Optimize xml_buffered_writer::write(const char_t*)

Instead of computing the length and doing memcpy we now copy the head of
the string into the buffer (like strcpy) and then use memcpy for tail if
necessary. This results in 10-15% speedup for writing typical documents with
a mix of short and long strings.

git-svn-id: https://pugixml.googlecode.com/svn/trunk@1023 99668b35-9821-0410-8761-19e4c4f06640

1 files changed, 28 insertions, 5 deletions

diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index 18c89e2..b9eab78 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -2888,7 +2888,7 @@ PUGI__NS_BEGIN
 #ifdef PUGIXML_WCHAR_MODE
 	PUGI__FN size_t get_valid_length(const char_t* data, size_t length)
 	{
-		assert(length > 0);
+		if (length < 1) return 0;
 
 		// discard last character if it's the lead of a surrogate pair 
 		return (sizeof(wchar_t) == 2 && static_cast<unsigned int>(static_cast<uint16_t>(data[length - 1]) - 0xD800) < 0x400) ? length - 1 : length;
@@ -2960,7 +2960,7 @@ PUGI__NS_BEGIN
 #else
 	PUGI__FN size_t get_valid_length(const char_t* data, size_t length)
 	{
-		assert(length > 4);
+		if (length < 5) return 0;
 
 		for (size_t i = 1; i <= 4; ++i)
 		{
@@ -3080,6 +3080,7 @@ PUGI__NS_BEGIN
 					// get chunk size by selecting such number of characters that are guaranteed to fit into scratch buffer
 					// and form a complete codepoint sequence (i.e. discard start of last codepoint if necessary)
 					size_t chunk_size = get_valid_length(data, bufcapacity);
+					assert(chunk_size);
 
 					// convert chunk and write
 					flush(data, chunk_size);
@@ -3112,7 +3113,27 @@ PUGI__NS_BEGIN
 
 		void write(const char_t* data)
 		{
-			write(data, strlength(data));
+			// write the part of the string that fits in the buffer
+			size_t offset = bufsize;
+
+			while (*data && offset < bufcapacity)
+				buffer[offset++] = *data++;
+
+			// write the rest
+			if (offset < bufcapacity)
+			{
+				bufsize = offset;
+			}
+			else
+			{
+				// backtrack a bit if we have split the codepoint
+				size_t length = offset - bufsize;
+				size_t extra = length - get_valid_length(data - length, length);
+
+				bufsize = offset - extra;
+
+				write_direct(data - extra, strlength(data) + extra);
+			}
 		}
 
 		void write(char_t d0)
@@ -8265,7 +8286,8 @@ PUGI__NS_BEGIN
 			switch (_test)
 			{
 			case nodetest_name:
-				if (strequal(name, _data.nodetest)) ns.push_back(xpath_node(a, parent), alloc);
+				if (strequal(name, _data.nodetest))
+					ns.push_back(xpath_node(a, parent), alloc);
 				break;
 				
 			case nodetest_type_node:
@@ -8290,7 +8312,8 @@ PUGI__NS_BEGIN
 			switch (_test)
 			{
 			case nodetest_name:
-				if (n.type() == node_element && strequal(n.name(), _data.nodetest)) ns.push_back(n, alloc);
+				if (n.type() == node_element && strequal(n.name(), _data.nodetest))
+					ns.push_back(n, alloc);
 				break;
 				
 			case nodetest_type_node: