parser.py 文件源码

def processAssignment(self, var, operand, rhs):
        subsystem = self.currentSubsystem()
        scope = self.currentScope()
        #error if this is a diffvar
        if var in subsystem.diffvars:
            raise XXXSyntaxError("Can't assign to differential variable '%s'." % var)
        if var in subsystem.inputs:
            raise XXXSyntaxError("Can't assign to shared variable '%s'." % var)
        if var == self.timeVar:
            raise XXXSyntaxError("Can't assign to integration variable '%s'." % var)
        if var in subsystem.accums:
            if operand != '+=' and operand != '-=':
                raise XXXSyntaxError("Can only += or -= accumulation variable '%s'."%var)
        if var not in subsystem.outputs and not scope.hasSymbol(var):
            (exists, dontcare) = self.searchForJunction(var)
            if exists:
                raise XXXSyntaxError("Can't assign to shared variable '%s'." % var)

        if operand != '=':
            if not scope.hasSymbol(var):
                if var in subsystem.accums:
                    lhs = textToAST("0",ASTUnit(scope.getUnit(var),False))
                else:
                    raise XXXSyntaxError("'%s' used before assignment."%var)
            else:
                lhs = self.readAccessVar(var)

            if operand == '+=' or operand == '-=':
                if operand == '-=':
                    rhs = AST(sympy.Mul(sympy.Integer(-1),rhs.sympy), rhs.astUnit)
                rhs = AST(sympy.Add(lhs.sympy,rhs.sympy), self.checkExactUnits(lhs.astUnit,rhs.astUnit))
            elif operand == '*=' or operand == '/=':
                if operand == "/=":
                    rhs = AST(sympy.Pow(rhs.sympy,sympy.Integer(-1)), rhs.astUnit ** -1)
                rhs = AST(sympy.Mul(lhs.sympy,rhs.sympy), lhs.astUnit*rhs.astUnit)
            elif operand == '^=':
                rhs = self.powerProcess(lhs, rhs)
            else:
                assert(0)

        #Time to do final unit checks
        if scope.hasUnit(var):
            #print var
            #print scope.getUnit(var)
            #print rhs
            rhs = self.checkExplicitCast(scope.getUnit(var), rhs)

        #ok, we're ready to do the assignment!
        if var in subsystem.frozen:
            XXXSyntaxError('"%s" cannot be assigned once it has been read.' % var)
        symbol = Symbol(var)
        subsystem.ssa[symbol] = rhs
        scope.addInstruction(symbol)
        scope.setSymbol(var, symbol)

        #parameter checking code.
        #FIXME
        nameDepend = set([symbol.name for symbol in rhs.dependencies()])
        newlyReadParams = (set(subsystem.attributeMap.keys()) & nameDepend) - subsystem.frozen
        newlyReadParams -= set([var])
        subsystem.frozen |= newlyReadParams