From 803acc23f8cea3079681e9e624702e104adfd775 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sat, 10 Oct 2015 06:12:31 +0200
Subject: Implement disfigure step in build command

---
 bpkg/utility.cxx | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

(limited to 'bpkg/utility.cxx')

diff --git a/bpkg/utility.cxx b/bpkg/utility.cxx
index 9b194df..6cf6c35 100644
--- a/bpkg/utility.cxx
+++ b/bpkg/utility.cxx
@@ -4,6 +4,7 @@
 
 #include <bpkg/utility>
 
+#include <iostream>     // cout cin
 #include <system_error>
 
 #include <butl/process>
@@ -17,6 +18,46 @@ using namespace butl;
 namespace bpkg
 {
   bool
+  yn_prompt (const char* prompt, char def)
+  {
+    // Writing a robust Y/N prompt is more difficult than one would
+    // expect...
+    //
+    string a;
+    do
+    {
+      *diag_stream << prompt << ' ';
+
+      // getline() will set the failbit if it failed to extract anything,
+      // not even the delimiter and eofbit if it reached eof before seeing
+      // the delimiter.
+      //
+      //
+      getline (cin, a);
+
+      bool f (cin.fail ());
+      bool e (cin.eof ());
+
+      if (f || e)
+        *diag_stream << endl; // Assume no delimiter (newline).
+
+      if (f)
+        fail << "unable to read y/n answer from STDOUT";
+
+      if (a.empty () && def != '\0')
+      {
+        // Don't treat eof as the default answer. We need to see the
+        // actual newline.
+        //
+        if (!e)
+          a = def;
+      }
+    } while (a != "y" && a != "n");
+
+    return a == "y";
+  }
+
+  bool
   exists (const path& f)
   {
     try
-- 
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