require "big.cr"

module False

  enum Command
    DUP # ( n -- n n )
    DROP # ( n1 n2 -- n1 )
    SWAP # ( n1 n2 -- n2 n1 )
    ROT # ( n1 n2 n3 -- n2 n3 n1 )
    PICK # push the n-th stack item (top of stack is index 0)
    ADD # ( n1 n2 -- (n1+n2) )
    SUBTRACT # ( n1 n2 -- (n1-n2) )
    MULTIPLY # ( n1 n2 -- (n1-n2) )
    DIVIDE # ( n1 n2 -- (n1/n2) )
    NEGATE # ( n1 -- (-1*n1) )
    BAND # ( n1 n2 -- (n1&n2) )
    BOR # ( n1 n2 -- (n1|n2) )
    BNOT # invert each bit of top of the stack
    GREATER # ( n1 n2 -- (n1>n2) )
    EQUAL # ( n1 n2 -- (n1==n2) )
    EXECUTE # lambda execution
    CONDITIONAL # ( cond lambda -- ... ) execute lambda if cond is true, pops both
    LOOP # ( cond lambda -- ... ) execute lambda repeatedly until cond is false, then pop both
    STORE # ( value reference -- ) stores value at the given variable reference, pops both
    FETCH # ( reference -- ) pops the reference and pushes the value stored at the reference
    READ # read character from STDIN and push its character code
    WRITE_CHAR # pop the stack and print the value's character ("65," prints "A")
    WRITE_INT # pop the stack and print the value as an integer ("65." prints "65")
    FLUSH # flush input and output buffers
  end

  alias PushInt = BigInt # int literal pushes int
  alias PushCharCode = Char # char literal ( 'c ) pushes char
  alias PushVarRef = Char # variable name pushes its address
  alias WriteString = String # string literal prints the string

  alias Operation = Command | PushInt | PushCharCode | PushVarRef | WriteString
end