1 files changed, 49 insertions, 0 deletions
diff --git a/Source/cmGeneratorExpression.cxx b/Source/cmGeneratorExpression.cxx
index 3f8e962..7d8df37 100644
--- a/Source/cmGeneratorExpression.cxx
+++ b/Source/cmGeneratorExpression.cxx
@@ -13,6 +13,7 @@
 
 #include "cmMakefile.h"
 #include "cmTarget.h"
+#include "assert.h"
 
 #include <cmsys/String.h>
 
@@ -129,3 +130,51 @@ cmCompiledGeneratorExpression::~cmCompiledGeneratorExpression()
     delete *it;
     }
 }
+
+std::string cmGeneratorExpression::Preprocess(const std::string &input,
+                                              PreprocessContext context)
+{
+  if (context != StripAllGeneratorExpressions)
+  {
+    assert(!"cmGeneratorExpression::Preprocess called with invalid args");
+    return std::string();
+  }
+
+  std::string result;
+  std::string::size_type pos = 0;
+  std::string::size_type lastPos = pos;
+  while((pos = input.find("$<", lastPos)) != input.npos)
+    {
+    result += input.substr(lastPos, pos - lastPos);
+    pos += 2;
+    int nestingLevel = 1;
+    const char *c = input.c_str() + pos;
+    const char * const cStart = c;
+    for ( ; *c; ++c)
+      {
+      if(c[0] == '$' && c[1] == '<')
+        {
+        ++nestingLevel;
+        ++c;
+        continue;
+        }
+      if(c[0] == '>')
+        {
+        --nestingLevel;
+        if (nestingLevel == 0)
+          {
+          break;
+          }
+        }
+      }
+    const std::string::size_type traversed = (c - cStart) + 1;
+    if (!*c)
+      {
+      result += "$<" + input.substr(pos, traversed);
+      }
+    pos += traversed;
+    lastPos = pos;
+    }
+  result += input.substr(lastPos);
+  return result;
+}