def logo_if(val, exp, env):
"""Apply the "if" primitive, which takes a boolean and a list.
***YOUR DOCTEST HERE***
>>> val = 'equal? 1 difference 6 5'
>>> exp = 'print word "snake "yes'
>>> env = Environment()
>>> logo_if(val, exp, env)
'print word "snake "yes'
>>> val = 'True'
>>> exp = ['print', '3']
>>> env = Environment()
>>> logo_if(val, exp, env)
3
"""
"*** YOUR CODE HERE ***"
bool_val = eval_line(Buffer(parse_line(val)), env)
if bool_val == 'True':
if type(exp) == list:
return eval_line(Buffer(exp), env)
else:
return exp
elif bool_val == 'False':
return None
else:
error('First argument to "if" is not Ture or False: ' + str(bool_val))
def logo_if(val, exp, env):
"""Apply the "if" primitive, which takes a boolean and a list.
***YOUR DOCTEST HERE***
>>> val = 'equal? 1 difference 6 5'
>>> exp = 'print word "snake "yes'
>>> env = Environment()
>>> logo_if(val, exp, env)
'print word "snake "yes'
>>> val = 'True'
>>> exp = ['print', '3']
>>> env = Environment()
>>> logo_if(val, exp, env)
3
"""
"*** YOUR CODE HERE ***"
bool_val = eval_line(Buffer(parse_line(val)), env)
if bool_val == 'True':
if type(exp) == list:
return eval_line(Buffer(exp), env)
else:
return exp
elif bool_val == 'False':
return None
else:
error('First argument to "if" is not Ture or False: ' + str(bool_val))
def eval_definition(line, env):
"""Evaluate a definition and return a corresponding procedure.
line: The definition line, following "to", of the multi-line definition.
Hint: create a user-defined Procedure object using
Procedure(name, len(params), body, formal_params=params, needs_env=True)
- name is a string defining the procedure name
- body is a list of Buffer objects (one per line of source code)
- params is a list of strings defining the name of each formal parameter
- needs_env is always True
>>> to_line = Buffer(parse_line('to double :n'))
>>> body = ['output sum :n :n\\n', 'end']
>>> env = Environment(generate_lines(body, '>'))
>>> eval_line(to_line, env)
> output sum :n :n
> end
>>> print(env.procedures['double'])
to double :n
>>> env.procedures['double'].needs_env
True
>>> env.procedures['double'].body
[['output', 'sum', ':n', ':n']]
"""
procedure_name = line.pop()
params = []
while line.current != None:
params.append(line.pop()[1:])
next_line = lambda: parse_line(env.get_continuation_line())
body = []
cur = next_line()
while cur != parse_line("end"):
body.append(cur)
cur = next_line()
proc = Procedure(procedure_name, len(params), body, formal_params=params, needs_env=True)
env.procedures[procedure_name] = proc
def eval_definition(line, env):
"""Evaluate a definition and return a corresponding procedure.
line: The definition line, following "to", of the multi-line definition.
Hint: create a user-defined Procedure object using
Procedure(name, len(params), body, formal_params=params, needs_env=True)
- name is a string defining the procedure name
- body is a list of Buffer objects (one per line of source code)
- params is a list of strings defining the name of each formal parameter
- needs_env is always True
>>> to_line = Buffer(parse_line('to double :n'))
>>> body = ['output sum :n :n\\n', 'end']
>>> env = Environment(generate_lines(body, '>'))
>>> eval_line(to_line, env)
> output sum :n :n
> end
>>> print(env.procedures['double'])
to double :n
>>> env.procedures['double'].needs_env
True
>>> env.procedures['double'].body
[['output', 'sum', ':n', ':n']]
"""
procedure_name = line.pop()
para_len = 0
params = []
while line.current:
para_len += 1
params.append(line.pop())
next_line = lambda: parse_line(env.get_continuation_line())
body = []
new_line = next_line()
while new_line != ['end']:
body += new_line
new_line = next_line()
body = [body]
new_proc = Procedure(procedure_name,
para_len,
body,
isprimitive=False,
needs_env=True,
formal_params=params)
env.procedures[procedure_name] = new_proc
def eval_definition(line, env):
"""Evaluate a definition and create a corresponding procedure.
line: The definition line, following "to", of the multi-line definition.
Hint: create a user-defined Procedure object using
Procedure(name, len(formal_params), body, False, True, formal_params)
- name is a string defining the procedure name
- body is a list of lists representing Logo sentences (one per line)
- False indicates that it is not a primitive procedure
- True indicates that evaluation requires the environment
- formal_params is a list of strings naming each formal parameter
If you were to evaluate the following Logo definition,
? to double :n
> output sum :n :n
> end
the Procedure object you would create should be equivalent to:
Procedure('double', 1, [['output', 'sum', ':n', ':n']], False, True, ['n'])
Note: The doctest for this function was removed because of cross-platform
compatibility issues with the Python doctest module. (11/17 @ 3:15 PM)
"""
"*** YOUR CODE HERE ***"
procedure_name = line.pop()
formal_params = []
while line.current:
formal_params.append(line.pop())
next_line = lambda: parse_line(env.get_continuation_line())
body = []
while True:
a_line = next_line()
if a_line == ['end']:
break
body.append(a_line)
env.procedures[procedure_name] = Procedure(procedure_name,
len(formal_params), body, False,
True, formal_params)
return
def logo_ifelse(val, true_exp, false_exp, env):
"""Apply the "ifelse" primitive, which takes a boolean and two lists.
***YOUR DOCTEST HERE***
"""
"*** YOUR CODE HERE ***"
bool_val = eval_line(Buffer(parse_line(val)), env)
if bool_val == 'True':
if type(true_exp) == list:
return eval_line(Buffer(true_exp), env)
else:
return true_exp
elif bool_val == 'False':
if type(false_exp) == list:
return eval_line(Buffer(false_exp), env)
else:
return false_exp
else:
error('First argument to "ifelse" is not Ture or False: ' + str(bool_val))
def eval_line(line, env):
"""Evaluate a line (buffer) of Logo.
>>> line = Buffer(parse_line('1 2'))
>>> eval_line(line, Environment())
'1'
>>> line = Buffer(parse_line('print 1 2'))
>>> eval_line(line, Environment())
1
'2'
"""
"*** YOUR CODE HERE ***"
try:
line.contents[0]
except IndexError as e:
return eval_line(Buffer(parse_line(prompt_for_line())), env)
result = logo_eval(line, env)
if not result and line.current:
return eval_line(line, env)
return result
def logo_ifelse(val, true_exp, false_exp, env):
"""Apply the "ifelse" primitive, which takes a boolean and two lists.
***YOUR DOCTEST HERE***
"""
"*** YOUR CODE HERE ***"
bool_val = eval_line(Buffer(parse_line(val)), env)
if bool_val == 'True':
if type(true_exp) == list:
return eval_line(Buffer(true_exp), env)
else:
return true_exp
elif bool_val == 'False':
if type(false_exp) == list:
return eval_line(Buffer(false_exp), env)
else:
return false_exp
else:
error('First argument to "ifelse" is not Ture or False: ' +
str(bool_val))
def eval_line(line, env):
"""Evaluate a line (buffer) of Logo.
>>> line = Buffer(parse_line('1 2'))
>>> eval_line(line, Environment())
'1'
>>> line = Buffer(parse_line('print 1 2'))
>>> eval_line(line, Environment())
1
'2'
"""
"*** YOUR CODE HERE ***"
try:
line.contents[0]
except IndexError as e:
return eval_line(Buffer(parse_line(prompt_for_line())), env)
result = logo_eval(line, env)
if not result and line.current:
return eval_line(line, env)
return result
def eval_definition(line, env):
"""Evaluate a definition and create a corresponding procedure.
line: The definition line, following "to", of the multi-line definition.
Hint: create a user-defined Procedure object using
Procedure(name, len(params), body, formal_params=params, needs_env=True)
- name is a string defining the procedure name
- body is a list of lists representing Logo sentences (one per line)
- params is a list of strings naming each formal parameter
- needs_env is always True
>>> to_line = Buffer(parse_line('to double :n'))
>>> body = ['output sum :n :n\\n', 'end']
>>> env = Environment(generate_lines(body, '>'))
>>> eval_line(to_line, env)
> output sum :n :n
> end
>>> print(env.procedures['double'])
to double :n
>>> env.procedures['double'].needs_env
True
>>> env.procedures['double'].body
[['output', 'sum', ':n', ':n']]
"""
procedure_name = line.pop()
next_line = lambda: parse_line(env.get_continuation_line())
# "*** YOUR CODE HERE ***"
# DONE
params = []
while line.current != None:
params.append(line.pop().lstrip(':'))
body = []
current_line = next_line()
while current_line != ['end']:
body.append(current_line)
current_line = next_line()
p = Procedure(procedure_name, len(params), body, formal_params=params, needs_env=True)
env.procedures[procedure_name] = p
def eval_definition(line, env):
"""Evaluate a definition and create a corresponding procedure.
line: The definition line, following "to", of the multi-line definition.
Hint: create a user-defined Procedure object using
Procedure(name, len(formal_params), body, False, True, formal_params)
- name is a string defining the procedure name
- body is a list of lists representing Logo sentences (one per line)
- False indicates that it is not a primitive procedure
- True indicates that evaluation requires the environment
- formal_params is a list of strings naming each formal parameter
If you were to evaluate the following Logo definition,
? to double :n
> output sum :n :n
> end
the Procedure object you would create should be equivalent to:
Procedure('double', 1, [['output', 'sum', ':n', ':n']], False, True, ['n'])
Note: The doctest for this function was removed because of cross-platform
compatibility issues with the Python doctest module. (11/17 @ 3:15 PM)
"""
procedure_name = line.pop()
next_line = lambda: parse_line(env.get_continuation_line())
args, body = [], []
while line.current is not None:
arg = line.pop()
args.append(text_of_quotation(arg))
while True:
line = next_line()
if len(line) == 1 and line[0] == 'end':
break
body.append(line)
proc = Procedure(procedure_name, len(args), body, False, True, args)
#print(procedure_name, args, body)
env.procedures[procedure_name] = proc
def interpret_line(line, env):
"""Interpret a single line in the read-eval loop."""
result = eval_line(Buffer(parse_line(line)), env)
if result is not None:
error('You do not say what to do with {0}.'.format(result))
def interpret_line(line, env):
"""Interpret a single line in the read-eval loop."""
result = eval_line(Buffer(parse_line(line)), env)
if result is not None:
error('You do not say what to do with {0}.'.format(result))