Remove the valist from the ISlangWriter interface. Replace with begin/endAppendBuffer. (#751)

3 files changed, 78 insertions, 41 deletions

diff --git a/slang.h b/slang.h
index 5ea1d13f8..23bc830e7 100644
--- a/slang.h
+++ b/slang.h
@@ -352,8 +352,6 @@ convention for interface methods.
 #include <stddef.h>
 #endif // ! SLANG_NO_STDDEF
 
-#include <stdarg.h>
-
 #ifdef __cplusplus
 extern "C"
 {
@@ -851,17 +849,23 @@ extern "C"
     struct ISlangWriter : public ISlangUnknown
     {
     public:
-            /** Write the formatted string with the used args. If returns SLANG_E_NOT_IMPLEMENTED, will use a default internal implementation, and call write with result
-            @param format Format string
-            @param args The arguments
-            @return SLANG_E_NOT_IMPLEMENTED if not implemented, SLANG_OK on success */
-        virtual SLANG_NO_THROW SlangResult SLANG_MCALL writeVaList(const char* format, va_list args) = 0;
+            /** Begin an append buffer.
+            NOTE! Only one append buffer can be active at any time.
+            @param maxNumChars The maximum of chars that will be appended
+            @returns The start of the buffer for appending to. */    
+        virtual SLANG_NO_THROW char* SLANG_MCALL beginAppendBuffer(size_t maxNumChars) = 0;
+            /** Ends the append buffer, and is equivalent to a write of the append buffer.
+            NOTE! That an endAppendBuffer is not necessary if there are no characters to write.
+            @param buffer is the start of the data to append and must be identical to last value returned from beginAppendBuffer
+            @param numChars must be a value less than or equal to what was returned from last call to beginAppendBuffer
+            @returns Result, will be SLANG_OK on success */
+        virtual SLANG_NO_THROW SlangResult SLANG_MCALL endAppendBuffer(char* buffer, size_t numChars) = 0;
             /** Write text to the writer
             @param chars The characters to write out
             @param numChars The amount of characters
             @returns SLANG_OK on success */
         virtual SLANG_NO_THROW SlangResult SLANG_MCALL write(const char* chars, size_t numChars) = 0;
-            /** Flushes any content to the ouput */
+            /** Flushes any content to the output */
         virtual SLANG_NO_THROW void SLANG_MCALL flush() = 0;
             /** Determines if the writer stream is to the console, and can be used to alter the output 
             @returns Returns true if is a console writer */
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;
 }
 
diff --git a/source/core/slang-writer.h b/source/core/slang-writer.h
index 0fa336d6e..4c30ddb96 100644
--- a/source/core/slang-writer.h
+++ b/source/core/slang-writer.h
@@ -4,11 +4,11 @@
 #include "slang-string.h"
 
 #include "../../slang-com-helper.h"
+#include "../../source/core/list.h"
 
 namespace Slang
 {
 
-
 class WriterHelper
 {
 public:
@@ -48,7 +48,6 @@ public:
     SLANG_NO_THROW uint32_t SLANG_MCALL release() { return (m_flags & WriterFlag::IsStatic) ? 1 : (uint32_t)releaseReference(); }
 
     // ISlangWriter - default impl
-    SLANG_NO_THROW virtual SlangResult SLANG_MCALL writeVaList(const char* format, va_list args) { SLANG_UNUSED(args); SLANG_UNUSED(format); return SLANG_E_NOT_IMPLEMENTED; }
     SLANG_NO_THROW virtual void SLANG_MCALL flush() SLANG_OVERRIDE {}
     SLANG_NO_THROW virtual bool SLANG_MCALL isConsole() SLANG_OVERRIDE { return (m_flags & WriterFlag::IsConsole) != 0; }
     SLANG_NO_THROW virtual SlangResult SLANG_MCALL setMode(SlangWriterMode mode) SLANG_OVERRIDE { SLANG_UNUSED(mode);  return SLANG_FAIL; }
@@ -63,10 +62,28 @@ protected:
     WriterFlags m_flags;
 };
 
-class CallbackWriter : public BaseWriter
+/* Implemented the append buffer part of the writer, such that calls to begin/endAppendBuffer are transformed into appropriate calls to write method */
+class AppendBufferWriter : public BaseWriter
 {
 public:
-    typedef BaseWriter Parent;   
+    typedef BaseWriter Parent;
+
+    // ISlangWriter default impl for appendBuffer
+    SLANG_NO_THROW char* SLANG_MCALL beginAppendBuffer(size_t maxNumChars) SLANG_OVERRIDE;
+    SLANG_NO_THROW SlangResult SLANG_MCALL endAppendBuffer(char* buffer, size_t numChars) SLANG_OVERRIDE;
+
+    AppendBufferWriter(WriterFlags flags) :
+        Parent(flags)
+    {}
+
+protected:
+    List<char> m_appendBuffer;
+};
+
+class CallbackWriter : public AppendBufferWriter
+{
+public:
+    typedef AppendBufferWriter Parent;
     // ISlangWriter
     SLANG_NO_THROW virtual SlangResult SLANG_MCALL write(const char* chars, size_t numChars) SLANG_OVERRIDE;
     
@@ -82,12 +99,11 @@ protected:
     const void* m_data;
 };
 
-class FileWriter : public BaseWriter
+class FileWriter : public AppendBufferWriter
 {
 public:
-    typedef BaseWriter Parent;
+    typedef AppendBufferWriter Parent;
     // ISlangWriter
-    SLANG_NO_THROW virtual SlangResult SLANG_MCALL writeVaList(const char* format, va_list args) SLANG_OVERRIDE;
     SLANG_NO_THROW virtual SlangResult SLANG_MCALL write(const char* chars, size_t numChars) SLANG_OVERRIDE;
     SLANG_NO_THROW virtual void SLANG_MCALL flush() SLANG_OVERRIDE;
     SLANG_NO_THROW virtual SlangResult SLANG_MCALL setMode(SlangWriterMode mode) SLANG_OVERRIDE;
@@ -113,7 +129,8 @@ class StringWriter : public BaseWriter
 public:
     typedef BaseWriter Parent;
     // ISlangWriter
-    SLANG_NO_THROW virtual SlangResult SLANG_MCALL writeVaList(const char* format, va_list args) SLANG_OVERRIDE;
+    SLANG_NO_THROW char* SLANG_MCALL beginAppendBuffer(size_t maxNumChars) SLANG_OVERRIDE;
+    SLANG_NO_THROW SlangResult SLANG_MCALL endAppendBuffer(char* buffer, size_t numChars) SLANG_OVERRIDE;
     SLANG_NO_THROW virtual SlangResult SLANG_MCALL write(const char* chars, size_t numChars) SLANG_OVERRIDE;
     
         /// Ctor
@@ -126,14 +143,12 @@ protected:
     StringBuilder* m_builder;
 };
 
-class NullWriter : public BaseWriter
+class NullWriter : public AppendBufferWriter
 {
 public:
-    typedef BaseWriter Parent;
+    typedef AppendBufferWriter Parent;
     // ISlangWriter
-    SLANG_NO_THROW virtual SlangResult SLANG_MCALL writeVaList(const char* format, va_list args) SLANG_OVERRIDE { SLANG_UNUSED(format); SLANG_UNUSED(args); return SLANG_OK; }
     SLANG_NO_THROW virtual SlangResult SLANG_MCALL write(const char* chars, size_t numChars) SLANG_OVERRIDE { SLANG_UNUSED(chars); SLANG_UNUSED(numChars); return SLANG_OK; }
-
     /// Ctor
     NullWriter(WriterFlags flags) :
         Parent(flags)