From 97d1a381e112e843ff014a05a083e42165b7bb01 Mon Sep 17 00:00:00 2001
From: Marc-Andre Lafortune <github@marc-andre.ca>
Date: Thu, 13 Aug 2020 21:50:16 -0400
Subject: [Fixes #137] Improve reporting

---
 libexec/racc | 39 ++++++++++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 9 deletions(-)

(limited to 'libexec')

diff --git a/libexec/racc b/libexec/racc
index 0f0f642cd6..2edd6bb07b 100755
--- a/libexec/racc
+++ b/libexec/racc
@@ -1,6 +1,6 @@
 #!/usr/bin/env ruby
 #
-# $Id$
+#
 #
 # Copyright (c) 1999-2006 Minero Aoki
 #
@@ -184,8 +184,12 @@ def main
       log_useless states.grammar
       log_conflict states
     else
-      report_useless states.grammar
-      report_conflict states
+      has_useless = report_useless states.grammar
+      has_conflicts = report_conflict states
+      if has_useless || has_conflicts
+        preamble = make_logfile ? 'C' : 'Turn on logging with "-v" and c'
+        $stderr.puts %Q{#{preamble}heck ".output" file for details}
+      end
     end
 
     profiler.report
@@ -201,13 +205,29 @@ def make_filename(path, suffix)
   path.sub(/(?:\..*?)?\z/, suffix)
 end
 
+LIST_LIMIT = 10
+def report_list(enum, label)
+  c = enum.count
+  if c > 0
+    $stderr.puts "#{c} #{label}:"
+    enum.first(LIST_LIMIT).each do |item|
+      $stderr.puts "  #{yield item}"
+    end
+    $stderr.puts "  ..." if c > LIST_LIMIT
+  end
+end
+
+# @return [Boolean] if anything was reported
 def report_conflict(states)
   if states.should_report_srconflict?
+    reported = true
     $stderr.puts "#{states.n_srconflicts} shift/reduce conflicts"
   end
   if states.rrconflict_exist?
+    reported = true
     $stderr.puts "#{states.n_rrconflicts} reduce/reduce conflicts"
   end
+  reported
 end
 
 def log_conflict(states)
@@ -222,16 +242,17 @@ def log_conflict(states)
   }
 end
 
+# @return [Boolean] if anything was reported
 def report_useless(grammar)
-  if grammar.useless_nonterminal_exist?
-    $stderr.puts "#{grammar.n_useless_nonterminals} useless nonterminals"
-  end
-  if grammar.useless_rule_exist?
-    $stderr.puts "#{grammar.n_useless_rules} useless rules"
-  end
+  reported = report_list(grammar.each_useless_nonterminal, 'useless nonterminals', &:to_s)
+
+  reported ||= report_list(grammar.each_useless_rule, 'useless rules') { |r| "##{r.ident} (#{r.target})" }
+
   if grammar.start.useless?
     $stderr.puts 'fatal: start symbol does not derive any sentence'
+    reported = true
   end
+  reported
 end
 
 def log_useless(grammar)
-- 
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