Index: lex.l
===================================================================
RCS file: /cvs/octave/src/lex.l,v
retrieving revision 1.236
diff -u -r1.236 lex.l
--- lex.l	8 Jun 2006 20:37:29 -0000	1.236
+++ lex.l	12 Jul 2006 06:43:45 -0000
@@ -26,6 +26,8 @@
 %s COMMAND_START
 %s MATRIX_START
 
+%x BLOCK_COMMENT_START
+
 %x NESTED_FUNCTION_END
 %x NESTED_FUNCTION_BEGIN
 
@@ -234,6 +236,8 @@
 
 static unsigned int Vtoken_count = 0;
 
+static std::string block_comment_text;
+
 // Forward declarations for functions defined at the bottom of this
 // file.
 
@@ -267,15 +271,15 @@
 
 %}
 
-D	[0-9]
-S	[ \t]
+D	([0-9])
+S	([ \t])
 NL	((\n)|(\r)|(\r\n))
 SNL	({S}|{NL})
 EL	(\.\.\.)
 BS	(\\)
 CONT	({EL}|{BS})
-Im	[iIjJ]
-CCHAR	[#%]
+Im	([iIjJ])
+CCHAR	([#%])
 COMMENT	({CCHAR}.*{NL})
 SNLCMT	({SNL}|{COMMENT})
 NOT	((\~)|(\!))
@@ -284,6 +288,9 @@
 IDENT	([_$a-zA-Z][_$a-zA-Z0-9]*)
 EXPON	([DdEe][+-]?{D}+)
 NUMBER	(({D}+\.?{D}*{EXPON}?)|(\.{D}+{EXPON}?)|(0[xX][0-9a-fA-F]+))
+
+BLOCK_COMMENT_BEGIN ^({S}*\%\{{S}*{NL})
+BLOCK_COMMENT_END   ^({S}*\%\}{S}*{NL})
 %%
 
 <NESTED_FUNCTION_END>. {
@@ -617,6 +624,65 @@
 }
 
 %{
+// Block comments.
+%}
+
+{BLOCK_COMMENT_BEGIN} {
+    block_comment_text = yytext;
+
+    lexer_flags.block_comment_nesting_level++;
+
+    lexer_flags.saved_start_state = YY_START;
+
+    input_line_number++;
+    current_input_column = 0;
+
+    BEGIN (BLOCK_COMMENT_START);
+  }
+
+<BLOCK_COMMENT_START>{BLOCK_COMMENT_BEGIN} {
+    block_comment_text += yytext;
+
+    lexer_flags.block_comment_nesting_level++;
+  }
+
+{BLOCK_COMMENT_END} {
+    warning_with_id ("Octave:block-comment",
+		     "end-block-comment outside block comment near line %d",
+		     input_line_number);
+
+    input_line_number++;
+  }
+
+<BLOCK_COMMENT_START>{BLOCK_COMMENT_END} {
+    block_comment_text += yytext;
+
+    input_line_number++;
+    current_input_column = 0;
+
+    if (--lexer_flags.block_comment_nesting_level == 0)
+      {
+	octave_comment_buffer::append (block_comment_text,
+				       octave_comment_elt::block);
+
+	block_comment_text = "";
+
+	BEGIN (lexer_flags.saved_start_state);
+      }
+  }
+
+<BLOCK_COMMENT_START>. {
+    block_comment_text += yytext;
+  }
+
+<BLOCK_COMMENT_START>{NL} {
+    block_comment_text += yytext;
+
+    input_line_number++;
+    current_input_column = 0;
+  }
+
+%{
 // Gobble comments.  If closest nesting is inside parentheses, don't
 // return a new line.
 %} 
@@ -2406,6 +2472,12 @@
 
   // Quote marks strings intially.
   quote_is_transpose = false;
+
+  // Count of the depth of block comment nesting.
+  block_comment_nesting_level = 0;
+
+  // Flex start state.
+  saved_start_state = INITIAL;
 }
 
 bool