from tpers import *
from scripting import Fail, Synt

class Vars(TPrs):
    def InitPersistent(self):
        self.rgmpsynt_sobj = [{}] # [0] is for globals?
    
    def Get(self, synt):
        for mpsynt_sobj in reversed(self.rgmpsynt_sobj):
            try:
                return mpsynt_sobj[synt]
            except:
                pass
        return Fail("Variable " + synt.name.St() + " not defined")
    
    def Define(self, synt, sobj):
        self.rgmpsynt_sobj[-1][synt] = sobj
        
    def Set(self, synt, sobj):
        for mpsynt_sobj in reversed(self.rgmpsynt_sobj):
            if synt in mpsynt_sobj:
                mpsynt_sobj[synt] = sobj
                return
        return Fail("Variable " + synt.name.St() + " not defined")
    
    def Push(self):
        self.rgmpsynt_sobj.append({})
        
    def Pop(self):
        self.rgmpsynt_sobj.pop()
        
class Vm(TPrs):
    def InitPersistent(self):
        self.vstack = []
        self.rstack = []
        self.vars = Vars()
    
    def Push(self, sobj):
        self.vstack.append(sobj)
    def Pop(self):
        return self.vstack.pop()
    
    def CallI(self, synt, r, ip):
        if ip < len(r): # tail call optimization
            self.rstack.append(r, ip)
        return (synt.Compile(), 0)
        
    def RunSynt(self, synt):
        r = synt.Compile()
        ip = 0
        while True:
            if ip < len(r):
                instr = r[ip]
                ip += 1
                if isinstance(instr, Synt):
                    (r, ip) = self.CallI(instr, r, ip)
                elif callable(instr):
                    synt = instr(self)
                    if synt != None:
                        (r, ip) = self.CallI(instr, r, ip)
                else:
                    assert False, "invalid opcode"
            else:
                if len(rstack) == 0:
                    break
                (r, ip) = self.rstack.pop()