Add $<CONFIG:...> boolean query generator expression

This expression evaluates to '1' or '0' to indicate whether the build
configuration for which the expression is evaluated matches tha named
configuration.  In combination with the "$<0:...>" and "$<1:...>"
expressions this allows per-configuration content to be generated.

Source/cmDocumentGeneratorExpressions.h

@@ -18,6 +18,7 @@
   "Valid expressions are:\n"                                            \
   "  $<0:...>                  = empty string (ignores \"...\")\n"      \
   "  $<1:...>                  = content of \"...\"\n"                  \
+  "  $<CONFIG:cfg>             = '1' if config is \"cfg\", else '0'\n"  \
   "  $<CONFIGURATION>          = configuration name\n"                  \
   "  $<TARGET_FILE:tgt>        = main file (.exe, .so.1.2, .a)\n"       \
   "  $<TARGET_LINKER_FILE:tgt> = file used to link (.a, .lib, .so)\n"   \

Source/cmGeneratorExpression.cxx

@@ -14,6 +14,8 @@
 #include "cmMakefile.h"
 #include "cmTarget.h"
 
+#include <cmsys/String.h>
+
 //----------------------------------------------------------------------------
 cmGeneratorExpression::cmGeneratorExpression(
   cmMakefile* mf, const char* config,
@@ -25,6 +27,7 @@ cmGeneratorExpression::cmGeneratorExpression(
                            "_FILE(|_NAME|_DIR):" // Filename component.
                            "([A-Za-z0-9_.-]+)"   // Target name.
                            ">$");
+  this->TestConfig.compile("^\\$<CONFIG:([A-Za-z0-9_]*)>$");
 }
 
 //----------------------------------------------------------------------------
@@ -162,6 +165,12 @@ bool cmGeneratorExpression::Evaluate(const char* expr, std::string& result)
     {
     return cmGeneratorExpressionBool(expr+5, result, "OR", "0", "1");
     }
+  else if(this->TestConfig.find(expr))
+    {
+    result = cmsysString_strcasecmp(this->TestConfig.match(1).c_str(),
+                                    this->Config? this->Config:"") == 0
+      ? "1":"0";
+    }
   else
     {
     result = "Expression syntax not recognized.";

Source/cmGeneratorExpression.h

@@ -51,6 +51,7 @@ private:
   std::vector<char> Data;
   std::stack<size_t> Barriers;
   cmsys::RegularExpression TargetInfo;
+  cmsys::RegularExpression TestConfig;
   std::set<cmTarget*> Targets;
   bool Evaluate();
   bool Evaluate(const char* expr, std::string& result);

Tests/GeneratorExpression/CMakeLists.txt

@@ -12,6 +12,8 @@ add_custom_target(check ALL
     -Dtest_and_1=$<AND:1>
     -Dtest_and_1_0=$<AND:1,0>
     -Dtest_and_1_1=$<AND:1,1>
+    -Dtest_config_0=$<CONFIG:$<CONFIGURATION>x>
+    -Dtest_config_1=$<CONFIG:$<CONFIGURATION>>
     -Dtest_not_0=$<NOT:0>
     -Dtest_not_1=$<NOT:1>
     -Dtest_or_0=$<OR:0>

Tests/GeneratorExpression/check.cmake

@@ -13,6 +13,8 @@ check(test_and_0_1 "0")
 check(test_and_1 "1")
 check(test_and_1_0 "0")
 check(test_and_1_1 "1")
+check(test_config_0 "0")
+check(test_config_1 "1")
 check(test_not_0 "1")
 check(test_not_1 "0")
 check(test_or_0 "0")

Tests/RunCMake/GeneratorExpression/BadCONFIG-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/GeneratorExpression/BadCONFIG-stderr.txt

@@ -0,0 +1,8 @@
+CMake Error at BadCONFIG.cmake:1 \(add_custom_target\):
+  Error evaluating generator expression:
+
+    \$<CONFIG:.>
+
+  Expression syntax not recognized.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)$

Tests/RunCMake/GeneratorExpression/BadCONFIG.cmake

@@ -0,0 +1,3 @@
+add_custom_target(check ALL COMMAND check
+  $<CONFIG:.>
+  VERBATIM)

Tests/RunCMake/GeneratorExpression/RunCMakeTest.cmake

@@ -1,5 +1,6 @@
 include(RunCMake)
 
+run_cmake(BadCONFIG)
 run_cmake(BadOR)
 run_cmake(BadAND)
 run_cmake(BadNOT)