Truth table: Difference between revisions

=={{header|Julia}}==

'''Module''':

<lang julia>module TruthTable

using Printf

using MacroTools

isvariablename(::Any) = false

isvariablename(s::Symbol) = all(x -> isletter(x) || x == '_', string(s))

function table(expr)

if !isvariablename(expr) && !Meta.isexpr(expr, :call)

throw(ArgumentError("expr must be a boolean expression"))

end

exprstr = string(expr)

# Collect variable names

symset = Set{Symbol}()

MacroTools.prewalk(expr) do node

isvariablename(node) && push!(symset, node)

return node

end

symlist = collect(symset)

# Create assignment assertions + evaluate

blocks = Vector{Expr}(undef, 2 ^ length(symlist) + 1)

blocks[1] = quote

println(join(lpad.($(symlist), 6), " | "), " || ", $exprstr)

end

for (i, tup) in enumerate(Iterators.product(Iterators.repeated((false, true), length(symlist))...))

blocks[i + 1] = quote

let $(Expr(:(=), Expr(:tuple, symlist...), Expr(:tuple, tup...)))

println(join(lpad.($(Expr(:tuple, symlist...)), 6), " | "), " || ", lpad($expr, $(length(exprstr))))

end

end

end

return esc(Expr(:block, blocks...))

end

macro table(expr)

return table(expr)

end

end # module TruthTable</lang>

'''Main''':

<lang julia>TruthTable.@table !a

TruthTable.@table a | b

TruthTable.@table (a ⊻ b) | (c & a)</lang>

{{out}}

<pre> a || !a

false || true

true || false

a | b || a | b

false | false || false

true | false || true

false | true || true

true | true || true

a | b | c || (a ⊻ b) | c & a

false | false | false || false

true | false | false || true

false | true | false || true

true | true | false || false

false | false | true || false

true | false | true || true

false | true | true || true

true | true | true || true</pre>