Source

ply / example / BASIC / basinterp.py

The default branch has multiple heads

  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
# This file provides the runtime support for running a basic program
# Assumes the program has been parsed using basparse.py

import sys
import math
import random

class BasicInterpreter:

    # Initialize the interpreter. prog is a dictionary
    # containing (line,statement) mappings
    def __init__(self,prog):
         self.prog = prog

         self.functions = {           # Built-in function table
             'SIN' : lambda z: math.sin(self.eval(z)),
             'COS' : lambda z: math.cos(self.eval(z)),
             'TAN' : lambda z: math.tan(self.eval(z)),
             'ATN' : lambda z: math.atan(self.eval(z)),
             'EXP' : lambda z: math.exp(self.eval(z)),
             'ABS' : lambda z: abs(self.eval(z)),
             'LOG' : lambda z: math.log(self.eval(z)),
             'SQR' : lambda z: math.sqrt(self.eval(z)),
             'INT' : lambda z: int(self.eval(z)),
             'RND' : lambda z: random.random()
         }

    # Collect all data statements
    def collect_data(self):
         self.data = []
         for lineno in self.stat:
              if self.prog[lineno][0] == 'DATA':
                  self.data = self.data + self.prog[lineno][1]
         self.dc = 0                  # Initialize the data counter

    # Check for end statements
    def check_end(self):
         has_end = 0
         for lineno in self.stat:
             if self.prog[lineno][0] == 'END' and not has_end:
                  has_end = lineno
         if not has_end:
             print "NO END INSTRUCTION"
             self.error = 1
         if has_end != lineno:
             print "END IS NOT LAST"
             self.error = 1

    # Check loops
    def check_loops(self):
         for pc in range(len(self.stat)):
             lineno = self.stat[pc]
             if self.prog[lineno][0] == 'FOR':
                  forinst = self.prog[lineno]
                  loopvar = forinst[1]
                  for i in range(pc+1,len(self.stat)):
                       if self.prog[self.stat[i]][0] == 'NEXT':
                            nextvar = self.prog[self.stat[i]][1]
                            if nextvar != loopvar: continue
                            self.loopend[pc] = i
                            break
                  else:
                       print "FOR WITHOUT NEXT AT LINE" % self.stat[pc]
                       self.error = 1
                  
    # Evaluate an expression
    def eval(self,expr):
        etype = expr[0]
        if etype == 'NUM': return expr[1]
        elif etype == 'GROUP': return self.eval(expr[1])
        elif etype == 'UNARY':
             if expr[1] == '-': return -self.eval(expr[2])
        elif etype == 'BINOP':
             if expr[1] == '+': return self.eval(expr[2])+self.eval(expr[3])
             elif expr[1] == '-': return self.eval(expr[2])-self.eval(expr[3])
             elif expr[1] == '*': return self.eval(expr[2])*self.eval(expr[3])
             elif expr[1] == '/': return float(self.eval(expr[2]))/self.eval(expr[3])
             elif expr[1] == '^': return abs(self.eval(expr[2]))**self.eval(expr[3])
        elif etype == 'VAR':
             var,dim1,dim2 = expr[1]
             if not dim1 and not dim2:
                  if self.vars.has_key(var):
                       return self.vars[var]
                  else:
                       print "UNDEFINED VARIABLE", var, "AT LINE", self.stat[self.pc]
                       raise RuntimeError
             # May be a list lookup or a function evaluation
             if dim1 and not dim2:
                if self.functions.has_key(var):
                      # A function
                      return self.functions[var](dim1)
                else:
                      # A list evaluation
                      if self.lists.has_key(var):
                            dim1val = self.eval(dim1)
                            if dim1val < 1 or dim1val > len(self.lists[var]):
                                 print "LIST INDEX OUT OF BOUNDS AT LINE", self.stat[self.pc]
                                 raise RuntimeError
                            return self.lists[var][dim1val-1]
             if dim1 and dim2:
                 if self.tables.has_key(var):
                      dim1val = self.eval(dim1)
                      dim2val = self.eval(dim2)
                      if dim1val < 1 or dim1val > len(self.tables[var]) or dim2val < 1 or dim2val > len(self.tables[var][0]):
                           print "TABLE INDEX OUT OUT BOUNDS AT LINE", self.stat[self.pc]
                           raise RuntimeError
                      return self.tables[var][dim1val-1][dim2val-1]
             print "UNDEFINED VARIABLE", var, "AT LINE", self.stat[self.pc]
             raise RuntimeError

    # Evaluate a relational expression
    def releval(self,expr):
         etype = expr[1]
         lhs   = self.eval(expr[2])
         rhs   = self.eval(expr[3])
         if etype == '<':
             if lhs < rhs: return 1
             else: return 0

         elif etype == '<=':
             if lhs <= rhs: return 1
             else: return 0

         elif etype == '>':
             if lhs > rhs: return 1
             else: return 0

         elif etype == '>=':
             if lhs >= rhs: return 1
             else: return 0

         elif etype == '=':
             if lhs == rhs: return 1
             else: return 0

         elif etype == '<>':
             if lhs != rhs: return 1
             else: return 0

    # Assignment
    def assign(self,target,value):
        var, dim1, dim2 = target
        if not dim1 and not dim2:
            self.vars[var] = self.eval(value)
        elif dim1 and not dim2:
            # List assignment
            dim1val = self.eval(dim1)
            if not self.lists.has_key(var):
                 self.lists[var] = [0]*10

            if dim1val > len(self.lists[var]):
                 print "DIMENSION TOO LARGE AT LINE", self.stat[self.pc]
                 raise RuntimeError
            self.lists[var][dim1val-1] = self.eval(value)
        elif dim1 and dim2:
            dim1val = self.eval(dim1)
            dim2val = self.eval(dim2)
            if not self.tables.has_key(var):
                 temp = [0]*10
                 v = []
                 for i in range(10): v.append(temp[:])
                 self.tables[var] = v
            # Variable already exists
            if dim1val > len(self.tables[var]) or dim2val > len(self.tables[var][0]):
                 print "DIMENSION TOO LARGE AT LINE", self.stat[self.pc]
                 raise RuntimeError
            self.tables[var][dim1val-1][dim2val-1] = self.eval(value)

    # Change the current line number
    def goto(self,linenum):
         if not self.prog.has_key(linenum):
              print "UNDEFINED LINE NUMBER %d AT LINE %d" % (linenum, self.stat[self.pc])
              raise RuntimeError
         self.pc = self.stat.index(linenum)

    # Run it
    def run(self):
        self.vars   = { }            # All variables
        self.lists  = { }            # List variables
        self.tables = { }            # Tables
        self.loops  = [ ]            # Currently active loops
        self.loopend= { }            # Mapping saying where loops end
        self.gosub  = None           # Gosub return point (if any)
        self.error  = 0              # Indicates program error

        self.stat = self.prog.keys()      # Ordered list of all line numbers
        self.stat.sort()
        self.pc = 0                  # Current program counter

        # Processing prior to running

        self.collect_data()          # Collect all of the data statements
        self.check_end()
        self.check_loops()

        if self.error: raise RuntimeError

        while 1:
            line  = self.stat[self.pc]
            instr = self.prog[line]
            
            op = instr[0]

            # END and STOP statements
            if op == 'END' or op == 'STOP':
                 break           # We're done

            # GOTO statement
            elif op == 'GOTO':
                 newline = instr[1]
                 self.goto(newline)
                 continue

            # PRINT statement
            elif op == 'PRINT':
                 plist = instr[1]
                 out = ""
                 for label,val in plist:
                     if out:
                          out += ' '*(15 - (len(out) % 15))
                     out += label
                     if val:
                          if label: out += " "
                          eval = self.eval(val)
                          out += str(eval)
                 sys.stdout.write(out)
                 end = instr[2]
                 if not (end == ',' or end == ';'): 
                     sys.stdout.write("\n")
                 if end == ',': sys.stdout.write(" "*(15-(len(out) % 15)))
                 if end == ';': sys.stdout.write(" "*(3-(len(out) % 3)))
                     
            # LET statement
            elif op == 'LET':
                 target = instr[1]
                 value  = instr[2]
                 self.assign(target,value)

            # READ statement
            elif op == 'READ':
                 for target in instr[1]:
                      if self.dc < len(self.data):
                          value = ('NUM',self.data[self.dc])
                          self.assign(target,value)
                          self.dc += 1
                      else:
                          # No more data.  Program ends
                          return
            elif op == 'IF':
                 relop = instr[1]
                 newline = instr[2]
                 if (self.releval(relop)):
                     self.goto(newline)
                     continue

            elif op == 'FOR':
                 loopvar = instr[1]
                 initval = instr[2]
                 finval  = instr[3]
                 stepval = instr[4]
              
                 # Check to see if this is a new loop
                 if not self.loops or self.loops[-1][0] != self.pc:
                        # Looks like a new loop. Make the initial assignment
                        newvalue = initval
                        self.assign((loopvar,None,None),initval)
                        if not stepval: stepval = ('NUM',1)
                        stepval = self.eval(stepval)    # Evaluate step here
                        self.loops.append((self.pc,stepval))
                 else:
                        # It's a repeat of the previous loop
                        # Update the value of the loop variable according to the step
                        stepval = ('NUM',self.loops[-1][1])
                        newvalue = ('BINOP','+',('VAR',(loopvar,None,None)),stepval)

                 if self.loops[-1][1] < 0: relop = '>='
                 else: relop = '<='
                 if not self.releval(('RELOP',relop,newvalue,finval)):
                      # Loop is done. Jump to the NEXT
                      self.pc = self.loopend[self.pc]
                      self.loops.pop()
                 else:
                      self.assign((loopvar,None,None),newvalue)

            elif op == 'NEXT':
                 if not self.loops:
                       print "NEXT WITHOUT FOR AT LINE",line
                       return
 
                 nextvar = instr[1]
                 self.pc = self.loops[-1][0]
                 loopinst = self.prog[self.stat[self.pc]]
                 forvar = loopinst[1]
                 if nextvar != forvar:
                       print "NEXT DOESN'T MATCH FOR AT LINE", line
                       return
                 continue
            elif op == 'GOSUB':
                 newline = instr[1]
                 if self.gosub:
                       print "ALREADY IN A SUBROUTINE AT LINE", line
                       return
                 self.gosub = self.stat[self.pc]
                 self.goto(newline)
                 continue

            elif op == 'RETURN':
                 if not self.gosub:
                      print "RETURN WITHOUT A GOSUB AT LINE",line
                      return
                 self.goto(self.gosub)
                 self.gosub = None

            elif op == 'FUNC':
                 fname = instr[1]
                 pname = instr[2]
                 expr  = instr[3]
                 def eval_func(pvalue,name=pname,self=self,expr=expr):
                      self.assign((pname,None,None),pvalue)
                      return self.eval(expr)
                 self.functions[fname] = eval_func

            elif op == 'DIM':
                 for vname,x,y in instr[1]:
                     if y == 0:
                          # Single dimension variable
                          self.lists[vname] = [0]*x
                     else:
                          # Double dimension variable
                          temp = [0]*y
                          v = []
                          for i in range(x):
                              v.append(temp[:])
                          self.tables[vname] = v

            self.pc += 1         

    # Utility functions for program listing
    def expr_str(self,expr):
        etype = expr[0]
        if etype == 'NUM': return str(expr[1])
        elif etype == 'GROUP': return "(%s)" % self.expr_str(expr[1])
        elif etype == 'UNARY':
             if expr[1] == '-': return "-"+str(expr[2])
        elif etype == 'BINOP':
             return "%s %s %s" % (self.expr_str(expr[2]),expr[1],self.expr_str(expr[3]))
        elif etype == 'VAR':
              return self.var_str(expr[1])

    def relexpr_str(self,expr):
         return "%s %s %s" % (self.expr_str(expr[2]),expr[1],self.expr_str(expr[3]))

    def var_str(self,var):
         varname,dim1,dim2 = var
         if not dim1 and not dim2: return varname
         if dim1 and not dim2: return "%s(%s)" % (varname, self.expr_str(dim1))
         return "%s(%s,%s)" % (varname, self.expr_str(dim1),self.expr_str(dim2))

    # Create a program listing
    def list(self):
         stat = self.prog.keys()      # Ordered list of all line numbers
         stat.sort()
         for line in stat:
             instr = self.prog[line]
             op = instr[0]
             if op in ['END','STOP','RETURN']:
                   print line, op
                   continue
             elif op == 'REM':
                   print line, instr[1]
             elif op == 'PRINT':
                   print line, op, 
                   first = 1
                   for p in instr[1]:
                         if not first: print ",",
                         if p[0] and p[1]: print '"%s"%s' % (p[0],self.expr_str(p[1])),
                         elif p[1]: print self.expr_str(p[1]),
                         else: print '"%s"' % (p[0],),
                         first = 0
                   if instr[2]: print instr[2]
                   else: print
             elif op == 'LET':
                   print line,"LET",self.var_str(instr[1]),"=",self.expr_str(instr[2])
             elif op == 'READ':
                   print line,"READ",
                   first = 1
                   for r in instr[1]:
                         if not first: print ",",
                         print self.var_str(r),
                         first = 0
                   print ""
             elif op == 'IF':
                   print line,"IF %s THEN %d" % (self.relexpr_str(instr[1]),instr[2])
             elif op == 'GOTO' or op == 'GOSUB':
                   print line, op, instr[1]
             elif op == 'FOR':
                   print line,"FOR %s = %s TO %s" % (instr[1],self.expr_str(instr[2]),self.expr_str(instr[3])),
                   if instr[4]: print "STEP %s" % (self.expr_str(instr[4])),
                   print
             elif op == 'NEXT':
                   print line,"NEXT", instr[1]
             elif op == 'FUNC':
                   print line,"DEF %s(%s) = %s" % (instr[1],instr[2],self.expr_str(instr[3]))
             elif op == 'DIM':
                   print line,"DIM",
                   first = 1
                   for vname,x,y in instr[1]:
                         if not first: print ",",
                         first = 0
                         if y == 0:
                               print "%s(%d)" % (vname,x),
                         else:
                               print "%s(%d,%d)" % (vname,x,y),
                         
                   print 
             elif op == 'DATA':
                   print line,"DATA",
                   first = 1
                   for v in instr[1]:
                        if not first: print ",",
                        first = 0
                        print v,
                   print

    # Erase the current program
    def new(self):
         self.prog = {}
 
    # Insert statements
    def add_statements(self,prog):
         for line,stat in prog.items():
              self.prog[line] = stat

    # Delete a statement
    def del_line(self,lineno):
         try:
             del self.prog[lineno]
         except KeyError:
             pass
Tip: Filter by directory path e.g. /media app.js to search for public/media/app.js.
Tip: Use camelCasing e.g. ProjME to search for ProjectModifiedEvent.java.
Tip: Filter by extension type e.g. /repo .js to search for all .js files in the /repo directory.
Tip: Separate your search with spaces e.g. /ssh pom.xml to search for src/ssh/pom.xml.
Tip: Use ↑ and ↓ arrow keys to navigate and return to view the file.
Tip: You can also navigate files with Ctrl+j (next) and Ctrl+k (previous) and view the file with Ctrl+o.
Tip: You can also navigate files with Alt+j (next) and Alt+k (previous) and view the file with Alt+o.