def swap_x_y(self, symbols, cmd, cmds):
# exchanges top two values on the stack
ret = 1
a = variables.pop(symbols)
b = variables.pop(symbols)
variables.push(symbols, a)
variables.push(symbols, b)
return ret
def subtract(self, symbols, cmd, cmds):
ret = 1
a = variables.pop(symbols)
b = variables.pop(symbols)
symbols[SYM_LOCAL]['last x'] = a
try:
c = b - a
except:
raise Exception("Error in subtraction: " + str(b) + " - " + str(a))
variables.push(symbols, c)
return ret
def mod(self, symbols, cmd, cmds):
ret = 1
a = variables.pop(symbols)
b = variables.pop(symbols)
symbols[SYM_LOCAL]['last x'] = a
try:
c = b % a
except:
raise Exception("Error in mod: " + str(b) + " % " +
str(a)) # Errors are highly possible here
variables.push(symbols, c)
return ret
def multiply(self, symbols, cmd, cmds):
ret = 1
a = variables.pop(symbols)
b = variables.pop(symbols)
symbols[SYM_LOCAL]['last x'] = a
try:
c = b * a
except:
raise Exception("Error in multiplication: " + str(b) + " * " +
str(a))
variables.push(symbols, c)
return ret
def y_to_x(self, symbols, cmd, cmds):
# calculates the square
ret = 1
a = variables.pop(symbols)
b = variables.pop(symbols)
symbols[SYM_LOCAL]['last x'] = a
try:
c = b**a
except:
raise Exception("Error raising: " + str(b) + " to the " + str(a) +
"th power") # Errors are highly possible here
variables.push(symbols, c)
return ret
def chs(self, symbols, cmd, cmds):
ret = 1
a = variables.pop(symbols)
try:
variables.push(symbols, -a)
except:
raise Exception("Error in chs: " +
str(a)) # Errors are highly improbable here
return ret
def one_on_x(self, symbols, cmd, cmds):
ret = 1
a = variables.pop(symbols)
symbols[SYM_LOCAL]['last x'] = a
try:
variables.push(symbols, 1 / a)
except:
raise Exception("Error in 1/x: " +
str(a)) # Errors are highly possible here
return ret
def frac_x(self, symbols, cmd, cmds):
# get the fractionasl part of x
ret = 1
a = variables.pop(symbols)
symbols[SYM_LOCAL]['last x'] = a
try:
variables.push(symbols, a - int(a))
except:
raise Exception("Error in '" + cmd + "' " +
str(a)) # Errors are highly unlikely here
return ret
def sqr(self, symbols, cmd, cmds):
# calculates the square
ret = 1
a = variables.pop(symbols)
symbols[SYM_LOCAL]['last x'] = a
try:
c = a**2
except:
raise Exception("Error in squaring: " + str(a))
variables.push(symbols, c)
return ret
def add(
self,
symbols, # the symbol table (stack, global vars, etc.)
cmd, # the current command
cmds): # the rest of the commands on the command line
ret = 1 # always initialise ret to 1, because the default is to
# step token by token along the expression
a = variables.pop(
symbols) # add requires 2 params, pop them off the stack...
b = variables.pop(symbols) #
symbols[SYM_LOCAL]['last x'] = a
try:
c = b + a # RPN functions are defined as b (operator) a
except:
raise Exception("Error in addition: " + str(b) + " + " +
str(a)) # error message in case of problem
variables.push(symbols, c) # the result is pushed back on the stack
return ret # and we return the number of tokens to skip (normally 1)
def pop(self, symbols, cmd, cmds):
# removes top item from the stack
ret = 1
variables.pop(symbols)
return ret
