search: various improvement

* Move listing all formula names in the top to speed up shell script.
* Simplify logic.
* Only search PR and check bad regex for tty?, which will benefit to
  shell script.

Closes Homebrew/homebrew#44985.

Signed-off-by: Xu Cheng <xucheng@me.com>

Library/Homebrew/cmd/search.rb

@@ -9,7 +9,9 @@ module Homebrew
   SEARCH_ERROR_QUEUE = Queue.new
 
   def search
-    if ARGV.include? "--macports"
+    if ARGV.empty?
+      puts_columns Formula.full_names
+    elsif ARGV.include? "--macports"
       exec_browser "https://www.macports.org/ports.php?by=name&substr=#{ARGV.next}"
     elsif ARGV.include? "--fink"
       exec_browser "http://pdb.finkproject.org/pdb/browse.php?summary=#{ARGV.next}"
@@ -25,8 +27,6 @@ module Homebrew
       query = ARGV.next
       rx = query_regexp(query)
       Descriptions.search(rx, :desc).print
-    elsif ARGV.empty?
-      puts_columns Formula.full_names
     elsif ARGV.first =~ HOMEBREW_TAP_FORMULA_REGEX
       query = ARGV.first
       user, repo, name = query.split("/", 3)
@@ -44,39 +44,43 @@ module Homebrew
       local_results = search_formulae(rx)
       local_results_installed = local_results.select { |f| f.end_with? "(installed)" }
       puts_columns(local_results, local_results_installed)
+      tap_results = search_taps(rx)
+      puts_columns(tap_results)
 
-      if !query.empty? && $stdout.tty? && msg = blacklisted?(query)
-        unless local_results.empty?
-          puts
-          puts "If you meant #{query.inspect} precisely:"
-          puts
+      if $stdout.tty?
+        count = local_results.length + tap_results.length
+
+        if msg = blacklisted?(query)
+          if count > 0
+            puts
+            puts "If you meant #{query.inspect} precisely:"
+            puts
+          end
+          puts msg
+        elsif count == 0
+          puts "No formula found for #{query.inspect}."
+          begin
+            GitHub.print_pull_requests_matching(query)
+          rescue GitHub::Error => e
+            SEARCH_ERROR_QUEUE << e
+          end
         end
-        puts msg
       end
+    end
 
-      tap_results = search_taps(rx)
-      puts_columns(tap_results)
-      count = local_results.length + tap_results.length
-
-      if count == 0 && !blacklisted?(query)
-        puts "No formula found for #{query.inspect}."
-        begin
-          GitHub.print_pull_requests_matching(query)
-        rescue GitHub::Error => e
-          SEARCH_ERROR_QUEUE << e
+    if $stdout.tty?
+      metacharacters = %w[\\ | ( ) [ ] { } ^ $ * + ? .]
+      bad_regex = metacharacters.any? do |char|
+        ARGV.any? do |arg|
+          arg.include?(char) && !arg.start_with?("/")
         end
       end
-    end
-    metacharacters = %w[\\ | ( ) [ ] { } ^ $ * + ? .]
-    bad_regex = metacharacters.any? do |char|
-      ARGV.any? do |arg|
-        arg.include?(char) && !arg.start_with?("/")
+      if ARGV.any? && bad_regex
+        ohai "Did you mean to perform a regular expression search?"
+        ohai "Surround your query with /slashes/ to search by regex."
       end
     end
-    if ARGV.any? && bad_regex
-      ohai "Did you mean to perform a regular expression search?"
-      ohai "Surround your query with /slashes/ to search by regex."
-    end
+
     raise SEARCH_ERROR_QUEUE.pop unless SEARCH_ERROR_QUEUE.empty?
   end