Fixes implementation of __FlashStringHelper (#183)

Previous __FlashStringHelper implementation was defines as a char which brought problem in case the method with char* parameter used overloading with __FlashStringHelper* parameter (they was identical). Now __FlashStringHelper is defined as a class and all casts between char* and __FlashStringHelper* are made with reinterpret_cast sugar.

cores/esp32/Print.cpp

@@ -68,19 +68,12 @@ size_t Print::printf(const char *format, ...)
     }
     return len;
 }
-/*
-size_t Print::print(const __FlashStringHelper *ifsh) {
-    PGM_P p = reinterpret_cast<PGM_P>(ifsh);
 
-    size_t n = 0;
-    while (1) {
-        uint8_t c = pgm_read_byte(p++);
-        if (c == 0) break;
-        n += write(c);
-    }
-    return n;
+size_t Print::print(const __FlashStringHelper *ifsh)
+{
+    return print(reinterpret_cast<const char *>(ifsh));
 }
-*/
+
 size_t Print::print(const String &s)
 {
     return write(s.c_str(), s.length());
@@ -140,14 +133,14 @@ size_t Print::print(double n, int digits)
 {
     return printFloat(n, digits);
 }
-/*
+
 size_t Print::println(const __FlashStringHelper *ifsh)
 {
     size_t n = print(ifsh);
     n += println();
     return n;
 }
-*/
+
 size_t Print::print(const Printable& x)
 {
     return x.printTo(*this);

cores/esp32/Print.h

@@ -72,7 +72,7 @@ public:
     }
 
     size_t printf(const char * format, ...)  __attribute__ ((format (printf, 2, 3)));
-    //size_t print(const __FlashStringHelper *);
+    size_t print(const __FlashStringHelper *);
     size_t print(const String &);
     size_t print(const char[]);
     size_t print(char);
@@ -85,7 +85,7 @@ public:
     size_t print(const Printable&);
     size_t print(struct tm * timeinfo, const char * format = NULL);
 
-    //size_t println(const __FlashStringHelper *);
+    size_t println(const __FlashStringHelper *);
     size_t println(const String &s);
     size_t println(const char[]);
     size_t println(char);

cores/esp32/WString.cpp

@@ -44,12 +44,7 @@ String::String(const String &value)
     init();
     *this = value;
 }
-/*
-String::String(const __FlashStringHelper *pstr) {
-    init();
-    *this = pstr; // see operator =
-}
-*/
+
 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 String::String(String &&rval)
 {
@@ -200,17 +195,12 @@ String & String::copy(const char *cstr, unsigned int length)
     strcpy(buffer, cstr);
     return *this;
 }
-/*
-String & String::copy(const __FlashStringHelper *pstr, unsigned int length) {
-    if (!reserve(length)) {
-        invalidate();
-        return *this;
-    }
-    len = length;
-    strcpy_P(buffer, (PGM_P)pstr);
-    return *this;
+
+String & String::copy(const __FlashStringHelper *pstr, unsigned int length)
+{
+    return copy(reinterpret_cast<const char *>(pstr), length);
 }
-*/
+
 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 void String::move(String &rhs)
 {
@@ -276,7 +266,7 @@ String & String::operator =(const char *cstr)
 
     return *this;
 }
-/*
+
 String & String::operator = (const __FlashStringHelper *pstr)
 {
     if (pstr) copy(pstr, strlen_P((PGM_P)pstr));
@@ -284,7 +274,7 @@ String & String::operator = (const __FlashStringHelper *pstr)
 
     return *this;
 }
-*/
+
 // /*********************************************/
 // /*  concat                                   */
 // /*********************************************/
@@ -375,18 +365,12 @@ unsigned char String::concat(double num)
     char* string = dtostrf(num, 4, 2, buf);
     return concat(string, strlen(string));
 }
-/*
-unsigned char String::concat(const __FlashStringHelper * str) {
-    if (!str) return 0;
-    int length = strlen_P((PGM_P)str);
-    if (length == 0) return 1;
-    unsigned int newlen = len + length;
-    if (!reserve(newlen)) return 0;
-    strcpy_P(buffer + len, (PGM_P)str);
-    len = newlen;
-    return 1;
+
+unsigned char String::concat(const __FlashStringHelper * str)
+{
+    return concat(reinterpret_cast<const char *>(str));
 }
-*/
+
 /*********************************************/
 /*  Concatenate                              */
 /*********************************************/
@@ -480,14 +464,14 @@ StringSumHelper & operator +(const StringSumHelper &lhs, double num)
     }
     return a;
 }
-/*
+
 StringSumHelper & operator + (const StringSumHelper &lhs, const __FlashStringHelper *rhs)
 {
     StringSumHelper &a = const_cast<StringSumHelper&>(lhs);
     if (!a.concat(rhs))	a.invalidate();
     return a;
 }
-*/
+
 // /*********************************************/
 // /*  Comparison                               */
 // /*********************************************/

cores/esp32/WString.h

@@ -34,7 +34,8 @@ class StringSumHelper;
 
 // an abstract class used as a means to proide a unique pointer type
 // but really has no body
-//class __FlashStringHelper;
+class __FlashStringHelper;
+#define F(string_literal) (reinterpret_cast<const __FlashStringHelper *>(PSTR(string_literal)))
 
 // The string class
 class String
@@ -55,7 +56,7 @@ public:
     // be false).
     String(const char *cstr = "");
     String(const String &str);
-    //String(const __FlashStringHelper *str);
+    String(const __FlashStringHelper *str) : String(reinterpret_cast<const char *>(str)) {};
 #ifdef __GXX_EXPERIMENTAL_CXX0X__
     String(String &&rval);
     String(StringSumHelper &&rval);
@@ -89,7 +90,7 @@ public:
     // marked as invalid ("if (s)" will be false).
     String & operator =(const String &rhs);
     String & operator =(const char *cstr);
-    //String & operator = (const __FlashStringHelper *str);
+    String & operator = (const __FlashStringHelper *str);
 #ifdef __GXX_EXPERIMENTAL_CXX0X__
     String & operator =(String &&rval);
     String & operator =(StringSumHelper &&rval);
@@ -110,7 +111,7 @@ public:
     unsigned char concat(unsigned long num);
     unsigned char concat(float num);
     unsigned char concat(double num);
-    //unsigned char concat(const __FlashStringHelper * str);
+    unsigned char concat(const __FlashStringHelper * str);
 
     // if there's not enough memory for the concatenated value, the string
     // will be left unchanged (but this isn't signalled in any way)
@@ -164,10 +165,11 @@ public:
         concat(num);
         return (*this);
     }
-    //String & operator += (const __FlashStringHelper *str){
-    //    concat(str);
-    //    return (*this);
-    //}
+    String & operator += (const __FlashStringHelper *str)
+    {
+        concat(str);
+        return (*this);
+    }
 
     friend StringSumHelper & operator +(const StringSumHelper &lhs, const String &rhs);
     friend StringSumHelper & operator +(const StringSumHelper &lhs, const char *cstr);
@@ -179,7 +181,7 @@ public:
     friend StringSumHelper & operator +(const StringSumHelper &lhs, unsigned long num);
     friend StringSumHelper & operator +(const StringSumHelper &lhs, float num);
     friend StringSumHelper & operator +(const StringSumHelper &lhs, double num);
-    //friend StringSumHelper & operator +(const StringSumHelper &lhs, const __FlashStringHelper *rhs);
+    friend StringSumHelper & operator +(const StringSumHelper &lhs, const __FlashStringHelper *rhs);
 
     // comparison (only works w/ Strings and "strings")
     operator StringIfHelperType() const
@@ -270,7 +272,7 @@ protected:
 
     // copy and move
     String & copy(const char *cstr, unsigned int length);
-    //String & copy(const __FlashStringHelper *pstr, unsigned int length);
+    String & copy(const __FlashStringHelper *pstr, unsigned int length);
 #ifdef __GXX_EXPERIMENTAL_CXX0X__
     void move(String &rhs);
 #endif

cores/esp32/pgmspace.h

@@ -29,8 +29,6 @@ typedef unsigned short prog_uint16_t;
 typedef long prog_int32_t;
 typedef unsigned long prog_uint32_t;
 
-typedef char __FlashStringHelper;
-
 #define SIZE_IRRELEVANT 0x7fffffff
 
 #define PROGMEM
@@ -38,7 +36,6 @@ typedef char __FlashStringHelper;
 #define PGM_VOID_P    const void *
 #define FPSTR(p)      ((const char *)(p))
 #define PSTR(s)       (s)
-#define F(s)          (s)
 #define _SFR_BYTE(n)  (n)
 
 #define pgm_read_byte(addr)   (*(const unsigned char *)(addr))