<b>在C++程序中增添逻辑流程掌握</b>[VC/C++编程]

问题的引出

在计算机程序中,除了常见的履行流程掌握,还有逻辑流程掌握;有时,履行流程即为逻辑流程,但在大大都情形下还是有所辨别的,比方,假定有一个Web服务器利用同步套接字读取HTTP恳求,那么会编写以下的代码:

void read(HTTP_REQUEST& http_request)
{
read(http_request.header);
read(http_request.body, http_request.header);
}
void read(HTTP_REQUEST_HEADER& header)
{
string line = read_line();
parse_request_link(line, header.method, header.uri,
header.version);
while (TRUE)
{
line = read_line();
if (line.empty())
break;
parse_header_field(line, header);
}
}
void read(BYTE[]& body, HTTP_REQUEST_HEADER& header)
{
string transfer_encoding = header.fields['Transfer-Encoding'];
if (transfer_encoding != b.chunkedb.)
body = read_bytes(header.fields['Content-Length']);
else
{
while (TRUE)
{
string chunk_header = read_line();
DWORD chunk_size = atoi(chunk_header);
if (chunk_size == 0)
break;
BYTE[] chunk_body = read_bytes(chunk_size);
body += chunk_body;
}
}
}
string read_line()
{
while (TRUE)
{
int n = strpos(read_buffer, b.
b., read_buffer.size());
if (n > 0)
break;
read_buffer += socket.read();
}
return read_buffer.extract(n);
}
Byte[] read_bytes(int sz)
{
while (TRUE)
{
if (sz <= read_buffer.size())
break;
read_buffer += socket.read();
}
return read_buffer.extract(sz);
}
　　在这段代码中,履行流程与逻辑流程是一致的,但是,假如在那些被动接纳事件的场所利用了异步套接字,就必须编写下面这样的代码了:
read()
{
read_buffer += socket.read();
if (state == read_request_line)
{
if (!read_line(line))
return;
parse_request_link(line, method, uri, version);
state = read_header_field;
}
while (state == read_request_line)
{
if (!read_line(line))
return;
if (line.empty())
{
transfer_encoding = header.fields['Transfer-Encoding'];
if (transfer_encoding != b.chunkedb.)
{
content_length = header.fields['Content-Length'];
state = read_body;
}
else
state = read_chunk_header;
}
else
parse_header_field(line, header, value);
}
if (state == read_body)
{
request_body += read_buffer;
read_buffer.clear();
if (request_body.size() >= content_length)
state = read_finished;
return;
}
if (state == read_chunk_header)
{
if (!read_line(line))
return;
chunk_size = atoi(line);
if (chunk_size == 0)
{
state = read_finished;
return;
}
state = read_body;
}
if (state == read_chunk_body)
{
request_body.append(read_buffer, chunk_size);
if (chunk_size == 0)
state = read_chunk_header;
return;
}
}
　　以上是“<b>在C++程序中增添逻辑流程掌握</b>[VC/C++编程]”的内容，如果你对以上该文章内容感兴趣，你可以看看七道奇为您推荐以下文章：