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Copy pathsymtable.py
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212 lines (169 loc) · 6.81 KB
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from error import *
class SymTable:
glob = dict()
temp = None
temp_defined = False
local_stack = []
local_defined = False
var_stack = []
max_defined_vars = 0
def __is_frame_defined__(self, arg):
""" Returns whether variable's frame is defined """
if arg.frame == "GF":
return True
elif arg.frame == "TF" and self.temp_defined == True:
return True
elif arg.frame == "LF" and self.local_defined == True:
return True
else:
return False
def __is_var_defined__(self, arg):
""" Returns whether a variable is defined """
if arg.frame == "GF" and arg.value in self.glob:
return True
elif arg.frame == "TF" and arg.value in self.temp:
return True
elif arg.frame == "LF" and arg.value in self.local_stack[-1]:
return True
else:
return False
def create_frame(self):
""" Creates an empty temporary frame """
if self.temp_defined == False:
self.temp = dict()
self.temp_defined = True
else:
self.temp.clear()
def push_frame(self):
""" Pushes a temporary frame to the local frame stack """
if self.temp_defined == False:
err.exit_script(err.undef_frame)
else:
self.local_stack.append(self.temp)
self.local_defined = True
self.temp = None
self.temp_defined = False
def pop_frame(self):
""" Pops a frame from the local frame stack """
if len(self.local_stack) == 0:
err.exit_script(err.undef_frame)
else:
self.temp = self.local_stack.pop()
self.temp_defined = True
if len(self.local_stack) == 0:
self.local_defined = False
def defvar(self, arg):
""" Defines a variable """
if self.__is_frame_defined__(arg) == False:
err.exit_script(err.undef_frame)
if self.__is_var_defined__(arg) == True:
err.exit_script(err.semantics) # Undefined variable
if arg.frame == "GF":
self.glob[arg.value] = None
elif arg.frame == "TF":
self.temp[arg.value] = None
elif arg.frame == "LF":
self.local_stack[-1][arg.value] = None
def set_var(self, arg1, arg2):
""" Assigns a value to a variable """
if self.__is_frame_defined__(arg1) == False:
err.exit_script(err.undef_frame)
if self.__is_var_defined__(arg1) == False:
err.exit_script(err.undef_var)
if arg1.frame == "GF":
self.glob[arg1.value] = arg2
elif arg1.frame == "TF":
self.temp[arg1.value] = arg2
elif arg1.frame == "LF":
self.local_stack[-1][arg1.value] = arg2
def get_var (self, arg):
""" Gets a value from a variable """
if self.__is_frame_defined__(arg) == False:
err.exit_script(err.undef_frame)
if self.__is_var_defined__(arg) == False:
err.exit_script(err.undef_var)
if arg.frame == "GF":
arg_get = self.glob[arg.value]
elif arg.frame == "TF":
arg_get = self.temp[arg.value]
elif arg.frame == "LF":
arg_get = self.local_stack[-1][arg.value]
if arg_get == None:
err.exit_script(err.missing_value)
return arg_get
def get_var_even_uninitialised(self, arg):
""" Gets a value from a variable, doesn't check whether the variable is initialised """
if self.__is_frame_defined__(arg) == False:
err.exit_script(err.undef_frame)
if self.__is_var_defined__(arg) == False:
err.exit_script(err.undef_var)
if arg.frame == "GF":
arg_get = self.glob[arg.value]
elif arg.frame == "TF":
arg_get = self.temp[arg.value]
elif arg.frame == "LF":
arg_get = self.local_stack[-1][arg.value]
return arg_get
def get_value(self, arg):
""" Returns a constant or gets a value from a variable """
if arg.datatype == "var":
return self.get_var(arg)
else:
return arg
def print(self):
""" Prints frame contents """
sys.stderr.write("Frame contents:\n")
sys.stderr.write("Global frame:\n")
for var in self.glob:
if self.glob[var] == None:
sys.stderr.write("\tVar: " + var + ",\tUndefined value\n")
else:
sys.stderr.write("\tVar: " + var + ",\ttype: " + self.glob[var].datatype + ",\tvalue: " + str(self.glob[var].value) + "\n")
sys.stderr.write("Temporary frame: defined: " + str(self.temp_defined) + "\n")
if self.temp_defined:
for var in self.temp:
if self.temp[var] == None:
sys.stderr.write("\tVar: " + var + ",\tUndefined value\n")
else:
sys.stderr.write("\tVar: " + var + ",\ttype: " + self.temp[var].datatype + ",\tvalue: " + str(self.temp[var].value) + "\n")
sys.stderr.write("Local frame: defined: " + str(self.local_defined) + "\n")
if self.local_defined:
frame_cntr = 0
for frame in self.local_stack:
sys.stderr.write("\tFrame " + str(frame_cntr) + ":\n")
frame_cntr += 1
for var in frame:
if frame[var] == None:
sys.stderr.write("\t\tVar: " + var + ",\tUndefined value\n")
else:
sys.stderr.write("\t\tVar: " + var + ",\ttype: " + frame[var].datatype + ",\tvalue: " + frame[var].value + "\n")
def pushs(self, arg):
""" Pushes a value to the value stack """
self.var_stack.append(self.get_value(arg))
def pops(self):
""" Pops a value from the value stack """
if len(self.var_stack) == 0:
err.exit_script(err.missing_value)
else:
return self.var_stack.pop()
def clears(self):
""" Clears the value stack """
self.var_stack.clear()
def count_vars(self):
""" Counts initialised variables in all frames and sets the maximum value """
counter = 0
for var, value in self.glob.items():
print(var,value)
if value != None:
counter += 1
if self.temp_defined:
for var, value in self.temp.items():
if value != None:
counter += 1
if self.local_defined:
for frame in self.local_stack:
for var, value in frame.items():
if value != None:
counter += 1
if counter > self.max_defined_vars:
self.max_defined_vars = counter