cmUVProcessChain: Add cmUVProcessChain

This class is ultimately intended as a replacement for cmsys::Process.
It spawns a series of processes using libuv, piping the output of each
command into the next.

Note: input support has not yet been implemented because write
support has not yet been implemented on cmUVStreambuf.

1 files changed, 72 insertions, 0 deletions

diff --git a/Tests/CMakeLib/testUVProcessChainHelper.cxx b/Tests/CMakeLib/testUVProcessChainHelper.cxx
new file mode 100644
index 0000000..263665d
--- /dev/null
+++ b/Tests/CMakeLib/testUVProcessChainHelper.cxx
@@ -0,0 +1,72 @@
+#include <chrono>
+#include <iostream>
+#include <set>
+#include <sstream>
+#include <string>
+#include <thread>
+
+#include <cctype>
+#include <cstdlib>
+
+std::string getStdin()
+{
+  char buffer[1024];
+  std::ostringstream str;
+  do {
+    std::cin.read(buffer, 1024);
+    str.write(buffer, std::cin.gcount());
+  } while (std::cin.gcount() > 0);
+  return str.str();
+}
+
+int main(int argc, char** argv)
+{
+  if (argc < 2) {
+    return -1;
+  }
+
+  std::string command = argv[1];
+  if (command == "echo") {
+    std::this_thread::sleep_for(std::chrono::milliseconds(3000));
+    std::cout << "HELLO world!" << std::flush;
+    std::cerr << "1" << std::flush;
+    return 0;
+  }
+  if (command == "capitalize") {
+    std::this_thread::sleep_for(std::chrono::milliseconds(9000));
+    std::string input = getStdin();
+    for (auto& c : input) {
+      c = static_cast<char>(std::toupper(c));
+    }
+    std::cout << input << std::flush;
+    std::cerr << "2" << std::flush;
+    return 1;
+  }
+  if (command == "dedup") {
+    // Use a nested scope to free all resources before aborting below.
+    {
+      std::string input = getStdin();
+      std::set<char> seen;
+      std::string output;
+      for (auto c : input) {
+        if (!seen.count(c)) {
+          seen.insert(c);
+          output += c;
+        }
+      }
+      std::cout << output << std::flush;
+      std::cerr << "3" << std::flush;
+    }
+
+    // On Windows, the exit code of abort() is different between debug and
+    // release builds, and does not yield a term_signal in libuv in either
+    // case. For the sake of simplicity, we just return another non-zero code.
+#ifdef _WIN32
+    return 2;
+#else
+    std::abort();
+#endif
+  }
+
+  return -1;
+}