Class: ABNF

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

Constant Summary collapse

FIXUP_NAMES = 
Hash.new {|h, k| k}
@@parser = 
ABNFGrammarParser.new
@@gensym = 
0

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ast_) ⇒ ABNF

Returns a new instance of ABNF.



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# File 'lib/abnftt.rb', line 57

def initialize(ast_)
  @ast = ast_
  @tree = ast.ast
  @rules = {}
  @tree.each do |x|
    op, name, val, rest = x
    fail rest if rest
    fail op unless op == "="  # XXX
    if @rules[name]
      fail "duplicate rule for name #{name}"
    end
    @rules[name] = val
  end
end

Instance Attribute Details

#ast ⇒ Object

Returns the value of attribute ast.



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

def ast
  @ast
end

#parser ⇒ Object

Returns the value of attribute parser.



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# File 'lib/abnftt.rb', line 190

def parser
  @parser
end

#rules ⇒ Object

Returns the value of attribute rules.



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

def rules
  @rules
end

#tree ⇒ Object

Returns the value of attribute tree.



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

def tree
  @tree
end

Class Method Details

.from_abnf(s) ⇒ Object 



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# File 'lib/abnftt.rb', line 48

def self.from_abnf(s)
  ast = @@parser.parse s
  if !ast
    fail self.reason(@@parser, s)
  end
  ABNF.new(ast)
end

.reason(parser, s) ⇒ Object 



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# File 'lib/abnftt.rb', line 37

def self.reason(parser, s)
  reason = [parser.failure_reason]
  parser.failure_reason =~ /^(Expected .+) after/m
  reason << "#{$1.gsub("\n", '<<<NEWLINE>>>')}:" if $1
  if line = s.lines.to_a[parser.failure_line - 1]
    reason << line
    reason << "#{'~' * (parser.failure_column - 1)}^"
  end
  reason.join("\n")
end

Instance Method Details

#generate ⇒ Object 



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# File 'lib/abnftt.rb', line 72

def generate
  generate1(rules.first.first)
end

#generate1(what) ⇒ Object 



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# File 'lib/abnftt.rb', line 76

def generate1(what)
  case what
  when String
    expansion = rules[what]
    fail "can't find rules #{what}" unless expansion
    generate1(expansion)
  when Array
    op, *args = what
    case op
    when "seq"
      args.map {|arg| generate1(arg)}.join
    when "alt"
      generate1(args.sample)
    when "rep"
      l, h, x, rest = args
      fail rest if rest
      h = l+3 if h == true
      n = rand(h-l+1)+l
      (0...n).map { generate1(x) }.join
    when "ci"
      s, rest = args
      fail rest if rest
      s.chars.map{|x|[x.upcase, x.downcase].sample}.join
    when "cs"
      s, rest = args
      fail rest if rest
      s
    when "char-range"
      l, r = args
      fail rest if rest
      (rand(r.ord-l.ord+1)+l.ord).chr(Encoding::UTF_8)
    when "prose" # ["prose", text]
      fail "prose not implemented #{what.inspect}"
    when "im"
      warn "abnftt-style inline module ignored #{what.inspect}"
      ''
    else
      fail [op, args].inspect
    end
  else
    fail
  end
end

#to_treetop(modname) ⇒ Object 



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# File 'lib/abnftt.rb', line 121

def to_treetop(modname)
  <<~EOS
  # Encoding: UTF-8
  grammar #{modname}
  #{tree.map {|x| to_treetop0(x)}.join}
  end
EOS
end

#to_treetop0(ast) ⇒ Object 



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

def to_treetop0(ast)
  fail ast.inspect unless ast[0] == "="
  <<~EOS
  rule #{to_treetop1(ast[1])}
  #{to_treetop1(ast[2])}
  end
EOS
end

#to_treetop1(ast) ⇒ Object 



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# File 'lib/abnftt.rb', line 141

def to_treetop1(ast)
  case ast
  when String
    FIXUP_NAMES[ast].gsub("-", "_")
  when Array
    case ast[0]
    when "alt" # ["alt", *a]
      "(#{ast[1..-1].map {|x| to_treetop1(x)}.join(" / ")})"
    when "seq" # ["seq", *a]
      "(#{ast[1..-1].map {|x| to_treetop1(x)}.join(" ")})"
    when "rep" # ["rep", s, e, a]
      t = to_treetop1(ast[3]) || "@@@"
      case [ast[1], ast[2]]
      when [0, 1]
        t + "?"
      when [0, true]
        t + "*"
      when [1, true]
        t + "+"
      else
        t + " #{ast[1]}..#{ast[2] == true ? '' : ast[2]}"
      end
    when "prose" # ["prose", text]
      fail "prose not implemented #{ast.inspect}"
    when "ci" # ["ci", text]
      s = ast[1]
      if s =~ /\A[^A-Za-z]*\z/
        s.inspect
      else
        s.inspect << "i"        # could do this always, but reduce noise
      end
    when "cs" # ["cs", text]
      ast[1].inspect
    when "char-range" # ["char-range", c1, c2]
      c1 = Regexp.quote(ast[1])
      c2 = Regexp.quote(ast[2])
      "[#{c1}-#{c2}]"           # XXX does that always work
    when "im" # ["im", a, text]
      to_treetop1(ast[1]) + " " + ast[2]
    else
      fail "to_treetop(#{ast.inspect})"
    end
  else
    fail "to_treetop(#{ast.inspect})"
  end
end

#validate(s) ⇒ Object 



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# File 'lib/abnftt.rb', line 191

def validate(s)
  @parser ||= Treetop.load_from_string(to_treetop("ABNF_Mod" << (@@gensym += 1).to_s))
  parser_instance ||= @parser.new
  unless result1 = parser_instance.parse(s)
    fail self.class.reason(parser_instance, s)
  end
end