Issue 2162 (#2163)

* Resolve #2162

* Update

example/Makefile

@@ -18,7 +18,7 @@ ZLIB_SUPPORT = -DCPPHTTPLIB_ZLIB_SUPPORT -lz
 BROTLI_DIR = $(PREFIX)/opt/brotli
 BROTLI_SUPPORT = -DCPPHTTPLIB_BROTLI_SUPPORT -I$(BROTLI_DIR)/include -L$(BROTLI_DIR)/lib -lbrotlicommon -lbrotlienc -lbrotlidec
 
-all: server client hello simplecli simplesvr upload redirect ssesvr ssecli benchmark one_time_request server_and_client
+all: server client hello simplecli simplesvr upload redirect ssesvr ssecli benchmark one_time_request server_and_client accept_header
 
 server : server.cc ../httplib.h Makefile
 	$(CXX) -o server $(CXXFLAGS) server.cc $(OPENSSL_SUPPORT) $(ZLIB_SUPPORT) $(BROTLI_SUPPORT)
@@ -56,9 +56,12 @@ one_time_request : one_time_request.cc ../httplib.h Makefile
 server_and_client : server_and_client.cc ../httplib.h Makefile
 	$(CXX) -o server_and_client $(CXXFLAGS) server_and_client.cc $(OPENSSL_SUPPORT) $(ZLIB_SUPPORT) $(BROTLI_SUPPORT)
 
+accept_header : accept_header.cc ../httplib.h Makefile
+	$(CXX) -o accept_header $(CXXFLAGS) accept_header.cc $(OPENSSL_SUPPORT) $(ZLIB_SUPPORT) $(BROTLI_SUPPORT)
+
 pem:
 	openssl genrsa 2048 > key.pem
 	openssl req -new -key key.pem | openssl x509 -days 3650 -req -signkey key.pem > cert.pem
 
 clean:
-	rm server client hello simplecli simplesvr upload redirect ssesvr ssecli benchmark one_time_request server_and_client *.pem
+	rm server client hello simplecli simplesvr upload redirect ssesvr ssecli benchmark one_time_request server_and_client accept_header *.pem

example/accept_header.cc

@@ -0,0 +1,134 @@
+#include "httplib.h"
+#include <iostream>
+
+int main() {
+    using namespace httplib;
+    
+    // Example usage of parse_accept_header function
+    std::cout << "=== Accept Header Parser Example ===" << std::endl;
+    
+    // Example 1: Simple Accept header
+    std::string accept1 = "text/html,application/json,text/plain";
+    std::vector<std::string> result1;
+    if (detail::parse_accept_header(accept1, result1)) {
+        std::cout << "\nExample 1: " << accept1 << std::endl;
+        std::cout << "Parsed order:" << std::endl;
+        for (size_t i = 0; i < result1.size(); ++i) {
+            std::cout << "  " << (i + 1) << ". " << result1[i] << std::endl;
+        }
+    } else {
+        std::cout << "\nExample 1: Failed to parse Accept header" << std::endl;
+    }
+    
+    // Example 2: Accept header with quality values
+    std::string accept2 = "text/html;q=0.9,application/json;q=1.0,text/plain;q=0.8";
+    std::vector<std::string> result2;
+    if (detail::parse_accept_header(accept2, result2)) {
+        std::cout << "\nExample 2: " << accept2 << std::endl;
+        std::cout << "Parsed order (sorted by priority):" << std::endl;
+        for (size_t i = 0; i < result2.size(); ++i) {
+            std::cout << "  " << (i + 1) << ". " << result2[i] << std::endl;
+        }
+    } else {
+        std::cout << "\nExample 2: Failed to parse Accept header" << std::endl;
+    }
+    
+    // Example 3: Browser-like Accept header
+    std::string accept3 = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";
+    std::vector<std::string> result3;
+    if (detail::parse_accept_header(accept3, result3)) {
+        std::cout << "\nExample 3: " << accept3 << std::endl;
+        std::cout << "Parsed order:" << std::endl;
+        for (size_t i = 0; i < result3.size(); ++i) {
+            std::cout << "  " << (i + 1) << ". " << result3[i] << std::endl;
+        }
+    } else {
+        std::cout << "\nExample 3: Failed to parse Accept header" << std::endl;
+    }
+    
+    // Example 4: Invalid Accept header examples
+    std::cout << "\n=== Invalid Accept Header Examples ===" << std::endl;
+    
+    std::vector<std::string> invalid_examples = {
+        "text/html;q=1.5,application/json",  // q > 1.0
+        "text/html;q=-0.1,application/json", // q < 0.0
+        "text/html;q=invalid,application/json", // invalid q value
+        "invalidtype,application/json",      // invalid media type
+        ",application/json"                  // empty entry
+    };
+    
+    for (const auto& invalid_accept : invalid_examples) {
+        std::vector<std::string> temp_result;
+        std::cout << "\nTesting invalid: " << invalid_accept << std::endl;
+        if (detail::parse_accept_header(invalid_accept, temp_result)) {
+            std::cout << "  Unexpectedly succeeded!" << std::endl;
+        } else {
+            std::cout << "  Correctly rejected as invalid" << std::endl;
+        }
+    }
+    
+    // Example 4: Server usage example
+    std::cout << "\n=== Server Usage Example ===" << std::endl;
+    Server svr;
+    
+    svr.Get("/api/data", [](const Request& req, Response& res) {
+        // Get Accept header
+        auto accept_header = req.get_header_value("Accept");
+        if (accept_header.empty()) {
+            accept_header = "*/*";  // Default if no Accept header
+        }
+        
+        // Parse accept header to get preferred content types
+        std::vector<std::string> preferred_types;
+        if (!detail::parse_accept_header(accept_header, preferred_types)) {
+            // Invalid Accept header
+            res.status = 400;  // Bad Request
+            res.set_content("Invalid Accept header", "text/plain");
+            return;
+        }
+        
+        std::cout << "Client Accept header: " << accept_header << std::endl;
+        std::cout << "Preferred types in order:" << std::endl;
+        for (size_t i = 0; i < preferred_types.size(); ++i) {
+            std::cout << "  " << (i + 1) << ". " << preferred_types[i] << std::endl;
+        }
+        
+        // Choose response format based on client preference
+        std::string response_content;
+        std::string content_type;
+        
+        for (const auto& type : preferred_types) {
+            if (type == "application/json" || type == "application/*" || type == "*/*") {
+                response_content = "{\"message\": \"Hello, World!\", \"data\": [1, 2, 3]}";
+                content_type = "application/json";
+                break;
+            } else if (type == "text/html" || type == "text/*") {
+                response_content = "<html><body><h1>Hello, World!</h1><p>Data: 1, 2, 3</p></body></html>";
+                content_type = "text/html";
+                break;
+            } else if (type == "text/plain") {
+                response_content = "Hello, World!\nData: 1, 2, 3";
+                content_type = "text/plain";
+                break;
+            }
+        }
+        
+        if (response_content.empty()) {
+            // No supported content type found
+            res.status = 406;  // Not Acceptable
+            res.set_content("No acceptable content type found", "text/plain");
+            return;
+        }
+        
+        res.set_content(response_content, content_type);
+        std::cout << "Responding with: " << content_type << std::endl;
+    });
+    
+    std::cout << "Server configured. You can test it with:" << std::endl;
+    std::cout << "  curl -H \"Accept: application/json\" http://localhost:8080/api/data" << std::endl;
+    std::cout << "  curl -H \"Accept: text/html\" http://localhost:8080/api/data" << std::endl;
+    std::cout << "  curl -H \"Accept: text/plain\" http://localhost:8080/api/data" << std::endl;
+    std::cout << "  curl -H \"Accept: text/html;q=0.9,application/json;q=1.0\" http://localhost:8080/api/data" << std::endl;
+    
+    return 0;
+}