cmFilePathUuid: Add class to generate deterministic unique file names

The class generates a semi-unique (checksum based) pathless file name
from a full source file path.

1 files changed, 77 insertions, 0 deletions

diff --git a/Source/cmFilePathUuid.h b/Source/cmFilePathUuid.h
new file mode 100644
index 0000000..42e89b1
--- /dev/null
+++ b/Source/cmFilePathUuid.h
@@ -0,0 +1,77 @@
+/*============================================================================
+  CMake - Cross Platform Makefile Generator
+  Copyright 2016 Sebastian Holtermann (sebholt@xwmw.org)
+
+  Distributed under the OSI-approved BSD License (the "License");
+  see accompanying file Copyright.txt for details.
+
+  This software is distributed WITHOUT ANY WARRANTY; without even the
+  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the License for more information.
+============================================================================*/
+
+#ifndef cmFilePathUuid_h
+#define cmFilePathUuid_h
+
+#include "cmStandardIncludes.h"
+
+#include <string>
+#include <utility>
+
+class cmMakefile;
+
+/** \class cmFilePathUuid
+ * @brief Generates a unique pathless file name with a checksum component
+ *        calculated from the file path.
+ *
+ * The checksum is calculated from the relative file path to the
+ * closest known project directory. This guarantees reproducibility
+ * when source and build directory differ e.g. for different project
+ * build directories.
+ */
+class cmFilePathUuid
+{
+public:
+  /// Maximum number of characters to use from the file name
+  static const size_t partLengthName = 14;
+  /// Maximum number of characters to use from the path checksum
+  static const size_t partLengthCheckSum = 14;
+
+  /// @brief Initilizes the parent directories from a makefile
+  cmFilePathUuid(cmMakefile* makefile);
+
+  /// @brief Initilizes the parent directories manually
+  cmFilePathUuid(const std::string& currentSrcDir,
+                 const std::string& currentBinDir,
+                 const std::string& projectSrcDir,
+                 const std::string& projectBinDir);
+
+  /* @brief Calculates and returns the uuid for a file path
+   *
+   * @arg outputPrefix optional string to prepend to the result
+   * @arg outputSuffix optional string to append to the result
+   */
+  std::string get(const std::string& filePath, const char* outputPrefix = NULL,
+                  const char* outputSuffix = NULL);
+
+private:
+  void initParentDirs(const std::string& currentSrcDir,
+                      const std::string& currentBinDir,
+                      const std::string& projectSrcDir,
+                      const std::string& projectBinDir);
+
+  /// Returns the relative path and the parent directory key string (seed)
+  void GetRelPathSeed(const std::string& filePath, std::string& sourceRelPath,
+                      std::string& sourceRelSeed);
+
+  std::string GetChecksumString(const std::string& sourceFilename,
+                                const std::string& sourceRelPath,
+                                const std::string& sourceRelSeed);
+
+  /// Size of the parent directory list
+  static const size_t numParentDirs = 4;
+  /// List of (directory name, seed name) pairs
+  std::pair<std::string, std::string> parentDirs[numParentDirs];
+};
+
+#endif