aboutsummaryrefslogtreecommitdiff
path: root/sketch.py
blob: cf930222587814eb2d13d90d6230b1d95d11ad76 (plain) (blame)
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
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
#! /bin/env python

class EvalObj(object):
    def __str__(self):
        return "#<Object>"

class UnspecObj(EvalObj):
    def __str__(self):
        return "#<Unspecified>"
    def ext_repr(self):
        return self.__str__()


class NumberObj(EvalObj):
    def __str__(selfl):
        return "#<Number>"

class IntObj(NumberObj):
    def __init__(self, num):
        self.val = int(num)
    def __str__(self):
        return "#<Integer>"
    def ext_repr(self):
        return str(self.val)

class FloatObj(NumberObj):
    def __init__(self, num):
        self.val = float(num)
    def __str__(self):
        return "#<Float>"
    def ext_repr(self):
        return str(self.val)

class StringObj(EvalObj):
    def __init__(self, string):
        self.val = string
    def __str__(self):
        return "#<String>"
    def ext_repr(self):
        return self.val

class BoolObj(EvalObj):
    def __init__(self, b):
        self.val = b
    def __str__(self):
        return "#<Boolean>"
    def ext_repr(self):
        if self.val:
            return "#t"
        else:
            return "#f"

class OptObj(EvalObj):
    pass

class ProcObj(OptObj):
    def __init__(self, body, envt, para_list):
        self.body = body
        self.envt = envt
        self.para_list = para_list
    def ext_repr(self):
        return "#<Procedure>"
    def __str__(self):
        return self.ext_repr()

class SpecialOptObj(OptObj):
    def prepare(self, pc):
        pass
    def call(self, arg_list, pc, envt, cont):
        pass

class BuiltinProcObj():
    def __init__(self, f, name):
        self.handler = f
        self.name = name
    def ext_repr(self):
        return "#<Builtin Procedure: " + self.name + ">"
    def __str__(self):
        return self.ext_repr()
    def call(self, arg_list):
        return self.handler(arg_list)

def to_bool(obj):
    if obj.val is False:
        return BoolObj(False)
    else:
        return BoolObj(True)

class _builtin_if(SpecialOptObj):
    def prepare(self, pc):
        self.state = 0 # prepare
        # TODO: check number of arguments 
        pc = pc.chd
        pc.skip = False
        pc.sib.skip = True
        if pc.sib.sib:
            pc.sib.sib.skip = True
        # Delay the calculation
    def pre_call(self, arg_list, pc, envt, cont):
        self.state = 1 # calling
        # print "Received if signal: " + str(arg_list[0].val)
        # print "And it is regared as: " + str(to_bool(arg_list[0]).val)
        if (to_bool(arg_list[0])).val:
            pc = pc.chd
            pc.skip = True
            pc.sib.skip = False
            if pc.sib.sib:
                pc.sib.sib.skip = True
            return (None, True) # Re-eval
        else:
            pc = pc.chd
            pc.skip = True
            pc.sib.skip = True
            if pc.sib.sib:
                pc.sib.sib.skip = False
            return (None, True) # Re-eval
    def post_call(self, arg_list, pc, envt, cont):
        return (arg_list[0], False)

    def call(self, arg_list, pc, envt, cont):
        if self.state == 0:
            return self.pre_call(arg_list, pc, envt, cont)
        else:
            return self.post_call(arg_list, pc, envt, cont)
    def ext_repr(self):
        return "#<Builtin Macro: if>"
    def __str__(self):
        return self.ext_repr()

class _builtin_lambda(SpecialOptObj):
    def _clear_marks(self, pc, flag):
        pc = pc.chd
        while pc:
            pc.skip = flag
            pc = pc.sib

    def prepare(self, pc):
        # TODO: check number of arguments 
        self._clear_marks(pc, True)

    def call(self, arg_list, pc, envt, cont):
        para_list = list()
        par = pc.chd
        if par.obj:
            para_list.append(par.obj)
            if par.chd: 
                par = par.chd
                while par: 
                    para_list.append(par.obj)
                    par = par.sib
        self._clear_marks(pc, False)
        pc = pc.chd.sib
        #TODO: check body
        body = list()
        while pc:
            body.append(pc)
            pc.next = None # Detach
            pc = pc.sib
            # Add exps
        return (ProcObj(body, envt, para_list), False)
    def ext_repr(self):
        return "#<Builtin Macro: lambda>"
    def __str__(self):
        return self.ext_repr()

class _builtin_define(SpecialOptObj):
    def _clear_marks(self, pc, flag):
        pc = pc.chd
        while pc:
            pc.skip = flag
            pc = pc.sib

    def prepare(self, pc):
        if is_arg(pc.chd): # Normal Def
            pc.chd.skip = True
            pc.chd.sib.skip = False
        else:
            self._clear_marks(pc, True)
        return (None, True) # Re-eval

    def call(self, arg_list, pc, envt, cont):
        # TODO: check identifier
        id = pc.chd.obj
        if is_arg(pc.chd): 
            obj = arg_list[0]
        else: # Function definition
            par = pc.chd
            para_list = list()
            if par.chd:
                par = par.chd
                while par:
                    para_list.append(par.obj)
                    par = par.sib
            # Collection para list
            self._clear_marks(pc, False)
            pc = pc.chd.sib
            body = list()
            while pc:
                body.append(pc)
                pc.next = None
                pc = pc.sib
            obj = ProcObj(body, envt, para_list)
        
        envt.add_binding(id, obj)
        return (UnspecObj(), False)

    def ext_repr(self):
        return "#<Builtin Macro: define>"
    def __str__(self):
        return self.ext_repr()

class _builtin_set(SpecialOptObj):
    def prepare(self, pc):
        # TODO: check number of arguments 
        pc = pc.chd
        pc.skip = True
        pc.sib.skip = False

    def call(self, arg_list, pc, envt, cont):
        id = pc.chd.obj
        if envt.has_obj(id):
            envt.add_binding(id, arg_list[0])
        return (UnspecObj(), False)

    def ext_repr(self):
        return "#<Builtin Macro: set!>"
    def __str__(self):
        return self.ext_repr()

class IdObj(EvalObj):
    def __init__(self, string):
        self.name = string
    def __str__(self):
        return "#<Identifier: " + self.name + ">"
    def get_name():
        return self.name

class Tokenizor():

    def __init__(self):
        self.data = ""
        self.tokenized = list()
        self.extended_chars = "!$%&*+-./:<=>?@^_~"

    def is_identifier(self, string):
        if string[0].isdigit(): return False
        for i in string[1:]:
            if not (i.isalnum() or i in self.extended_chars):
                return False
        return True

    def feed(self, data):
        self.data = data

    def read(self): 
        if len(self.tokenized) == 0:
            if len(self.data) == 0:
                return None
            self.tokenized = self.data.replace('(', '( ')\
                                    .replace(')', ' )')\
                                    .split()
            self.data = ""
            if len(self.tokenized) == 0:
                return None
        return self.tokenized.pop(0)

class Node(object):
    def __init__(self, obj, sib):
        self.obj = obj
        self.sib = sib
        self.skip = None    # delay calcuation
        self.next = sib
    def __str__(self):
        return "#<AST Node>"
    def __expr__(self):
        return self.__str__()

class ArgNode(Node):
    def __init__(self, obj, sib = None):
        super(ArgNode, self).__init__(obj, sib)
    def __str__(self):
        return "#<AST ArgNode>"
    def __expr__(self):
        return self.__str__()

    def print_(self):
        print \
            "======================" + "\n" + \
            "Obj: " + str(self.obj) + "\n" + \
            "Sib: " + str(self.sib) + "\n" + \
            "======================" 

class OptNode(Node):
    def __init__(self, obj, sib = None, chd = None):
        super(OptNode, self).__init__(obj, sib)
        self.chd = chd

    def __str__(self):
        return "#<AST OptNode>"
    def __expr__(self):
        return self.__str__()

    def print_(self):
        print \
            "======================" + "\n" + \
            "Obj: " + str(self.obj) + "\n" + \
            "Sib: " + str(self.sib) + "\n" + \
            "Chd: " + str(self.chd) + "\n" + \
            "======================" 

class RetAddr(object):
    def __init__(self, addr):
        self.addr = addr
    def __str__(self):
        return "#<Return Address>"

class ASTree(EvalObj):

    def to_obj(self, obj):
        if isinstance(obj, Node): return obj
        try: return IntObj(obj)
        except Exception:
            try: return FloatObj(obj)
            except Exception: return IdObj(obj)
 
    def to_node(self, obj):
        if isinstance(obj, Node): return obj
        return ArgNode(obj)
        # else the obj is a string
       
    def __init__(self, stream):
        self.stream = stream
        self.stack = list()  # Empty stack

    def absorb(self):
        stack = self.stack
        while True:
            if len(stack) > 0 and stack[0] != '(':
                return self.to_node(stack.pop(0)) # Got an expression
            token = self.stream.read()
            if token is None: return None
            if token == '(':
                stack.append(token) 
            elif token == ')':
                lst = list()
                while stack[-1] != '(':
                    lst = stack[-1:] + lst
                    del stack[-1]
                if len(lst) > 0:
                    root = OptNode(lst[0])
                    if len(lst) > 1:
                        root.chd = self.to_node(lst[1])
                        ref = root.chd
                        for i in lst[2:]:
                            ref.sib = self.to_node(i)
                            ref.next = ref.sib
                            ref = ref.sib
                    stack[-1] = root
                else:
                    stack[-1] = self.to_node(None)
            else:
                stack.append(self.to_obj(token))

def is_obj(string):
    return isinstance(string, EvalObj)
def is_identifier(string):
    return isinstance(string, IdObj)
def is_arg(node):
    return isinstance(node, ArgNode)
def is_ret_addr(val):
    return isinstance(val, RetAddr)
def is_builtin_proc(val):
    return isinstance(val, BuiltinProcObj)
def is_special_opt(val):
    return isinstance(val, SpecialOptObj)
def is_user_defined_proc(val):
    return isinstance(val, ProcObj)

class Environment(object):
    def __init__(self, prev_envt = None):
        self.prev_envt = prev_envt
        self.binding = dict()

    def add_binding(self, id_obj, eval_obj):
        self.binding[id_obj.name] = eval_obj

    def has_obj(self, id_obj):
        ptr = self
        while ptr:
            try:
                t = ptr.binding[id_obj.name]
                return True
            except KeyError: 
                ptr = ptr.prev_envt
        return False

    def get_obj(self, id_obj):
        if is_identifier(id_obj):
            ptr = self
            while ptr:
                try:
                    return ptr.binding[id_obj.name]
                except KeyError:
                    ptr = ptr.prev_envt
            raise KeyError
        else:
            # print "Not an id: " + str(id_obj)
            return id_obj

class Continuation(object):
    def __init__(self, envt, pc, old_cont, proc_body, proc_body_cur = 0):    
        self.envt = envt
        self.pc = pc
        self.old_cont = old_cont
        self.proc_body = proc_body
        self.proc_body_cur = 0
        
    def get_envt(self):
        return self.envt
    def get_cont(self):
        return self.cont

def _builtin_plus(arg_list):
    res = 0
    for i in arg_list:
        res += i.val
    return IntObj(res)

def _builtin_minus(arg_list):
    res = arg_list[0].val
    for i in arg_list[1:]:
        res -= i.val
    return IntObj(res)

def _builtin_times(arg_list):
    res = 1
    for i in arg_list:
        res *= i.val
    return IntObj(res)

def _builtin_div(arg_list):
    res = arg_list[0].val
    for i in arg_list[1:]:
        res /= i.val
    return IntObj(res)

def _builtin_lt(arg_list):
    #TODO: need support to multiple operands
    return BoolObj(arg_list[0].val < arg_list[1].val)

def _builtin_gt(arg_list):
    return BoolObj(arg_list[0].val > arg_list[1].val)

def _builtin_eq(arg_list):
    return BoolObj(arg_list[0].val == arg_list[1].val)

def _builtin_display(arg_list):
    print "Display: " + arg_list[0].ext_repr()
    return UnspecObj()

_default_mapping = {
        IdObj("+") : BuiltinProcObj(_builtin_plus, "+"),
        IdObj("-") : BuiltinProcObj(_builtin_minus, "-"),
        IdObj("*") : BuiltinProcObj(_builtin_times, "*"),
        IdObj("/") : BuiltinProcObj(_builtin_div, "/"),
        IdObj("<") : BuiltinProcObj(_builtin_lt, "<"),
        IdObj(">") : BuiltinProcObj(_builtin_gt, ">"),
        IdObj("=") : BuiltinProcObj(_builtin_eq, "="),
        IdObj("display") : BuiltinProcObj(_builtin_display, "display"),
        IdObj("lambda") : _builtin_lambda(),
        IdObj("if") : _builtin_if(),
        IdObj("define") : _builtin_define(),
        IdObj("set!") : _builtin_set()}

class Evaluator(object):

    def _add_builtin_routines(self, envt):
        for sym in _default_mapping:
            envt.add_binding(sym, _default_mapping[sym])

    def __init__(self):
        self.envt = Environment() # Top-level Env
        self._add_builtin_routines(self.envt)
    def run_expr(self, prog):
        stack = [0] * 100   # Stack 
        ostack = [0] * 100     # Pending operators 
        pc = prog       # Set to the root
        cont = Continuation(None, pc, None, None)
        envt = self.envt
        top = -1 # Stack top
        otop = -1

        def print_stack():
            print '++++++++++STACK++++++++'
            if len(stack) > 0:
                for i in range(0, top + 1):
                    print stack[i]
            print '----------STACK--------'
        
        def mask_eval(pc, mask):
            pc = pc.chd
            for i in mask:
                # print i
                # print pc
                pc.skip = not i
                pc = pc.sib

        def nxt_addr(ret_addr, otop):
            notop = otop
            if otop > -1 and ret_addr is ostack[notop]:
                notop -= 1
                res = ostack[notop].chd
                notop -= 1
            else:
                res = ret_addr.next
            return (res, notop)


        def push(pc, top, otop):
            ntop = top
            notop = otop
            if is_arg(pc):
                # print "first"
                ntop += 1
                if pc.skip:
                    new_obj = pc.obj
                else:
                    new_obj = envt.get_obj(pc.obj)
                stack[ntop] = new_obj
                npc = pc.next
                # pc.print_()
                #print "this val is: " + str(stack[ntop].val)
            else:
                # print "second"
                ntop += 1
                stack[ntop] = RetAddr(pc) # Return address
                if isinstance(pc.obj, Node):
                    # print "Operator need to be resolved!"
                    notop += 1
                    ostack[notop] = pc
                    notop += 1
                    ostack[notop] = pc.obj
                    # pc.obj.print_() # Step in to resolve operator
                    npc = pc.obj
                else:
                    # print "Getting operator: " + str(pc.obj.name)
                    ntop += 1
                    stack[ntop] = envt.get_obj(pc.obj)
                    if is_special_opt(stack[ntop]):
                        stack[ntop].prepare(pc)
                        #mask = stack[ntop].prepare()
                        #mask_eval(pc, mask)
                    npc = pc.chd
            return (npc, ntop, notop)

        # print " Pushing..."
        # print_stack()
        (pc, top, otop) = push(pc, top, otop)
        # print_stack()
        # print " Done...\n"
        while is_ret_addr(stack[0]):    # Still need to evaluate
            # print "- Top: " + str(stack[top])
            # print "- Pc at: " + str(pc)
            while pc and pc.skip: 
                # print "skipping masked branch: " + str(pc)
                pc = pc.next  # Skip the masked branches

            if pc is None:

               # print "Poping..."
               arg_list = list()
               while not is_ret_addr(stack[top]):
                   arg_list = [stack[top]] + arg_list
                   top -= 1
               # Top is now pointing to the return address
               # print "Arg List: " + str(arg_list)
               opt = arg_list[0]
               ret_addr = stack[top].addr

               if ret_addr is False: # Fake return
                    body = cont.proc_body
                    cont.proc_body_cur += 1
                    ncur = cont.proc_body_cur
                    if ncur == len(body):   # All exps in the body are evaled
                        stack[top] = arg_list[0]
                        envt = cont.envt
                        (pc, otop) = nxt_addr(cont.pc, otop)
                        cont = cont.old_cont
                    else:
                        pc = body[ncur]     # Load the next exp

                    continue
                    # Revert to the original cont.
   
               if is_builtin_proc(opt):                # Built-in Procedures
                   # print "builtin"
                   stack[top] = opt.call(arg_list[1:])
                   (pc, otop) = nxt_addr(ret_addr, otop)
    
               elif is_special_opt(opt):               # Sepecial Operations
                   # print "specialopt"
                   (res, flag) = opt.call(arg_list[1:], ret_addr, envt, cont)
                   if flag: # Need to call again
                       # print "AGAIN with the mask: " + str(res)
                       # mask_eval(ret_addr, res)
                       top += 1
                       pc = ret_addr.chd # Again
                   else:
                       stack[top] = res # Done
                       (pc, otop) = nxt_addr(ret_addr, otop)
               elif is_user_defined_proc(opt):   # User-defined Procedures
                   ncont = Continuation(envt, ret_addr, cont, opt.body)  # Create a new continuation
                   cont = ncont                          # Make chain
                   envt = Environment(opt.envt)         # New ENV and recover the closure
                   #TODO: Compare the arguments to the parameters
                   for i in xrange(1, len(arg_list)):
                       envt.add_binding(opt.para_list[i - 1], 
                                       arg_list[i])      # Create bindings
                   stack[top] = RetAddr(False)            # Mark the exit of the continuation
                   pc = opt.body[0]                 # Get to the entry point
                
                # print_stack()
                # print "Poping done."
            else: 
                # print " Pushing..."
                # print_stack()
                (pc, top, otop) = push(pc, top, otop)
                # print_stack()
                # print " Done...\n"
        return stack[0]

t = Tokenizor()
e = Evaluator()

import sys, pdb

a = ASTree(t)
while True:
    sys.stdout.write("Syasi> ")
    while True:
        exp = a.absorb()
        if exp: break
        cmd = sys.stdin.readline()
        t.feed(cmd)
    try:
        print e.run_expr(exp).ext_repr()
    except Exception as exc:
        print exc