From: Charles D Hixson <charleshixsn@...>
Date: 2001-09-05T07:08:29+09:00
Subject: [ruby-talk:20893] Code Style (a bit long)

I have the beginnings of a string parser here, but the style feels 
wrong.  Is there a more Ruby-esque way to do this that doesn't rely 
on using the built-in Tree function?  (I wouldn't want this to be 
restricted to Ruby syntax.  That's just where I'm starting.)

aFile  =  File.open("riddle.rb", "r")
strings  =  []  ;  str_ndx  =  0
comments  =  []  ;  com_ndx  =  0

AString  = /"|'|%q|%Q/
body  =  ""

#  state table
#  0  normal text
#  1  in a # comment
#  2  in a ' string
#  3  in a " string
#  4  in a ` string  (command string)
#  5  in a %q string (delimited single quote string)
#  6  in a %Q string (delimited double quote string)
#  7  in a / string (regexp pattern)
state  =  0

#  read in the file
str  =  ""
str_ndx  =  0
while  (ch = aFile.getc)
  case  ch.chr
  when  "#"
    str  =  ""
    last  =  ""
    while (c = aFile.getc)  and  (c.chr != "\n")
      str  <<  c
    end
    comments[com_ndx]  =  str
    body  <<  "#comments[#{com_ndx}]\n"  
    com_ndx  +=  1
    last  =  "\n"
  when  "'"
    str  =  ""
    last  =  ""
    while (c2 = aFile.getc)
      c  =  c2.chr
      if  c == "'" and  last == "\\"
        str  <<  c
        last  =  ""
      elsif c == "'"
        str  <<  last
        break
      elsif  (last == "\\") and (c =~ /[abefnrstv]|\\/)
        str  <<  case  c
              when  "a"  then  0x07  #  Bell
              when  "b"  then  0x08  #  Backspace
              when  "e"  then  0x1b  #  Escape
              when  "f"  then  0x0c  #  Formfeed
              when  "n"  then  0x0a  #  New Line
              when  "r"  then  0x0d  #  Carriage Return
              when  "s"  then  0x20  #  Space
              when  "t"  then  0x09  #  Tab
              when  "v"  then  0x0b  #  Vertical Tab
              when  "\\"  then  "\\"  #  BackSlash
              end
        last  =  ""
      else
        str  <<  last
        last  =  c
      end
    end
    strings[str_ndx]  =  str
    body  <<  "strings[#{str_ndx}]"
    str_ndx  +=  1
  when  '"'
    str  =  ""
    last  =  ""
    while (c2 = aFile.getc)
      c  =  c2.chr
      if  c == "\"" and  last == "\\"
        str  <<  c
        last  =  ""
      elsif c == "\""
        str  <<  last
        break
      elsif  (last == "\\") and (c =~ /[abefnrstv]|\\/)
        str  <<  case  c
              when  "a"  then  0x07  #  Bell
              when  "b"  then  0x08  #  Backspace
              when  "e"  then  0x1b  #  Escape
              when  "f"  then  0x0c  #  Formfeed
              when  "n"  then  0x0a  #  New Line
              when  "r"  then  0x0d  #  Carriage Return
              when  "s"  then  0x20  #  Space
              when  "t"  then  0x09  #  Tab
              when  "v"  then  0x0b  #  Vertical Tab
              when  "\\"  then  "\\"  #  BackSlash
              end
        last  =  ""
      elsif (last == "\\") and (c =~ /[0-7]/)
        print "octal parsing not yet implemented"
        str <<  last
        last  ==  c
      elsif (last == "\\") and (c =~ /[xX]/)
        print "hex parsing not yet implemented"
        str <<  last
        last  ==  c
      elsif (last == "\\") and (c =~ "[cC]")
        print "control parsing not yet implemented"
        str <<  last
        last  ==  c
      elsif (last == "\\") and (c == "M")
        print "Meta parsing not yet implemented"
        str <<  last
        last  ==  c
      elsif (last == "\\") and (c == "M")
        print "Meta-control parsing not yet implemented"
        str <<  last
        last  ==  c
      elsif (last == "#") and (c == "{")
        print "expression parsing not yet implemented"
        str <<  last
        last  ==  c
      else
        str  <<  last
        last  =  c
      end
    end
    strings[str_ndx]  =  str
    body  <<  "strings[#{str_ndx}]"
    str_ndx  +=  1
  else
    body  <<  ch
  end  #  case
end  #  while
print  "\nstrings: #{str_ndx}\n", strings.inspect
print  "\ncomments: #{com_ndx}\n", comments.inspect, "\n"
print body


-- 
 Charles Hixson
 
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