From 76280cfc114e489f4b596dc2b0e2a560b7f13a55 Mon Sep 17 00:00:00 2001
From: jsmall-nvidia <jsmall@nvidia.com>
Date: Wed, 12 Dec 2018 15:17:54 -0500
Subject: Remove the valist from the ISlangWriter interface. Replace with
 begin/endAppendBuffer. (#751)

---
 source/core/slang-writer.cpp | 60 ++++++++++++++++++++++++++++----------------
 1 file changed, 39 insertions(+), 21 deletions(-)

(limited to 'source/core/slang-writer.cpp')

diff --git a/source/core/slang-writer.cpp b/source/core/slang-writer.cpp
index 4c5df0c8a..21c8c6209 100644
--- a/source/core/slang-writer.cpp
+++ b/source/core/slang-writer.cpp
@@ -25,15 +25,23 @@ SlangResult WriterHelper::print(const char* format, ...)
 {
     va_list args;
     va_start(args, format);
-    SlangResult res = m_writer->writeVaList(format, args);
 
-    if (res == SLANG_E_NOT_IMPLEMENTED)
+    SlangResult res = SLANG_OK;
+
+    size_t numChars;
     {
-        StringBuilder builder;
-        StringUtil::append(format, args, builder);
+        // Create a copy of args, as will be consumed by calcFormattedSize
+        va_list argsCopy;
+        va_copy(argsCopy, args);
+        numChars = StringUtil::calcFormattedSize(format, argsCopy);
+        va_end(argsCopy);
+    }
 
-        // Write if there is anything to write
-        res = (builder.Length()) ? m_writer->write(builder.Buffer(), builder.Length()) : SLANG_OK;
+    if (numChars > 0)
+    {
+        char* appendBuffer = m_writer->beginAppendBuffer(numChars);
+        StringUtil::calcFormatted(format, args, numChars, appendBuffer);
+        res = m_writer->endAppendBuffer(appendBuffer, numChars);
     }
 
     va_end(args);
@@ -52,6 +60,24 @@ ISlangUnknown* BaseWriter::getInterface(const Guid& guid)
     return (guid == IID_ISlangUnknown || guid == IID_ISlangWriter) ? static_cast<ISlangWriter*>(this) : nullptr;
 }
 
+/* !!!!!!!!!!!!!!!!!!!!!!!!! AppendBufferWriter !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*/
+
+SLANG_NO_THROW char* SLANG_MCALL AppendBufferWriter::beginAppendBuffer(size_t maxNumChars)
+{
+    m_appendBuffer.SetSize(maxNumChars);
+    return m_appendBuffer.Buffer();
+}
+
+SLANG_NO_THROW SlangResult SLANG_MCALL AppendBufferWriter::endAppendBuffer(char* buffer, size_t numChars)
+{
+    SLANG_ASSERT(m_appendBuffer.Buffer() == buffer && buffer + numChars <= m_appendBuffer.end());
+    // Do the actual write
+    SlangResult res = write(buffer, numChars);
+    // Clear so that buffer can't be written from again without assert
+    m_appendBuffer.Clear();
+    return res;
+}
+
 /* !!!!!!!!!!!!!!!!!!!!!!!!! CallbackWriter !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*/
 
 SlangResult CallbackWriter::write(const char* chars, size_t numChars)
@@ -78,19 +104,6 @@ FileWriter::~FileWriter()
     }
 }
 
-SlangResult FileWriter::writeVaList(const char* format, va_list args)
-{
-    // http://www.cplusplus.com/reference/cstdio/vfprintf/
-    ::vfprintf(m_file, format, args);
-
-    if (m_flags & WriterFlag::AutoFlush)
-    {
-        ::fflush(m_file);
-    }
-
-    return SLANG_OK;
-}
-
 SlangResult FileWriter::write(const char* text, size_t numChars)
 {
     const size_t numWritten = ::fwrite(text, sizeof(char), numChars, m_file);
@@ -133,9 +146,14 @@ SlangResult FileWriter::setMode(SlangWriterMode mode)
 
 /* !!!!!!!!!!!!!!!!!!!!!!!!! StringWriter !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*/
 
-SlangResult StringWriter::writeVaList(const char* format, va_list args)
+SLANG_NO_THROW char* SLANG_MCALL StringWriter::beginAppendBuffer(size_t maxNumChars)
+{
+    return m_builder->prepareForAppend(maxNumChars);
+}
+
+SLANG_NO_THROW SlangResult SLANG_MCALL StringWriter::endAppendBuffer(char* buffer, size_t numChars)
 {
-    StringUtil::append(format, args, *m_builder);
+    m_builder->appendInPlace(buffer, numChars);
     return SLANG_OK;
 }
 
-- 
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