New class, useful for command-line interactive programs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10662 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 56 insertions, 0 deletions

diff --git a/include/Support/SlowOperationInformer.h b/include/Support/SlowOperationInformer.h
new file mode 100644
index 0000000..f27a055
--- /dev/null
+++ b/include/Support/SlowOperationInformer.h
@@ -0,0 +1,56 @@
+//===- SlowOperationInformer.h - Keep the user informed ---------*- C++ -*-===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file defines a simple object which can be used to let the user know what
+// is going on when a slow operation is happening,l and gives them the ability
+// to cancel it.  Potentially slow operations can stack allocate one of these
+// objects, and periodically call the "progress" method to update the progress
+// bar.  If the operation takes more than 3 seconds to complete, the progress
+// bar is automatically shown and updated every second.  As such, the slow
+// operation should not print stuff to the screen, and should not be confused if
+// an extra line appears on the screen (ie, the cursor should be at the start of
+// the line).
+//
+// If the user presses CTRL-C during the operation, the next invocation of the
+// progress method with throw an std::string object indicating that the
+// operation was cancelled.  As such, client code must be exception safe around
+// the progress method.
+//
+// Because SlowOperationInformers fiddle around with signals, they cannot be
+// nested.  The SIGINT signal handler is restored after the
+// SlowOperationInformer is destroyed, but the SIGALRM handlers is set back to
+// the default.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUPPORT_SLOW_OPERATION_INFORMER_H
+#define SUPPORT_SLOW_OPERATION_INFORMER_H
+
+#include <string>
+
+namespace llvm {
+  class SlowOperationInformer {
+    std::string OperationName;
+    unsigned LastPrintAmount;
+    
+    SlowOperationInformer(const SlowOperationInformer&);   // DO NOT IMPLEMENT
+    void operator=(const SlowOperationInformer&);          // DO NOT IMPLEMENT
+  public:
+    SlowOperationInformer(const std::string &Name);
+    ~SlowOperationInformer();
+    
+    /// progress - Clients should periodically call this method when they are in
+    /// an exception-safe state.  The Amount variable should indicate how far
+    /// along the operation is, given in 1/10ths of a percent (in other words,
+    /// Amount should range from 0 to 1000).
+    void progress(unsigned Amount);
+  };
+} // end namespace llvm
+
+#endif /* SLOW_OPERATION_INFORMER_H */