1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
from .tokens import Token
from .utils import *
OPS = "+-*/&|<>="
UNARY_OPS = "-~"
CONSTANTS = ["true", "false", "null", "this"]
class Term:
def __init__(self):
pass
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
if not tokens:
return (None, 0)
if tokens[0].type in ["integer", "string"] or tokens[0] in CONSTANTS:
return (ConstantTerm(tokens[0]), 1)
if tokens[0].token in UNARY_OPS:
"""Format: <unary op> <term>"""
term, dt = Term.from_tokens(tokens[1:])
return (UnaryTerm(tokens[0], term), dt + 1)
if tokens[0] == LEFT_PAREN:
"""Format: '(' <expression> ')'"""
expr, dt = Expression.from_tokens(tokens[1:])
if tokens[dt + 1] != RIGHT_PAREN:
raise UnaryTerm(RIGHT_PAREN, tokens[dt])
return (expr, dt + 2)
if tokens[0].type == "identifier":
if tokens[1] in [LEFT_PAREN, "."]:
# subroutine(...) or Class.subroutine(...)
return SubroutineCall.from_tokens(tokens)
if tokens[1] == LEFT_BRACKET:
# array[index]
return SubscriptTerm.from_tokens(tokens)
return (VarTerm(tokens[0]), 1)
return (None, 0)
class ConstantTerm:
def __init__(self, term: Token):
self.term = term
def __str__(self):
return self.term.token
class SubscriptTerm:
def __init__(self, var: Token, subscript: Token):
self.var = var
self.subscript = subscript
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
"""Construct a subscripted array term.
Format:
<var> '[' <expression> ']'
"""
if tokens[0].type != "identifier" or tokens[1] != LEFT_BRACKET:
return (None, 0)
var = tokens[0]
t = 2
sub, dt = Expression.from_tokens(tokens[2:])
if sub is None:
raise JackSyntaxError(f"Expected subscript", tokens[2])
t += dt
if tokens[t] != RIGHT_BRACKET:
raise UnexpectedToken(RIGHT_BRACKET, tokens[t])
return (SubscriptTerm(var, sub), t + 1)
def __str__(self):
return f"{self.var}[{self.subscript}]"
class VarTerm:
def __init__(self, var: Token):
self.var = var
def __str__(self):
return self.var.token
class UnaryTerm:
def __init__(self, op: Token, term: Term):
self.op = op
self.term = term
def __str__(self):
return f"({self.op}{self.term})"
class Expression:
def __init__(self, lhs: Term, op=None, rhs=None):
self.lhs = lhs
self.op = op
self.rhs = rhs
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
"""Construct expression.
Format:
<term> (<op> <term>)?
"""
lhs, dt = Term.from_tokens(tokens)
if lhs is None:
return (None, 0)
t = dt
op = tokens[t]
if op.token not in OPS:
return (Expression(lhs), t)
t += 1
rhs, dt = Term.from_tokens(tokens[t:])
if rhs is None:
raise UnexpectedToken("other term", rhs)
t += dt
return (Expression(lhs, op, rhs), t)
def __str__(self):
if self.op is not None:
return f"({self.lhs} {self.op} {self.rhs})"
else:
return str(self.lhs)
class ExpressionList:
def __init__(self, exprs: list[Expression]):
self.exprs = exprs
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
"""Construct list of expressions.
Format:
(<expression> (',' <expression>)*)?
"""
t = 0
exprs = []
while True:
expr, dt = Expression.from_tokens(tokens[t:])
if expr is None:
if t == 0:
# only allow lack of expression right after paren
break
else:
# expect expression after comma
raise JackSyntaxError(f"Expected expression", tokens[t])
t += dt
exprs.append(expr)
if tokens[t] != ",":
break
t += 1
return (ExpressionList(exprs), t)
def __str__(self):
return ", ".join([str(expr) for expr in self.exprs])
class SubroutineCall:
def __init__(self, jack_class: Token, name: Token, exprs: ExpressionList):
self.jack_class = jack_class
self.name = name
self.exprs = exprs
@classmethod
def from_tokens(cls, tokens: list) -> tuple:
"""Construct invocation of subroutine.
Format:
(<class> '.')? <subroutine> '(' <expression list> ')'
"""
t = 0
jack_class = None
if tokens[1] == ".":
jack_class = tokens[0]
t = 2
name = tokens[t]
if name.type != "identifier":
raise UnexpectedToken("subroutine name", name)
t += 1
if tokens[t] != LEFT_PAREN:
raise UnexpectedToken(LEFT_PAREN, tokens[t])
t += 1
exprs, dt = ExpressionList.from_tokens(tokens[t:])
t += dt
if tokens[t] != RIGHT_PAREN:
raise UnexpectedToken(RIGHT_PAREN, tokens[t])
return (SubroutineCall(jack_class, name, exprs), t + 1)
def __str__(self):
if self.jack_class is None:
return f"{self.name}({self.exprs})"
return f"{self.jack_class}.{self.name}({self.exprs})"
|
