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 Complete(e,ig):
# current item is an infix operator
# return longest initial subexpression
q = pio.NextItem(ig) # q is the infix operator
f = Factor(ig)
if f=='':
if e == '': return Operation1C(q,unterm)
return exp.Operation2C(q,e,exp.Unterm)
while pio.CurrentItem(ig) != '' and exp.InfixP(pio.CurrentItem(ig)) and YieldsP(q,pio.CurrentItem(ig)):
f = Complete(f,ig)
if e == '': return exp.Operation1C(q,f)
#if q == WVRWord or q==WHILEWord or q==SWVRWord: return exp.CallC(exp.VarC(q),exp.List2(e,f))
if q in definables:
defined.add(q)
return exp.CallC(exp.VarC(q),exp.List2(e,f))
return exp.Operation2C(q,e,f)
def Expr(ig):
"""Parse the next expression in item generator ig"""
# leave ig pointing to following item or eod
f = Factor(ig) #pickup lefthand factor
if f=='': return '' #nothing there
ci = pio.CurrentItem(ig)
if ci=='': return f #nothing more to parse
while pio.CurrentItem(ig)!='' and exp.InfixP(pio.CurrentItem(ig)):
f=Complete(f,ig)
w = pio.CurrentItem(ig)
if w!= exp.WHEREWord and w != exp.WHERELOOPWord: return f
if w == exp.WHEREWord:
e1 = Where(f,ig)
else:
e1 = Whereloop(f,ig)
return e1