2 files changed, 28 insertions, 0 deletions
diff --git a/Source/cmStringCommand.cxx b/Source/cmStringCommand.cxx
index 5a6cf48..b07eae1 100644
--- a/Source/cmStringCommand.cxx
+++ b/Source/cmStringCommand.cxx
@@ -62,6 +62,9 @@ bool cmStringCommand::InitialPass(std::vector<std::string> const& args,
   if (subCommand == "APPEND") {
     return this->HandleAppendCommand(args);
   }
+  if (subCommand == "PREPEND") {
+    return this->HandlePrependCommand(args);
+  }
   if (subCommand == "CONCAT") {
     return this->HandleConcatCommand(args);
   }
@@ -643,6 +646,30 @@ bool cmStringCommand::HandleAppendCommand(std::vector<std::string> const& args)
   return true;
 }
 
+bool cmStringCommand::HandlePrependCommand(
+  std::vector<std::string> const& args)
+{
+  if (args.size() < 2) {
+    this->SetError("sub-command PREPEND requires at least one argument.");
+    return false;
+  }
+
+  // Skip if nothing to prepend.
+  if (args.size() < 3) {
+    return true;
+  }
+
+  const std::string& variable = args[1];
+
+  std::string value = cmJoin(cmMakeRange(args).advance(2), std::string());
+  const char* oldValue = this->Makefile->GetDefinition(variable);
+  if (oldValue) {
+    value += oldValue;
+  }
+  this->Makefile->AddDefinition(variable, value.c_str());
+  return true;
+}
+
 bool cmStringCommand::HandleConcatCommand(std::vector<std::string> const& args)
 {
   if (args.size() < 2) {
diff --git a/Source/cmStringCommand.h b/Source/cmStringCommand.h
index 88015ad..0dded15 100644
--- a/Source/cmStringCommand.h
+++ b/Source/cmStringCommand.h
@@ -46,6 +46,7 @@ protected:
   bool HandleLengthCommand(std::vector<std::string> const& args);
   bool HandleSubstringCommand(std::vector<std::string> const& args);
   bool HandleAppendCommand(std::vector<std::string> const& args);
+  bool HandlePrependCommand(std::vector<std::string> const& args);
   bool HandleConcatCommand(std::vector<std::string> const& args);
   bool HandleStripCommand(std::vector<std::string> const& args);
   bool HandleRandomCommand(std::vector<std::string> const& args);