Class: ABNF

Inherits:
Object
  • Object
show all
Defined in:
lib/abnftt.rb,
lib/abnftt/abnf-writer.rb,
lib/abnftt/abnf-visitor.rb,
lib/abnftt/abnf-squasher.rb,
lib/abnftt/abnf-flattener.rb

Constant Summary collapse

FIXUP_NAMES = 
Hash.new {|h, k| k}
UNESCAPED_SQSTR_RANGES = 
[[0xA, 0xA], [0x20, 0x26],  # "'"
   # [0x28, 0x5b], [0x5d, 0x7e], [0xa0, 0xd7ff], -- but JSON allows 7F-9F
   [0x28, 0x5b], [0x5d, 0xd7ff], # \
   [0xe000, 0x10ffff]].map {|l, r|
  [l.chr(Encoding::UTF_8), r.chr(Encoding::UTF_8)]
}
ESCAPED_SQSTR_MAPPINGS = 
[
["\x08", "b"],
["\x09", "t"],
["\x0A", "n"],
["\x0C", "f"],
["\x0D", "r"],
["\x27", "'"],
["\x2F", "/"],
["\x5C", "\\"]]
@@parser = 
ABNFGrammarParser.new
@@gensym = 
0

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ast_ = nil, rules_ = {}) ⇒ ABNF

Returns a new instance of ABNF.



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# File 'lib/abnftt.rb', line 61

def initialize(ast_ = nil, rules_ = {})
  if ast_
    @ast = ast_
    @tree = ast.ast
  end
  @rules = rules_
  @tree.each do |x|
    op, name, val, rest = x
    fail rest if rest
    @rules[name] =
      if old = @rules[name]
        fail "duplicate rule for name #{name}" if op == "="
        if Array === old && old[0] == "alt"
          old.dup << val
        else
          ["alt", old, val]
        end
      else
        val
      end
  end if @tree
  # warn "** rules #{rules.inspect}"
end

Instance Attribute Details

#ast ⇒ Object

Returns the value of attribute ast.



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# File 'lib/abnftt.rb', line 60

def ast
  @ast
end

#parser ⇒ Object

Returns the value of attribute parser.



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# File 'lib/abnftt.rb', line 206

def parser
  @parser
end

#rules ⇒ Object

Returns the value of attribute rules.



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# File 'lib/abnftt.rb', line 60

def rules
  @rules
end

#tree ⇒ Object

Returns the value of attribute tree.



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# File 'lib/abnftt.rb', line 60

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

.from_rules(r) ⇒ Object 



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

def self.from_rules(r)
  ABNF.new(nil, r)
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

#breaker(s, col = 69) ⇒ Object

primitively break down lines so they fit on a teletype



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# File 'lib/abnftt/abnf-writer.rb', line 90

def breaker(s, col = 69)
  ret = ""
  s.each_line do |*l|
    while l[-1].size > col
      breakpoint = l[-1][0...col].rindex(' ')
      break unless breakpoint && breakpoint > 4
      while (partial = l[-1][0...breakpoint]).count('"').odd?
        break1 = partial.rindex('"')
        breakpoint = l[-1][0...break1].rindex(' ')
        break unless breakpoint && breakpoint > 4
      end
      l[-1..-1] = [
        l[-1][0...breakpoint],
        "    " << l[-1][breakpoint+1..-1]
      ]
    end
    ret << l.join("\n")
  end
  ret
end

#expand_op_into(s, op, out = [op]) ⇒ Object 



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# File 'lib/abnftt/abnf-flattener.rb', line 4

def expand_op_into(s, op, out = [op])
  s.each do |el|
    case el
    in [^op, *inner]
      expand_op_into(inner, op, out)
    else
      out << flatten_ops_1(el)
    end
  end
  out
end

#flatten_ops ⇒ Object 



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# File 'lib/abnftt/abnf-flattener.rb', line 27

def flatten_ops
  rules.each do |name, prod|
    rules[name] = flatten_ops_1(prod)
  end
end

#flatten_ops_1(prod) ⇒ Object 



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# File 'lib/abnftt/abnf-flattener.rb', line 15

def flatten_ops_1(prod)
  visit(prod) do |here|
      case here
      in ["seq", *rest]
        [true, expand_op_into(rest, "seq")]
      in ["alt", *rest]
        [true, expand_op_into(rest, "alt")]
      else
        false
      end
  end
end

#generate ⇒ Object 



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# File 'lib/abnftt.rb', line 85

def generate
  generate1(rules.first.first)
end

#generate1(what) ⇒ Object 



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# File 'lib/abnftt.rb', line 89

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

#prec_check(inner, targetprec, prec) ⇒ Object

precedence: 1: / alt -> (type1) 2: »« seq 4: atomic



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# File 'lib/abnftt/abnf-writer.rb', line 19

def prec_check(inner, targetprec, prec)
  if targetprec >= prec
    "(#{inner})"
  else
    inner
  end
end

#squash_edn_levels(**options) ⇒ Object 



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# File 'lib/abnftt/abnf-squasher.rb', line 59

def squash_edn_levels(**options)
  rules.each do |name, prod|
    rules[name] = squash_edn_levels_1(prod, **options)
  end
end

#squash_edn_levels_1(prod, **options) ⇒ Object 



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# File 'lib/abnftt/abnf-squasher.rb', line 27

def squash_edn_levels_1(prod, **options)
  f1 = visit(prod) do |here|
    case here
    in ["char-range", c1, c2]
      lit = UNESCAPED_SQSTR_RANGES.map { |u1, u2|
        overlap(here, u1, u2) }.compact
      esc = ESCAPED_SQSTR_MAPPINGS.map {|cv, ev|
        if cv >= c1 && cv <= c2
          ["seq", ["char-range", "\\", "\\"], ["char-range", ev, ev]]
        end
      }.compact
      u_escapes = []
      if options[:ascii]
        do_ranges_outside(here, " ", "~") do |l, r|
          u_escapes << alt_ranges_legacy(l, r) # old
          u_escapes << alt_ranges_modern(l, r) # new
        end
      else
        u_escapes << alt_ranges_legacy(c1.ord, c2.ord) # old
        u_escapes << alt_ranges_modern(c1.ord, c2.ord) # new
      end
      oldnew = ["seq",
                ["cs", "\\u"],
                wrap_flat("alt", u_escapes) ] if u_escapes != []
      [true, wrap_flat("alt", [*lit, *esc, oldnew].compact.sort)]
    else
      false
    end
  end
  flatten_ops_1(f1)
end

#stringify(s) ⇒ Object

return [precedence ((2 if seq needed)), string]



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# File 'lib/abnftt/abnf-writer.rb', line 5

def stringify(s)
  fail "Can't stringify #{s.inspect} yet" unless s =~ /\A[ !#-~]*\z/
  %{"#{s}"}
end

#to_s ⇒ Object 



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# File 'lib/abnftt/abnf-writer.rb', line 85

def to_s
  rules.map {|k, v| write_rule(k, v) }.join("\n").sub(/.\z/) {$& << "\n"}
end

#to_treetop(modname) ⇒ Object 



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# File 'lib/abnftt.rb', line 134

def to_treetop(modname)
  <<~EOS
  # Encoding: UTF-8
  grammar #{modname}
  #{rules.map {|k, v| to_treetop0(k, v)}.join}
  end
EOS
end

#to_treetop0(k, v) ⇒ Object 



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# File 'lib/abnftt.rb', line 142

def to_treetop0(k, v)
  <<~EOS
  rule #{to_treetop1(k)}
  #{to_treetop1(v)}
  end
EOS
end

#to_treetop1(ast) ⇒ Object 



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# File 'lib/abnftt.rb', line 154

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]) || "@@@"
      if ast[3][0] == "rep"
        t = "(#{t})"
      end
      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 207

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

#visit(prod, &block) ⇒ Object 



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# File 'lib/abnftt/abnf-visitor.rb', line 7

def visit(prod, &block)
  done, ret = block.call(prod, &block)
  if done
    return ret
  end

  case prod
  in ["alt", *prods]
    ["alt", *visit_all(prods, &block)]
  in ["tadd", *prods]
    ["tadd", *visit_all(prods, &block)]
  in ["seq", *prods]
    ["seq", *visit_all(prods, &block)]
  in ["rep", s, e, prod]
    ["rep", s, e, visit(prod, &block)]
  else
    prod
  end
end

#visit_all(prod_array, &block) ⇒ Object 



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# File 'lib/abnftt/abnf-visitor.rb', line 4

def visit_all(prod_array, &block)
  prod_array.map {|prod| visit(prod, &block)}
end

#write_lhs(k) ⇒ Object 



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# File 'lib/abnftt/abnf-writer.rb', line 10

def write_lhs(k)
    k
end

#write_rhs(v, targetprec = 0) ⇒ Object 



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# File 'lib/abnftt/abnf-writer.rb', line 27

def write_rhs(v, targetprec = 0)
  prec, ret =
  case v
  in String                   # this should really be ["name", id]
    [4, v]
  in ["name", id]
    [4, id]
  in ["alt" | "tadd", *types]
    [1, types.map{write_rhs(_1, 1)}.join(" / ")]
  in ["seq", *groups]
    case groups.size
    when 0; [4, ""]           # XXX
    else
      [2, "#{groups.map{write_rhs(_1, 2)}.join(" ")}"]
    end
  in ["ci", s]
    [4, stringify(s)]
  in ["cs", s]
    if s =~ /\A[^A-Za-z]*\z/
      [4, stringify(s)]
    else
      [4, "%s" << stringify(s)]  # reduce noise if no alphabetics
    end
  in ["char-range", c1, c2]
    nc1 = "%02x" % c1.ord

    nc2 = "%02x" % c2.ord
    nc2add = "-#{nc2}" if nc2 != nc1
    [4, "%x#{nc1}#{nc2add}"]
  in ["rep", s, e, group]
    if s == 0 && e == 1
      [4, "[#{write_rhs(group)}]"]
    else
      occur = case [s, e]
              in [1, 1];    ""
              in [0, true]; "*"
              in [n, ^n]; n.to_s
              else
                "#{s}*#{e != true ? e : ""}"
              end
      [4, "#{occur}#{write_rhs(group, 4)}"]
    end
  else
    fail [:WRITE_NOMATCH, v].inspect
  end
  prec_check(ret, targetprec, prec)
end

#write_rule(k, v) ⇒ Object 



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# File 'lib/abnftt/abnf-writer.rb', line 75

def write_rule(k, v)
    case v
    in ["tadd", *_rest]
      assign = "=/"
    else
      assign = "="
    end
    "#{write_lhs(k)} #{assign} #{write_rhs(v, 0)}"
end