AoC 2024, day 3 (smalltalk)

#!/usr/local/bin/gst -q

" Helper extensions: "
Symbol     extend [ value: arg  [^arg perform: self] ]
Collection extend [ sum [^self inject: 0 into: [:a :b | a + b]] ]

RegexResults extend [
    first   [ ^self at: 1 ]
    second  [ ^self at: 2 ]
]

" Extending String to sum mul() instructions: "
String extend [
    sumMul [
        | res |
        res := 0.
        self allOccurrencesOfRegex: 'mul\((\d{1,3}),(\d{1,3})\)' do: [:mul |
            res := mul first asNumber * mul second asNumber + res
        ].
        ^res
    ]
]

"
| Mainline
"
input := String join: stdin lines contents separatedBy: ' '.

" Get all do() blocks and run sumMul on them: "
part2 := ((input allOccurrencesOfRegex: '(^|do\(\)).*?(don''t\(\)|$)') collect: #sumMul) sum.

('Part 1: %1' % {input sumMul}) displayNl.
('Part 2: %1' % {part2}) displayNl.