[Guile-commits] 03/06: Optimize 'write' for strings.

[Ludovic Courtès]

civodul pushed a commit to branch stable-2.0
in repository guile.

commit 5943a62042432b86d757200ef595d7aebb5c9bac
Author: Ludovic Courtès <address@hidden>
Date:   Sun Jan 11 21:57:54 2015 +0100

    Optimize 'write' for strings.
    
    This shows a 19% improvement on the "string without escapes"
    micro-benchmark of 'write.bm', and 12% on "string with escapes".
    
    * libguile/print.c (iprin1) <scm_tc7_string>: Replace 'scm_i_string_ref'
      loop with a call to 'write_string'.
      (display_character): Adjust description of return value in comment.
      (write_string): New function.
---
 libguile/print.c |   78 ++++++++++++++++++++++++++++++++++++------------------
 1 files changed, 52 insertions(+), 26 deletions(-)

diff --git a/libguile/print.c b/libguile/print.c
index 122e035..86e0a03 100644
--- a/libguile/print.c
+++ b/libguile/print.c
@@ -1,5 +1,5 @@
 /* Copyright (C) 1995-1999, 2000, 2001, 2002, 2003, 2004, 2006, 2008,
- *   2009, 2010, 2011, 2012, 2013, 2014 Free Software Foundation, Inc.
+ *   2009, 2010, 2011, 2012, 2013, 2014, 2015 Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -69,6 +69,9 @@
 static size_t display_string (const void *, int, size_t, SCM,
                              scm_t_string_failed_conversion_handler);
 
+static size_t write_string (const void *, int, size_t, SCM,
+                           scm_t_string_failed_conversion_handler);
+
 static int display_character (scm_t_wchar, SCM,
                              scm_t_string_failed_conversion_handler);
 
@@ -634,32 +637,29 @@ iprin1 (SCM exp, SCM port, scm_print_state *pstate)
           }
          break;
         case scm_tc7_string:
-          if (SCM_WRITINGP (pstate))
-            {
-              size_t len, i;
-
-              display_character ('"', port, iconveh_question_mark);
-              len = scm_i_string_length (exp);
-              for (i = 0; i < len; ++i)
-               write_character (scm_i_string_ref (exp, i), port, 1);
-
-              display_character ('"', port, iconveh_question_mark);
-              scm_remember_upto_here_1 (exp);
-            }
-          else
-           {
-             size_t len, printed;
+         {
+           size_t len, printed;
 
-             len = scm_i_string_length (exp);
+           len = scm_i_string_length (exp);
+           if (SCM_WRITINGP (pstate))
+             {
+               printed = write_string (scm_i_string_data (exp),
+                                       scm_i_is_narrow_string (exp),
+                                       len, port,
+                                       PORT_CONVERSION_HANDLER (port));
+               len += 2;                   /* account for the quotes */
+             }
+           else
              printed = display_string (scm_i_string_data (exp),
                                        scm_i_is_narrow_string (exp),
                                        len, port,
                                        PORT_CONVERSION_HANDLER (port));
-             if (SCM_UNLIKELY (printed < len))
-               scm_encoding_error (__func__, errno,
-                                   "cannot convert to output locale",
-                                   port, scm_c_string_ref (exp, printed));
-           }
+
+           if (SCM_UNLIKELY (printed < len))
+             scm_encoding_error (__func__, errno,
+                                 "cannot convert to output locale",
+                                 port, scm_c_string_ref (exp, printed));
+         }
 
           scm_remember_upto_here_1 (exp);
           break;
@@ -1051,8 +1051,6 @@ display_string_using_iconv (const void *str, int 
narrow_p, size_t len,
   return printed;
 }
 
-#undef STR_REF
-
 /* Display the LEN codepoints in STR to PORT according to STRATEGY;
    return the number of codepoints successfully displayed.  If NARROW_P,
    then STR is interpreted as a sequence of `char', denoting a Latin-1
@@ -1075,8 +1073,8 @@ display_string (const void *str, int narrow_p,
                                       port, strategy);
 }
 
-/* Attempt to display CH to PORT according to STRATEGY.  Return non-zero
-   if CH was successfully displayed, zero otherwise (e.g., if it was not
+/* Attempt to display CH to PORT according to STRATEGY.  Return one if
+   CH was successfully displayed, zero otherwise (e.g., if it was not
    representable in PORT's encoding.)  */
 static int
 display_character (scm_t_wchar ch, SCM port,
@@ -1085,6 +1083,34 @@ display_character (scm_t_wchar ch, SCM port,
   return display_string (&ch, 0, 1, port, strategy) == 1;
 }
 
+/* Same as 'display_string', but using the 'write' syntax.  */
+static size_t
+write_string (const void *str, int narrow_p,
+             size_t len, SCM port,
+             scm_t_string_failed_conversion_handler strategy)
+{
+  size_t printed;
+
+  printed = display_character ('"', port, strategy);
+
+  if (printed > 0)
+    {
+      size_t i;
+
+      for (i = 0; i < len; ++i)
+       {
+         write_character (STR_REF (str, i), port, 1);
+         printed++;
+       }
+
+      printed += display_character ('"', port, strategy);
+    }
+
+  return printed;
+}
+
+#undef STR_REF
+
 /* Attempt to pretty-print CH, a combining character, to PORT.  Return
    zero upon failure, non-zero otherwise.  The idea is to print CH above
    a dotted circle to make it more visible.  */