Structures ( 062686 jl ) ---------- Adding a structure compiler to Forth. JL 26.6.86. This file defines a Pascal-like 'record' structure; a record is a template for instances of the structure. ( Example ) :record a >long field1 >word field2 ;record ( then do ) myrec r1 ( this creates an instance r1 of myrec whose fields may be accessed through myrec ^ field1 etc..) ( for 'late binding' usage, the word ^field is provided) ( structures, load block ) ( 062686 jl ) decimal 2 7 thru ( do.record, creating one instance of a record ) ( 062686 jl ) : do.record ( addr of master | -- ) create dup , begin dup c@ dup while ( not zero, i.e. end) 1+ =cells 4+ + ( next field in template ) repeat drop 2+ w@ ( length stored here ) allot does> ( nothing special ) ; ( :record ;record and friends) ( 062686 jl ) : :record create 13579 4 does> do.record ; : ;record 2 needed 0 w, ( end of list) w, ( total length ) 13579 = 0= abort" ;record without :record" ; : put.fieldname 32 word here over c@ 1+ dup =cells allot cmove ; ( field defining words ) ( 062686 jl ) : >long ( addr | addr+4) put.fieldname dup w, 4 w, 4+ ; : >word ( addr | addr+2) put.fieldname dup w, 2 w, 2+ ; : >byte ( addr | addr+1) put.fieldname dup w, 1 w, 1+ ; : >bytes ( addr \ n | addr+n ) put.fieldname over w, dup w, + ; ( ^field, addressing a field within a record ) ( 062686 jl ) : ^field ( addr name | address of field ) over @ ( addr name master ) begin 2dup -string while ( no match ) dup c@ 6+ =cells + dup c@ 0= ( end of list ) abort" RECORD- specified field does not exist" repeat ( match found ) dup c@ 1+ =cells + w@ ( start within record ) swap drop + ( address of field ) ; ( ^ , <[ , ]> ) ( 062686 jl ) : ^ 32 word ^field ; : <[ [compile] [ ; immediate : ]> ] [compile] literal ; immediate ( example of a record structure ) ( 062686 jl ) :record testrec >long date >long time >byte flag >word counts 30 >bytes description ;record testrec r1 testrec r2
