Support route parameters with regex patterns (#560)

* Fix compile warnings

* first test

* Add regex path

* Add simple example

* add support for esp8266

* Update AsyncJson.h

examples/regex_patterns/regex_patterns.ino

@@ -0,0 +1,65 @@
+//
+// A simple server implementation with regex routes:
+//  * serve static messages
+//  * read GET and POST parameters
+//  * handle missing pages / 404s
+//
+
+#include <Arduino.h>
+#ifdef ESP32
+#include <WiFi.h>
+#include <AsyncTCP.h>
+#elif defined(ESP8266)
+#include <ESP8266WiFi.h>
+#include <ESPAsyncTCP.h>
+#endif
+#include <ESPAsyncWebServer.h>
+
+AsyncWebServer server(80);
+
+const char* ssid = "YOUR_SSID";
+const char* password = "YOUR_PASSWORD";
+
+const char* PARAM_MESSAGE = "message";
+
+void notFound(AsyncWebServerRequest *request) {
+    request->send(404, "text/plain", "Not found");
+}
+
+void setup() {
+
+    Serial.begin(115200);
+    WiFi.mode(WIFI_STA);
+    WiFi.begin(ssid, password);
+    if (WiFi.waitForConnectResult() != WL_CONNECTED) {
+        Serial.printf("WiFi Failed!\n");
+        return;
+    }
+
+    Serial.print("IP Address: ");
+    Serial.println(WiFi.localIP());
+
+    server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
+        request->send(200, "text/plain", "Hello, world");
+    });
+
+    // Send a GET request to <IP>/sensor/<number>
+    server.on("^\\/sensor\\/([0-9]+)$", HTTP_GET, [] (AsyncWebServerRequest *request) {
+        String sensorNumber = request->pathArg(0);
+        request->send(200, "text/plain", "Hello, sensor: " + sensorNumber);
+    });
+	
+	// Send a GET request to <IP>/sensor/<number>/action/<action>
+    server.on("^\\/sensor\\/([0-9]+)\\/action\//([a-zA-Z0-9]+)$", HTTP_GET, [] (AsyncWebServerRequest *request) {
+        String sensorNumber = request->pathArg(0);
+        String action = request->pathArg(1);
+        request->send(200, "text/plain", "Hello, sensor: " + sensorNumber + ", with action: " + action);
+    });
+
+    server.onNotFound(notFound);
+
+    server.begin();
+}
+
+void loop() {
+}

src/ESPAsyncWebServer.h

@@ -129,6 +129,7 @@ class AsyncWebServerRequest {
   using File = fs::File;
   using FS = fs::FS;
   friend class AsyncWebServer;
+  friend class AsyncCallbackWebHandler;
   private:
     AsyncClient* _client;
     AsyncWebServer* _server;
@@ -158,6 +159,7 @@ class AsyncWebServerRequest {
 
     LinkedList<AsyncWebHeader *> _headers;
     LinkedList<AsyncWebParameter *> _params;
+    LinkedList<String *> _pathParams;
 
     uint8_t _multiParseState;
     uint8_t _boundaryPosition;
@@ -179,6 +181,7 @@ class AsyncWebServerRequest {
     void _onData(void *buf, size_t len);
 
     void _addParam(AsyncWebParameter*);
+    void _addPathParam(const char *param);
 
     bool _parseReqHead();
     bool _parseReqHeader();
@@ -268,6 +271,8 @@ class AsyncWebServerRequest {
     bool hasArg(const char* name) const;         // check if argument exists
     bool hasArg(const __FlashStringHelper * data) const;         // check if F(argument) exists
 
+    const String& pathArg(size_t i) const;
+
     const String& header(const char* name) const;// get request header value by name
     const String& header(const __FlashStringHelper * data) const;// get request header value by F(name)    
     const String& header(size_t i) const;        // get request header value by number

src/WebHandlerImpl.h

@@ -21,6 +21,8 @@
 #ifndef ASYNCWEBSERVERHANDLERIMPL_H_
 #define ASYNCWEBSERVERHANDLERIMPL_H_
 
+#include <string>
+#include <regex>
 
 #include "stddef.h"
 #include <time.h>
@@ -67,9 +69,13 @@ class AsyncCallbackWebHandler: public AsyncWebHandler {
     ArRequestHandlerFunction _onRequest;
     ArUploadHandlerFunction _onUpload;
     ArBodyHandlerFunction _onBody;
+    bool _isRegex;
   public:
-    AsyncCallbackWebHandler() : _uri(), _method(HTTP_ANY), _onRequest(NULL), _onUpload(NULL), _onBody(NULL){}
+    AsyncCallbackWebHandler() : _uri(), _method(HTTP_ANY), _onRequest(NULL), _onUpload(NULL), _onBody(NULL), _isRegex(false){}
-    void setUri(const String& uri){ _uri = uri; }
+    void setUri(const String& uri){ 
+      _uri = uri; 
+       _isRegex = uri.startsWith("^") && uri.endsWith("$");
+    }
     void setMethod(WebRequestMethodComposite method){ _method = method; }
     void onRequest(ArRequestHandlerFunction fn){ _onRequest = fn; }
     void onUpload(ArUploadHandlerFunction fn){ _onUpload = fn; }
@@ -83,7 +89,18 @@ class AsyncCallbackWebHandler: public AsyncWebHandler {
       if(!(_method & request->method()))
         return false;
 
-      if (_uri.length() && _uri.endsWith("*")) {
+      if (_isRegex) {
+        std::regex rgx(_uri.c_str());
+        std::smatch matches;
+        std::string s(request->url().c_str());
+        if(std::regex_search(s, matches, rgx)) {
+          for (size_t i = 1; i < matches.size(); ++i) { // start from 1
+            request->_addPathParam(matches[i].str().c_str());
+          }
+        } else {
+          return false;
+        }
+      } else if (_uri.length() && _uri.endsWith("*")) {
         String uriTemplate = String(_uri);
 	uriTemplate = uriTemplate.substring(0, uriTemplate.length() - 1);
         if (!request->url().startsWith(uriTemplate))

src/WebRequest.cpp

@@ -55,6 +55,7 @@ AsyncWebServerRequest::AsyncWebServerRequest(AsyncWebServer* s, AsyncClient* c)
   , _parsedLength(0)
   , _headers(LinkedList<AsyncWebHeader *>([](AsyncWebHeader *h){ delete h; }))
   , _params(LinkedList<AsyncWebParameter *>([](AsyncWebParameter *p){ delete p; }))
+  , _pathParams(LinkedList<String *>([](String *p){ delete p; }))
   , _multiParseState(0)
   , _boundaryPosition(0)
   , _itemStartIndex(0)
@@ -80,6 +81,7 @@ AsyncWebServerRequest::~AsyncWebServerRequest(){
   _headers.free();
 
   _params.free();
+  _pathParams.free();
 
   _interestingHeaders.free();
 
@@ -230,6 +232,10 @@ void AsyncWebServerRequest::_addParam(AsyncWebParameter *p){
   _params.add(p);
 }
 
+void AsyncWebServerRequest::_addPathParam(const char *p){
+  _pathParams.add(new String(p));
+}
+
 void AsyncWebServerRequest::_addGetParams(const String& params){
   size_t start = 0;
   while (start < params.length()){
@@ -912,6 +918,11 @@ const String& AsyncWebServerRequest::argName(size_t i) const {
   return getParam(i)->name();
 }
 
+const String& AsyncWebServerRequest::pathArg(size_t i) const {
+  auto param = _pathParams.nth(i);
+  return param ? **param : SharedEmptyString;
+}
+
 const String& AsyncWebServerRequest::header(const char* name) const {
   AsyncWebHeader* h = getHeader(String(name));
   return h ? h->value() : SharedEmptyString;