Add interface to cancel input continuation.

git-svn-id: http://root.cern.ch/svn/root/trunk@47803 27541ba8-7e3a-0410-8455-c3a389f83636

include/cling/MetaProcessor/MetaProcessor.h

@@ -129,6 +129,10 @@ namespace cling {
     int process(const char* input_line, cling::StoredValueRef* result = 0,
                 Interpreter::CompilationResult* compRes = 0);
 
+    ///\brief When continuation is requested, this cancels and ignores previous
+    /// input, resetting the continuation to a new line.
+    void cancelContinuation();
+
     ///\brief Executes a file given the CINT specific rules. Mainly used as:
     /// .x filename[(args)], which in turn includes the filename and runs a
     /// function with signature void filename(args)

lib/MetaProcessor/MetaProcessor.cpp

@@ -82,6 +82,10 @@ namespace cling {
     return 0;
   }
 
+  void MetaProcessor::cancelContinuation() {
+    m_InputValidator->reset();
+  }
+
   MetaProcessorOpts& MetaProcessor::getMetaProcessorOpts() {
     // Take interpreter's state
     m_Options.PrintingAST = m_Interp.isPrintingAST();