nxu/grep.tal

( grep.tal )
( )
( by d_m )

( print a character to STDOUT )
%emitt { #18 DEO }

( the first argument to grep is the regex )
( arguments are passed on STDIN, so we just )
( assume the first "line" is the argument )
( and the rest are lines to be grepped )
|0100
    ;r-read-stdin #10 DEO2 BRK

@regex 0000   ( compiled regex address (if any) )
@buffer $1000 ( buffer to read user input )
@ptr :buffer  ( next byte to write in buffer )

@println ( s* -> )
    &loop LDAk #00 EQU ,&eof JCN ( did we reach \0 ? )
    LDAk emitt INC2 ,&loop JMP    ( no so emit a char and repeat )
    &eof #0a emitt POP2 JMP2r     ( yes so emit \n and return )

@r-read-stdin ( -> )
    #12 DEI #0a EQU ,&execute JCN     ( did we read \n ? )
    #12 DEI ;ptr LDA2 STA             ( no, so save in buffer )
    ;ptr LDA2k INC2 SWP2 STA2         ( ptr++ )
    BRK                               ( return )

    &execute                          ( we saw a newline, so do something )
    #00 ;ptr LDA2 STA                 ( null terminate str )
    ;buffer ;ptr STA2                 ( reset ptr )
    ;regex LDA2 #0000 EQU2            ( is regex initialized? )
    ,&need-regex JCN                  ( jump if unset )

                                      ( regex is set )
    ;buffer ;regex LDA2 ;search JSR2  ( search line for a regex match )
    #00 EQU ,&no-match JCN            ( did we match? )
    ;buffer ;println JSR2             ( print any match )
    &no-match BRK                     ( return )

                                      ( regex is unset )
    &need-regex ;buffer ;compile JSR2 ( compile regex )
    ;regex STA2 BRK                   ( save regex and return )

( include the actual regex machinery )
~regex.tal