From a4cb3e3de8531a7694f675e26074f0b1da4f23d7 Mon Sep 17 00:00:00 2001
From: Pralit Patel <pralit.patel@pnnl.gov>
Date: Thu, 25 May 2023 14:18:16 -0400
Subject: [PATCH] We seem to really have to call the R/python level flush
 commands to ensure our "cout" reaches Jupyter notebooks in a timely fashion

---
 R/query_library.R               |  1 +
 inst/include/interp_interface.h | 47 ++++++++++++++++++++++++---------
 2 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/R/query_library.R b/R/query_library.R
index f1ce5e4..3956aac 100644
--- a/R/query_library.R
+++ b/R/query_library.R
@@ -47,6 +47,7 @@ wrap_get_query <- function() {
 #' @return (string) The raw query from the query file with units set as an attribute
 #' if specified.
 #' @importFrom yaml read_yaml
+#' @export
 get_query <- wrap_get_query()
 
 
diff --git a/inst/include/interp_interface.h b/inst/include/interp_interface.h
index 2e9bc00..3b16cb2 100644
--- a/inst/include/interp_interface.h
+++ b/inst/include/interp_interface.h
@@ -4,6 +4,10 @@
 #include <exception>
 #include <string>
 
+// use boost::iostreams to wrap Interp API for cout
+#include <boost/iostreams/stream.hpp>
+#include <boost/iostreams/categories.hpp>
+
 #if __has_include("Rcpp.h")
 #define IS_INTERP_R
 #define STRICT_R_HEADERS
@@ -13,9 +17,6 @@
 #include <boost/python.hpp>
 #include <boost/python/numpy.hpp>
 
-// use boost::iostreams to wrap Python's C API for cout
-#include <boost/iostreams/stream.hpp>
-#include <boost/iostreams/categories.hpp>
 #include <boost/format.hpp>
 #else
 #error "Could not determine, or using an unknown interpreter. Only R and Python are currently supported."
@@ -32,6 +33,26 @@ class gcam_exception : public std::exception {
 };
 
 #if defined(USING_R)
+
+/*!
+ * \brief Wrap Rprintf in a boost::iostreams so we can use a C++ interface.
+ * \details We couldn't just use Rcout directly because we need to add a flush
+ *          for it to show up in a notebook in a timeley manner.
+ */
+class RStdoutSink {
+public:
+    typedef char char_type;
+    typedef boost::iostreams::sink_tag category;
+
+    inline std::streamsize write(const char* aString, std::streamsize aSize) {
+        Rprintf("%.*s", aSize, aString);
+        // using R_FlushConsole() doesn't work for whatever reason
+        Rcpp::Function flush("flush.console");
+        flush();
+        return aSize;
+    }
+};
+
 namespace Interp {
     using Rcpp::stop;
     using Rcpp::warning;
@@ -42,7 +63,8 @@ namespace Interp {
     using Rcpp::NumericMatrix;
 
     inline std::ostream& getInterpCout() {
-      return Rcpp::Rcout;
+        static boost::iostreams::stream<RStdoutSink> sRCout;
+        return sRCout;
     }
 
     inline std::string extract(const Rcpp::String& aStr) {
@@ -101,15 +123,16 @@ namespace Interp {
  */
 class PySysStdoutSink {
 public:
-  typedef char char_type;
-  typedef boost::iostreams::sink_tag category;
+    typedef char char_type;
+    typedef boost::iostreams::sink_tag category;
 
-  inline std::streamsize write(const char* aString, std::streamsize aSize) {
-    const std::streamsize MAX_PY_SIZE = 1000;
-    std::streamsize actualSize = std::min(aSize, MAX_PY_SIZE);
-    PySys_WriteStdout((boost::format("%%.%1%s") % actualSize).str().c_str(), aString);
-    return actualSize;
-  }
+    inline std::streamsize write(const char* aString, std::streamsize aSize) {
+        const std::streamsize MAX_PY_SIZE = 1000;
+        std::streamsize actualSize = std::min(aSize, MAX_PY_SIZE);
+        PySys_WriteStdout((boost::format("%%.%1%s") % actualSize).str().c_str(), aString);
+        boost::python::call_method<void>(PySys_GetObject("stdout"), "flush");
+        return actualSize;
+    }
 };
 
 namespace Interp {