def Operation(t):
s = exp.OperationSymbol(t)
al = exp.OperationOperandL(t)
n = pop.Length(al)
if (n == 0):
printf(" ")
pio.WriteItem(exp.OperationSymbol(t))
printf(" ")
return
if (exp.PrefixP(s)):
Prefix(t)
return
if (exp.InfixP(s)):
Infix(t)
return
if (s == exp.LLISTPARENWord):
printf("[% ")
Termlist(al)
printf(" %]")
return
if s == exp.LSETPARENWord:
printf("{% ")
Termlist(al)
printf(" %}")
return
pio.WriteItem(exp.OperationSymbol(t))
printf("(")
Termlist(al)
printf(")")
def TermLprecedence(t):
# the force with which term t binds from the left (to its right operands) */
if (exp.VarP(t) or exp.LiteralP(t)): return 100
if (exp.OperationP(t)):
s = exp.OperationSymbol(t)
if (exp.InfixP(s) or exp.PrefixP(s)):
return exp.Lprecedence(exp.OperationSymbol(t))
return 100
return 100
def Prefix(t):
s = exp.OperationSymbol(t)
a = exp.OperationOperand1(t)
pio.WriteItem(s)
printf(" ")
if (exp.Rprecedence(s) > TermLprecedence(a)):
bprp(a)
else:
Term(a)
def Infix(t):
"""print a term with an infix operator"""
s = exp.OperationSymbol(t)
#print('Infix called with ',s) #debug
a1 = exp.OperationOperand1(t)
a2 = exp.OperationOperand2(t)
if (exp.Lprecedence(s) > TermRprecedence(a1)):
bprp(a1)
else:
Term(a1)
printf(" ")
pio.WriteItem(s)
printf(" ")
if (exp.Rprecedence(s) > TermLprecedence(a2)):
bprp(a2)
else:
Term(a2)
def Aoperation(e):
""" returns e1 dl where dl is the list of atomic definitions generated
and e1 is the new atomic expression """
o = exp.OperationSymbol(e) #operator
l = exp.OperationOperandL(e) #operands
vl = pop.Empty #new variables introduced
aeqs = pop.Empty #list of equations generated
while l != pop.Empty: #iterate down operand list
opd = pop.Head(l);l = pop.Tail(l) #get next operand and advance
if exp.VarP(opd): #if it's a var nothing to do
vl = pop.Cons(opd,vl)
continue
ae, dl = Aexpr(opd) # process the operand
aeqs = pop.Append(dl,aeqs) # collect equations generated
if not exp.VarP(ae):
nv = VarGen() # generate a new variable
vl = pop.Cons(nv,vl) # save it
d = exp.DefinitionC(nv,pop.EQUALWord,ae) # generate new atomic definition
aeqs = pop.Cons(d,aeqs)
else:
vl = pop.Cons(ae,vl)
vl = pop.Reverse(vl) # variables accumulated in reverse order
e1 = exp.OperationC(o,vl) # new atomic expression
return e1, aeqs # return the atomic expression and equations generated