Fix StreamString read O(n^2); improve range read performance

.gitignore

@@ -17,6 +17,7 @@ tests/hosts/lcov/
 *.gch
 
 boards.local.txt
+platform.local.txt
 
 *.gcov
 *.gcno

cores/esp8266/StreamString.cpp

@@ -39,23 +39,28 @@ size_t StreamString::write(uint8_t data) {
     return concat((char) data);
 }
 
+size_t StreamString::readBytes(char *buffer, size_t length) {
+    size_t cpylen = min(length, (size_t)available());
+    memcpy(buffer, begin()+_offset, cpylen);
+    _offset += cpylen;
+    return cpylen;
+}
+
 int StreamString::available() {
-    return length();
+    return length() - _offset;
 }
 
 int StreamString::read() {
-    if(length()) {
-        char c = charAt(0);
-        remove(0, 1);
+    if(available()) {
+        char c = charAt(_offset++);
         return c;
-
     }
     return -1;
 }
 
 int StreamString::peek() {
-    if(length()) {
-        char c = charAt(0);
+    if(available()) {
+        char c = charAt(_offset);
         return c;
     }
     return -1;

cores/esp8266/StreamString.h

@@ -25,14 +25,20 @@
 
 
 class StreamString: public Stream, public String {
+protected:
+    size_t _offset = 0;
 public:
     size_t write(const uint8_t *buffer, size_t size) override;
     size_t write(uint8_t data) override;
 
+    size_t readBytes(char *buffer, size_t length) override;
+
     int available() override;
     int read() override;
     int peek() override;
     void flush() override;
+
+    void reset() { _offset = 0; }
 };