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#1 erik.price   User is offline

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Brainf*ck Interpreter

Posted 12 January 2010 - 01:39 PM

Description: Input is a string containing valid BF code.Evaluates a brainf*ck program
def parseBF(bf)
  
    ptrIndex = 0
    i = 0
    x = -1
    ptr = Array.new(bf.length, 0)
    #create an array that would work in the case that every element of the BF string is '>', and fill it up with 0s
    #the classic distrobutuion has an array of 30,000 spaces, but this gives in essence unlimited room
    
    while i < bf.length
      case bf[i].chr   
        
        when '+': ptr[ptrIndex] += 1
        
        when '-': ptr[ptrIndex] -= 1
        
        when '>': ptrIndex += 1 
        
        when '<': ptrIndex -= 1     
        
        when '.': print(ptr[ptrIndex].chr)
        
        when ',': ptr[ptrIndex] = STDIN.getc #get a single character
        
        when '[':  if ptr[ptrIndex] == 0
        
                          i += 1
                          x = 0
                          while  x > 0  or bf[i].chr != ']' do
                              
                              if bf[i].chr == '['
                                x += 1
                                
                              elsif bf[i].chr == ']'
                                x -= 1                                
                              end #end if
                              
                            i += 1
                          end #end while
                          
                        end #end if
                          
        when ']':  x = 0
                        i -= 1
                        while x > 0 or bf[i].chr != '['
                          if bf[i].chr == ']'
                            x += 1
                          elsif bf[i].chr == '['
                            x -= 1
                          end #end if
                          i -= 1
                        end #end while
                        i -= 1
                        
        else #nothing , we ignore all extra characters   
          
        end #end case
        i += 1        
      end   #end while   
end #end method


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Replies To: Brainf*ck Interpreter

#2 erik.price   User is offline

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Re: Brainf*ck Interpreter

Posted 12 January 2010 - 01:39 PM

Description: Input is a string containing valid BF code. Works in 1.8/1.9, but runs much faster in Ruby 1.9Evaluates a brainf*ck program
def parseBF(bf)
  
    ptrIndex = 0
    i = 0
    x = -1
    ptr = Array.new(bf.length, 0)
    #create an array that would work in the case that every element of the BF string is '>', and fill it up with 0s
    #the classic distrobutuion has an array of 30,000 spaces, but this gives in essence unlimited room
    
    while i < bf.length
      case bf[i].chr   
        
        when '+'then ptr[ptrIndex] += 1
        
        when '-'then ptr[ptrIndex] -= 1
        
        when '>'then ptrIndex += 1 
        
        when '<'then ptrIndex -= 1     
        
        when '.'then print(ptr[ptrIndex].chr)
        
        when ','then ptr[ptrIndex] = STDIN.getc #get a single character
        
        when '['then  if ptr[ptrIndex] == 0
        
                          i += 1
                          x = 0
                          while  x > 0  or bf[i].chr != ']' do
                              
                              if bf[i].chr == '['
                                x += 1
                                
                              elsif bf[i].chr == ']'
                                x -= 1                                
                              end #end if
                              
                            i += 1
                          end #end while
                          
                        end #end if
                          
        when ']'then  x = 0
                        i -= 1
                        while x > 0 or bf[i].chr != '['
                          if bf[i].chr == ']'
                            x += 1
                          elsif bf[i].chr == '['
                            x -= 1
                          end #end if
                          i -= 1
                        end #end while
                        i -= 1
                        
        else #nothing , we ignore all extra characters   
          
        end #end case
        i += 1        
      end   #end while   
end #end method

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