* parser.l: Support hex and octal escapes in string and quasiliterals,

as the documentation says. Also support an optional trailing ;
delimiter in hex escapes.

* txr.1: Documented.

3 files changed, 20 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 0f2d8d79..7eef7d0b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2012-01-27  Kaz Kylheku  <kaz@kylheku.com>
 
+	* parser.l: Support hex and octal escapes in string and quasiliterals,
+	as the documentation says. Also support an optional trailing ;
+	delimiter in hex escapes.
+
+	* txr.1: Documented.
+
+2012-01-27  Kaz Kylheku  <kaz@kylheku.com>
+
 	* txr.vim: Properly show @[...] inside quasiliteral.
 
 2012-01-27  Kaz Kylheku  <kaz@kylheku.com>
diff --git a/parser.l b/parser.l
index d9883e6c..5ef544e1 100644
--- a/parser.l
+++ b/parser.l
@@ -584,6 +584,11 @@ UONLY   {U2}{U}|{U3}{U}{U}|{U4}{U}{U}{U}
                                   lineno++;
                                 }
                                 
+<STRLIT,QSILIT>[\\](x{HEX}+;?|o{OCT}+)  {
+                                          yylval.chr = num_esc(yytext+1);
+                                          return LITCHAR;
+                                        }
+
 <CHRLIT>(x{HEX}+|o{OCT}+) {
                             yylval.chr = num_esc(yytext);
                             return LITCHAR;
diff --git a/txr.1 b/txr.1
index 54d46384..ea53026f 100644
--- a/txr.1
+++ b/txr.1
@@ -1034,8 +1034,13 @@ for character literals is similar to that of the Scheme language.
 String literals are delimited by double respectively, and may not span multiple
 lines. A double quote within a string literal is encoded using \e"
 and a backslash is encoded as \e\e. Backslash escapes like \en and \et
-are recognized, as are hexadecimal escapes like \exFF and octal
-escapes like \e123.
+are recognized, as are hexadecimal escapes like \exFF or \exxabc and octal
+escapes like \e123.  Ambiguity between a hex escape and subsequent
+text can be resolved by using trailing semicolon delimiter: "\exabc;d" is a
+string consisting of the character U+0ABC followed by "d". The semicolon
+delimiter disappears. To write a literal semicolon immediately after a hex
+escape, write two semicolons, the first of which will be interpreted as a
+delimiter. Thus, "\ex21;;" represents "!;".
 
 .SS String Quasiliterals