ENH: Refactor find_library search logic

Previously we searched for library files by enumerating every possible
combination of prefix and suffix.  Now we load (and cache) directory
content from disk and search for matching file names.  This should
reduce disk access.  It will also allow more advanced matching rules in
the future.  See issue #3470.

Source/cmFindLibraryCommand.cxx

@@ -16,6 +16,8 @@
 =========================================================================*/
 #include "cmFindLibraryCommand.h"
 #include "cmCacheManager.h"
+#include <cmsys/Directory.hxx>
+#include <cmsys/stl/algorithm>
 
 cmFindLibraryCommand::cmFindLibraryCommand()
 { 
@@ -227,74 +229,229 @@ std::string cmFindLibraryCommand::FindLibrary()
 }
 
 //----------------------------------------------------------------------------
-std::string cmFindLibraryCommand::FindNormalLibrary()
+struct cmFindLibraryHelper
 {
+  cmFindLibraryHelper(cmMakefile* mf);
+
+  // Context information.
+  cmMakefile* Makefile;
+  cmGlobalGenerator* GG;
+
+  // List of valid prefixes and suffixes.
+  std::vector<std::string> Prefixes;
+  std::vector<std::string> Suffixes;
+  std::string PrefixRegexStr;
+  std::string SuffixRegexStr;
+
+  // Keep track of the best library file found so far.
+  typedef std::vector<std::string>::size_type size_type;
+  std::string BestPath;
+  size_type BestPrefix;
+  size_type BestSuffix;
+
+  // Current name under consideration.
+  cmsys::RegularExpression NameRegex;
+  bool TryRawName;
+  std::string RawName;
+
+  // Current full path under consideration.
+  std::string TestPath;
+
+  void RegexFromLiteral(std::string& out, std::string const& in);
+  void RegexFromList(std::string& out, std::vector<std::string> const& in);
+  size_type GetPrefixIndex(std::string const& prefix)
+    {
+    return cmsys_stl::find(this->Prefixes.begin(), this->Prefixes.end(),
+                           prefix) - this->Prefixes.begin();
+    }
+  size_type GetSuffixIndex(std::string const& suffix)
+    {
+    return cmsys_stl::find(this->Suffixes.begin(), this->Suffixes.end(),
+                           suffix) - this->Suffixes.begin();
+    }
+  bool HasValidSuffix(std::string const& name);
+  void SetName(std::string const& name);
+  bool CheckDirectory(std::string const& path);
+};
+
+//----------------------------------------------------------------------------
+cmFindLibraryHelper::cmFindLibraryHelper(cmMakefile* mf):
+  Makefile(mf)
+{
+  this->GG = this->Makefile->GetLocalGenerator()->GetGlobalGenerator();
+
   // Collect the list of library name prefixes/suffixes to try.
   const char* prefixes_list =
     this->Makefile->GetRequiredDefinition("CMAKE_FIND_LIBRARY_PREFIXES");
   const char* suffixes_list =
     this->Makefile->GetRequiredDefinition("CMAKE_FIND_LIBRARY_SUFFIXES");
-  std::vector<std::string> prefixes;
+  cmSystemTools::ExpandListArgument(prefixes_list, this->Prefixes, true);
-  std::vector<std::string> suffixes;
+  cmSystemTools::ExpandListArgument(suffixes_list, this->Suffixes, true);
-  cmSystemTools::ExpandListArgument(prefixes_list, prefixes, true);
+  this->RegexFromList(this->PrefixRegexStr, this->Prefixes);
-  cmSystemTools::ExpandListArgument(suffixes_list, suffixes, true);
+  this->RegexFromList(this->SuffixRegexStr, this->Suffixes);
 
-  // Search the entire path for each name.
+  this->TryRawName = false;
-  std::string tryPath;
+
-  for(std::vector<std::string>::const_iterator ni = this->Names.begin();
+  // No library file has yet been found.
-      ni != this->Names.end() ; ++ni)
+  this->BestPrefix = this->Prefixes.size();
+  this->BestSuffix = this->Suffixes.size();
+}
+
+//----------------------------------------------------------------------------
+void cmFindLibraryHelper::RegexFromLiteral(std::string& out,
+                                           std::string const& in)
 {
-    // If the original library name provided by the user matches one of
+  for(std::string::const_iterator ci = in.begin(); ci != in.end(); ++ci)
-    // the suffixes, try it first.
+    {
-    bool tryOrig = false;
+    char ch = *ci;
-    std::string const& name = *ni;
+    if(ch == '[' || ch == ']' || ch == '(' || ch == ')' || ch == '\\' ||
-    for(std::vector<std::string>::const_iterator si = suffixes.begin();
+       ch == '.' || ch == '*' || ch == '+' || ch == '?' || ch == '-' ||
-        !tryOrig && si != suffixes.end(); ++si)
+       ch == '^' || ch == '$')
+      {
+      out += "\\";
+      }
+#if defined(_WIN32) || defined(__APPLE__)
+    out += tolower(ch);
+#else
+    out += ch;
+#endif
+    }
+}
+
+//----------------------------------------------------------------------------
+void cmFindLibraryHelper::RegexFromList(std::string& out,
+                                        std::vector<std::string> const& in)
+{
+  // Surround the list in parens so the '|' does not apply to anything
+  // else and the result can be checked after matching.
+  out += "(";
+  const char* sep = "";
+  for(std::vector<std::string>::const_iterator si = in.begin();
+      si != in.end(); ++si)
+    {
+    // Separate from previous item.
+    out += sep;
+    sep = "|";
+
+    // Append this item.
+    this->RegexFromLiteral(out, *si);
+    }
+  out += ")";
+}
+
+//----------------------------------------------------------------------------
+bool cmFindLibraryHelper::HasValidSuffix(std::string const& name)
+{
+  // Check if the given name ends in a valid library suffix.
+  for(std::vector<std::string>::const_iterator si = this->Suffixes.begin();
+      si != this->Suffixes.end(); ++si)
     {
     std::string const& suffix = *si;
     if(name.length() > suffix.length() &&
        name.substr(name.size()-suffix.length()) == suffix)
       {
-        tryOrig = true;
+      return true;
+      }
+    }
+  return false;
+}
+
+//----------------------------------------------------------------------------
+void cmFindLibraryHelper::SetName(std::string const& name)
+{
+  // Consider checking the raw name too.
+  this->TryRawName = this->HasValidSuffix(name);
+  this->RawName = name;
+
+  // Build a regular expression to match library names.
+  std::string regex = "^";
+  regex += this->PrefixRegexStr;
+  this->RegexFromLiteral(regex, name);
+  regex += this->SuffixRegexStr;
+  regex += "$";
+  this->NameRegex.compile(regex.c_str());
+}
+
+//----------------------------------------------------------------------------
+bool cmFindLibraryHelper::CheckDirectory(std::string const& path)
+{
+  // If the original library name provided by the user matches one of
+  // the suffixes, try it first.  This allows users to search
+  // specifically for a static library on some platforms (on MS tools
+  // one cannot tell just from the library name whether it is a static
+  // library or an import library).
+  if(this->TryRawName)
+    {
+    this->TestPath = path;
+    this->TestPath += this->RawName;
+    if(cmSystemTools::FileExists(this->TestPath.c_str(), true))
+      {
+      this->BestPath =
+        cmSystemTools::CollapseFullPath(this->TestPath.c_str());
+      cmSystemTools::ConvertToUnixSlashes(this->BestPath);
+      return true;
       }
     }
 
+  // Search for a file matching the library name regex.
+  std::string dir = path;
+  cmSystemTools::ConvertToUnixSlashes(dir);
+  std::set<cmStdString> const& files = this->GG->GetDirectoryContent(dir);
+  for(std::set<cmStdString>::const_iterator fi = files.begin();
+      fi != files.end(); ++fi)
+    {
+    std::string const& origName = *fi;
+#if defined(_WIN32) || defined(__APPLE__)
+    std::string testName = cmSystemTools::LowerCase(origName);
+#else
+    std::string const& testName = origName;
+#endif
+    if(this->NameRegex.find(testName))
+      {
+      this->TestPath = path;
+      this->TestPath += origName;
+      if(!cmSystemTools::FileIsDirectory(this->TestPath.c_str()))
+        {
+        // This is a matching file.  Check if it is better than the
+        // best name found so far.  Earlier prefixes are preferred,
+        // followed by earlier suffixes.
+        size_type prefix = this->GetPrefixIndex(this->NameRegex.match(1));
+        size_type suffix = this->GetSuffixIndex(this->NameRegex.match(2));
+        if(this->BestPath.empty() || prefix < this->BestPrefix ||
+           (prefix == this->BestPrefix && suffix < this->BestSuffix))
+          {
+          this->BestPath = this->TestPath;
+          this->BestPrefix = prefix;
+          this->BestSuffix = suffix;
+          }
+        }
+      }
+    }
+
+  // Use the best candidate found in this directory, if any.
+  return !this->BestPath.empty();
+}
+
+//----------------------------------------------------------------------------
+std::string cmFindLibraryCommand::FindNormalLibrary()
+{
+  // Search the entire path for each name.
+  cmFindLibraryHelper helper(this->Makefile);
+  for(std::vector<std::string>::const_iterator ni = this->Names.begin();
+      ni != this->Names.end() ; ++ni)
+    {
+    // Switch to searching for this name.
+    std::string const& name = *ni;
+    helper.SetName(name);
+
+    // Search every directory.
     for(std::vector<std::string>::const_iterator
           p = this->SearchPaths.begin();
         p != this->SearchPaths.end(); ++p)
       {
-      // Try the original library name as specified by the user.
+      if(helper.CheckDirectory(*p))
-      if(tryOrig)
         {
-        tryPath = *p;
+        return helper.BestPath;
-        tryPath += name;
-        if(cmSystemTools::FileExists(tryPath.c_str(), true))
-          {
-          tryPath = cmSystemTools::CollapseFullPath(tryPath.c_str());
-          cmSystemTools::ConvertToUnixSlashes(tryPath);
-          return tryPath;
-          }
-        }
-
-      // Try various library naming conventions.
-      for(std::vector<std::string>::iterator prefix = prefixes.begin();
-          prefix != prefixes.end(); ++prefix)
-        {
-        for(std::vector<std::string>::iterator suffix = suffixes.begin();
-            suffix != suffixes.end(); ++suffix)
-          {
-          tryPath = *p;
-          tryPath += *prefix;
-          tryPath += name;
-          tryPath += *suffix;
-          if(cmSystemTools::FileExists(tryPath.c_str())
-             && !cmSystemTools::FileIsDirectory(tryPath.c_str()))
-            {
-            tryPath = cmSystemTools::CollapseFullPath(tryPath.c_str());
-            cmSystemTools::ConvertToUnixSlashes(tryPath);
-            return tryPath;
-            }
-          }
         }
       }
     }