| Current File : //opt/alt/ruby27/share/ruby/racc/state.rb |
#
# $Id: 6bd3136439c94cb8d928917f5e0de9c593181527 $
#
# 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/iset'
require 'racc/statetransitiontable'
require 'racc/exception'
require 'forwardable'
module Racc
# A table of LALR states.
class States
include Enumerable
def initialize(grammar, debug_flags = DebugFlags.new)
@grammar = grammar
@symboltable = grammar.symboltable
@d_state = debug_flags.state
@d_la = debug_flags.la
@d_prec = debug_flags.prec
@states = []
@statecache = {}
@actions = ActionTable.new(@grammar, self)
@nfa_computed = false
@dfa_computed = false
end
attr_reader :grammar
attr_reader :actions
def size
@states.size
end
def inspect
'#<state table>'
end
alias to_s inspect
def [](i)
@states[i]
end
def each_state(&block)
@states.each(&block)
end
alias each each_state
def each_index(&block)
@states.each_index(&block)
end
extend Forwardable
def_delegator "@actions", :shift_n
def_delegator "@actions", :reduce_n
def_delegator "@actions", :nt_base
def should_report_srconflict?
srconflict_exist? and
(n_srconflicts() != @grammar.n_expected_srconflicts)
end
def srconflict_exist?
n_srconflicts() != 0
end
def n_srconflicts
@n_srconflicts ||= inject(0) {|sum, st| sum + st.n_srconflicts }
end
def rrconflict_exist?
n_rrconflicts() != 0
end
def n_rrconflicts
@n_rrconflicts ||= inject(0) {|sum, st| sum + st.n_rrconflicts }
end
def state_transition_table
@state_transition_table ||= StateTransitionTable.generate(self.dfa)
end
#
# NFA (Non-deterministic Finite Automaton) Computation
#
public
def nfa
return self if @nfa_computed
compute_nfa
@nfa_computed = true
self
end
private
def compute_nfa
@grammar.init
# add state 0
core_to_state [ @grammar[0].ptrs[0] ]
# generate LALR states
cur = 0
@gotos = []
while cur < @states.size
generate_states @states[cur] # state is added here
cur += 1
end
@actions.init
end
def generate_states(state)
puts "dstate: #{state}" if @d_state
table = {}
state.closure.each do |ptr|
if sym = ptr.dereference
addsym table, sym, ptr.next
end
end
table.each do |sym, core|
puts "dstate: sym=#{sym} ncore=#{core}" if @d_state
dest = core_to_state(core.to_a)
state.goto_table[sym] = dest
id = sym.nonterminal?() ? @gotos.size : nil
g = Goto.new(id, sym, state, dest)
@gotos.push g if sym.nonterminal?
state.gotos[sym] = g
puts "dstate: #{state.ident} --#{sym}--> #{dest.ident}" if @d_state
# check infinite recursion
if state.ident == dest.ident and state.closure.size == 1
raise CompileError,
sprintf("Infinite recursion: state %d, with rule %d",
state.ident, state.ptrs[0].rule.ident)
end
end
end
def addsym(table, sym, ptr)
unless s = table[sym]
table[sym] = s = ISet.new
end
s.add ptr
end
def core_to_state(core)
#
# convert CORE to a State object.
# If matching state does not exist, create it and add to the table.
#
k = fingerprint(core)
unless dest = @statecache[k]
# not registered yet
dest = State.new(@states.size, core)
@states.push dest
@statecache[k] = dest
puts "core_to_state: create state ID #{dest.ident}" if @d_state
else
if @d_state
puts "core_to_state: dest is cached ID #{dest.ident}"
puts "core_to_state: dest core #{dest.core.join(' ')}"
end
end
dest
end
def fingerprint(arr)
arr.map {|i| i.ident }.pack('L*')
end
#
# DFA (Deterministic Finite Automaton) Generation
#
public
def dfa
return self if @dfa_computed
nfa
compute_dfa
@dfa_computed = true
self
end
private
def compute_dfa
la = lookahead()
@states.each do |state|
state.la = la
resolve state
end
set_accept
@states.each do |state|
pack state
end
check_useless
end
def lookahead
#
# lookahead algorithm ver.3 -- from bison 1.26
#
gotos = @gotos
if @d_la
puts "\n--- goto ---"
gotos.each_with_index {|g, i| print i, ' '; p g }
end
### initialize_LA()
### set_goto_map()
la_rules = []
@states.each do |state|
state.check_la la_rules
end
### initialize_F()
f = create_tmap(gotos.size)
reads = []
edge = []
gotos.each do |goto|
goto.to_state.goto_table.each do |t, st|
if t.terminal?
f[goto.ident] |= (1 << t.ident)
elsif t.nullable?
edge.push goto.to_state.gotos[t].ident
end
end
if edge.empty?
reads.push nil
else
reads.push edge
edge = []
end
end
digraph f, reads
if @d_la
puts "\n--- F1 (reads) ---"
print_tab gotos, reads, f
end
### build_relations()
### compute_FOLLOWS
path = nil
edge = []
lookback = Array.new(la_rules.size, nil)
includes = []
gotos.each do |goto|
goto.symbol.heads.each do |ptr|
path = record_path(goto.from_state, ptr.rule)
lastgoto = path.last
st = lastgoto ? lastgoto.to_state : goto.from_state
if st.conflict?
addrel lookback, st.rruleid(ptr.rule), goto
end
path.reverse_each do |g|
break if g.symbol.terminal?
edge.push g.ident
break unless g.symbol.nullable?
end
end
if edge.empty?
includes.push nil
else
includes.push edge
edge = []
end
end
includes = transpose(includes)
digraph f, includes
if @d_la
puts "\n--- F2 (includes) ---"
print_tab gotos, includes, f
end
### compute_lookaheads
la = create_tmap(la_rules.size)
lookback.each_with_index do |arr, i|
if arr
arr.each do |g|
la[i] |= f[g.ident]
end
end
end
if @d_la
puts "\n--- LA (lookback) ---"
print_tab la_rules, lookback, la
end
la
end
def create_tmap(size)
Array.new(size, 0) # use Integer as bitmap
end
def addrel(tbl, i, item)
if a = tbl[i]
a.push item
else
tbl[i] = [item]
end
end
def record_path(begst, rule)
st = begst
path = []
rule.symbols.each do |t|
goto = st.gotos[t]
path.push goto
st = goto.to_state
end
path
end
def transpose(rel)
new = Array.new(rel.size, nil)
rel.each_with_index do |arr, idx|
if arr
arr.each do |i|
addrel new, i, idx
end
end
end
new
end
def digraph(map, relation)
n = relation.size
index = Array.new(n, nil)
vertices = []
@infinity = n + 2
index.each_index do |i|
if not index[i] and relation[i]
traverse i, index, vertices, map, relation
end
end
end
def traverse(i, index, vertices, map, relation)
vertices.push i
index[i] = height = vertices.size
if rp = relation[i]
rp.each do |proci|
unless index[proci]
traverse proci, index, vertices, map, relation
end
if index[i] > index[proci]
# circulative recursion !!!
index[i] = index[proci]
end
map[i] |= map[proci]
end
end
if index[i] == height
while true
proci = vertices.pop
index[proci] = @infinity
break if i == proci
map[proci] |= map[i]
end
end
end
# for debug
def print_atab(idx, tab)
tab.each_with_index do |i,ii|
printf '%-20s', idx[ii].inspect
p i
end
end
def print_tab(idx, rel, tab)
tab.each_with_index do |bin,i|
print i, ' ', idx[i].inspect, ' << '; p rel[i]
print ' '
each_t(@symboltable, bin) {|t| print ' ', t }
puts
end
end
# for debug
def print_tab_i(idx, rel, tab, i)
bin = tab[i]
print i, ' ', idx[i].inspect, ' << '; p rel[i]
print ' '
each_t(@symboltable, bin) {|t| print ' ', t }
end
# for debug
def printb(i)
each_t(@symboltable, i) do |t|
print t, ' '
end
puts
end
def each_t(tbl, set)
0.upto( set.size ) do |i|
(0..7).each do |ii|
if set[idx = i * 8 + ii] == 1
yield tbl[idx]
end
end
end
end
#
# resolve
#
def resolve(state)
if state.conflict?
resolve_rr state, state.ritems
resolve_sr state, state.stokens
else
if state.rrules.empty?
# shift
state.stokens.each do |t|
state.action[t] = @actions.shift(state.goto_table[t])
end
else
# reduce
state.defact = @actions.reduce(state.rrules[0])
end
end
end
def resolve_rr(state, r)
r.each do |item|
item.each_la(@symboltable) do |t|
act = state.action[t]
if act
unless act.kind_of?(Reduce)
raise "racc: fatal: #{act.class} in action table"
end
# Cannot resolve R/R conflict (on t).
# Reduce with upper rule as default.
state.rr_conflict act.rule, item.rule, t
else
# No conflict.
state.action[t] = @actions.reduce(item.rule)
end
end
end
end
def resolve_sr(state, s)
s.each do |stok|
goto = state.goto_table[stok]
act = state.action[stok]
unless act
# no conflict
state.action[stok] = @actions.shift(goto)
else
unless act.kind_of?(Reduce)
puts 'DEBUG -------------------------------'
p stok
p act
state.action.each do |k,v|
print k.inspect, ' ', v.inspect, "\n"
end
raise "racc: fatal: #{act.class} in action table"
end
# conflict on stok
rtok = act.rule.precedence
case do_resolve_sr(stok, rtok)
when :Reduce
# action is already set
when :Shift
# overwrite
act.decref
state.action[stok] = @actions.shift(goto)
when :Error
act.decref
state.action[stok] = @actions.error
when :CantResolve
# shift as default
act.decref
state.action[stok] = @actions.shift(goto)
state.sr_conflict stok, act.rule
end
end
end
end
ASSOC = {
:Left => :Reduce,
:Right => :Shift,
:Nonassoc => :Error
}
def do_resolve_sr(stok, rtok)
puts "resolve_sr: s/r conflict: rtok=#{rtok}, stok=#{stok}" if @d_prec
unless rtok and rtok.precedence
puts "resolve_sr: no prec for #{rtok}(R)" if @d_prec
return :CantResolve
end
rprec = rtok.precedence
unless stok and stok.precedence
puts "resolve_sr: no prec for #{stok}(S)" if @d_prec
return :CantResolve
end
sprec = stok.precedence
ret = if rprec == sprec
ASSOC[rtok.assoc] or
raise "racc: fatal: #{rtok}.assoc is not Left/Right/Nonassoc"
else
(rprec > sprec) ? (:Reduce) : (:Shift)
end
puts "resolve_sr: resolved as #{ret.id2name}" if @d_prec
ret
end
#
# complete
#
def set_accept
anch = @symboltable.anchor
init_state = @states[0].goto_table[@grammar.start]
targ_state = init_state.action[anch].goto_state
acc_state = targ_state.action[anch].goto_state
acc_state.action.clear
acc_state.goto_table.clear
acc_state.defact = @actions.accept
end
def pack(state)
### find most frequently used reduce rule
act = state.action
arr = Array.new(@grammar.size, 0)
act.each do |t, a|
arr[a.ruleid] += 1 if a.kind_of?(Reduce)
end
i = arr.max
s = (i > 0) ? arr.index(i) : nil
### set & delete default action
if s
r = @actions.reduce(s)
if not state.defact or state.defact == r
act.delete_if {|t, a| a == r }
state.defact = r
end
else
state.defact ||= @actions.error
end
end
def check_useless
used = []
@actions.each_reduce do |act|
if not act or act.refn == 0
act.rule.useless = true
else
t = act.rule.target
used[t.ident] = t
end
end
@symboltable.nt_base.upto(@symboltable.nt_max - 1) do |n|
unless used[n]
@symboltable[n].useless = true
end
end
end
end # class StateTable
# A LALR state.
class State
def initialize(ident, core)
@ident = ident
@core = core
@goto_table = {}
@gotos = {}
@stokens = nil
@ritems = nil
@action = {}
@defact = nil
@rrconf = nil
@srconf = nil
@closure = make_closure(@core)
end
attr_reader :ident
alias stateid ident
alias hash ident
attr_reader :core
attr_reader :closure
attr_reader :goto_table
attr_reader :gotos
attr_reader :stokens
attr_reader :ritems
attr_reader :rrules
attr_reader :action
attr_accessor :defact # default action
attr_reader :rrconf
attr_reader :srconf
def inspect
"<state #{@ident}>"
end
alias to_s inspect
def ==(oth)
@ident == oth.ident
end
alias eql? ==
def make_closure(core)
set = ISet.new
core.each do |ptr|
set.add ptr
if t = ptr.dereference and t.nonterminal?
set.update_a t.expand
end
end
set.to_a
end
def check_la(la_rules)
@conflict = false
s = []
r = []
@closure.each do |ptr|
if t = ptr.dereference
if t.terminal?
s[t.ident] = t
if t.ident == 1 # $error
@conflict = true
end
end
else
r.push ptr.rule
end
end
unless r.empty?
if not s.empty? or r.size > 1
@conflict = true
end
end
s.compact!
@stokens = s
@rrules = r
if @conflict
@la_rules_i = la_rules.size
@la_rules = r.map {|i| i.ident }
la_rules.concat r
else
@la_rules_i = @la_rules = nil
end
end
def conflict?
@conflict
end
def rruleid(rule)
if i = @la_rules.index(rule.ident)
@la_rules_i + i
else
puts '/// rruleid'
p self
p rule
p @rrules
p @la_rules_i
raise 'racc: fatal: cannot get reduce rule id'
end
end
def la=(la)
return unless @conflict
i = @la_rules_i
@ritems = r = []
@rrules.each do |rule|
r.push Item.new(rule, la[i])
i += 1
end
end
def rr_conflict(high, low, ctok)
c = RRconflict.new(@ident, high, low, ctok)
@rrconf ||= {}
if a = @rrconf[ctok]
a.push c
else
@rrconf[ctok] = [c]
end
end
def sr_conflict(shift, reduce)
c = SRconflict.new(@ident, shift, reduce)
@srconf ||= {}
if a = @srconf[shift]
a.push c
else
@srconf[shift] = [c]
end
end
def n_srconflicts
@srconf ? @srconf.size : 0
end
def n_rrconflicts
@rrconf ? @rrconf.size : 0
end
end # class State
#
# Represents a transition on the grammar.
# "Real goto" means a transition by nonterminal,
# but this class treats also terminal's.
# If one is a terminal transition, .ident returns nil.
#
class Goto
def initialize(ident, sym, from, to)
@ident = ident
@symbol = sym
@from_state = from
@to_state = to
end
attr_reader :ident
attr_reader :symbol
attr_reader :from_state
attr_reader :to_state
def inspect
"(#{@from_state.ident}-#{@symbol}->#{@to_state.ident})"
end
end
# LALR item. A set of rule and its lookahead tokens.
class Item
def initialize(rule, la)
@rule = rule
@la = la
end
attr_reader :rule
attr_reader :la
def each_la(tbl)
la = @la
0.upto(la.size - 1) do |i|
(0..7).each do |ii|
if la[idx = i * 8 + ii] == 1
yield tbl[idx]
end
end
end
end
end
# The table of LALR actions. Actions are either of
# Shift, Reduce, Accept and Error.
class ActionTable
def initialize(rt, st)
@grammar = rt
@statetable = st
@reduce = []
@shift = []
@accept = nil
@error = nil
end
def init
@grammar.each do |rule|
@reduce.push Reduce.new(rule)
end
@statetable.each do |state|
@shift.push Shift.new(state)
end
@accept = Accept.new
@error = Error.new
end
def reduce_n
@reduce.size
end
def reduce(i)
case i
when Rule then i = i.ident
when Integer then ;
else
raise "racc: fatal: wrong class #{i.class} for reduce"
end
r = @reduce[i] or raise "racc: fatal: reduce action #{i.inspect} not exist"
r.incref
r
end
def each_reduce(&block)
@reduce.each(&block)
end
def shift_n
@shift.size
end
def shift(i)
case i
when State then i = i.ident
when Integer then ;
else
raise "racc: fatal: wrong class #{i.class} for shift"
end
@shift[i] or raise "racc: fatal: shift action #{i} does not exist"
end
def each_shift(&block)
@shift.each(&block)
end
attr_reader :accept
attr_reader :error
end
class Shift
def initialize(goto)
@goto_state = goto
end
attr_reader :goto_state
def goto_id
@goto_state.ident
end
def inspect
"<shift #{@goto_state.ident}>"
end
end
class Reduce
def initialize(rule)
@rule = rule
@refn = 0
end
attr_reader :rule
attr_reader :refn
def ruleid
@rule.ident
end
def inspect
"<reduce #{@rule.ident}>"
end
def incref
@refn += 1
end
def decref
@refn -= 1
raise 'racc: fatal: act.refn < 0' if @refn < 0
end
end
class Accept
def inspect
"<accept>"
end
end
class Error
def inspect
"<error>"
end
end
class SRconflict
def initialize(sid, shift, reduce)
@stateid = sid
@shift = shift
@reduce = reduce
end
attr_reader :stateid
attr_reader :shift
attr_reader :reduce
def to_s
sprintf('state %d: S/R conflict rule %d reduce and shift %s',
@stateid, @reduce.ruleid, @shift.to_s)
end
end
class RRconflict
def initialize(sid, high, low, tok)
@stateid = sid
@high_prec = high
@low_prec = low
@token = tok
end
attr_reader :stateid
attr_reader :high_prec
attr_reader :low_prec
attr_reader :token
def to_s
sprintf('state %d: R/R conflict with rule %d and %d on %s',
@stateid, @high_prec.ident, @low_prec.ident, @token.to_s)
end
end
end