Class SyTab
In: sytab.rb
Parent: Hash

Symbol table that provides for one-pass replacement of all symbols surrounded by delimiters with the symbol values

Methods
<<    []=    compile!    delete    new    replace    store   
Attributes
:delims  [R] 
:var_restr  [R] 
Public Class methods
new(delims)
delims
pre- and post-name delimiters for symbol dereferencing, separated by whitespace (e.g., "$ $"). A symbol not bracketed by these will not be substituted. 
# File sytab.rb, line 49
  def initialize(delims)
    darr = delims.split
    @mpos = darr[0].size
    @mend = -(darr[1].size)
    @delims = darr.map { 
      |s| Regexp.escape(s)
    }
    @regex = nil
    @var_restr = [ @delims[0], "[a-zA-Z_][a-zA-Z_0-9]*", @delims[1] ].join
    @var_regex = Regexp.new(@var_restr)
  end
Public Instance methods
delete(k)

Call Hash#delete and invalidate match expression. 

# File sytab.rb, line 65
  def delete(k)
    super(k)
    @regex = nil
  end
[]=(k,v)

Call Array#[]= and invalidate match expression. 

# File sytab.rb, line 72
  def []=(k,v)
    super(k,v)
    @regex = nil
  end
store(k,v)

Call Array#store and invalidate match expression. 

# File sytab.rb, line 79
  def store(k,v)
    super(k,v)
    @regex = nil
  end
compile!()

Build a new match expression consisting of each key of the hash surrounded by delimiters, then grouped with parens, and each group separated by "|". 

# File sytab.rb, line 88
  def compile!()
    @regex = Regexp.new(keys.map { 
      |k| "(" + @delims[0] + k + @delims[1] + ")"
    }.join("|"))
  end
replace(s)

Return a string with each occurrence of a key surrounded by delimiters replaced with the lookup value for the key. 

# File sytab.rb, line 97
  def replace(s)
    if keys.size < 1
      s
    else
      compile! unless @regex
      s.gsub!(@regex) {
	|match|	fetch(match[@mpos...@mend])
      }
      s.gsub(@var_regex, "*UNDEFINED*")
    end
  end
<<(s)

Shorthand for replace(s). 

# File sytab.rb, line 111
  def <<(s)
    replace(s)
  end