some optimizations

src/BXParser.cc

@@ -6,31 +6,31 @@
 #include <errno.h>
 
 int BXParser::get() {
-	if (dataidx_ < datalen_) {
-		return buf_[dataidx_++];
+	if (bufidx_ < buflen_) {
+		return buf_[bufidx_++];
 	}
 
-	dataidx_ = 0;
+	bufidx_ = 0;
 	stream_.read(buf_, sizeof(buf_));
-	datalen_ = stream_.gcount();
-	if (datalen_ == 0) {
+	buflen_ = stream_.gcount();
+	if (buflen_ == 0) {
 		return EOF;
 	}
 
-	return buf_[dataidx_++];
+	return buf_[bufidx_++];
 }
 
 int BXParser::peek() {
-	if (dataidx_ < datalen_) {
-		return buf_[dataidx_];
+	if (bufidx_ < buflen_) {
+		return buf_[bufidx_];
 	} else {
 		return stream_.peek();
 	}
 }
 
 int BXParser::peek2() {
-	if (dataidx_ + 1 < datalen_) { 
-		return buf_[dataidx_ + 1];
+	if (bufidx_ + 1 < buflen_) { 
+		return buf_[bufidx_ + 1];
 	} else {
 		stream_.get();
 		int ch = stream_.peek();
@@ -380,20 +380,35 @@ void BXParser::parseList(const BXVariables &vars, std::vector<std::string> &valu
 	}
 }
 
+BXWriter::~BXWriter() {
+	if (bufidx_ > 0) {
+		stream_.write(buf_, bufidx_);
+	}
+}
+
 void BXWriter::put(char ch) {
-	ch_ += 1;
-	stream_ << ch;
+	buf_[bufidx_++] = ch;
+
+	if (bufidx_ == sizeof(buf_)) {
+		stream_.write(buf_, sizeof(buf_));
+		bufidx_ = 0;
+	}
 }
 
 void BXWriter::put(const std::string &str) {
-	ch_ += str.size();
-	stream_ << str;
-}
+	size_t w = sizeof(buf_) - bufidx_;
+	if (w > str.size()) {
+		w = str.size();
+	}
 
-void BXWriter::newline() {
-	ch_ = 1;
-	line_ += 1;
-	stream_ << '\n';
+	memcpy(buf_ + bufidx_, str.c_str(), w);
+	if (str.size() - w > 0) {
+		stream_.write(buf_, bufidx_ + w);
+		stream_.write(str.c_str() + w, str.size() - w);
+		bufidx_ = 0;
+	} else {
+		bufidx_ += w;
+	}
 }
 
 void BXWriter::escape(const std::string &str) {
@@ -409,18 +424,21 @@ void BXWriter::escape(const std::string &str) {
 
 void BXWriter::write(const BXVariables &vars) {
 	for (const auto &pair: vars) {
+		size_t chars = 0;
 		put(pair.first);
 		put(" :=");
 		for (auto &val: pair.second) {
-			if (ch_ >= 80) {
-				newline();
+			if (chars >= 80) {
+				put('\n');
 				put('\t');
+				chars = 0;
 			} else {
 				put(' ');
 			}
 
 			escape(val);
+			chars += val.size();
 		}
-		newline();
+		put('\n');
 	}
 }

src/BXParser.h

@@ -61,17 +61,17 @@ private:
 	int flags_;
 	int line_;
 	int ch_;
-	std::istream &stream_;
 
+	std::istream &stream_;
 	char buf_[1024];
-	size_t dataidx_ = 0;
-	size_t datalen_ = 0;
+	size_t bufidx_ = 0;
+	size_t buflen_ = 0;
 };
 
 class BXWriter {
 public:
-	BXWriter(std::ostream &stream, int line = 1, int ch = 1):
-		line_(line), ch_(ch), stream_(stream) {}
+	BXWriter(std::ostream &stream): stream_(stream) {}
+	~BXWriter();
 
 	void write(const BXVariables &vars);
 
@@ -81,7 +81,7 @@ private:
 	void newline();
 	void escape(const std::string &str);
 
-	int line_;
-	int ch_;
 	std::ostream &stream_;
+	char buf_[1024];
+	size_t bufidx_ = 0;
 };

src/compdb.cc

@@ -4,6 +4,7 @@ namespace compdb {
 
 std::string escape(const std::string &str) {
 	std::string out;
+	out.reserve(str.size() * 1.5);
 
 	// TODO: Handle unicode according to JSON spec
 	for (char ch: str) {

src/sys.cc

@@ -79,7 +79,8 @@ void execute(const std::vector<std::string> &args, std::string *output, bool pri
 	// argv[0] should be interpreted as a shell command, because being able to run
 	// CC='gcc --sysroot=/blah' is used by some systems.
 	std::string command = std::string(args[0]) + " \"$@\"";
-	std::vector<const char *> argv;
+	static thread_local std::vector<const char *> argv;
+	argv.clear();
 	argv.push_back("/bin/sh"); // TODO: Use $SHELL?
 	argv.push_back("-c");
 	argv.push_back(command.c_str());