Error handling improvement in read.

* parser.y (spec): New grammar production to handle the cases
that SECRET_ESCAPE_E is not followed by anything (the input
ends before any object is scanned, or there is no input
token which starts an object).

* parser.c (lisp_parse): Deal with EOF indication from parser
(the syntax_tree member of parser_t set to nao).

3 files changed, 25 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 40aaea74..846a2fab 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,17 @@
 2015-06-10  Kaz Kylheku  <kaz@kylheku.com>
 
+	Error handling improvement in read.
+
+	* parser.y (spec): New grammar production to handle the cases
+	that SECRET_ESCAPE_E is not followed by anything (the input
+	ends before any object is scanned, or there is no input
+	token which starts an object).
+
+	* parser.c (lisp_parse): Deal with EOF indication from parser
+	(the syntax_tree member of parser_t set to nao).
+
+2015-06-10  Kaz Kylheku  <kaz@kylheku.com>
+
 	* parser.y (yybadtoken): Print unexpected character
 	literally rather than as a Lisp character literal.
 
diff --git a/parser.c b/parser.c
index 6081c538..34903ce9 100644
--- a/parser.c
+++ b/parser.c
@@ -181,17 +181,19 @@ val lisp_parse(val source_in, val error_stream, val error_return_val, val name_i
 
   {
     int gc = gc_state(0);
-    name = if3(std_error != std_null, name, lit(""));
-    set(mkloc(pi->name, parser), name);
+    set(mkloc(pi->name, parser), if3(std_error != std_null, name, lit("")));
     parse(pi);
     gc_state(gc);
   }
 
   dyn_env = saved_dyn;
 
-  if (pi->errors) {
+  if (pi->errors || pi->syntax_tree == nao) {
     if (missingp(error_return_val))
-      uw_throwf(syntax_error_s, lit("read: syntax error"), nao);
+      uw_throwf(syntax_error_s, lit("read: ~a: ~a"), name,
+                if3(pi->syntax_tree == nao,
+                    lit("end of input reached without seeing object"),
+                    lit("errors encountered")), nao);
     return error_return_val;
   }
 
diff --git a/parser.y b/parser.y
index 343981f0..01e7295e 100644
--- a/parser.y
+++ b/parser.y
@@ -137,6 +137,13 @@ spec : clauses                  { parser->syntax_tree = $1; }
      | /* empty */              { parser->syntax_tree = nil; }
      | SECRET_ESCAPE_R regexpr  { parser->syntax_tree = $2; end_of_regex(scnr); }
      | SECRET_ESCAPE_E n_expr   { parser->syntax_tree = $2; YYACCEPT; }
+     | SECRET_ESCAPE_E          { if (yychar == YYEOF) {
+                                    parser->syntax_tree = nao;
+                                    YYACCEPT;
+                                  } else {
+                                    yybadtok(yychar, nil);
+                                    parser->syntax_tree = nil;
+                                  } }
      | error '\n'               { parser->syntax_tree = nil;
                                   if (parser->errors >= 8)
                                     YYABORT;