Make CMake read Ceres version directly from include/ceres/version.h.

- Previously we had the Ceres version defined in two places, one in
  include/ceres/version.h, and one in the main CMakeLists.
- Now the main CMakeLists reads the Ceres version directly from
  version.h, as does the make_release script, so that we have a single
  place (version.h) in which the current Ceres version is defined.

Change-Id: Ie80aa7d38f5b576d3ed4d6109dd699f565c91027

cmake/ReadCeresVersionFromSource.cmake

@@ -0,0 +1,81 @@
+# Ceres Solver - A fast non-linear least squares minimizer
+# Copyright 2015 Google Inc. All rights reserved.
+# http://ceres-solver.org/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+#   this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+# * Neither the name of Google Inc. nor the names of its contributors may be
+#   used to endorse or promote products derived from this software without
+#   specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+# Author: alexs.mac@gmail.com (Alex Stewart)
+#
+
+# Extract Ceres version from <CERES_SOURCE_ROOT>/include/ceres/version.h
+# so that we only have a single definition of the Ceres version, not two
+# one in the source and one in the CMakeLists.txt.
+macro(read_ceres_version_from_source CERES_SOURCE_ROOT)
+  set(CERES_VERSION_FILE ${CERES_SOURCE_ROOT}/include/ceres/version.h)
+  if (NOT EXISTS ${CERES_VERSION_FILE})
+    message(FATAL_ERROR "Cannot find Ceres version.h file in specified "
+      "Ceres source directory: ${CERES_SOURCE_ROOT}, it is not here: "
+      "${CERES_VERSION_FILE}")
+  endif()
+
+  file(READ ${CERES_VERSION_FILE} CERES_VERSION_FILE_CONTENTS)
+
+  string(REGEX MATCH "#define CERES_VERSION_MAJOR [0-9]+"
+    CERES_VERSION_MAJOR "${CERES_VERSION_FILE_CONTENTS}")
+  string(REGEX REPLACE "#define CERES_VERSION_MAJOR ([0-9]+)" "\\1"
+    CERES_VERSION_MAJOR "${CERES_VERSION_MAJOR}")
+  # NOTE: if (VAR) is FALSE if VAR is numeric and <= 0, as such we cannot use
+  #       it for testing version numbers, which might well be zero, at least
+  #       for the patch version, hence check for empty string explicitly.
+  if ("${CERES_VERSION_MAJOR}" STREQUAL "")
+    message(FATAL_ERROR "Failed to extract Ceres major version from "
+      "${CERES_VERSION_FILE}")
+  endif()
+
+  string(REGEX MATCH "#define CERES_VERSION_MINOR [0-9]+"
+    CERES_VERSION_MINOR "${CERES_VERSION_FILE_CONTENTS}")
+  string(REGEX REPLACE "#define CERES_VERSION_MINOR ([0-9]+)" "\\1"
+    CERES_VERSION_MINOR "${CERES_VERSION_MINOR}")
+  if ("${CERES_VERSION_MINOR}" STREQUAL "")
+    message(FATAL_ERROR "Failed to extract Ceres minor version from "
+      "${CERES_VERSION_FILE}")
+  endif()
+
+  string(REGEX MATCH "#define CERES_VERSION_REVISION [0-9]+"
+    CERES_VERSION_PATCH "${CERES_VERSION_FILE_CONTENTS}")
+  string(REGEX REPLACE "#define CERES_VERSION_REVISION ([0-9]+)" "\\1"
+    CERES_VERSION_PATCH "${CERES_VERSION_PATCH}")
+  if ("${CERES_VERSION_PATCH}" STREQUAL "")
+    message(FATAL_ERROR "Failed to extract Ceres patch version from "
+      "${CERES_VERSION_FILE}")
+  endif()
+
+  # This is on a single line s/t CMake does not interpret it as a list of
+  # elements and insert ';' separators which would result in 3.;2.;0 nonsense.
+  set(CERES_VERSION "${CERES_VERSION_MAJOR}.${CERES_VERSION_MINOR}.${CERES_VERSION_PATCH}")
+
+  message(STATUS "Detected Ceres version: ${CERES_VERSION} from "
+    "${CERES_VERSION_FILE}")
+endmacro()