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Sentence.expand_syntax refined.

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git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@13114 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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akr 2007-08-19 15:43:04 +00:00
parent 1d23c250f0
commit cf82149d21
1 changed files with 61 additions and 42 deletions
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103
test/ruby/sentence.rb
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@ -33,7 +33,7 @@
# The third argument, 2, limits derivation to restrict results finitely.
#
# Some arithmetic expressions including parenthesis can be generated as follows.
#
#
# syntax = {
# :factor => [["n"],
# ["(", :exp, ")"]],
@ -160,10 +160,10 @@ class Sentence
# returns the number of top level elements.
#
# Sentence.new(%w[foo bar]).length
# Sentence.new(%w[foo bar]).length
# #=> 2
#
# Sentence(%w[2 * 7], "+", %w[3 * 5]).length
# Sentence(%w[2 * 7], "+", %w[3 * 5]).length
# #=> 3
#
def length
@ -310,7 +310,7 @@ class Sentence
# #<Sentence: "n">
# #<Sentence: ("n") "+" ("n")>
# #<Sentence: ("n") "*" ("n")>
#
#
# Sentence.each({
# :exp => [["n"],
# [:exp, "+", :exp],
@ -336,33 +336,47 @@ class Sentence
end
# Sentence.expand_syntax returns an expanded syntax:
# * no underivable rule
# * no rule which derives only to empty sequence indirectly
# * no rule which is derivable to empty and non-empty
# * no channel rule
# * No rule derives to empty sequence
# * Underivable rule simplified
# * No channel rule
# * Symbols which has zero or one choices are not appered in rhs.
#
# Note that the rules which can derive empty and non-empty
# sequences are modified to derive only non-empty sequences.
#
# Sentence.expand_syntax({
# :underivable => [[:underivable]],
# :just_empty1 => [[]],
# :just_empty2 => [[:just_empty1, :just_empty1]],
# :underivable1 => [],
# :underivable2 => [[:underivable1]],
# :underivable3 => [[:underivable3]],
# :empty_only1 => [[]],
# :empty_only2 => [[:just_empty1, :just_empty1]],
# :empty_or_not => [[], ["foo"]],
# :empty_or_not_2 => [[:empty_or_not, :empty_or_not]],
# :data => [["a", "b"], ["c", "d"]],
# :channel => [[:data]],
# })
# :empty_or_not_3 => [[:empty_or_not, :empty_or_not, :empty_or_not]],
# :empty_or_not_4 => [[:empty_or_not_2, :empty_or_not_2]],
# :channel1 => [[:channeled_data]],
# :channeled_data => [["a", "b"], ["c", "d"]],
# :single_choice => [["single", "choice"]],
# :single_choice_2 => [[:single_choice, :single_choice]],
# })
# #=>
# {:channel=>[["a", "b"], ["c", "d"]],
# :data=>[["a", "b"], ["c", "d"]],
# :empty_or_not=>[["foo"]],
# :empty_or_not_2=>[[], ["foo"], ["foo", "foo"]],
# :just_empty1=>[],
# :just_empty2=>[]}
# {
# :underivable1=>[], # underivable rules are simplified to [].
# :underivable2=>[],
# :underivable3=>[],
# :empty_only1=>[], # derivation to empty sequence are removed.
# :empty_only2=>[],
# :empty_or_not=>[["foo"]], # empty sequences are removed too.
# :empty_or_not_2=>[["foo"], ["foo", "foo"]],
# :empty_or_not_3=>[["foo"], ["foo", "foo"], ["foo", "foo", "foo"]],
# :empty_or_not_4=> [["foo"], ["foo", "foo"], [:empty_or_not_2, :empty_or_not_2]],
# :channel1=>[["a", "b"], ["c", "d"]], # channel rules are removed.
# :channeled_data=>[["a", "b"], ["c", "d"]],
# :single_choice=>[["single", "choice"]], # single choice rules are expanded.
# :single_choice_2=>[["single", "choice", "single", "choice"]],
# }
#
#
# Sentence.expand_syntax({
# Sentence.expand_syntax({
# :factor => [["n"],
# ["(", :exp, ")"]],
# :term => [[:factor],
@ -406,16 +420,16 @@ class Sentence
end
def self.expand_syntax(syntax)
syntax = remove_underivable_rules(syntax)
syntax = expand_justempty_rules(syntax)
syntax = remove_emptyable_rules(syntax)
syntax = simplify_underivable_rules(syntax)
syntax = simplify_emptyonly_rules(syntax)
syntax = make_rules_no_empseq(syntax)
syntax = expand_channel_rules(syntax)
syntax = expand_noalt_rules(syntax)
syntax = reorder_rules(syntax)
end
def self.remove_underivable_rules(syntax)
def self.simplify_underivable_rules(syntax)
deribable_syms = {}
changed = true
while changed
@ -433,24 +447,27 @@ class Sentence
end
result = {}
syntax.each {|sym, rules|
next if !deribable_syms[sym]
rules2 = []
rules.each {|rhs|
rules2 << rhs if rhs.all? {|e| String === e || deribable_syms[e] }
}
result[sym] = rules2.uniq
if deribable_syms[sym]
rules2 = []
rules.each {|rhs|
rules2 << rhs if rhs.all? {|e| String === e || deribable_syms[e] }
}
result[sym] = rules2.uniq
else
result[sym] = []
end
}
result
end
def self.expand_justempty_rules(syntax)
def self.simplify_emptyonly_rules(syntax)
justempty_syms = {}
changed = true
while changed
changed = false
syntax.each {|sym, rules|
next if justempty_syms[sym]
if rules.all? {|rhs| rhs.all? {|e| justempty_syms[e] } }
if !rules.empty? && rules.all? {|rhs| rhs.all? {|e| justempty_syms[e] } }
justempty_syms[sym] = true
changed = true
end
@ -473,21 +490,22 @@ class Sentence
yield rhs
end
else
butfirst = rhs[1..-1]
if emptyable_syms[rhs[0]]
expand_emptyable_syms(butfirst, emptyable_syms) {|rhs2|
yield [rhs[0]] + rhs2
rest = rhs.dup
first = rest.shift
if emptyable_syms[first]
expand_emptyable_syms(rest, emptyable_syms) {|rhs2|
yield [first] + rhs2
yield rhs2
}
else
expand_emptyable_syms(butfirst, emptyable_syms) {|rhs2|
yield [rhs[0]] + rhs2
expand_emptyable_syms(rest, emptyable_syms) {|rhs2|
yield [first] + rhs2
}
end
end
end
def self.remove_emptyable_rules(syntax)
def self.make_rules_no_empseq(syntax)
emptyable_syms = {}
changed = true
while changed
@ -508,6 +526,7 @@ class Sentence
rules2 = []
rules.each {|rhs|
expand_emptyable_syms(rhs, emptyable_syms) {|rhs2|
next if rhs2.empty?
rules2 << rhs2
}
}
@ -528,7 +547,7 @@ class Sentence
}
changed = true
while changed
changed = false
changed = false
channel_rules.each {|sym, set|
n1 = set.size
set.keys.each {|s|