Class: Lrama::Grammar

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

Overview

Grammar is the result of parsing an input grammar file

Defined Under Namespace

Classes: Aux

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Grammar

Returns a new instance of Grammar.



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# File 'lib/lrama/grammar.rb', line 296

def initialize
  @printers = []
  @symbols = []
  @types = []
  @_rules = []
  @rules = []
  @sym_to_rules = {}
  @empty_symbol = nil
  @eof_symbol = nil
  @error_symbol = nil
  @undef_symbol = nil
  @accept_symbol = nil
  @aux = Aux.new

  append_special_symbols
end

Instance Attribute Details

#_rules ⇒ Object

Returns the value of attribute _rules.



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# File 'lib/lrama/grammar.rb', line 289

def _rules
  @_rules
end

#accept_symbol ⇒ Object (readonly)

Returns the value of attribute accept_symbol.



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# File 'lib/lrama/grammar.rb', line 288

def accept_symbol
  @accept_symbol
end

#aux ⇒ Object (readonly)

Returns the value of attribute aux.



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# File 'lib/lrama/grammar.rb', line 288

def aux
  @aux
end

#eof_symbol ⇒ Object (readonly)

Returns the value of attribute eof_symbol.



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# File 'lib/lrama/grammar.rb', line 288

def eof_symbol
  @eof_symbol
end

#error_symbol ⇒ Object (readonly)

Returns the value of attribute error_symbol.



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# File 'lib/lrama/grammar.rb', line 288

def error_symbol
  @error_symbol
end

#expect ⇒ Object

Returns the value of attribute expect.



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# File 'lib/lrama/grammar.rb', line 289

def expect
  @expect
end

#initial_action ⇒ Object

Returns the value of attribute initial_action.



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# File 'lib/lrama/grammar.rb', line 289

def initial_action
  @initial_action
end

#lex_param ⇒ Object

Returns the value of attribute lex_param.



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# File 'lib/lrama/grammar.rb', line 289

def lex_param
  @lex_param
end

#parse_param ⇒ Object

Returns the value of attribute parse_param.



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# File 'lib/lrama/grammar.rb', line 289

def parse_param
  @parse_param
end

#printers ⇒ Object

Returns the value of attribute printers.



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# File 'lib/lrama/grammar.rb', line 289

def printers
  @printers
end

#rules ⇒ Object

Returns the value of attribute rules.



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# File 'lib/lrama/grammar.rb', line 289

def rules
  @rules
end

#sym_to_rules ⇒ Object

Returns the value of attribute sym_to_rules.



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# File 'lib/lrama/grammar.rb', line 289

def sym_to_rules
  @sym_to_rules
end

#symbols ⇒ Object

Returns the value of attribute symbols.



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# File 'lib/lrama/grammar.rb', line 289

def symbols
  @symbols
end

#types ⇒ Object

Returns the value of attribute types.



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# File 'lib/lrama/grammar.rb', line 289

def types
  @types
end

#undef_symbol ⇒ Object (readonly)

Returns the value of attribute undef_symbol.



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# File 'lib/lrama/grammar.rb', line 288

def undef_symbol
  @undef_symbol
end

#union ⇒ Object

Returns the value of attribute union.



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# File 'lib/lrama/grammar.rb', line 289

def union
  @union
end

Instance Method Details

#add_left(sym, precedence) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 363

def add_left(sym, precedence)
  set_precedence(sym, Precedence.new(type: :left, precedence: precedence))
end

#add_nonassoc(sym, precedence) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 359

def add_nonassoc(sym, precedence)
  set_precedence(sym, Precedence.new(type: :nonassoc, precedence: precedence))
end

#add_nterm(id:, alias_name: nil, tag: nil) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 342

def add_nterm(id:, alias_name: nil, tag: nil)
  return if @symbols.find {|s| s.id == id }

  sym = Symbol.new(
    id: id, alias_name: alias_name, number: nil, tag: tag,
    term: false, token_id: nil, nullable: nil,
  )
  @symbols << sym
  @nterms = nil

  return sym
end

#add_printer(ident_or_tags:, code:, lineno:) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 313

def add_printer(ident_or_tags:, code:, lineno:)
  @printers << Printer.new(ident_or_tags: ident_or_tags, code: code, lineno: lineno)
end

#add_right(sym, precedence) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 367

def add_right(sym, precedence)
  set_precedence(sym, Precedence.new(type: :right, precedence: precedence))
end

#add_rule(lhs:, rhs:, lineno:) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 380

def add_rule(lhs:, rhs:, lineno:)
  @_rules << [lhs, rhs, lineno]
end

#add_term(id:, alias_name: nil, tag: nil, token_id: nil, replace: false) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 317

def add_term(id:, alias_name: nil, tag: nil, token_id: nil, replace: false)
  if token_id && (sym = @symbols.find {|s| s.token_id == token_id })
    if replace
      sym.id = id
      sym.alias_name = alias_name
      sym.tag = tag
    end

    return sym
  end

  if sym = @symbols.find {|s| s.id == id }
    return sym
  end

  sym = Symbol.new(
    id: id, alias_name: alias_name, number: nil, tag: tag,
    term: true, token_id: token_id, nullable: false
  )
  @symbols << sym
  @terms = nil

  return sym
end

#add_type(id:, tag:) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 355

def add_type(id:, tag:)
  @types << Type.new(id: id, tag: tag)
end

#build_code(type, token_code) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 392

def build_code(type, token_code)
  build_references(token_code)
  Code.new(type: type, token_code: token_code)
end

#build_references(token_code) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 384

def build_references(token_code)
  token_code.references.map! do |type, number, tag, first_column, last_column|
    Reference.new(type: type, number: number, ex_tag: tag, first_column: first_column, last_column: last_column)
  end

  token_code
end

#compute_nullable ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 430

def compute_nullable
  @rules.each do |rule|
    case
    when rule.rhs.empty?
      rule.nullable = true
    when rule.rhs.any?(&:term)
      rule.nullable = false
    else
      # noop
    end
  end

  while true do
    rs  = @rules.select {|e| e.nullable.nil? }
    nts = nterms.select {|e| e.nullable.nil? }
    rule_count_1  = rs.count
    nterm_count_1 = nts.count

    rs.each do |rule|
      if rule.rhs.all?(&:nullable)
        rule.nullable = true
      end
    end

    nts.each do |nterm|
      find_rules_by_symbol!(nterm).each do |rule|
        if rule.nullable
          nterm.nullable = true
        end
      end
    end

    rule_count_2  = @rules.count {|e| e.nullable.nil? }
    nterm_count_2 = nterms.count {|e| e.nullable.nil? }

    if (rule_count_1 == rule_count_2) && (nterm_count_1 == nterm_count_2)
      break
    end
  end

  rules.select {|r| r.nullable.nil? }.each do |rule|
    rule.nullable = false
  end

  nterms.select {|r| r.nullable.nil? }.each do |nterm|
    nterm.nullable = false
  end
end

#epilogue=(epilogue) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 409

def epilogue=(epilogue)
  @aux.epilogue = epilogue
end

#epilogue_first_lineno=(epilogue_first_lineno) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 405

def epilogue_first_lineno=(epilogue_first_lineno)
  @aux.epilogue_first_lineno = epilogue_first_lineno
end

#find_rules_by_symbol(sym) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 513

def find_rules_by_symbol(sym)
  @sym_to_rules[sym.number]
end

#find_rules_by_symbol!(sym) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 509

def find_rules_by_symbol!(sym)
  find_rules_by_symbol(sym) || (raise "Rules for #{sym} not found")
end

#find_symbol_by_id(id) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 489

def find_symbol_by_id(id)
  @symbols.find do |sym|
    # TODO: validate uniqueness of Token#s_value and Symbol#alias_name
    sym.id == id || sym.alias_name == id.s_value
  end
end

#find_symbol_by_id!(id) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 496

def find_symbol_by_id!(id)
  find_symbol_by_id(id) || (raise "Symbol not found: #{id}")
end

#find_symbol_by_number!(number) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 500

def find_symbol_by_number!(number)
  sym = @symbols[number]

  raise "Symbol not found: #{number}" unless sym
  raise "[BUG] Symbol number mismatch. #{number}, #{sym}" if sym.number != number

  sym
end

#find_symbol_by_s_value(s_value) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 479

def find_symbol_by_s_value(s_value)
  @symbols.find do |sym|
    sym.id.s_value == s_value
  end
end

#find_symbol_by_s_value!(s_value) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 485

def find_symbol_by_s_value!(s_value)
  find_symbol_by_s_value(s_value) || (raise "Symbol not found: #{s_value}")
end

#nterms ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 529

def nterms
  @nterms ||= @symbols.select(&:nterm?)
end

#nterms_count ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 525

def nterms_count
  nterms.count
end

#prepare ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 413

def prepare
  normalize_rules
  collect_symbols
  replace_token_with_symbol
  fill_symbol_number
  fill_default_precedence
  fill_sym_to_rules
  fill_nterm_type
  fill_symbol_printer
  @symbols.sort_by!(&:number)
end

#prologue=(prologue) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 401

def prologue=(prologue)
  @aux.prologue = prologue
end

#prologue_first_lineno=(prologue_first_lineno) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 397

def prologue_first_lineno=(prologue_first_lineno)
  @aux.prologue_first_lineno = prologue_first_lineno
end

#set_precedence(sym, precedence) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 371

def set_precedence(sym, precedence)
  raise "" if sym.nterm?
  sym.precedence = precedence
end

#set_union(code, lineno) ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 376

def set_union(code, lineno)
  @union = Union.new(code: code, lineno: lineno)
end

#terms ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 521

def terms
  @terms ||= @symbols.select(&:term?)
end

#terms_count ⇒ Object 



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# File 'lib/lrama/grammar.rb', line 517

def terms_count
  terms.count
end

#validate! ⇒ Object

TODO: More validation methods



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# File 'lib/lrama/grammar.rb', line 426

def validate!
  validate_symbol_number_uniqueness!
end