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require "forwardable"
require "lrama/grammar/auxiliary"
require "lrama/grammar/binding"
require "lrama/grammar/code"
require "lrama/grammar/counter"
require "lrama/grammar/destructor"
require "lrama/grammar/error_token"
require "lrama/grammar/parameterizing_rule"
require "lrama/grammar/percent_code"
require "lrama/grammar/precedence"
require "lrama/grammar/printer"
require "lrama/grammar/reference"
require "lrama/grammar/rule"
require "lrama/grammar/rule_builder"
require "lrama/grammar/symbol"
require "lrama/grammar/symbols"
require "lrama/grammar/type"
require "lrama/grammar/union"
require "lrama/lexer"
module Lrama
# Grammar is the result of parsing an input grammar file
class Grammar
extend Forwardable
attr_reader :percent_codes, :eof_symbol, :error_symbol, :undef_symbol, :accept_symbol, :aux
attr_accessor :union, :expect,
:printers, :error_tokens,
:lex_param, :parse_param, :initial_action,
:after_shift, :before_reduce, :after_reduce, :after_shift_error_token, :after_pop_stack,
:symbols_resolver, :types,
:rules, :rule_builders,
:sym_to_rules, :no_stdlib
def_delegators "@symbols_resolver", :symbols, :nterms, :terms, :add_nterm, :add_term,
:find_symbol_by_number!, :find_symbol_by_id!, :token_to_symbol,
:find_symbol_by_s_value!, :fill_symbol_number, :fill_nterm_type,
:fill_printer, :fill_destructor, :fill_error_token, :sort_by_number!
def initialize(rule_counter)
@rule_counter = rule_counter
# Code defined by "%code"
@percent_codes = []
@printers = []
@destructors = []
@error_tokens = []
@symbols_resolver = Grammar::Symbols::Resolver.new
@types = []
@rule_builders = []
@rules = []
@sym_to_rules = {}
@parameterizing_rule_resolver = ParameterizingRule::Resolver.new
@empty_symbol = nil
@eof_symbol = nil
@error_symbol = nil
@undef_symbol = nil
@accept_symbol = nil
@aux = Auxiliary.new
@no_stdlib = false
append_special_symbols
end
def add_percent_code(id:, code:)
@percent_codes << PercentCode.new(id.s_value, code.s_value)
end
def add_destructor(ident_or_tags:, token_code:, lineno:)
@destructors << Destructor.new(ident_or_tags: ident_or_tags, token_code: token_code, lineno: lineno)
end
def add_printer(ident_or_tags:, token_code:, lineno:)
@printers << Printer.new(ident_or_tags: ident_or_tags, token_code: token_code, lineno: lineno)
end
def add_error_token(ident_or_tags:, token_code:, lineno:)
@error_tokens << ErrorToken.new(ident_or_tags: ident_or_tags, token_code: token_code, lineno: lineno)
end
def add_type(id:, tag:)
@types << Type.new(id: id, tag: tag)
end
def add_nonassoc(sym, precedence)
set_precedence(sym, Precedence.new(type: :nonassoc, precedence: precedence))
end
def add_left(sym, precedence)
set_precedence(sym, Precedence.new(type: :left, precedence: precedence))
end
def add_right(sym, precedence)
set_precedence(sym, Precedence.new(type: :right, precedence: precedence))
end
def add_precedence(sym, precedence)
set_precedence(sym, Precedence.new(type: :precedence, precedence: precedence))
end
def set_precedence(sym, precedence)
raise "" if sym.nterm?
sym.precedence = precedence
end
def set_union(code, lineno)
@union = Union.new(code: code, lineno: lineno)
end
def add_rule_builder(builder)
@rule_builders << builder
end
def add_parameterizing_rule(rule)
@parameterizing_rule_resolver.add_parameterizing_rule(rule)
end
def parameterizing_rules
@parameterizing_rule_resolver.rules
end
def insert_before_parameterizing_rules(rules)
@parameterizing_rule_resolver.rules = rules + @parameterizing_rule_resolver.rules
end
def prologue_first_lineno=(prologue_first_lineno)
@aux.prologue_first_lineno = prologue_first_lineno
end
def prologue=(prologue)
@aux.prologue = prologue
end
def epilogue_first_lineno=(epilogue_first_lineno)
@aux.epilogue_first_lineno = epilogue_first_lineno
end
def epilogue=(epilogue)
@aux.epilogue = epilogue
end
def prepare
normalize_rules
collect_symbols
set_lhs_and_rhs
fill_default_precedence
fill_symbols
fill_sym_to_rules
compute_nullable
compute_first_set
end
# TODO: More validation methods
#
# * Validation for no_declared_type_reference
def validate!
@symbols_resolver.validate!
validate_rule_lhs_is_nterm!
end
def find_rules_by_symbol!(sym)
find_rules_by_symbol(sym) || (raise "Rules for #{sym} not found")
end
def find_rules_by_symbol(sym)
@sym_to_rules[sym.number]
end
private
def compute_nullable
@rules.each do |rule|
case
when rule.empty_rule?
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 {|e| e.nullable.nil? }.each do |nterm|
nterm.nullable = false
end
end
def compute_first_set
terms.each do |term|
term.first_set = Set.new([term]).freeze
term.first_set_bitmap = Lrama::Bitmap.from_array([term.number])
end
nterms.each do |nterm|
nterm.first_set = Set.new([]).freeze
nterm.first_set_bitmap = Lrama::Bitmap.from_array([])
end
while true do
changed = false
@rules.each do |rule|
rule.rhs.each do |r|
if rule.lhs.first_set_bitmap | r.first_set_bitmap != rule.lhs.first_set_bitmap
changed = true
rule.lhs.first_set_bitmap = rule.lhs.first_set_bitmap | r.first_set_bitmap
end
break unless r.nullable
end
end
break unless changed
end
nterms.each do |nterm|
nterm.first_set = Lrama::Bitmap.to_array(nterm.first_set_bitmap).map do |number|
find_symbol_by_number!(number)
end.to_set
end
end
def setup_rules
@rule_builders.each do |builder|
builder.setup_rules(@parameterizing_rule_resolver)
end
end
def append_special_symbols
# YYEMPTY (token_id: -2, number: -2) is added when a template is evaluated
# term = add_term(id: Token.new(Token::Ident, "YYEMPTY"), token_id: -2)
# term.number = -2
# @empty_symbol = term
# YYEOF
term = add_term(id: Lrama::Lexer::Token::Ident.new(s_value: "YYEOF"), alias_name: "\"end of file\"", token_id: 0)
term.number = 0
term.eof_symbol = true
@eof_symbol = term
# YYerror
term = add_term(id: Lrama::Lexer::Token::Ident.new(s_value: "YYerror"), alias_name: "error")
term.number = 1
term.error_symbol = true
@error_symbol = term
# YYUNDEF
term = add_term(id: Lrama::Lexer::Token::Ident.new(s_value: "YYUNDEF"), alias_name: "\"invalid token\"")
term.number = 2
term.undef_symbol = true
@undef_symbol = term
# $accept
term = add_nterm(id: Lrama::Lexer::Token::Ident.new(s_value: "$accept"))
term.accept_symbol = true
@accept_symbol = term
end
def normalize_rules
# Add $accept rule to the top of rules
lineno = @rule_builders.first ? @rule_builders.first.line : 0
@rules << Rule.new(id: @rule_counter.increment, _lhs: @accept_symbol.id, _rhs: [@rule_builders.first.lhs, @eof_symbol.id], token_code: nil, lineno: lineno)
setup_rules
@rule_builders.each do |builder|
builder.rules.each do |rule|
add_nterm(id: rule._lhs, tag: rule.lhs_tag)
@rules << rule
end
end
@rules.sort_by!(&:id)
end
# Collect symbols from rules
def collect_symbols
@rules.flat_map(&:_rhs).each do |s|
case s
when Lrama::Lexer::Token::Char
add_term(id: s)
when Lrama::Lexer::Token
# skip
else
raise "Unknown class: #{s}"
end
end
end
def set_lhs_and_rhs
@rules.each do |rule|
rule.lhs = token_to_symbol(rule._lhs) if rule._lhs
rule.rhs = rule._rhs.map do |t|
token_to_symbol(t)
end
end
end
# Rule inherits precedence from the last term in RHS.
#
# https://www.gnu.org/software/bison/manual/html_node/How-Precedence.html
def fill_default_precedence
@rules.each do |rule|
# Explicitly specified precedence has the highest priority
next if rule.precedence_sym
precedence_sym = nil
rule.rhs.each do |sym|
precedence_sym = sym if sym.term?
end
rule.precedence_sym = precedence_sym
end
end
def fill_symbols
fill_symbol_number
fill_nterm_type(@types)
fill_printer(@printers)
fill_destructor(@destructors)
fill_error_token(@error_tokens)
sort_by_number!
end
def fill_sym_to_rules
@rules.each do |rule|
key = rule.lhs.number
@sym_to_rules[key] ||= []
@sym_to_rules[key] << rule
end
end
def validate_rule_lhs_is_nterm!
errors = []
rules.each do |rule|
next if rule.lhs.nterm?
errors << "[BUG] LHS of #{rule} (line: #{rule.lineno}) is term. It should be nterm."
end
return if errors.empty?
raise errors.join("\n")
end
end
end
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