AoC/2015/Day7/Day7/main.swift

import Foundation

enum EvaluationError: Error {
    case signalMissing(String)
    case circularDefinition(String)
}

protocol Context {
    func evaluate(_ signal: String) throws -> UInt16
}

enum Ref {
    case value(UInt16)
    case signal(String)

    func evaluate(context: Context) throws -> UInt16 {
        switch self {
        case .value(let value): return value
        case .signal(let name): return try context.evaluate(name)
        }
    }
}

enum Signal {
    case value(Ref)
    case and(Ref, Ref)
    case leftShift(Ref, amount: Int)
    case rightShift(Ref, amount: Int)
    case not(Ref)
    case or(Ref, Ref)

    func evaluate(context: Context) throws -> UInt16 {
        switch self {
        case .value(let value): return try value.evaluate(context: context)
        case .and(let a, let b): return try a.evaluate(context: context) & b.evaluate(context: context)
        case .or(let a, let b): return try a.evaluate(context: context) | b.evaluate(context: context)
        case .not(let other): return try ~other.evaluate(context: context)
        case .leftShift(let other, amount: let amount): return try other.evaluate(context: context) << amount
        case .rightShift(let other, amount: let amount): return try other.evaluate(context: context) >> amount
        }
    }
}


enum ParseError: Error {
    case expected(String)
    case nameExpected
    case intExpected
    case operatorExpected
}

extension Scanner {
    func expect(_ string: String) throws {
        guard scanString(string) != nil else {
            throw ParseError.expected(string)
        }
    }

    func circuit() throws -> [String: Signal] {
        var result: [String: Signal] = [:]
        while !isAtEnd {
            let (signal, name) = try connection()
            result[name] = signal
        }

        return result
    }

    func connection() throws -> (Signal, String) {
        let signal = try signal()
        try expect("->")
        let name = try name()

        return (signal, name)
    }

    func signal() throws -> Signal {
        if scanString("NOT") != nil {
            let signal = try ref()
            return .not(signal)
        }

        let firstOperand = try ref()

        if let op = binaryOperator() {
            let secondOperand = try ref()
            switch op {
            case .and: return .and(firstOperand, secondOperand)
            case .or: return .or(firstOperand, secondOperand)
            }
        }

        if let (shift, amount) = try shiftOperator() {
            switch shift {
            case .left: return .leftShift(firstOperand, amount: amount)
            case .right: return .rightShift(firstOperand, amount: amount)
            }
        }

        return .value(firstOperand)

    }

    enum BinaryOperator: String, CaseIterable {
        case and = "AND"
        case or = "OR"
    }

    func oneOf<T>() -> T? where T: RawRepresentable, T: CaseIterable, T.RawValue == String {
        for item in T.allCases {
            if scanString(item.rawValue) != nil {
                return item
            }
        }

        return nil
    }

    func binaryOperator() -> BinaryOperator? {
        oneOf()
    }


    enum Shift: String, CaseIterable {
        case left = "LSHIFT"
        case right = "RSHIFT"
    }

    func shiftOperator() throws -> (Shift, Int)? {
        guard let direction: Shift = oneOf() else { return nil }
        guard let amount = scanInt() else {
            throw ParseError.intExpected
        }
        return (direction, amount)
    }

    func ref() throws -> Ref {
        if let int = scanInt() {
            return .value(UInt16(int))
        }

        return try .signal(name())
    }

    func name() throws -> String {
        guard let name = scanCharacters(from: .letters) else {
            throw ParseError.nameExpected
        }

        return name
    }
}

let input = """
af AND ah -> ai
NOT lk -> ll
hz RSHIFT 1 -> is
NOT go -> gp
du OR dt -> dv
x RSHIFT 5 -> aa
at OR az -> ba
eo LSHIFT 15 -> es
ci OR ct -> cu
b RSHIFT 5 -> f
fm OR fn -> fo
NOT ag -> ah
v OR w -> x
g AND i -> j
an LSHIFT 15 -> ar
1 AND cx -> cy
jq AND jw -> jy
iu RSHIFT 5 -> ix
gl AND gm -> go
NOT bw -> bx
jp RSHIFT 3 -> jr
hg AND hh -> hj
bv AND bx -> by
er OR es -> et
kl OR kr -> ks
et RSHIFT 1 -> fm
e AND f -> h
u LSHIFT 1 -> ao
he RSHIFT 1 -> hx
eg AND ei -> ej
bo AND bu -> bw
dz OR ef -> eg
dy RSHIFT 3 -> ea
gl OR gm -> gn
da LSHIFT 1 -> du
au OR av -> aw
gj OR gu -> gv
eu OR fa -> fb
lg OR lm -> ln
e OR f -> g
NOT dm -> dn
NOT l -> m
aq OR ar -> as
gj RSHIFT 5 -> gm
hm AND ho -> hp
ge LSHIFT 15 -> gi
jp RSHIFT 1 -> ki
hg OR hh -> hi
lc LSHIFT 1 -> lw
km OR kn -> ko
eq LSHIFT 1 -> fk
1 AND am -> an
gj RSHIFT 1 -> hc
aj AND al -> am
gj AND gu -> gw
ko AND kq -> kr
ha OR gz -> hb
bn OR by -> bz
iv OR jb -> jc
NOT ac -> ad
bo OR bu -> bv
d AND j -> l
bk LSHIFT 1 -> ce
de OR dk -> dl
dd RSHIFT 1 -> dw
hz AND ik -> im
NOT jd -> je
fo RSHIFT 2 -> fp
hb LSHIFT 1 -> hv
lf RSHIFT 2 -> lg
gj RSHIFT 3 -> gl
ki OR kj -> kk
NOT ak -> al
ld OR le -> lf
ci RSHIFT 3 -> ck
1 AND cc -> cd
NOT kx -> ky
fp OR fv -> fw
ev AND ew -> ey
dt LSHIFT 15 -> dx
NOT ax -> ay
bp AND bq -> bs
NOT ii -> ij
ci AND ct -> cv
iq OR ip -> ir
x RSHIFT 2 -> y
fq OR fr -> fs
bn RSHIFT 5 -> bq
0 -> c
14146 -> b
d OR j -> k
z OR aa -> ab
gf OR ge -> gg
df OR dg -> dh
NOT hj -> hk
NOT di -> dj
fj LSHIFT 15 -> fn
lf RSHIFT 1 -> ly
b AND n -> p
jq OR jw -> jx
gn AND gp -> gq
x RSHIFT 1 -> aq
ex AND ez -> fa
NOT fc -> fd
bj OR bi -> bk
as RSHIFT 5 -> av
hu LSHIFT 15 -> hy
NOT gs -> gt
fs AND fu -> fv
dh AND dj -> dk
bz AND cb -> cc
dy RSHIFT 1 -> er
hc OR hd -> he
fo OR fz -> ga
t OR s -> u
b RSHIFT 2 -> d
NOT jy -> jz
hz RSHIFT 2 -> ia
kk AND kv -> kx
ga AND gc -> gd
fl LSHIFT 1 -> gf
bn AND by -> ca
NOT hr -> hs
NOT bs -> bt
lf RSHIFT 3 -> lh
au AND av -> ax
1 AND gd -> ge
jr OR js -> jt
fw AND fy -> fz
NOT iz -> ja
c LSHIFT 1 -> t
dy RSHIFT 5 -> eb
bp OR bq -> br
NOT h -> i
1 AND ds -> dt
ab AND ad -> ae
ap LSHIFT 1 -> bj
br AND bt -> bu
NOT ca -> cb
NOT el -> em
s LSHIFT 15 -> w
gk OR gq -> gr
ff AND fh -> fi
kf LSHIFT 15 -> kj
fp AND fv -> fx
lh OR li -> lj
bn RSHIFT 3 -> bp
jp OR ka -> kb
lw OR lv -> lx
iy AND ja -> jb
dy OR ej -> ek
1 AND bh -> bi
NOT kt -> ku
ao OR an -> ap
ia AND ig -> ii
NOT ey -> ez
bn RSHIFT 1 -> cg
fk OR fj -> fl
ce OR cd -> cf
eu AND fa -> fc
kg OR kf -> kh
jr AND js -> ju
iu RSHIFT 3 -> iw
df AND dg -> di
dl AND dn -> do
la LSHIFT 15 -> le
fo RSHIFT 1 -> gh
NOT gw -> gx
NOT gb -> gc
ir LSHIFT 1 -> jl
x AND ai -> ak
he RSHIFT 5 -> hh
1 AND lu -> lv
NOT ft -> fu
gh OR gi -> gj
lf RSHIFT 5 -> li
x RSHIFT 3 -> z
b RSHIFT 3 -> e
he RSHIFT 2 -> hf
NOT fx -> fy
jt AND jv -> jw
hx OR hy -> hz
jp AND ka -> kc
fb AND fd -> fe
hz OR ik -> il
ci RSHIFT 1 -> db
fo AND fz -> gb
fq AND fr -> ft
gj RSHIFT 2 -> gk
cg OR ch -> ci
cd LSHIFT 15 -> ch
jm LSHIFT 1 -> kg
ih AND ij -> ik
fo RSHIFT 3 -> fq
fo RSHIFT 5 -> fr
1 AND fi -> fj
1 AND kz -> la
iu AND jf -> jh
cq AND cs -> ct
dv LSHIFT 1 -> ep
hf OR hl -> hm
km AND kn -> kp
de AND dk -> dm
dd RSHIFT 5 -> dg
NOT lo -> lp
NOT ju -> jv
NOT fg -> fh
cm AND co -> cp
ea AND eb -> ed
dd RSHIFT 3 -> df
gr AND gt -> gu
ep OR eo -> eq
cj AND cp -> cr
lf OR lq -> lr
gg LSHIFT 1 -> ha
et RSHIFT 2 -> eu
NOT jh -> ji
ek AND em -> en
jk LSHIFT 15 -> jo
ia OR ig -> ih
gv AND gx -> gy
et AND fe -> fg
lh AND li -> lk
1 AND io -> ip
kb AND kd -> ke
kk RSHIFT 5 -> kn
id AND if -> ig
NOT ls -> lt
dw OR dx -> dy
dd AND do -> dq
lf AND lq -> ls
NOT kc -> kd
dy AND ej -> el
1 AND ke -> kf
et OR fe -> ff
hz RSHIFT 5 -> ic
dd OR do -> dp
cj OR cp -> cq
NOT dq -> dr
kk RSHIFT 1 -> ld
jg AND ji -> jj
he OR hp -> hq
hi AND hk -> hl
dp AND dr -> ds
dz AND ef -> eh
hz RSHIFT 3 -> ib
db OR dc -> dd
hw LSHIFT 1 -> iq
he AND hp -> hr
NOT cr -> cs
lg AND lm -> lo
hv OR hu -> hw
il AND in -> io
NOT eh -> ei
gz LSHIFT 15 -> hd
gk AND gq -> gs
1 AND en -> eo
NOT kp -> kq
et RSHIFT 5 -> ew
lj AND ll -> lm
he RSHIFT 3 -> hg
et RSHIFT 3 -> ev
as AND bd -> bf
cu AND cw -> cx
jx AND jz -> ka
b OR n -> o
be AND bg -> bh
1 AND ht -> hu
1 AND gy -> gz
NOT hn -> ho
ck OR cl -> cm
ec AND ee -> ef
lv LSHIFT 15 -> lz
ks AND ku -> kv
NOT ie -> if
hf AND hl -> hn
1 AND r -> s
ib AND ic -> ie
hq AND hs -> ht
y AND ae -> ag
NOT ed -> ee
bi LSHIFT 15 -> bm
dy RSHIFT 2 -> dz
ci RSHIFT 2 -> cj
NOT bf -> bg
NOT im -> in
ev OR ew -> ex
ib OR ic -> id
bn RSHIFT 2 -> bo
dd RSHIFT 2 -> de
bl OR bm -> bn
as RSHIFT 1 -> bl
ea OR eb -> ec
ln AND lp -> lq
kk RSHIFT 3 -> km
is OR it -> iu
iu RSHIFT 2 -> iv
as OR bd -> be
ip LSHIFT 15 -> it
iw OR ix -> iy
kk RSHIFT 2 -> kl
NOT bb -> bc
ci RSHIFT 5 -> cl
ly OR lz -> ma
z AND aa -> ac
iu RSHIFT 1 -> jn
cy LSHIFT 15 -> dc
cf LSHIFT 1 -> cz
as RSHIFT 3 -> au
cz OR cy -> da
kw AND ky -> kz
lx -> a
iw AND ix -> iz
lr AND lt -> lu
jp RSHIFT 5 -> js
aw AND ay -> az
jc AND je -> jf
lb OR la -> lc
NOT cn -> co
kh LSHIFT 1 -> lb
1 AND jj -> jk
y OR ae -> af
ck AND cl -> cn
kk OR kv -> kw
NOT cv -> cw
kl AND kr -> kt
iu OR jf -> jg
at AND az -> bb
jp RSHIFT 2 -> jq
iv AND jb -> jd
jn OR jo -> jp
x OR ai -> aj
ba AND bc -> bd
jl OR jk -> jm
b RSHIFT 1 -> v
o AND q -> r
NOT p -> q
k AND m -> n
as RSHIFT 2 -> at
"""

class Evaluator: Context {
    var program: [String: Signal]
    var stack: [String] = []

    init(_ program: [String: Signal]) {
        self.program = program
    }

    func evaluate(_ signal: String) throws -> UInt16 {
        guard !stack.contains(signal) else {
            throw EvaluationError.circularDefinition(signal)
        }
        stack.append(signal)
        defer { stack.removeLast() }

        guard let def = program[signal] else { throw EvaluationError.signalMissing(signal) }
        let result =  try def.evaluate(context: self)

        program[signal] = .value(.value(result))

        return result
    }
}

let scanner = Scanner(string: input)
var circuit = try scanner.circuit()
let evaluator = Evaluator(circuit)
let a = try evaluator.evaluate("a")
print(a)

circuit["b"] = .value(.value(a))

let otherEvaluator = Evaluator(circuit)
let newA = try otherEvaluator.evaluate("a")

print(newA)