Arduino String/Stream add features

api/String.cpp

@@ -234,10 +234,10 @@ void String::move(String &rhs)
 String & String::operator = (const String &rhs)
 {
 	if (this == &rhs) return *this;
-	
+
 	if (rhs.buffer) copy(rhs.buffer, rhs.len);
 	else invalidate();
-	
+
 	return *this;
 }
 
@@ -253,7 +253,7 @@ String & String::operator = (const char *cstr)
 {
 	if (cstr) copy(cstr, strlen(cstr));
 	else invalidate();
-	
+
 	return *this;
 }
 
@@ -484,7 +484,7 @@ bool String::equalsIgnoreCase( const String &s2 ) const
 	const char *p2 = s2.buffer;
 	while (*p1) {
 		if (tolower(*p1++) != tolower(*p2++)) return false;
-	} 
+	}
 	return true;
 }
 
@@ -515,7 +515,7 @@ char String::charAt(unsigned int loc) const
 	return operator[](loc);
 }
 
-void String::setCharAt(unsigned int loc, char c) 
+void String::setCharAt(unsigned int loc, char c)
 {
 	if (loc < len) buffer[loc] = c;
 }
@@ -631,6 +631,18 @@ String String::substring(unsigned int left, unsigned int right) const
 /*  Modification                             */
 /*********************************************/
 
+void String::insert(const String &str, unsigned int index, unsigned int length)
+{
+    if (index > len) return;
+    length = length < str.len ? length : str.len;
+    unsigned int size = len + length;
+    if (size > capacity && !changeBuffer(size)) return; // XXX: tell user!
+    memmove(buffer + index + length, buffer + index, len - index + length);
+    memcpy(buffer + index, str.buffer, length);
+    len += length;
+    return;
+}
+
 void String::replace(char find, char replace)
 {
 	if (!buffer) return;

api/String.h

@@ -206,7 +206,9 @@ class String
 	String substring( unsigned int beginIndex, unsigned int endIndex ) const;
 
 	// modification
-	void replace(char find, char replace);
+	void insert(char c, unsigned int index) { return insert(&c, index, 1); };
+    	void insert(const String &str, unsigned int index, unsigned int length);
+    	void replace(char find, char replace);
 	void replace(const String& find, const String& replace);
 	void remove(unsigned int index);
 	void remove(unsigned int index, unsigned int count);

test/CMakeLists.txt

@@ -72,6 +72,7 @@ set(TEST_SRCS
   src/String/test_indexOf.cpp
   src/String/test_lastIndexOf.cpp
   src/String/test_length.cpp
+  src/String/test_insert.cpp
   src/String/test_move.cpp
   src/String/test_remove.cpp
   src/String/test_replace.cpp

test/src/String/test_insert.cpp

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2023 Arduino.  All rights reserved.
+ */
+
+/**************************************************************************************
+ * INCLUDE
+ **************************************************************************************/
+
+#include <catch.hpp>
+
+#include <String.h>
+
+#include "StringPrinter.h"
+
+/**************************************************************************************
+ * TEST CODE
+ **************************************************************************************/
+
+TEST_CASE ("Testing String::insert(char, index)", "[String-insert-01]")
+{
+  arduino::String str = "ello";
+  str.insert('h', 0);
+  REQUIRE(str == String("hello"));
+}
+
+TEST_CASE ("Testing String::insert(char, index) with index > length", "[String-insert-02]")
+{
+  arduino::String str = "Hello Arduino";
+  str.insert('!', str.length() + 1);
+  REQUIRE(str == String("Hello Arduino"));
+}
+
+
+TEST_CASE ("Testing String::insert(String, index, length) with length >= inserted length", "[String-insert-03]")
+{
+    arduino::String str = "hello ";
+    str.insert("world", str.length(), 5);
+    REQUIRE(str == String("hello world"));
+}
+
+TEST_CASE ("Testing String::insert(String, index, length) with length < inserted length", "[String-insert-04]")
+{
+    arduino::String str = "Hello ";
+    str.insert("Arduino 1234", str.length(), 7);
+    REQUIRE(str == String("Hello Arduino"));
+}
+