From 5d5cf261386aafd4276e443b3a2ccdf3a43cb024 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Wed, 12 Sep 2012 16:02:02 +0000
Subject: [PATCH] Added osgDB::getSortedDirectoryContents and
 osgDB::FileNameComparator to help with sorting directory contents into
 alphabetic and numerical order.

---
 include/osgDB/FileNameUtils | 50 +++++++++++++++++++++++++++++++++++++
 include/osgDB/FileUtils     |  5 ++++
 src/osgDB/FileUtils.cpp     |  7 ++++++
 3 files changed, 62 insertions(+)

diff --git a/include/osgDB/FileNameUtils b/include/osgDB/FileNameUtils
index 0094cb6aa..ed1e552b4 100644
--- a/include/osgDB/FileNameUtils
+++ b/include/osgDB/FileNameUtils
@@ -81,6 +81,56 @@ extern OSGDB_EXPORT std::string getRealPath(const std::string& path);
 /** Splits a path into elements between separators (including Windows' root, if any). */
 extern OSGDB_EXPORT void getPathElements(const std::string& path, std::vector<std::string> & out_elements);
 
+/** Functor for helping sort filename in alphabetical and numerical order when using in conjunction with std::sort.*/
+struct FileNameComparator
+{
+    inline bool operator() (const std::string& lhs, const std::string& rhs) const
+    {
+        std::string::size_type size_lhs = lhs.size();
+        std::string::size_type size_rhs = rhs.size();
+        std::string::size_type pos_lhs = 0;
+        std::string::size_type pos_rhs = 0;
+        while(pos_lhs<size_lhs && pos_rhs<size_rhs)
+        {
+            char c_lhs = lhs[pos_rhs];
+            char c_rhs = rhs[pos_rhs];
+            bool numeric_lhs = lhs[pos_lhs]>='0' && lhs[pos_lhs]<='9';
+            bool numeric_rhs = rhs[pos_rhs]>='0' && rhs[pos_rhs]<='9';
+            if (numeric_lhs && numeric_rhs)
+            {
+                std::string::size_type start_lhs = pos_lhs;
+                ++pos_lhs;
+                while(pos_lhs<size_lhs && (lhs[pos_lhs]>='0' && lhs[pos_lhs]<='9')) ++pos_lhs;
+
+                std::string::size_type start_rhs = pos_rhs;
+                ++pos_rhs;
+                while(pos_rhs<size_rhs && (rhs[pos_rhs]>='0' && rhs[pos_rhs]<='9')) ++pos_rhs;
+
+                if (pos_lhs<pos_rhs) return true;
+                else if (pos_rhs<pos_lhs) return false;
+
+                while(start_lhs<pos_lhs && start_rhs<pos_rhs)
+                {
+                    if (lhs[start_lhs]<rhs[start_rhs]) return true;
+                    if (lhs[start_lhs]>rhs[start_rhs]) return false;
+                    ++start_lhs;
+                    ++start_rhs;
+                }
+            }
+            else
+            {
+                if (c_lhs<c_rhs) return true;
+                else if (c_rhs<c_lhs) return false;
+
+                ++pos_lhs;
+                ++pos_rhs;
+            }
+        }
+
+        return pos_lhs<pos_rhs;
+    }
+};
+
 }
 
 #endif
diff --git a/include/osgDB/FileUtils b/include/osgDB/FileUtils
index 83758ff78..797fdf391 100644
--- a/include/osgDB/FileUtils
+++ b/include/osgDB/FileUtils
@@ -71,6 +71,11 @@ typedef std::vector<std::string> DirectoryContents;
   * Returns an empty array on any error.*/
 extern OSGDB_EXPORT DirectoryContents getDirectoryContents(const std::string& dirName);
 
+/** Return the contents of a directory, sorting the names into alphabetic and numberical order.
+  * Return value will contain filenames only, not absolute paths.
+  * Returns an empty array on any error.*/
+extern OSGDB_EXPORT DirectoryContents getSortedDirectoryContents(const std::string& dirName);
+
 /** Return the list of filenames that match the given filename with wildcards.
   * Will only expand '*', and will not expand wildcards in directory, only in
   * filename part of the given filename.
diff --git a/src/osgDB/FileUtils.cpp b/src/osgDB/FileUtils.cpp
index bb919f381..a018675d6 100644
--- a/src/osgDB/FileUtils.cpp
+++ b/src/osgDB/FileUtils.cpp
@@ -549,6 +549,13 @@ static void appendInstallationLibraryFilePaths(osgDB::FilePathList& filepath)
 
 #endif // unix getDirectoryContexts
 
+osgDB::DirectoryContents osgDB::getSortedDirectoryContents(const std::string& dirName)
+{
+    osgDB::DirectoryContents filenames = osgDB::getDirectoryContents(dirName);
+    std::sort(filenames.begin(), filenames.end(), osgDB::FileNameComparator());
+    return filenames;
+}
+
 
 osgDB::DirectoryContents osgDB::expandWildcardsInFilename(const std::string& filename)
 {