SWP ( size* ) ;arena-pos LDA2 STH2k ADD2 ( pos+size* {pos} ) ( TODO: ensure we don't exceed our space ) ;arena-pos STA2 ( pos <- pos+size ) STH2r JMP2 ( return old pos ) @arena-pos :arena-bot ( the next position to allocate ) @arena-bot $400 @arena-top ( holds up to 1024 bytes )