1 files changed, 29 insertions, 0 deletions
diff --git a/tool/lrama/lib/lrama/state/resolved_conflict.rb b/tool/lrama/lib/lrama/state/resolved_conflict.rb
new file mode 100644
index 0000000000..02ea892147
--- /dev/null
+++ b/tool/lrama/lib/lrama/state/resolved_conflict.rb
@@ -0,0 +1,29 @@
+module Lrama
+  class State
+    # * symbol: A symbol under discussion
+    # * reduce: A reduce under discussion
+    # * which: For which a conflict is resolved. :shift, :reduce or :error (for nonassociative)
+    class ResolvedConflict < Struct.new(:symbol, :reduce, :which, :same_prec, keyword_init: true)
+      def report_message
+        s = symbol.display_name
+        r = reduce.rule.precedence_sym.display_name
+        case
+        when which == :shift && same_prec
+          msg = "resolved as #{which} (%right #{s})"
+        when which == :shift
+          msg = "resolved as #{which} (#{r} < #{s})"
+        when which == :reduce && same_prec
+          msg = "resolved as #{which} (%left #{s})"
+        when which == :reduce
+          msg = "resolved as #{which} (#{s} < #{r})"
+        when which == :error
+          msg = "resolved as an #{which} (%nonassoc #{s})"
+        else
+          raise "Unknown direction. #{self}"
+        end
+
+        "Conflict between rule #{reduce.rule.id} and token #{s} #{msg}."
+      end
+    end
+  end
+end