From: Martin Duerst <duerst@...>
Date: 2007-10-24T15:58:14+09:00
Subject: Re: Improving 'syntax error, unexpected $end, expecting kEND'?

At 04:15 07/10/24, David Flanagan wrote:
>The patch below changes this message to:
>
>syntax error, unexpected "end-of-file", expecting "end"
>
>It doesn't tell you where the outermost open block begins, but at least the message isn't so cryptic.  I don't know any way to get rid of the quotes around "end-of-file".

This looks extremely helpful, in particular for (relative) beginners.
Looking at the patch below, it seems to be easy to improve things for
a few other cases, too. I just tried to fill in the blanks; maybe
some of this stuff doesn't make sense, but I have included a patch
below.

As for personal experiences, when I get an error of this kind,
I often add an "end" at some arbitrary place and see what happens.
Then I move that "end" around a bit and see again what happens.
That usually leads to a solution pretty quickly. Seems that sometimes
randomized algorithms are useful even for programming :-).

Regards,    Martin.


Index: parse.y
===================================================================
--- parse.y     (revision 13764)
+++ parse.y     (working copy)
@@ -596,54 +596,55 @@
 /*%
 %token <val>
 %*/
-       keyword_class
-       keyword_module
-       keyword_def
-       keyword_undef
-       keyword_begin
-       keyword_rescue
-       keyword_ensure
-       keyword_end
-       keyword_if
-       keyword_unless
-       keyword_then
-       keyword_elsif
-       keyword_else
-       keyword_case
-       keyword_when
-       keyword_while
-       keyword_until
-       keyword_for
-       keyword_break
-       keyword_next
-       keyword_redo
-       keyword_retry
-       keyword_in
-       keyword_do
-       keyword_do_cond
-       keyword_do_block
+       end_of_file 0   "end-of-file"
+       keyword_class   "class"
+       keyword_module  "module"
+       keyword_def     "def"
+       keyword_undef   "undef"
+       keyword_begin   "begin"
+       keyword_rescue  "rescue"
+       keyword_ensure  "ensure"
+       keyword_end     "end"
+       keyword_if      "if"
+       keyword_unless  "unless"
+       keyword_then    "then"
+       keyword_elsif   "elsif"
+       keyword_else    "else"
+       keyword_case    "case"
+       keyword_when    "when"
+       keyword_while   "while"
+       keyword_until   "until"
+       keyword_for     "for"
+       keyword_break   "break"
+       keyword_next    "next"
+       keyword_redo    "redo"
+       keyword_retry   "retry"
+       keyword_in      "in"
+       keyword_do      "do"
+       keyword_do_cond "do"
+       keyword_do_block        "do"
        keyword_do_LAMBDA
-       keyword_return
-       keyword_yield
-       keyword_super
-       keyword_self
-       keyword_nil
-       keyword_true
-       keyword_false
-       keyword_and
-       keyword_or
-       keyword_not
-       modifier_if
-       modifier_unless
-       modifier_while
-       modifier_until
-       modifier_rescue
-       keyword_alias
-       keyword_defined
-       keyword_BEGIN
-       keyword_END
-       keyword__LINE__
-       keyword__FILE__
+       keyword_return  "return"
+       keyword_yield   "yield"
+       keyword_super   "super"
+       keyword_self    "self"
+       keyword_nil     "nil"
+       keyword_true    "true"
+       keyword_false   "false"
+       keyword_and     "and"
+       keyword_or      "or"
+       keyword_not     "not"
+       modifier_if     "if"
+       modifier_unless "unless"
+       modifier_while  "while"
+       modifier_until  "until"
+       modifier_rescue "rescue"
+       keyword_alias   "alias"
+       keyword_defined "defined"
+       keyword_BEGIN   "BEGIN"
+       keyword_END     "END"
+       keyword__LINE__ "__LINE__"
+       keyword__FILE__ "__FILE__"
 
 %token <id>   tIDENTIFIER tFID tGVAR tIVAR tCONSTANT tCVAR tLABEL
 %token <node> tINTEGER tFLOAT tSTRING_CONTENT tCHAR



#-#-#  Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University
#-#-#  http://www.sw.it.aoyama.ac.jp       mailto:duerst@it.aoyama.ac.jp