Class: Nydp::Parser

Inherits:
Object show all
Defined in:
lib/nydp/parser.rb

Constant Summary collapse

SYMBOL_OPERATORS = 
[
  [ /\!/,     "bang-syntax"       ],
  [ /::/,     "colon-colon-syntax"],
  [ /:/,      "colon-syntax"      ],
  [ /&/,      "ampersand-syntax"  ],
  [ /%/,      "percent-syntax"    ],
  [ /\./,     "dot-syntax"        ],
  [ /\$/,     "dollar-syntax"     ],
  [ /->/,     "arrow-syntax"      ],
  [ /[=][>]/, "rocket-syntax"     ],
  [ /@/,      "at-syntax"         ],
]
INTERPOLATION_SIGN = 
/~/
INTERPOLATION_ESCAPES = 
{ /~\s/ => true, /~~/ => "~" }

Instance Method Summary collapse

Instance Method Details

#close_delimiter_for(opener) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 86

def close_delimiter_for opener
  case opener
  when '"'
    /"/
  when /.*{$/
    /}/
  when /<<(.+)$/
    Regexp.new $1
  end
end

#embedded(token_stream) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 124

def embedded token_stream
  string token_stream, "", :eof
end

#expression(token_stream) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 117

def expression token_stream
  next_form token_stream.next_token, token_stream
end

#next_form(token, token_stream) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 97

def next_form token, token_stream
  return nil if token.nil?
  case token.first
  when :string_open_delim
    string token_stream, token.last, close_delimiter_for(token.last)
  when :sym_open_delim
    sym token_stream.next_string_fragment(token.last, /\|/, nil).string
  when :left_paren
    prefix_list token[1], read_list(token_stream, :right_paren)
  when :left_brace
    prefix_list token[1], read_list(token_stream, :right_brace, [sym("brace-list")])
  when :symbol
    parse_symbol token.last
  when :comment
    Pair.from_list [sym(:comment), token.last]
  else
    token.last
  end
end

#parse_symbol(txt) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 57

def parse_symbol txt
  txt = txt.to_s
  case txt
  when /^[-+]?[0-9]*\.[0-9]+([eE][-+]?[0-9]+)?$/
    txt.to_f
  when /^[-+]?[0-9]+$/
    txt.to_i
  when /^'(.*)$/
    Pair.from_list [sym(:quote), parse_symbol($1)]
  when /^`(.*)$/
    Pair.from_list [sym(:quasiquote), parse_symbol($1)]
  when /^,@(.*)$/
    Pair.from_list [sym(:"unquote-splicing"), parse_symbol($1)]
  when /^,(.*)$/
    Pair.from_list [sym(:unquote), parse_symbol($1)]
  when /^\.$/
    sym txt
  when /^@$/
    sym txt
  else
    SYMBOL_OPERATORS.each do |rgx, name|
      syms = txt.split(rgx, -1)
      return split_sym syms, sym(name) if syms.length > 1
    end

    sym txt
  end
end

#prefix_list(prefix, list) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 23

def prefix_list prefix, list
  return list if prefix == ''
  case prefix
  when /^(.*)'$/
    prefix_list $1, Pair.from_list([sym(:quote), list])
  when /^(.*)`$/
    prefix_list $1, Pair.from_list([sym(:quasiquote), list])
  when /^(.*),$/
    prefix_list $1, Pair.from_list([sym(:unquote), list])
  when /^(.*),@$/
    prefix_list $1, Pair.from_list([sym(:"unquote-splicing"), list])
  else
    Pair.from_list([sym(:"prefix-list"), prefix, list])
  end
end

#read_list(token_stream, termination_token, list = []) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 14

def read_list token_stream, termination_token, list=[]
  token = token_stream.next_token
  while token != nil && token.first != termination_token
    list << next_form(token, token_stream)
    token = token_stream.next_token
  end
  Pair.parse_list list
end

#split_sym(syms, pfx) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 39

def split_sym syms, pfx
  return Pair.from_list [pfx] + syms.map { |s| parse_symbol s }
end

#string(token_stream, open_delimiter, close_delimiter) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 128

def string token_stream, open_delimiter, close_delimiter
  fragments = [sym(:"string-pieces")]
  string_token = token_stream.next_string_fragment(open_delimiter, close_delimiter, INTERPOLATION_SIGN, INTERPOLATION_ESCAPES)
  raise "unterminated string" if string_token.nil?
  fragments << string_token.string if string_token.string != ""
  while !(string_token.is_a? StringFragmentCloseToken)
    fragments << expression(token_stream)
    string_token = token_stream.next_string_fragment('', close_delimiter, INTERPOLATION_SIGN, INTERPOLATION_ESCAPES)
    fragments << string_token.string if string_token.string != ""
  end

  if fragments.size == 1
    return ""
  elsif fragments.size == 2
    return fragments[1]
  else
    return Pair.from_list fragments
  end
end

#sym(name) ⇒ Object 



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# File 'lib/nydp/parser.rb', line 3

def sym name
  n = name.to_s.to_sym
  if n == :nil
    nil
  elsif n == :t
    true
  else
    n
  end
end