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path: root/ext/ply/example/BASIC/basinterp.py
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diff --git a/ext/ply/example/BASIC/basinterp.py b/ext/ply/example/BASIC/basinterp.py
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+# 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
+
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