experiment with -x option

ppremake/config_msvc.h

@@ -86,5 +86,5 @@
  **         Also be sure to change the version number        **
  **             at the beginning of configure.in.            **
  ****************                              ****************/
-#define VERSION "1.14"
+#define VERSION "1.15"
 /****************  UPDATE VERSION NUMBER HERE  ****************/

ppremake/configure.in

@@ -5,7 +5,7 @@ dnl ****************  UPDATE VERSION NUMBER HERE  ****************
 dnl **         Also be sure to change the version number        **
 dnl **                at the end of config_msvc.h.              **
 dnl ****************                              ****************
-AM_INIT_AUTOMAKE(ppremake, 1.14)
+AM_INIT_AUTOMAKE(ppremake, 1.15)
 dnl ****************  UPDATE VERSION NUMBER HERE  ****************
 
 AM_CONFIG_HEADER(config.h)

ppremake/ppScope.cxx

@@ -3,6 +3,7 @@
 // 
 ////////////////////////////////////////////////////////////////////
 
+#include "ppremake.h"
 #include "ppScope.h"
 #include "ppNamedScopes.h"
 #include "ppFilenamePattern.h"
@@ -493,7 +494,29 @@ set_directory(PPDirectory *directory) {
 ////////////////////////////////////////////////////////////////////
 string PPScope::
 expand_string(const string &str) {
-  return r_expand_string(str, (ExpandedVariable *)NULL);
+  string result = r_expand_string(str, (ExpandedVariable *)NULL);
+
+  if (debug_expansions > 0 && str != result) {
+    // Look for the str in our table--how many times has this
+    // particular string been expanded?
+    ExpandResultCount &result_count = debug_expand[str];
+
+    // Then, how many times has it expanded to this same result?
+    // First, assuming this is the first time it has expanded to this
+    // result, try to insert the result string with an initial count
+    // of 1.
+    pair<ExpandResultCount::iterator, bool> r = 
+      result_count.insert(ExpandResultCount::value_type(result, 1));
+
+    if (!r.second) {
+      // If the result string was not successfully inserted into the
+      // map, it was already there--so increment the count.
+      ExpandResultCount::iterator rci = r.first;
+      (*rci).second++;
+    }
+  }
+
+  return result;
 }
 
 ////////////////////////////////////////////////////////////////////

ppremake/ppremake.cxx

@@ -33,6 +33,36 @@ bool windows_platform = false;
 bool dry_run = false;
 bool verbose_dry_run = false;
 int verbose = 0;
+int debug_expansions = 0;
+
+DebugExpand debug_expand;
+
+class DebugExpandReport {
+public:
+  DebugExpandReport(DebugExpand::const_iterator source, 
+                    ExpandResultCount::const_iterator result) :
+    _source(source),
+    _result(result)
+  { }
+
+  const string &get_source() const {
+    return (*_source).first;
+  }
+  const string &get_result() const {
+    return (*_result).first;
+  }
+  int get_count() const {
+    return (*_result).second;
+  }
+
+  bool operator < (const DebugExpandReport &other) const {
+    return get_count() > other.get_count();
+  }
+    
+  DebugExpand::const_iterator _source;
+  ExpandResultCount::const_iterator _result;
+};
+  
 
 static void
 usage() {
@@ -74,9 +104,15 @@ usage() {
     "  -I           Report the compiled-in default for INSTALL_DIR, and exit.\n"
     "  -v           Turn on verbose output (may help in debugging .pp files).\n"
     "  -vv          Be very verbose (if you're getting desperate).\n"
+    "  -x count     Print a histogram of the count most-frequently expanded strings\n"
+    "               and their results.  Useful to optimize .pp scripts so that\n"
+    "               variables are not needlessly repeatedly expanded.\n\n"
+
     "  -P           Report the current platform name, and exit.\n\n"
+
     "  -D pp.dep    Examine the given dependency file, and re-run ppremake\n"
     "               only if the dependency file is stale.\n\n"
+
     "  -d           Instead of generating makefiles, report the set of\n"
     "               subdirectories that the named subdirectory depends on.\n"
     "               Directories are named by their local name, not by the\n"
@@ -229,7 +265,7 @@ main(int argc, char *argv[]) {
   string progname = argv[0];
   extern char *optarg;
   extern int optind;
-  const char *optstr = "hVIvPD:drnNp:c:s:";
+  const char *optstr = "hVIvx:PD:drnNp:c:s:";
 
   bool any_d = false;
   bool dependencies_stale = false;
@@ -268,6 +304,10 @@ main(int argc, char *argv[]) {
       ++verbose;
       break;
 
+    case 'x':
+      debug_expansions = atoi(optarg);
+      break;
+
     case 'P':
       report_platform();
       exit(0);
@@ -408,6 +448,32 @@ main(int argc, char *argv[]) {
     }
   }
 
+  if (debug_expansions > 0) {
+    // Now report the worst expansion offenders.  These are the
+    // strings that were most often expanded to the same thing.
+    cerr << "\nExpansion report:\n";
+    vector<DebugExpandReport> report;
+
+    DebugExpand::const_iterator dei;
+    for (dei = debug_expand.begin(); dei != debug_expand.end(); ++dei) {
+      const ExpandResultCount &result_count = (*dei).second;
+      ExpandResultCount::const_iterator rci;
+      for (rci = result_count.begin(); rci != result_count.end(); ++rci) {
+        report.push_back(DebugExpandReport(dei, rci));
+      }
+    }
+
+    sort(report.begin(), report.end());
+
+    int num_reports = min((int)report.size(), debug_expansions);
+    for (int i = 0; i < num_reports; i++) {
+      cerr << "\"" << report[i].get_source() << "\" -> \"" 
+           << report[i].get_result()
+           << "\" (" << report[i].get_count() << ")\n";
+    }
+    cerr << "\n";
+  }
+
   cerr << "No errors.\n";
   return (0);
 }

ppremake/ppremake.h

@@ -50,6 +50,7 @@ typedef ios::seek_dir ios_seekdir;
 #endif
 
 #include <string>
+#include <map>
 
 #ifdef HAVE_NAMESPACE
 using namespace std;
@@ -92,6 +93,16 @@ extern bool windows_platform;
 extern bool dry_run;
 extern bool verbose_dry_run;
 extern int verbose; // 0..9 to set verbose level.  0 == off.
+extern int debug_expansions;
+
+/* This structure tracks the number of expansions that are performed
+   on a particular string, and the different values it produces, only
+   if debug_expansions (above) is set true by command-line parameter
+   -x. */
+typedef map<string, int> ExpandResultCount;
+typedef map<string, ExpandResultCount> DebugExpand;
+extern DebugExpand debug_expand;
+
 #endif
 
 /* These are defined so that we may build Filename, DSearchPath, and