class CompilationEngine:
"""
The compilation engine compile the jack code given in the input file
into an xml code saved in the out_file
"""
def __init__(self, in_file, out_file):
"""
A compilation engine constructor
:param in_file: the file we are currently compiling
:param out_file: the file where we save the output
"""
self.tokenizer = JackTokenizer(in_file)
self.out_file = open(out_file, 'w')
self._indent_count = 0
def compile_class(self):
"""
compiles a class according to the grammar
"""
self._write_outer_tag(CLASS_TAG)
self.tokenizer.advance()
if self.tokenizer.key_word() != CLASS_TAG:
print(COMPILE_CLASS_ERROR)
sys.exit()
self._write_token(self.tokenizer.token_type())
self._check_write_name()
self._check_write_symbol("{")
# there may be multiple variable declarations
while self._check_if_var_dec():
self.compile_class_var_dec()
# there may be multiple subroutine declarations
while self._check_subroutine_dec():
self.compile_subroutine_dec()
self._check_write_symbol("}")
self._write_outer_tag(CLASS_TAG, IS_ENDING_TAG)
def compile_class_var_dec(self):
"""
compiles the class's variables declarations
"""
self._write_outer_tag(CLASS_VAR_DEC_TAG)
# we only come in the function if the current token is correct so we
# can just write it
self._write_token(self.tokenizer.token_type())
self._check_write_type()
self._check_write_name()
while self._check_if_comma(): # there are more variables
self._check_write_symbol(",")
self._check_write_name()
self._check_write_symbol(";")
self._write_outer_tag(CLASS_VAR_DEC_TAG, IS_ENDING_TAG)
def compile_subroutine_dec(self):
"""
compiles the class's subroutine (methods and functions) declarations
"""
self._write_outer_tag(SUBROUTINE_DEC_TAG)
# we only come in the function if the current token is correct so we
# can just write it
self._write_token(self.tokenizer.token_type())
# the function is either void or has a type
if self.tokenizer.key_word() == 'void':
self._write_token(self.tokenizer.token_type())
else:
self._check_write_type()
self._check_write_name()
self._check_write_symbol("(")
self.compile_parameter_list()
self._check_write_symbol(")")
self.compile_subroutine_body()
self._write_outer_tag(SUBROUTINE_DEC_TAG, IS_ENDING_TAG)
def compile_parameter_list(self):
"""
compiles the parameter list for the subroutines
"""
self._write_outer_tag(PARAMETER_LIST_TAG)
# if curr_token is ')' it means the param list is empty
if self.tokenizer.symbol() != ')':
self._check_write_type()
self._check_write_name()
while self._check_if_comma(): # there are more params
self._check_write_symbol(",")
self._check_write_type()
self._check_write_name()
self._write_outer_tag(PARAMETER_LIST_TAG, IS_ENDING_TAG)
def compile_subroutine_body(self):
"""
compiles the body of the subroutine
"""
self._write_outer_tag(SUBROUTINE_BODY_TAG)
self._check_write_symbol("{")
# there may be multiple variable declarations at the beginning of
# the subroutine
while self.tokenizer.key_word() == 'var':
self.compile_var_dec()
self.compile_statements()
self._check_write_symbol("}")
self._write_outer_tag(SUBROUTINE_BODY_TAG, IS_ENDING_TAG)
def compile_var_dec(self):
"""
compiles the variable declarations
"""
self._write_outer_tag(VAR_DEC_TAG)
self._write_token(self.tokenizer.token_type())
self._check_write_type()
self._check_write_name()
# there may be multiple variable names in the dec
while self._check_if_comma():
self._check_write_symbol(",")
self._check_write_name()
self._check_write_symbol(";")
self._write_outer_tag(VAR_DEC_TAG, IS_ENDING_TAG)
def compile_statements(self):
"""
compiles the statements (0 or more statements)
"""
self._write_outer_tag(STATEMENTS_TAG)
while self._check_if_statement():
if self.tokenizer.key_word() == 'let':
self.compile_let()
elif self.tokenizer.key_word() == 'if':
self.compile_if()
elif self.tokenizer.key_word() == 'while':
self.compile_while()
elif self.tokenizer.key_word() == 'do':
self.compile_do()
elif self.tokenizer.key_word() == 'return':
self.compile_return()
self._write_outer_tag(STATEMENTS_TAG, IS_ENDING_TAG)
def compile_do(self):
"""
compiles the do statement
"""
self._write_outer_tag(DO_STATEMENT_TAG)
self._write_token(self.tokenizer.token_type())
self.compile_subroutine_call()
self._check_write_symbol(";")
self._write_outer_tag(DO_STATEMENT_TAG, IS_ENDING_TAG)
def compile_let(self):
"""
compiles the let statement
"""
self._write_outer_tag(LET_STATEMENT_TAG)
self._write_token(self.tokenizer.token_type())
self._check_write_name()
if self.tokenizer.symbol() == '[': # if there is an array
self._check_write_symbol("[")
self.compile_expression()
self._check_write_symbol("]")
self._check_write_symbol("=")
self.compile_expression()
self._check_write_symbol(";")
self._write_outer_tag(LET_STATEMENT_TAG, IS_ENDING_TAG)
def compile_if(self):
"""
compiles the if statements
"""
self._write_outer_tag(IF_STATEMENT_TAG)
self._write_token(self.tokenizer.token_type())
self._check_write_symbol("(")
self.compile_expression()
self._check_write_symbol(")")
self._check_write_symbol("{")
self.compile_statements()
self._check_write_symbol("}")
# there can also be an if else scenario
if self.tokenizer.key_word() == 'else':
self._write_token(self.tokenizer.token_type())
self._check_write_symbol("{")
self.compile_statements()
self._check_write_symbol("}")
self._write_outer_tag(IF_STATEMENT_TAG, IS_ENDING_TAG)
def compile_while(self):
"""
compiles the while statements
"""
self._write_outer_tag("whileStatement")
self._write_token(self.tokenizer.token_type())
self._check_write_symbol("(")
self.compile_expression()
self._check_write_symbol(")")
self._check_write_symbol("{")
self.compile_statements()
self._check_write_symbol("}")
self._write_outer_tag("whileStatement", IS_ENDING_TAG)
def compile_return(self):
"""
compiles the return statements
"""
self._write_outer_tag(RETURN_STATEMENT_TAG)
self._write_token(self.tokenizer.token_type())
# if cur token is ; we return nothing, otherwise we return something
if not self.tokenizer.symbol() == ';':
self.compile_expression()
self._check_write_symbol(";")
self._write_outer_tag(RETURN_STATEMENT_TAG, IS_ENDING_TAG)
def compile_subroutine_call(self):
"""
compiles the subroutine calls ( when we actually call a subroutine
as opposed to declaring it)
"""
self._check_write_name()
# there may be a '.' if it is a foo.bar() scenario (or Foo.bar())
if self.tokenizer.symbol() == ".":
self._check_write_symbol(".")
self._check_write_name()
self._check_write_symbol("(")
self.compile_expression_list()
self._check_write_symbol(")")
def compile_expression(self):
"""
compiles expressions which are terms and possibly operators and more
terms
"""
self._write_outer_tag(EXPRESSION_TAG)
self.compile_term()
# there may be a few operators in one expression
while self.tokenizer.symbol() in OPERATIONS:
self._write_op()
self.compile_term()
self._write_outer_tag(EXPRESSION_TAG, IS_ENDING_TAG)
def compile_term(self):
"""
compiles terms according to the grammar
"""
self._write_outer_tag(TERM_TAG)
cur_type = self.tokenizer.token_type()
# either a string/int constant
if self.tokenizer.token_type() in ["INT_CONST", "STRING_CONST"]:
self._write_token(cur_type)
# or a constant keyword (true, false, null, this)
elif self.tokenizer.key_word() in KEYWORD_CONST:
self._write_token(cur_type)
# or an expression within brown brackets
elif self.tokenizer.symbol() == '(':
self._write_token(cur_type)
self.compile_expression()
self._check_write_symbol(")")
# or a unary op and then a term
elif self.tokenizer.symbol() in UNARY_OPS:
self._write_op()
self.compile_term()
# or it is an identifier which could be:
elif self.tokenizer.identifier():
self._compile_term_identifier()
else:
print(COMPILE_TERM_ERROR)
sys.exit()
self._write_outer_tag(TERM_TAG, IS_ENDING_TAG)
def _compile_term_identifier(self):
"""
compiles terms in case of identifier token
"""
# an array
if self.tokenizer.get_next_token() == '[':
self._check_write_name()
self._check_write_symbol("[")
self.compile_expression()
self._check_write_symbol("]")
# or a subroutine call
elif self.tokenizer.get_next_token() in [".", "("]:
self.compile_subroutine_call()
else:
self._check_write_name() # or just a variable name
def compile_expression_list(self):
"""
compiles the expression lists
"""
self._write_outer_tag(EXPRESSION_LIST_TAG)
# if it is ')' then the expression list is empty
if self.tokenizer.symbol() != ')':
self.compile_expression()
while self._check_if_comma(): # while there are more expressions
self._write_token(self.tokenizer.token_type())
self.compile_expression()
self._write_outer_tag(EXPRESSION_LIST_TAG, IS_ENDING_TAG)
def _check_if_var_dec(self):
"""
check if we are currently compiling a variable declaration
:return: true iff the current token is either 'static' or 'field'
"""
return self.tokenizer.key_word() in CLASS_VAR_KEYWORDS
def _check_subroutine_dec(self):
"""
checks if we are currently compiling a subroutine declaration
:return: true iff the current token is either 'constructor' or
'function' or 'method'
"""
return self.tokenizer.key_word() in SUBROUTINE
def _check_if_comma(self):
"""
checks if current token is a comma
:return: true iff the current token is a ','
"""
return self.tokenizer.symbol() == ','
def _check_if_statement(self):
"""
checks if we are currently compiling a statement
:return: true iff the current token
is in ['let', 'if', 'while', 'do', 'return']
"""
return self.tokenizer.key_word() in STATEMENTS
def _check_write_type(self):
"""
checks if the current token is a valid type and if so, it writes it
to the output file
"""
if self.tokenizer.key_word() in TYPE_KEYWORDS:
self._write_token(self.tokenizer.token_type())
else:
self._check_write_name()
def _check_write_symbol(self, expected_symbol):
"""
checks if the current token is the expected symbol, if so it write
it to the output file
:param expected_symbol: the symbol we are validating is the current
token
:return: prints illegal statement error if it is not the expected
symbol and exits the program
"""
if self.tokenizer.symbol() != expected_symbol:
print(ILLEGAL_STATEMENT_ERROR)
sys.exit()
self._write_token(self.tokenizer.token_type())
def _check_write_name(self):
"""
checks the current token is a name (identifier), and if so, write
it to the output file
:return: prints illegal statement error if it is not a name and
exits the program
"""
if self.tokenizer.identifier():
self._write_token("IDENTIFIER")
else:
print(ILLEGAL_STATEMENT_ERROR)
sys.exit()
def _write_outer_tag(self, tag_str, end=False):
"""
writes the outer tags of the different sections we are compiling
:param tag_str: the string of the current section we are compiling
:param end: true iff it is an end tag
"""
if end: # we decrease the indent count before the closing tag
self._indent_count -= 1
self.out_file.write("\t" * self._indent_count)
self.out_file.write("</" + tag_str + ">\n")
else: # we increase the indent count after the opening tag
self.out_file.write("\t" * self._indent_count)
self.out_file.write("<" + tag_str + ">\n")
self._indent_count += 1
def _write_op(self):
"""
writes an op symbol to the out file
"""
self.out_file.write("\t" * self._indent_count)
self.out_file.write("<symbol> ")
if self.tokenizer.symbol() == '<':
self.out_file.write("<")
elif self.tokenizer.symbol() == '>':
self.out_file.write(">")
elif self.tokenizer.symbol() == '&':
self.out_file.write("&")
elif self.tokenizer.symbol() == '\"':
self.out_file.write(""")
else:
self.out_file.write(self.tokenizer.symbol())
self.out_file.write(" </symbol>\n")
self.tokenizer.advance()
def _write_token(self, cur_type):
"""
writes the current token to the output file
:param cur_type: the type of the current token
"""
self.out_file.write("\t" * self._indent_count)
self.out_file.write("<" + TOKEN_TYPE_STR[cur_type] + "> ")
self.out_file.write(str(self.tokenizer.get_token_str()))
self.out_file.write(" </" + TOKEN_TYPE_STR[cur_type] + ">\n")
self.tokenizer.advance()
class CompilationEngine:
"""
The compilation engine compile the jack code given in the input file
into an xml code saved in the out_file
"""
def __init__(self, in_file, out_file):
"""
A compilation engine constructor
:param in_file: the file we are currently compiling
:param out_file: the file where we save the output
"""
self._tokenizer = JackTokenizer(in_file)
self._class_table = SymbolTable()
self._method_table = SymbolTable()
self._cur_class_name = ""
self._vm_writer = VMWriter(out_file)
self._label_count_while = 0
self._label_count_if = 0
def compile_class(self):
"""
compiles a class according to the grammar
"""
self._class_table.start_subroutine()
self._tokenizer.advance()
# check if the current keyword is the right class tag
if self._tokenizer.key_word() != CLASS_TAG:
print(COMPILE_CLASS_ERROR)
sys.exit()
self._tokenizer.advance()
self._cur_class_name = self.get_cur_token()
self._tokenizer.advance()
self._check_symbol("{")
# there may be multiple variable declarations
while self._check_if_var_dec():
self.compile_class_var_dec()
# there may be multiple subroutine declarations
while self._check_subroutine_dec():
self.compile_subroutine_dec()
self._check_symbol("}")
def compile_class_var_dec(self):
"""
compiles the class's variables declarations
"""
cur_kind = self.get_cur_token()
self._tokenizer.advance()
cur_type = self.get_cur_token()
self._check_type()
cur_name = self.get_cur_token()
self._check_name()
self._class_table.define(cur_name, cur_type, cur_kind)
while self._check_if_comma(): # there are more variables
self._tokenizer.advance()
cur_name = self.get_cur_token()
self._check_name()
self._class_table.define(cur_name, cur_type, cur_kind)
self._check_symbol(";")
def get_cur_token(self):
return self._tokenizer.get_token_str()
def compile_subroutine_dec(self):
"""
compiles the class's subroutine (methods and functions) declarations
"""
# re-initialize the method symbol table
self._method_table.start_subroutine()
key_word = self._tokenizer.key_word()
self._tokenizer.advance()
self._tokenizer.advance()
cur_name = self.get_cur_token()
self._tokenizer.advance()
# method get the as argument the base address of the current object
if key_word == "method":
self._method_table.define("this", self._cur_class_name, "argument")
self._check_symbol("(")
self.compile_parameter_list()
self._check_symbol(")")
subroutine_path = self._cur_class_name + '.' + cur_name
# the function is either void or has a type
self.compile_subroutine_body(subroutine_path, key_word)
def compile_parameter_list(self):
"""
compiles the parameter list for the subroutines
"""
# if curr_token is ')' it means the param list is empty
if self._tokenizer.symbol() == ')':
return
cur_type = self.get_cur_token()
self._check_type()
cur_name = self.get_cur_token()
self._check_name()
self._method_table.define(cur_name, cur_type, "argument")
while self._check_if_comma(): # there are more params
self._tokenizer.advance()
cur_type = self.get_cur_token()
self._check_type()
cur_name = self.get_cur_token()
self._check_name()
self._method_table.define(cur_name, cur_type, "argument")
def compile_subroutine_body(self, subroutine_name, subroutine_kind):
"""
compiles the body of the subroutine
"""
self._check_symbol("{")
# there may be multiple variable declarations at the beginning of
# the subroutine
while self._tokenizer.key_word() == 'var':
self.compile_var_dec()
# define the subroutine
n_locals = self._method_table.var_count("local")
self._vm_writer.write_function(subroutine_name, n_locals)
if subroutine_kind == "constructor":
# allocating memory for the object's fields
num_of_fields = self._class_table.var_count("field")
self._vm_writer.write_push("constant", num_of_fields)
self._vm_writer.write_call("Memory.alloc", 1)
# make 'this' to point to address returned by Memory.alloc
self._vm_writer.write_pop("pointer", 0)
if subroutine_kind == "method":
# assign pointer[0] to the object's base address in order to
# get access to 'this' segment
self._vm_writer.write_push("argument", 0)
self._vm_writer.write_pop("pointer", 0)
self.compile_statements()
self._check_symbol("}")
def compile_var_dec(self):
"""
compiles the variable declarations
"""
self._tokenizer.advance()
cur_type = self.get_cur_token()
self._check_type()
cur_name = self.get_cur_token()
self._check_name()
self._method_table.define(cur_name, cur_type, "local")
# there may be multiple variable names in the dec
while self._check_if_comma():
self._tokenizer.advance()
self._method_table.define(self.get_cur_token(), cur_type, "local")
self._check_name()
self._check_symbol(";")
def compile_statements(self):
"""
compiles the statements (0 or more statements)
"""
while self._check_if_statement():
if self._tokenizer.key_word() == 'let':
self.compile_let()
elif self._tokenizer.key_word() == 'if':
self.compile_if()
elif self._tokenizer.key_word() == 'while':
self.compile_while()
elif self._tokenizer.key_word() == 'do':
self.compile_do()
elif self._tokenizer.key_word() == 'return':
self.compile_return()
def compile_do(self):
"""
compiles the do statement
"""
self._tokenizer.advance()
self.compile_subroutine_call()
self._check_symbol(";")
self._vm_writer.write_pop("temp", 0)
def compile_let(self):
"""
compiles the let statement
"""
self._tokenizer.advance()
name = self.get_cur_token()
info = self._get_symbol_info(name)
self._check_if_declared(info)
s_type, s_kind, s_id = info
seg = self._get_segment(s_kind)
is_and_array = False
if self._tokenizer.get_next_token() == '[': # if there is an array
is_and_array = True
self.compile_term()
else:
self._tokenizer.advance()
self._check_symbol("=")
self.compile_expression()
if is_and_array:
# save the value created after compiling the expression which
# appears right after '=' in temp[0]
self._vm_writer.write_pop("temp", 0)
# now the top of the stack should be the address of the right cell
# in the array so we assign it to pointer[1]
self._vm_writer.write_pop("pointer", 1)
# re-pushing the value we saved in temp[0]
self._vm_writer.write_push("temp", 0)
# the value of the array is located in that[0]
seg = "that"
s_id = 0
# execute the assignment
self._vm_writer.write_pop(seg, s_id)
self._check_symbol(";")
@staticmethod
def _check_if_declared(info):
if info is None:
print("Unknown Symbol")
sys.exit()
def compile_if(self):
"""
compiles the if statements
"""
false_label = self._get_if_label()
end_label = self._get_if_label()
self._tokenizer.advance()
self._check_symbol("(")
self.compile_expression()
self._check_symbol(")")
self._check_symbol("{")
self._vm_writer.write_arithmetic("not")
self._vm_writer.write_if_goto(false_label)
self.compile_statements()
self._check_symbol("}")
# there can also be an if else scenario
self._vm_writer.write_goto(end_label)
self._vm_writer.write_label(false_label)
if self._tokenizer.key_word() == 'else':
self._tokenizer.advance()
self._check_symbol("{")
self.compile_statements()
self._check_symbol("}")
self._vm_writer.write_label(end_label)
def compile_while(self):
"""
compiles the while statements
"""
self._tokenizer.advance()
first_label = self._get_while_label()
second_label = self._get_while_label(END_WHILE)
self._check_symbol("(")
self._vm_writer.write_label(first_label)
self.compile_expression()
self._vm_writer.write_arithmetic("not")
self._vm_writer.write_if_goto(second_label)
self._check_symbol(")")
self._check_symbol("{")
self.compile_statements()
self._vm_writer.write_goto(first_label)
self._vm_writer.write_label(second_label)
self._check_symbol("}")
def compile_return(self):
"""
compiles the return statements
"""
self._tokenizer.advance()
# if cur token is ; we return nothing, otherwise we return something
if not self._tokenizer.symbol() == ';':
self.compile_expression()
else:
self._vm_writer.write_push("constant", 0)
self._check_symbol(";")
self._vm_writer.write_return()
def compile_subroutine_call(self):
"""
compiles the subroutine calls ( when we actually call a subroutine
as opposed to declaring it)
"""
method_name = self.get_cur_token()
self._check_name()
num_of_args = 0
# there may be a '.' if it is a foo.bar() scenario (or Foo.bar())
if self._tokenizer.symbol() == ".":
self._tokenizer.advance()
class_name = method_name
method_name = self.get_cur_token()
self._check_name()
symbol_info = self._get_symbol_info(class_name)
if symbol_info is None:
cur_name = class_name + '.' + method_name
else:
type_of, kind_of, id_of = symbol_info
num_of_args += 1
self._vm_writer.write_push(self._get_segment(kind_of), id_of)
cur_name = type_of + '.' + method_name
else:
cur_name = self._cur_class_name + '.' + method_name
num_of_args += 1
self._vm_writer.write_push("pointer", 0)
self._check_symbol("(")
num_of_args += self.compile_expression_list()
self._check_symbol(")")
self._vm_writer.write_call(cur_name, num_of_args)
def compile_expression(self):
"""
compiles expressions which are terms and possibly operators and more
terms
"""
symbol = self._tokenizer.symbol()
self.compile_term()
# write the 'not' operator if necessary
if symbol == '~':
self._vm_writer.write_arithmetic("not")
# there may be a few operators in one expression
while self._tokenizer.symbol() in OPERATIONS:
symbol = self._tokenizer.symbol()
self.compile_term()
# executing operators after handling the the operands
# in order to evaluate the current expression as postfix expression
op = self._get_op(symbol)
self._vm_writer.write_arithmetic(op)
def compile_term(self):
"""
compiles terms according to the grammar
"""
cur_type = self._tokenizer.token_type()
key_word = self._tokenizer.key_word()
cur_token = self.get_cur_token()
# either a string/int constant
if cur_type in ["INT_CONST", "STRING_CONST"]:
self._compile_string_int_term(cur_token, cur_type)
# or a constant keyword (true, false, null, this)
elif key_word in KEYWORD_CONST:
self._compile_const_keyword_term(key_word)
# or an expression within brown brackets
elif self._tokenizer.symbol() == '(':
self._tokenizer.advance()
self.compile_expression()
self._check_symbol(")")
# or a unary op and then a term
elif self._tokenizer.symbol() in OPERATIONS:
self._tokenizer.advance()
self.compile_term()
# or it is an identifier which could be:
elif self._tokenizer.identifier():
self._compile_term_identifier()
else:
print(COMPILE_TERM_ERROR)
sys.exit()
def _compile_const_keyword_term(self, key_word):
"""
compile term in case the current token type is constant keyword
:param key_word: string from {'true', 'false', 'null', 'this'}
"""
if key_word == "this":
self._vm_writer.write_push("pointer", 0)
else:
self._vm_writer.write_push("constant", 0)
if key_word == "true":
self._vm_writer.write_arithmetic("not")
self._tokenizer.advance()
def _compile_string_int_term(self, cur_token, cur_type):
"""
compile term in case the given token type is constant string
or constant integer
:param cur_token: the current token as a string
:param cur_type: the type of the current token
"""
if cur_type == "INT_CONST":
self._vm_writer.write_push("constant", cur_token)
else: # is string
n = len(cur_token)
self._vm_writer.write_push("constant", n)
self._vm_writer.write_call("String.new", 1)
for c in cur_token:
self._vm_writer.write_push("constant", ord(c))
self._vm_writer.write_call("String.appendChar", 2)
self._tokenizer.advance()
def _compile_term_identifier(self):
"""
compiles terms in case of identifier token
"""
cur_token = self.get_cur_token()
info = self._get_symbol_info(cur_token)
next_token = self._tokenizer.get_next_token()
if info is not None and next_token not in [".", "("]:
type_of, kind_of, id_of = info
seg = self._get_segment(kind_of)
self._vm_writer.write_push(seg, id_of)
# an array
if next_token == '[':
self._check_name()
self._check_symbol("[")
self.compile_expression()
self._check_symbol("]")
self._vm_writer.write_arithmetic("add")
if self._tokenizer.symbol() != '=':
self._vm_writer.write_pop("pointer", 1)
self._vm_writer.write_push("that", 0)
# or a subroutine call
elif next_token in [".", "("]:
self.compile_subroutine_call()
else:
self._tokenizer.advance()
def compile_expression_list(self):
"""
compiles the expression lists
"""
# if it is ')' then the expression list is empty
if self._tokenizer.symbol() == ')':
return 0
num_of_args = 1 # at least one argument
self.compile_expression()
# while there are more expressions
while self._check_if_comma():
self._tokenizer.advance()
cur_symbol = self._tokenizer.symbol()
self.compile_expression()
if cur_symbol == '-': # negative int
self._vm_writer.write_arithmetic("neg")
num_of_args += 1
return num_of_args
def _check_if_var_dec(self):
"""
check if we are currently compiling a variable declaration
:return: true iff the current token is either 'static' or 'field'
"""
return self._tokenizer.key_word() in CLASS_VAR_KEYWORDS
def _check_subroutine_dec(self):
"""
checks if we are currently compiling a subroutine declaration
:return: true iff the current token is either 'constructor' or
'function' or 'method'
"""
return self._tokenizer.key_word() in SUBROUTINE
def _check_if_comma(self):
"""
checks if current token is a comma
:return: true iff the current token is a ','
"""
return self._tokenizer.symbol() == ','
def _check_if_statement(self):
"""
checks if we are currently compiling a statement
:return: true iff the current token
is in ['let', 'if', 'while', 'do', 'return']
"""
return self._tokenizer.key_word() in STATEMENTS
def _check_type(self):
"""
checks if the current token is a valid type and if so, it writes it
to the output file
"""
if not self._tokenizer.key_word() in TYPE_KEYWORDS:
self._check_name()
else:
self._tokenizer.advance()
def _check_symbol(self, expected_symbol):
"""
checks if the current token is the expected symbol, if so it write
it to the output file
:param expected_symbol: the symbol we are validating is the current
token
:return: prints illegal statement error if it is not the expected
symbol and exits the program
"""
if self._tokenizer.symbol() != expected_symbol:
print(ILLEGAL_STATEMENT_ERROR)
sys.exit()
self._tokenizer.advance()
def _check_name(self):
"""
checks the current token is a name (identifier), and if so, write
it to the output file
:return: prints illegal statement error if it is not a name and
exits the program
"""
if not self._tokenizer.identifier():
print(ILLEGAL_STATEMENT_ERROR)
sys.exit()
self._tokenizer.advance()
@staticmethod
def _get_op(symbol):
"""
writes an op symbol to the out file
"""
if symbol == '<':
return "lt"
elif symbol == '>':
return "gt"
elif symbol == '=':
return "eq"
elif symbol == '&':
return "and"
elif symbol == '|':
return "or"
elif symbol == '+':
return "add"
elif symbol == '-':
return "sub"
elif symbol == '~':
return "not"
elif symbol == "*":
return "call Math.multiply 2"
elif symbol == "/":
return "call Math.divide 2"
def _get_symbol_info(self, symbol_name):
"""
first checks if the given symbol in the method symbol table
if the method table contains the symbol it returns it's information:
(type,kind,id)
otherwise check if the class symbol table contains the symbol
if it does it return the symbol information from the class table
else returns None
:param symbol_name: string
"""
info = self._method_table.get_info(symbol_name)
if info is None:
info = self._class_table.get_info(symbol_name)
return info
@staticmethod
def _get_segment(cur_kind):
"""
:param cur_kind: Jack kind - from the list:
["var", "argument", "field", "class", "subroutine", "local", "static"]
:return: if the given kind is "field" it returns 'this'
otherwise returns the given kind
"""
if cur_kind == "field":
return "this"
else:
return cur_kind
def _get_if_label(self):
"""
create new if label and increment the if label counter
:return: if unused label
"""
curr_counter = str(self._label_count_if)
self._label_count_if += 1
return "IF" + curr_counter
def _get_while_label(self, is_end_while=False):
"""
creates label according to the given flag, if the method creates
end while label it increments the while label counter
:param is_end_while: if true creates end while label
otherwise creates while label
:return: unused while label or end while label according to the flag
"""
curr_counter = str(self._label_count_while)
if is_end_while:
self._label_count_while += 1
return "WHILE_END" + curr_counter
return "WHILE" + curr_counter
