Parsing

Parsing Pipe

As we will use the pipe (|) character as a divider, we will need tools to parse around it. Something like this:

testing parsing +≡

: |halt! ;
parse..| testing
Hello there
123|halt!
atom" testing" atom-cr+
atom" Hello there" atom+ atom-cr+
atom" 123" atom+ = assert

Implement Parsing Pipe

We'll need to manipulate the input buffer.

parsing +≡

: source@ source ( -- a )
    drop >in @ + ;
: source-remaining ( -- n )
   source nip >in @ - ;

Then parse through multiple lines until (but not including), the next pipe character.

parsing +≡

: drop| ( -- )
    source@ 1- c@ [char] | = if -1 >in +! then ;
: need-refill? ( -- f)
    source nip >in @ <= ;
: on|? ( -- f )
    need-refill? if false exit then source@ c@ [char] | = ;
: replenish ( -- f )
    need-refill? if refill else true then ;
: ?atom-cr+ ( A -- A )
    on|? 0= if atom-cr+ then ;
: eat| ( -- )
    [char] | parse drop| atom atom+ ?atom-cr+ ;
: parse..| ( -- A )
    atom"" begin replenish 0=
    if exit then eat| on|? until ;

We'll also have some words that grab input until the end of the line.

parsing +≡

: parse-cr ( -- A )
    source@ source-remaining atom   source nip >in ! ;