From bcefbe737dee16c58bc578d4d483727ff859f8de Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matth=C3=A4us=20G=2E=20Chajdas?= <cmake@anteru.net>
Date: Sat, 22 Feb 2014 19:46:48 +0100
Subject: [PATCH] FindHg: Add Hg_WC_INFO macro

Add a macro to extract information from a Hg work tree much like the
Subversion_WC_INFO macro does for Subversion work tree.
---
 Modules/FindHg.cmake | 35 ++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/Modules/FindHg.cmake b/Modules/FindHg.cmake
index 8dea65232..c418afdd2 100644
--- a/Modules/FindHg.cmake
+++ b/Modules/FindHg.cmake
@@ -2,7 +2,7 @@
 # FindHg
 # ------
 #
-#
+# Extract information from a mercurial working copy.
 #
 # The module defines the following variables:
 #
@@ -12,6 +12,20 @@
 #    HG_FOUND - true if the command line client was found
 #    HG_VERSION_STRING - the version of mercurial found
 #
+# If the command line client executable is found the following macro is defined:
+#
+# ::
+#
+#   HG_WC_INFO(<dir> <var-prefix>)
+#
+# Hg_WC_INFO extracts information of a mercurial working copy
+# at a given location.  This macro defines the following variables:
+#
+# ::
+#
+#   <var-prefix>_WC_CHANGESET - current changeset
+#   <var-prefix>_WC_REVISION - current revision
+#
 # Example usage:
 #
 # ::
@@ -19,11 +33,15 @@
 #    find_package(Hg)
 #    if(HG_FOUND)
 #      message("hg found: ${HG_EXECUTABLE}")
+#      HG_WC_INFO(${PROJECT_SOURCE_DIR} Project)
+#      message("Current revision is ${Project_WC_REVISION}")
+#      message("Current changeset is ${Project_WC_CHANGESET}")
 #    endif()
 
 #=============================================================================
 # Copyright 2010-2012 Kitware, Inc.
 # Copyright 2012      Rolf Eike Beer <eike@sf-mail.de>
+# Copyright 2014      Matthaeus G. Chajdas
 #
 # Distributed under the OSI-approved BSD License (the "License");
 # see accompanying file Copyright.txt for details.
@@ -53,6 +71,21 @@ if(HG_EXECUTABLE)
     set(HG_VERSION_STRING "${CMAKE_MATCH_1}")
   endif()
   unset(hg_version)
+
+  macro(HG_WC_INFO dir prefix)
+    execute_process(COMMAND ${HG_EXECUTABLE} id -i -n
+      WORKING_DIRECTORY ${dir}
+      RESULT_VARIABLE hg_id_result
+      ERROR_VARIABLE hg_id_error
+      OUTPUT_VARIABLE ${prefix}_WC_DATA
+      OUTPUT_STRIP_TRAILING_WHITESPACE)
+    if(NOT ${hg_id_result} EQUAL 0)
+      message(SEND_ERROR "Command \"${HG_EXECUTBALE} id -n\" in directory ${dir} failed with output:\n${hg_id_error}")
+    endif()
+
+    string(REGEX REPLACE "([0-9a-f]+)\\+? [0-9]+\\+?" "\\1" ${prefix}_WC_CHANGESET ${${prefix}_WC_DATA})
+    string(REGEX REPLACE "[0-9a-f]+\\+? ([0-9]+)\\+?" "\\1" ${prefix}_WC_REVISION ${${prefix}_WC_DATA})
+  endmacro(HG_WC_INFO)
 endif()
 
 # Handle the QUIETLY and REQUIRED arguments and set HG_FOUND to TRUE if