Merge pull request #251 from zheng-yongping/improve-SyntaxError-error-message

Improve syntax error error message

Author: kojix2

lib/iruby/backend.rb

@@ -57,7 +57,7 @@ class PryBackend
 
     def initialize
       require 'pry'
-      Pry.memory_size = 3 
+      Pry.memory_size = 3
       Pry.pager = false # Don't use the pager
       Pry.print = proc {|output, value|} # No result printing
       Pry.exception_handler = proc {|output, exception, _| }
@@ -72,11 +72,21 @@ def eval(code, store_history)
         reset
         raise SystemExit
       end
-      unless @pry.eval_string.empty?
+
+      # Pry::Code.complete_expression? return false
+      if !@pry.eval_string.empty?
         syntax_error = @pry.eval_string
         @pry.reset_eval_string
-        @pry.evaluate_ruby syntax_error
+        @pry.evaluate_ruby(syntax_error)
+
+      # Pry::Code.complete_expression? raise SyntaxError
+      # evaluate again for current line number
+      elsif @pry.last_result_is_exception? &&
+              @pry.last_exception.is_a?(SyntaxError) &&
+              @pry.last_exception.is_a?(Pry::UserError)
+         @pry.evaluate_ruby(code)
       end
+
       raise @pry.last_exception if @pry.last_result_is_exception?
       @pry.push_initial_binding unless @pry.current_binding # ensure that we have a binding
       @pry.last_result

lib/iruby/kernel.rb

@@ -112,7 +112,7 @@ def execute_request(msg)
 
     def error_content(e)
       rindex = e.backtrace.rindex{|line| line.start_with?(@backend.eval_path)} || -1
-      backtrace = e.backtrace[0..rindex]
+      backtrace = SyntaxError === e  && rindex == -1 ? [] : e.backtrace[0..rindex]
       { ename: e.class.to_s,
         evalue: e.message,
         traceback: ["#{RED}#{e.class}#{RESET}: #{e.message}", *backtrace] }