Add an optimized version of `str(…) | str(…) | …`

1 files changed, 37 insertions, 1 deletions

diff --git a/app/lib/search_query_parser.rb b/app/lib/search_query_parser.rb
index fd8e2202fb1..e32e299b4da 100644
--- a/app/lib/search_query_parser.rb
+++ b/app/lib/search_query_parser.rb
@@ -1,11 +1,47 @@
 # frozen_string_literal: true
 
 class SearchQueryParser < Parslet::Parser
+  # Efficiently matches disjoint strings
+  class StrList < Parslet::Atoms::Base
+    attr_reader :strings
+
+    def initialize(strings)
+      super()
+
+      @strings = strings
+      @pattern = Regexp.union(strings)
+      @min_length = strings.map(&:length).min
+    end
+
+    def error_msgs
+      @error_msgs ||= {
+        premature: 'Premature end of input',
+        failed: "Expected any of #{strings.inspect}, but got ",
+      }
+    end
+
+    def try(source, context, _consume_all)
+      match = source.match(@pattern)
+      return succ(source.consume(match)) unless match.nil?
+
+      # Input ending early:
+      return context.err(self, source, error_msgs[:premature]) if source.chars_left < @min_length
+
+      # Expected something, but got something else instead:
+      error_pos = source.pos
+      context.err_at(self, source, [error_msgs[:failed], source.consume(@len)], error_pos)
+    end
+
+    def to_s_inner(_prec)
+      "[#{strings.map { |str| "'#{str}'" }.join(',')}]"
+    end
+  end
+
   rule(:term)      { match('[^\s]').repeat(1).as(:term) }
   rule(:colon)     { str(':') }
   rule(:space)     { match('\s').repeat(1) }
   rule(:operator)  { (str('+') | str('-')).as(:operator) }
-  rule(:prefix_operator) { str('has') | str('is') | str('language') | str('from') | str('before') | str('after') | str('during') | str('in') }
+  rule(:prefix_operator) { StrList.new(%w(has is language from before after during in)) }
   rule(:prefix)    { prefix_operator.as(:prefix_operator) >> colon }
   rule(:phrase)    do
     (str('"') >> match('[^"]').repeat.as(:phrase) >> str('"')) |