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Do not build ItemSet follow sets - #28

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This commit is contained in:
Josh Holtrop 2024-07-25 20:02:00 -04:00
parent 588c5e21c7
commit 74d94fef72
2 changed files with 0 additions and 50 deletions
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46
lib/propane/parser.rb
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@ -39,7 +39,6 @@ class Propane
end
build_reduce_actions!
build_follow_sets!
build_tables!
write_log!
if @warnings.size > 0 && @options[:warnings_as_errors]
@ -233,51 +232,6 @@ class Propane
lookahead_tokens
end
# Build the follow sets for each ItemSet.
#
# @return [void]
def build_follow_sets!
@item_sets.each do |item_set|
item_set.follow_set = build_follow_set_for_item_set(item_set)
end
end
# Build the follow set for the given ItemSet.
#
# @param item_set [ItemSet]
# The ItemSet to build the follow set for.
#
# @return [Set]
# Follow set for the given ItemSet.
def build_follow_set_for_item_set(item_set)
follow_set = Set.new
rule_sets_to_check_after = Set.new
item_set.items.each do |item|
(1..).each do |offset|
case symbol = item.next_symbol(offset)
when nil
rule_sets_to_check_after << item.rule.rule_set
break
when Token
follow_set << symbol
break
when RuleSet
follow_set += symbol.start_token_set
unless symbol.could_be_empty?
break
end
end
end
end
reduce_lookaheads = build_lookahead_reduce_actions_for_item_set(item_set)
reduce_lookaheads.each do |token, rule_set|
if rule_sets_to_check_after.include?(rule_set)
follow_set << token
end
end
follow_set
end
def write_log!
@log.puts Util.banner("Parser Rules")
@grammar.rules.each do |rule|

4
lib/propane/parser/item_set.rb
View File

@ -30,10 +30,6 @@ class Propane
# more than one rule that could be reduced.
attr_accessor :reduce_actions
# @return [Set<Token>]
# Follow set for the ItemSet.
attr_accessor :follow_set
# Build an ItemSet.
#
# @param items [Array<Item>]