Class: Unpickle::PickleMachine

Inherits:
Object
  • Object
show all
Defined in:
lib/unpickle.rb

Overview

:nodoc: all

Instance Method Summary collapse

Constructor Details

#initialize(input) ⇒ PickleMachine

Returns a new instance of PickleMachine.



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# File 'lib/unpickle.rb', line 19

def initialize(input)
    @stack = []
    @memo = {}
    @input = input
    @idx = 0
end

Instance Method Details

#at_end? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/unpickle.rb', line 26

def at_end?
    @idx >= @input.length
end

#marker ⇒ Object

Raises:



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# File 'lib/unpickle.rb', line 56

def marker
    idx = @stack.length-1
    while idx >= 0
        if @stack[idx].is_a?(Mark)
            return idx
        end
        idx -= 1
    end
    raise UnpickleException, "Couldn't find Mark"
end

#next_char ⇒ Object 



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# File 'lib/unpickle.rb', line 30

def next_char
    rv = @input[@idx..@idx]
    @idx += 1
    return rv
end

#peek_char ⇒ Object 



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# File 'lib/unpickle.rb', line 36

def peek_char
    @input[@idx..@idx]
end

#read_int ⇒ Object 



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# File 'lib/unpickle.rb', line 40

def read_int
    strout = ""
    while peek_char != "\n"
        strout += next_char
    end
    next_char
    case strout
    when '00'
        return false
    when '01'
        return true
    else
        return strout.to_i
    end
end

#read_string ⇒ Object

read from the input stream to read the python string.

returns the value.



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# File 'lib/unpickle.rb', line 70

def read_string
    strout = ''
    if next_char != '\''
        raise UnpickleException, "Couldn't find leading quote for string"
    end
    while not at_end?
        c = next_char
        case c
        when "\\"
            opt = next_char
            case opt
            when 'x'
                num = ''
                while peek_char.match(/[\dA-Fa-f]/)
                    num += next_char
                    if num.length >= 2
                        break
                    end
                end
                unless (1..2).include?(num.length)
                    raise UnpickleException, "Bad \\x sequence in string"
                end
                strout += num.to_i(16).chr
            when '0'
                num = ''
                while peek_char.match(/[0-7]/)
                    num += next_char
                    if num.length >= 3
                        break
                    end
                end
                unless (1..3).include?(num.length)
                    raise UnpickleException, "Bad \\0 sequence in string"
                end
                strout += num.to_i(8).chr
            when 'n'
                strout += "\n"
            when "\\"
                strout += "\\"
            when 't'
                strout += "\t"
            when "'"
                strout += "'"
            else
                raise UnpickleException, "Unexpected \\ escape: \\#{opt}"
            end
        when "'"
            # valid end of string...
            break
        else
            strout += c
        end
    end
    if next_char != "\n"
        raise UnpickleException, "Expected \\n after string"
    end
    return strout
end

#unpickle ⇒ Object

Raises:



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# File 'lib/unpickle.rb', line 129

def unpickle
    while not at_end?
        op = next_char
        case op
        when '(' # MARK
            @stack.push(Mark.new)
        when 'd' # DICT
            newdict = {}
            while true
                if @stack.empty?
                    raise UnpickleException, "Stack empty during 'd'"
                end
                v = @stack.pop
                if v.is_a?(Mark)
                    break
                end
                if @stack.empty?
                    raise UnpickleException, "Stack empty during 'd'"
                end
                k = stack.pop
                if k.is_a?(Mark)
                    raise UnpickleException, "Odd number of elements during 'd' stack walk"
                end
                newdict[k] = v
            end
            @stack.push(newdict)
        when 'S' # STRING
            newstr = read_string
            @stack.push(newstr)
        when 'p' # PUT (string)
            index = read_int
            @memo[index] = @stack[-1]
        when 'g' # GET (string)
            index = read_int
            @stack.push(@memo[index])
        when 'I' # INT
            intarg = read_int
            @stack.push(intarg)
        when 's' # SETITEM
            value = @stack.pop
            key = @stack.pop
            dict = @stack[-1]
            dict[key] = value
        when 't' # TUPLE
            midx = marker
            tuple = @stack[midx+1..-1]
            @stack = @stack[0...midx]
            tuple.freeze
            @stack.push(tuple)
        when 'l' # LIST
            midx = marker
            list = @stack[midx+1..-1]
            @stack = @stack[0...midx]
            @stack.push(list)
        when 'N' # NONE
            @stack.push(nil)
        when 'a' # APPEND
            e = @stack.pop
            @stack[-1].push(e)
        when '0' # POP
            @stack.pop
        when '2' # DUP
            @stack.push(@stack[-1])
        when '.' # STOP
            return @stack.pop
        else
            raise UnpickleException, "Unsupported unpickle operation '#{op}'"
        end
    end
    raise UnpickleException, "Hit end of input stream"
end