Issue 3531: replaced function argument 'string' by 'const string&' where it makes sense to avoid unnecessary copying of 'string' objects.

Measurements on x86_64 (i7-2760QM, 2.40GHz) Fedora 19 with g++ 4.8.1, with
configure --enable-optimising --disable-debugging; tests run 10 times, average
elapsed time compared (/usr/bin/time)

* Bach, Concerto in E major or violin and strings, BWV 1042 (Mutopia source),
  38 pages:
  $ lilypond score.ly -> master: 15.4s, with patch: -0.1%
* lilypond regression tests (1153 .ly files):
  $ lilypond *.ly -> master: 276.6s, with patch: -2.5%

13 files changed, 60 insertions, 60 deletions

diff --git a/flower/file-name.cc b/flower/file-name.cc
index c24c0731e4..1746c2c28d 100644
--- a/flower/file-name.cc
+++ b/flower/file-name.cc
@@ -51,7 +51,7 @@ using namespace std;
 
 #ifdef __CYGWIN__
 static string
-dos_to_posix (string file_name)
+dos_to_posix (const string &file_name)
 {
   char buf[PATH_MAX] = "";
   char s[PATH_MAX] = {0};
@@ -78,7 +78,7 @@ slashify (string file_name)
 }
 
 string
-dir_name (string const file_name)
+dir_name (const string &file_name)
 {
   string s = file_name;
   s = slashify (s);
diff --git a/flower/file-path.cc b/flower/file-path.cc
index d0dd3a1f99..b19732d15e 100644
--- a/flower/file-path.cc
+++ b/flower/file-path.cc
@@ -47,13 +47,13 @@ File_path::directories () const
 
 #include <algorithm>
 void
-File_path::parse_path (string p)
+File_path::parse_path (const string &p)
 {
   concat (dirs_, string_split (p, PATHSEP));
 }
 
 bool
-is_file (string file_name)
+is_file (const string &file_name)
 {
 #if !STAT_MACROS_BROKEN
   struct stat sbuf;
@@ -106,7 +106,7 @@ directory, in this order.
 The file name if found, or empty string if not found. */
 
 string
-File_path::find (string name) const
+File_path::find (const string &name) const
 {
   if (!name.length () || (name == "-"))
     return name;
@@ -146,7 +146,7 @@ File_path::find (string name) const
   where EXT is from EXTENSIONS.
 */
 string
-File_path::find (string name, char const *extensions[])
+File_path::find (const string &name, char const *extensions[])
 {
   if (name.empty () || name == "-")
     return name;
@@ -195,13 +195,13 @@ File_path::to_string () const
 }
 
 void
-File_path::append (string str)
+File_path::append (const string &str)
 {
   dirs_.push_back (str);
 }
 
 void
-File_path::prepend (string str)
+File_path::prepend (const string &str)
 {
   dirs_.insert (dirs_.begin (), str);
 }
diff --git a/flower/include/file-name.hh b/flower/include/file-name.hh
index b30dd9cd5b..4822783fc6 100644
--- a/flower/include/file-name.hh
+++ b/flower/include/file-name.hh
@@ -23,7 +23,7 @@
 #include "std-vector.hh"
 #include "std-string.hh"
 
-std::string dir_name (std::string file_name);
+std::string dir_name (const std::string &file_name);
 std::string get_working_directory ();
 
 class File_name
diff --git a/flower/include/file-path.hh b/flower/include/file-path.hh
index 29ca17f246..8c8049391d 100644
--- a/flower/include/file-path.hh
+++ b/flower/include/file-path.hh
@@ -38,16 +38,16 @@ class File_path
 
 public:
   vector<string> directories () const;
-  string find (string name) const;
-  string find (string name, char const *extensions[]);
+  string find (const string &name) const;
+  string find (const string &name, char const *extensions[]);
   string to_string () const;
   bool try_append (string str);
-  void append (string str);
-  void parse_path (string);
-  void prepend (string str);
+  void append (const string&);
+  void parse_path (const string&);
+  void prepend (const string&);
 };
 
-bool is_file (string file_name);
+bool is_file (const string &file_name);
 bool is_dir (string file_name);
 
 #endif /* FILE_PATH */
diff --git a/flower/include/international.hh b/flower/include/international.hh
index 6dd46c28e9..5797a293f7 100644
--- a/flower/include/international.hh
+++ b/flower/include/international.hh
@@ -43,7 +43,7 @@ string _ (char const *ch);
 */
 string _f (char const *format, ...)
 __attribute__ ((format (printf, 1, 2)));
-string _f (char const *format, string s, string s2 = "", string s3 = "");
+string _f (char const *format, const string &s, const string &s2 = "", const string &s3 = "");
 /**
    va_list version of _f
  */
diff --git a/flower/include/std-string.hh b/flower/include/std-string.hh
index 5b7d2af11d..6b6e8ef972 100644
--- a/flower/include/std-string.hh
+++ b/flower/include/std-string.hh
@@ -39,7 +39,7 @@ using namespace std;
 typedef size_t ssize;
 #define NPOS string::npos
 
-string to_string (string s);
+string to_string (const string&);
 string to_string (char c, int n = 1);
 string to_string (int i, char const *format = 0);
 string to_string (double f, char const *format = 0);
@@ -53,7 +53,7 @@ __attribute__ ((format (printf, 1, 2)));
 
 string &replace_all (string *str, string const &find, string const &replace);
 string &replace_all (string *str, char find, char replace);
-char *string_copy (string s);
+char *string_copy (const string &s);
 
 int string_compare (string const &, string const &);
 
diff --git a/flower/include/std-vector.hh b/flower/include/std-vector.hh
index dd276df186..e7f29a8fcb 100644
--- a/flower/include/std-vector.hh
+++ b/flower/include/std-vector.hh
@@ -258,7 +258,7 @@ junk_pointers (vector<T> &v)
 }
 
 vector<string> string_split (string str, char c);
-string string_join (vector<string> const &strs, string infix);
+string string_join (vector<string> const &strs, const string &infix);
 
 #define iterof(i,s) typeof((s).begin()) i((s).begin())
 
diff --git a/flower/include/string-convert.hh b/flower/include/string-convert.hh
index 396eee2f91..6b4fba023f 100644
--- a/flower/include/string-convert.hh
+++ b/flower/include/string-convert.hh
@@ -19,19 +19,19 @@ class String_convert
   static int hex2nibble (Byte byte);
   static Byte nibble2hex_byte (Byte byte);
 public:
-  static string pad_to (string s, size_t length);
+  static string pad_to (const string &s, size_t length);
   static string bool_string (bool b);
   static string bin2hex (Byte bin_char);
-  static string bin2hex (string bin_string);
-  static int bin2int (string bin_string);
-  static unsigned bin2unsigned (string bin_string);
+  static string bin2hex (const string &bin_string);
+  static int bin2int (const string &bin_string);
+  static unsigned bin2unsigned (const string &bin_string);
   static string char_string (char c, int n);
-  static int dec2int (string dec_string);
-  static double dec2double (string dec_string);
+  static int dec2int (const string &dec_string);
+  static double dec2double (const string &dec_string);
   static string double_string (double f, char const *fmt = 0);
   static string form_string (char const *format, ...) __attribute__ ((format (printf, 1, 2)));
   static string vform_string (char const *format, va_list args);
-  static string hex2bin (string str);
+  static string hex2bin (const string &str);
   static string int_string (int i, char const *fmt = 0);
   static string unsigned_string (unsigned);
   static string unsigned_long_string (unsigned long);
diff --git a/flower/include/warn.hh b/flower/include/warn.hh
index 25240113ca..333e95a94e 100644
--- a/flower/include/warn.hh
+++ b/flower/include/warn.hh
@@ -44,25 +44,25 @@ extern int loglevel;
 extern bool warning_as_error;
 
 /* output messages, in decreasing order of importance */
-void error (string s, string location = ""); // Fatal error, exits lilypond!
-void programming_error (string s, string location = "");
-void non_fatal_error (string, string location = "");
-void warning (string s, string location = "");
-void basic_progress (string s, string location = "");
+void error (string s, const string &location = ""); // Fatal error, exits lilypond!
+void programming_error (const string &s, const string &location = "");
+void non_fatal_error (const string&, const string &location = "");
+void warning (const string &s, const string &location = "");
+void basic_progress (const string &s, const string &location = "");
 /* progress_indication does by default *NOT* start on a new line */
-void progress_indication (string s, bool newline = false, string location = "");
-void message (string s, bool newline = true, string location = "");
-void debug_output (string s, bool newline = true, string location = "");
+void progress_indication (const string &s, bool newline = false, const string &location = "");
+void message (const string &s, bool newline = true, const string &location = "");
+void debug_output (const string &s, bool newline = true, const string &location = "");
 
 /* Helper functions that always print out the message. Callers should ensure
    that the loglevel is obeyed */
-void print_message (int level, string location, string s, bool newline = true);
+void print_message (int level, const string &location, string s, bool newline = true);
 
 bool is_loglevel (int level);
 void set_loglevel (int level);
 void set_loglevel (string level);
 
-void expect_warning (string msg);
+void expect_warning (const string &msg);
 void check_expected_warnings ();
 
 #endif /* WARN_HH */
diff --git a/flower/international.cc b/flower/international.cc
index cbdcf58d6e..2e6a09df9f 100644
--- a/flower/international.cc
+++ b/flower/international.cc
@@ -55,7 +55,7 @@ v_f (char const *format, va_list args)
 }
 
 string
-_f (char const *format, string s, string s2, string s3)
+_f (char const *format, const string &s, const string &s2, const string &s3)
 {
   return String_convert::form_string (gettext (format), s.c_str (), s2.c_str (),
                                       s3.c_str ());
diff --git a/flower/std-string.cc b/flower/std-string.cc
index d2c2d624d2..7dc9d47311 100644
--- a/flower/std-string.cc
+++ b/flower/std-string.cc
@@ -21,7 +21,7 @@
 #include "string-convert.hh"
 
 string
-to_string (string s)
+to_string (const string &s)
 {
   return s;
 }
@@ -106,7 +106,7 @@ replace_all (string *str, char find, char replace)
 }
 
 char *
-string_copy (string s)
+string_copy (const string &s)
 {
   ssize len = s.length ();
   char *dest = new char[len + 1];
@@ -144,7 +144,7 @@ string_split (string str, char c)
 }
 
 string
-string_join (vector<string> const &strs, string infix)
+string_join (vector<string> const &strs, const string &infix)
 {
   string result;
   for (vsize i = 0; i < strs.size (); i++)
diff --git a/flower/string-convert.cc b/flower/string-convert.cc
index 68e6a0c0b8..eebcd92708 100644
--- a/flower/string-convert.cc
+++ b/flower/string-convert.cc
@@ -43,7 +43,7 @@ String_convert::bin2hex (Byte bin_char)
 }
 
 string
-String_convert::bin2hex (string bin_string)
+String_convert::bin2hex (const string &bin_string)
 {
   string str;
   Byte const *byte = (Byte const *)bin_string.data ();
@@ -56,13 +56,13 @@ String_convert::bin2hex (string bin_string)
 }
 
 int
-String_convert::bin2int (string bin_string)
+String_convert::bin2int (const string &bin_string)
 {
   return bin2unsigned (bin_string);
 }
 
 unsigned
-String_convert::bin2unsigned (string bin_string)
+String_convert::bin2unsigned (const string &bin_string)
 {
   assert (bin_string.length () <= (int)sizeof (unsigned));
 
@@ -76,7 +76,7 @@ String_convert::bin2unsigned (string bin_string)
 }
 
 int
-String_convert::dec2int (string dec_string)
+String_convert::dec2int (const string &dec_string)
 {
   if (!dec_string.length ())
     return 0;
@@ -100,7 +100,7 @@ String_convert::i64_string (I64 i64, char const *fmt)
 }
 // breendet imp from string
 double
-String_convert::dec2double (string dec_string)
+String_convert::dec2double (const string &dec_string)
 {
   if (!dec_string.length ())
     return 0;
@@ -134,7 +134,7 @@ String_convert::hex2bin (string hex_string, string &bin_string_r)
 }
 
 string
-String_convert::hex2bin (string hex_string)
+String_convert::hex2bin (const string &hex_string)
 {
   string str;
 
@@ -352,7 +352,7 @@ String_convert::unsigned_long_string (unsigned long ul)
 }
 
 string
-String_convert::pad_to (string s, size_t n)
+String_convert::pad_to (const string &s, size_t n)
 {
   return s + string (max (int (n - s.length ()), 0), ' ');
 }
@@ -360,13 +360,13 @@ String_convert::pad_to (string s, size_t n)
 string
 String_convert::to_upper (string s)
 {
-  return strnupr ((char *)s.c_str (), s.length ());
+  return strnupr (const_cast<char*>(s.c_str ()), s.length ());
 }
 
 string
 String_convert::to_lower (string s)
 {
-  return strnlwr ((char *)s.c_str (), s.length ());
+  return strnlwr (const_cast<char*>(s.c_str ()), s.length ());
 }
 
 string
diff --git a/flower/warn.cc b/flower/warn.cc
index f3f6e1c743..52e2a42508 100644
--- a/flower/warn.cc
+++ b/flower/warn.cc
@@ -99,7 +99,7 @@ set_loglevel (string level)
  * expected warnings again.
  */
 vector<string> expected_warnings;
-void expect_warning (string msg)
+void expect_warning (const string &msg)
 {
   expected_warnings.push_back (msg);
 }
@@ -119,7 +119,7 @@ void check_expected_warnings ()
   expected_warnings.clear ();
 }
 
-bool is_expected (string s)
+bool is_expected (const string &s)
 {
   bool expected = false;
   for (vsize i = 0; i < expected_warnings.size (); i++)
@@ -151,7 +151,7 @@ static bool message_newline = true;
    if newline is true, start the message on a new line.
 */
 void
-print_message (int level, string location, string s, bool newline)
+print_message (int level, const string &location, string s, bool newline)
 {
   /* Only print the message if the current loglevel allows it: */
   if (!is_loglevel (level))
@@ -178,7 +178,7 @@ print_message (int level, string location, string s, bool newline)
 
 /* Display a fatal error message.  Also exits lilypond.  */
 void
-error (string s, string location)
+error (string s, const string &location)
 {
   print_message (LOG_ERROR, location, _f ("fatal error: %s", s) + "\n");
   exit (1);
@@ -186,7 +186,7 @@ error (string s, string location)
 
 /* Display a severe programming error message, but don't exit.  */
 void
-programming_error (string s, string location)
+programming_error (const string &s, const string &location)
 {
   if (is_expected (s))
     print_message (LOG_DEBUG, location, _f ("suppressed programming error: %s", s) + "\n");
@@ -201,7 +201,7 @@ programming_error (string s, string location)
 
 /* Display a non-fatal error message, don't exit.  */
 void
-non_fatal_error (string s, string location)
+non_fatal_error (const string &s, const string &location)
 {
   if (is_expected (s))
     print_message (LOG_DEBUG, location, _f ("suppressed error: %s", s) + "\n");
@@ -213,7 +213,7 @@ non_fatal_error (string s, string location)
 
 /* Display a warning message. */
 void
-warning (string s, string location)
+warning (const string &s, const string &location)
 {
   if (is_expected (s))
     print_message (LOG_DEBUG, location, _f ("suppressed warning: %s", s) + "\n");
@@ -225,21 +225,21 @@ warning (string s, string location)
 
 /* Display a success message.  */
 void
-basic_progress (string s, string location)
+basic_progress (const string &s, const string &location)
 {
   print_message (LOG_BASIC, location, s + "\n", true);
 }
 
 /* Display information about the progress.  */
 void
-progress_indication (string s, bool newline, string location)
+progress_indication (const string &s, bool newline, const string &location)
 {
   print_message (LOG_PROGRESS, location, s, newline);
 }
 
 /* Display a single info message.  */
 void
-message (string s, bool newline, string location)
+message (const string &s, bool newline, const string &location)
 {
   // Use the progress loglevel for all normal messages (including progress msg)
   print_message (LOG_INFO, location, s, newline);
@@ -247,7 +247,7 @@ message (string s, bool newline, string location)
 
 /* Display a debug information, not necessarily on a new line.  */
 void
-debug_output (string s, bool newline, string location)
+debug_output (const string &s, bool newline, const string &location)
 {
   print_message (LOG_DEBUG, location, s, newline);
 }