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#
# $Id: 3fcabd58bef02540bf78e8142469681cb9f975c2 $
#
# Copyright (c) 1999-2006 Minero Aoki
#
# This program is free software.
# You can distribute/modify this program under the same terms of ruby.
# see the file "COPYING".
require 'racc/compat'
require 'racc/iset'
require 'racc/sourcetext'
require 'racc/logfilegenerator'
require 'racc/exception'
require 'forwardable'
module Racc
class Grammar
def initialize(debug_flags = DebugFlags.new)
@symboltable = SymbolTable.new
@debug_symbol = debug_flags.token
@rules = [] # :: [Rule]
@start = nil
@n_expected_srconflicts = nil
@prec_table = []
@prec_table_closed = false
@closed = false
@states = nil
end
attr_reader :start
attr_reader :symboltable
attr_accessor :n_expected_srconflicts
def [](x)
@rules[x]
end
def each_rule(&block)
@rules.each(&block)
end
alias each each_rule
def each_index(&block)
@rules.each_index(&block)
end
def each_with_index(&block)
@rules.each_with_index(&block)
end
def size
@rules.size
end
def to_s
"<Racc::Grammar>"
end
extend Forwardable
def_delegator "@symboltable", :each, :each_symbol
def_delegator "@symboltable", :each_terminal
def_delegator "@symboltable", :each_nonterminal
def intern(value, dummy = false)
@symboltable.intern(value, dummy)
end
def symbols
@symboltable.symbols
end
def nonterminal_base
@symboltable.nt_base
end
def useless_nonterminal_exist?
n_useless_nonterminals() != 0
end
def n_useless_nonterminals
@n_useless_nonterminals ||=
begin
n = 0
@symboltable.each_nonterminal do |sym|
n += 1 if sym.useless?
end
n
end
end
def useless_rule_exist?
n_useless_rules() != 0
end
def n_useless_rules
@n_useless_rules ||=
begin
n = 0
each do |r|
n += 1 if r.useless?
end
n
end
end
def nfa
(@states ||= States.new(self)).nfa
end
def dfa
(@states ||= States.new(self)).dfa
end
alias states dfa
def state_transition_table
states().state_transition_table
end
def parser_class
states = states() # cache
if $DEBUG
srcfilename = caller(1).first.slice(/\A(.*?):/, 1)
begin
write_log srcfilename + ".output"
rescue SystemCallError
end
report = lambda {|s| $stderr.puts "racc: #{srcfilename}: #{s}" }
if states.should_report_srconflict?
report["#{states.n_srconflicts} shift/reduce conflicts"]
end
if states.rrconflict_exist?
report["#{states.n_rrconflicts} reduce/reduce conflicts"]
end
g = states.grammar
if g.useless_nonterminal_exist?
report["#{g.n_useless_nonterminals} useless nonterminals"]
end
if g.useless_rule_exist?
report["#{g.n_useless_rules} useless rules"]
end
end
states.state_transition_table.parser_class
end
def write_log(path)
File.open(path, 'w') {|f|
LogFileGenerator.new(states()).output f
}
end
#
# Grammar Definition Interface
#
def add(rule)
raise ArgumentError, "rule added after the Grammar closed" if @closed
@rules.push rule
end
def added?(sym)
@rules.detect {|r| r.target == sym }
end
def start_symbol=(s)
raise CompileError, "start symbol set twice'" if @start
@start = s
end
def declare_precedence(assoc, syms)
raise CompileError, "precedence table defined twice" if @prec_table_closed
@prec_table.push [assoc, syms]
end
def end_precedence_declaration(reverse)
@prec_table_closed = true
return if @prec_table.empty?
table = reverse ? @prec_table.reverse : @prec_table
table.each_with_index do |(assoc, syms), idx|
syms.each do |sym|
sym.assoc = assoc
sym.precedence = idx
end
end
end
#
# Dynamic Generation Interface
#
def Grammar.define(&block)
env = DefinitionEnv.new
env.instance_eval(&block)
env.grammar
end
class DefinitionEnv
def initialize
@grammar = Grammar.new
@seqs = Hash.new(0)
@delayed = []
end
def grammar
flush_delayed
@grammar.each do |rule|
if rule.specified_prec
rule.specified_prec = @grammar.intern(rule.specified_prec)
end
end
@grammar.init
@grammar
end
def precedence_table(&block)
env = PrecedenceDefinitionEnv.new(@grammar)
env.instance_eval(&block)
@grammar.end_precedence_declaration env.reverse
end
def method_missing(mid, *args, &block)
unless mid.to_s[-1,1] == '='
super # raises NoMethodError
end
target = @grammar.intern(mid.to_s.chop.intern)
unless args.size == 1
raise ArgumentError, "too many arguments for #{mid} (#{args.size} for 1)"
end
_add target, args.first
end
def _add(target, x)
case x
when Sym
@delayed.each do |rule|
rule.replace x, target if rule.target == x
end
@grammar.symboltable.delete x
else
x.each_rule do |r|
r.target = target
@grammar.add r
end
end
flush_delayed
end
def _delayed_add(rule)
@delayed.push rule
end
def _added?(sym)
@grammar.added?(sym) or @delayed.detect {|r| r.target == sym }
end
def flush_delayed
return if @delayed.empty?
@delayed.each do |rule|
@grammar.add rule
end
@delayed.clear
end
def seq(*list, &block)
Rule.new(nil, list.map {|x| _intern(x) }, UserAction.proc(block))
end
def null(&block)
seq(&block)
end
def action(&block)
id = "@#{@seqs["action"] += 1}".intern
_delayed_add Rule.new(@grammar.intern(id), [], UserAction.proc(block))
id
end
alias _ action
def option(sym, default = nil, &block)
_defmetasyntax("option", _intern(sym), block) {|target|
seq() { default } | seq(sym)
}
end
def many(sym, &block)
_defmetasyntax("many", _intern(sym), block) {|target|
seq() { [] }\
| seq(target, sym) {|list, x| list.push x; list }
}
end
def many1(sym, &block)
_defmetasyntax("many1", _intern(sym), block) {|target|
seq(sym) {|x| [x] }\
| seq(target, sym) {|list, x| list.push x; list }
}
end
def separated_by(sep, sym, &block)
option(separated_by1(sep, sym), [], &block)
end
def separated_by1(sep, sym, &block)
_defmetasyntax("separated_by1", _intern(sym), block) {|target|
seq(sym) {|x| [x] }\
| seq(target, sep, sym) {|list, _, x| list.push x; list }
}
end
def _intern(x)
case x
when Symbol, String
@grammar.intern(x)
when Racc::Sym
x
else
raise TypeError, "wrong type #{x.class} (expected Symbol/String/Racc::Sym)"
end
end
private
def _defmetasyntax(type, id, action, &block)
if action
idbase = "#{type}@#{id}-#{@seqs[type] += 1}"
target = _wrap(idbase, "#{idbase}-core", action)
_regist("#{idbase}-core", &block)
else
target = _regist("#{type}@#{id}", &block)
end
@grammar.intern(target)
end
def _regist(target_name)
target = target_name.intern
unless _added?(@grammar.intern(target))
yield(target).each_rule do |rule|
rule.target = @grammar.intern(target)
_delayed_add rule
end
end
target
end
def _wrap(target_name, sym, block)
target = target_name.intern
_delayed_add Rule.new(@grammar.intern(target),
[@grammar.intern(sym.intern)],
UserAction.proc(block))
target
end
end
class PrecedenceDefinitionEnv
def initialize(g)
@grammar = g
@prechigh_seen = false
@preclow_seen = false
@reverse = false
end
attr_reader :reverse
def higher
if @prechigh_seen
raise CompileError, "prechigh used twice"
end
@prechigh_seen = true
end
def lower
if @preclow_seen
raise CompileError, "preclow used twice"
end
if @prechigh_seen
@reverse = true
end
@preclow_seen = true
end
def left(*syms)
@grammar.declare_precedence :Left, syms.map {|s| @grammar.intern(s) }
end
def right(*syms)
@grammar.declare_precedence :Right, syms.map {|s| @grammar.intern(s) }
end
def nonassoc(*syms)
@grammar.declare_precedence :Nonassoc, syms.map {|s| @grammar.intern(s)}
end
end
#
# Computation
#
def init
return if @closed
@closed = true
@start ||= @rules.map {|r| r.target }.detect {|sym| not sym.dummy? }
raise CompileError, 'no rule in input' if @rules.empty?
add_start_rule
@rules.freeze
fix_ident
compute_hash
compute_heads
determine_terminals
compute_nullable_0
@symboltable.fix
compute_locate
@symboltable.each_nonterminal {|t| compute_expand t }
compute_nullable
compute_useless
end
private
def add_start_rule
r = Rule.new(@symboltable.dummy,
[@start, @symboltable.anchor, @symboltable.anchor],
UserAction.empty)
r.ident = 0
r.hash = 0
r.precedence = nil
@rules.unshift r
end
# Rule#ident
# LocationPointer#ident
def fix_ident
@rules.each_with_index do |rule, idx|
rule.ident = idx
end
end
# Rule#hash
def compute_hash
hash = 4 # size of dummy rule
@rules.each do |rule|
rule.hash = hash
hash += (rule.size + 1)
end
end
# Sym#heads
def compute_heads
@rules.each do |rule|
rule.target.heads.push rule.ptrs[0]
end
end
# Sym#terminal?
def determine_terminals
@symboltable.each do |s|
s.term = s.heads.empty?
end
end
# Sym#self_null?
def compute_nullable_0
@symboltable.each do |s|
if s.terminal?
s.snull = false
else
s.snull = s.heads.any? {|loc| loc.reduce? }
end
end
end
# Sym#locate
def compute_locate
@rules.each do |rule|
t = nil
rule.ptrs.each do |ptr|
unless ptr.reduce?
tok = ptr.dereference
tok.locate.push ptr
t = tok if tok.terminal?
end
end
rule.precedence = t
end
end
# Sym#expand
def compute_expand(t)
puts "expand> #{t.to_s}" if @debug_symbol
t.expand = _compute_expand(t, ISet.new, [])
puts "expand< #{t.to_s}: #{t.expand.to_s}" if @debug_symbol
end
def _compute_expand(t, set, lock)
if tmp = t.expand
set.update tmp
return set
end
tok = nil
set.update_a t.heads
t.heads.each do |ptr|
tok = ptr.dereference
if tok and tok.nonterminal?
unless lock[tok.ident]
lock[tok.ident] = true
_compute_expand tok, set, lock
end
end
end
set
end
# Sym#nullable?, Rule#nullable?
def compute_nullable
@rules.each {|r| r.null = false }
@symboltable.each {|t| t.null = false }
r = @rules.dup
s = @symboltable.nonterminals
begin
rs = r.size
ss = s.size
check_rules_nullable r
check_symbols_nullable s
end until rs == r.size and ss == s.size
end
def check_rules_nullable(rules)
rules.delete_if do |rule|
rule.null = true
rule.symbols.each do |t|
unless t.nullable?
rule.null = false
break
end
end
rule.nullable?
end
end
def check_symbols_nullable(symbols)
symbols.delete_if do |sym|
sym.heads.each do |ptr|
if ptr.rule.nullable?
sym.null = true
break
end
end
sym.nullable?
end
end
# Sym#useless?, Rule#useless?
# FIXME: what means "useless"?
def compute_useless
@symboltable.each_terminal {|sym| sym.useless = false }
@symboltable.each_nonterminal {|sym| sym.useless = true }
@rules.each {|rule| rule.useless = true }
r = @rules.dup
s = @symboltable.nonterminals
begin
rs = r.size
ss = s.size
check_rules_useless r
check_symbols_useless s
end until r.size == rs and s.size == ss
end
def check_rules_useless(rules)
rules.delete_if do |rule|
rule.useless = false
rule.symbols.each do |sym|
if sym.useless?
rule.useless = true
break
end
end
not rule.useless?
end
end
def check_symbols_useless(s)
s.delete_if do |t|
t.heads.each do |ptr|
unless ptr.rule.useless?
t.useless = false
break
end
end
not t.useless?
end
end
end # class Grammar
class Rule
def initialize(target, syms, act)
@target = target
@symbols = syms
@action = act
@alternatives = []
@ident = nil
@hash = nil
@ptrs = nil
@precedence = nil
@specified_prec = nil
@null = nil
@useless = nil
end
attr_accessor :target
attr_reader :symbols
attr_reader :action
def |(x)
@alternatives.push x.rule
self
end
def rule
self
end
def each_rule(&block)
yield self
@alternatives.each(&block)
end
attr_accessor :ident
attr_reader :hash
attr_reader :ptrs
def hash=(n)
@hash = n
ptrs = []
@symbols.each_with_index do |sym, idx|
ptrs.push LocationPointer.new(self, idx, sym)
end
ptrs.push LocationPointer.new(self, @symbols.size, nil)
@ptrs = ptrs
end
def precedence
@specified_prec || @precedence
end
def precedence=(sym)
@precedence ||= sym
end
def prec(sym, &block)
@specified_prec = sym
if block
unless @action.empty?
raise CompileError, 'both of rule action block and prec block given'
end
@action = UserAction.proc(block)
end
self
end
attr_accessor :specified_prec
def nullable?() @null end
def null=(n) @null = n end
def useless?() @useless end
def useless=(u) @useless = u end
def inspect
"#<Racc::Rule id=#{@ident} (#{@target})>"
end
def ==(other)
other.kind_of?(Rule) and @ident == other.ident
end
def [](idx)
@symbols[idx]
end
def size
@symbols.size
end
def empty?
@symbols.empty?
end
def to_s
"#<rule#{@ident}>"
end
def accept?
if tok = @symbols[-1]
tok.anchor?
else
false
end
end
def each(&block)
@symbols.each(&block)
end
def replace(src, dest)
@target = dest
@symbols = @symbols.map {|s| s == src ? dest : s }
end
end # class Rule
class UserAction
def UserAction.source_text(src)
new(src, nil)
end
def UserAction.proc(pr = nil, &block)
if pr and block
raise ArgumentError, "both of argument and block given"
end
new(nil, pr || block)
end
def UserAction.empty
new(nil, nil)
end
private_class_method :new
def initialize(src, proc)
@source = src
@proc = proc
end
attr_reader :source
attr_reader :proc
def source?
not @proc
end
def proc?
not @source
end
def empty?
not @proc and not @source
end
def name
"{action type=#{@source || @proc || 'nil'}}"
end
alias inspect name
end
class OrMark
def initialize(lineno)
@lineno = lineno
end
def name
'|'
end
alias inspect name
attr_reader :lineno
end
class Prec
def initialize(symbol, lineno)
@symbol = symbol
@lineno = lineno
end
def name
"=#{@symbol}"
end
alias inspect name
attr_reader :symbol
attr_reader :lineno
end
#
# A set of rule and position in it's RHS.
# Note that the number of pointers is more than rule's RHS array,
# because pointer points right edge of the final symbol when reducing.
#
class LocationPointer
def initialize(rule, i, sym)
@rule = rule
@index = i
@symbol = sym
@ident = @rule.hash + i
@reduce = sym.nil?
end
attr_reader :rule
attr_reader :index
attr_reader :symbol
alias dereference symbol
attr_reader :ident
alias hash ident
attr_reader :reduce
alias reduce? reduce
def to_s
sprintf('(%d,%d %s)',
@rule.ident, @index, (reduce?() ? '#' : @symbol.to_s))
end
alias inspect to_s
def eql?(ot)
@hash == ot.hash
end
alias == eql?
def head?
@index == 0
end
def next
@rule.ptrs[@index + 1] or ptr_bug!
end
alias increment next
def before(len)
@rule.ptrs[@index - len] or ptr_bug!
end
private
def ptr_bug!
raise "racc: fatal: pointer not exist: self: #{to_s}"
end
end # class LocationPointer
class SymbolTable
include Enumerable
def initialize
@symbols = [] # :: [Racc::Sym]
@cache = {} # :: {(String|Symbol) => Racc::Sym}
@dummy = intern(:$start, true)
@anchor = intern(false, true) # Symbol ID = 0
@error = intern(:error, false) # Symbol ID = 1
end
attr_reader :dummy
attr_reader :anchor
attr_reader :error
def [](id)
@symbols[id]
end
def intern(val, dummy = false)
@cache[val] ||=
begin
sym = Sym.new(val, dummy)
@symbols.push sym
sym
end
end
attr_reader :symbols
alias to_a symbols
def delete(sym)
@symbols.delete sym
@cache.delete sym.value
end
attr_reader :nt_base
def nt_max
@symbols.size
end
def each(&block)
@symbols.each(&block)
end
def terminals(&block)
@symbols[0, @nt_base]
end
def each_terminal(&block)
@terms.each(&block)
end
def nonterminals
@symbols[@nt_base, @symbols.size - @nt_base]
end
def each_nonterminal(&block)
@nterms.each(&block)
end
def fix
terms, nterms = @symbols.partition {|s| s.terminal? }
@symbols = terms + nterms
@terms = terms
@nterms = nterms
@nt_base = terms.size
fix_ident
check_terminals
end
private
def fix_ident
@symbols.each_with_index do |t, i|
t.ident = i
end
end
def check_terminals
return unless @symbols.any? {|s| s.should_terminal? }
@anchor.should_terminal
@error.should_terminal
each_terminal do |t|
t.should_terminal if t.string_symbol?
end
each do |s|
s.should_terminal if s.assoc
end
terminals().reject {|t| t.should_terminal? }.each do |t|
raise CompileError, "terminal #{t} not declared as terminal"
end
nonterminals().select {|n| n.should_terminal? }.each do |n|
raise CompileError, "symbol #{n} declared as terminal but is not terminal"
end
end
end # class SymbolTable
# Stands terminal and nonterminal symbols.
class Sym
def initialize(value, dummyp)
@ident = nil
@value = value
@dummyp = dummyp
@term = nil
@nterm = nil
@should_terminal = false
@precedence = nil
case value
when Symbol
@to_s = value.to_s
@serialized = value.inspect
@string = false
when String
@to_s = value.inspect
@serialized = value.dump
@string = true
when false
@to_s = '$end'
@serialized = 'false'
@string = false
when ErrorSymbolValue
@to_s = 'error'
@serialized = 'Object.new'
@string = false
else
raise ArgumentError, "unknown symbol value: #{value.class}"
end
@heads = []
@locate = []
@snull = nil
@null = nil
@expand = nil
@useless = nil
end
class << self
def once_writer(nm)
nm = nm.id2name
module_eval(<<-EOS)
def #{nm}=(v)
raise 'racc: fatal: @#{nm} != nil' unless @#{nm}.nil?
@#{nm} = v
end
EOS
end
end
once_writer :ident
attr_reader :ident
alias hash ident
attr_reader :value
def dummy?
@dummyp
end
def terminal?
@term
end
def nonterminal?
@nterm
end
def term=(t)
raise 'racc: fatal: term= called twice' unless @term.nil?
@term = t
@nterm = !t
end
def should_terminal
@should_terminal = true
end
def should_terminal?
@should_terminal
end
def string_symbol?
@string
end
def serialize
@serialized
end
attr_writer :serialized
attr_accessor :precedence
attr_accessor :assoc
def to_s
@to_s.dup
end
alias inspect to_s
def |(x)
rule() | x.rule
end
def rule
Rule.new(nil, [self], UserAction.empty)
end
#
# cache
#
attr_reader :heads
attr_reader :locate
def self_null?
@snull
end
once_writer :snull
def nullable?
@null
end
def null=(n)
@null = n
end
attr_reader :expand
once_writer :expand
def useless?
@useless
end
def useless=(f)
@useless = f
end
end # class Sym
end # module Racc
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