Add Common::String::printf to format a string

svn-id: r42743

3 files changed, 43 insertions, 0 deletions

diff --git a/common/str.cpp b/common/str.cpp
index 0d24f2edac..deef8bb22d 100644
--- a/common/str.cpp
+++ b/common/str.cpp
@@ -28,6 +28,8 @@
 
 #include "common/memorypool.h"
 
+#include <stdarg.h>
+
 #if !defined(__SYMBIAN32__)
 #include <new>
 #endif
@@ -435,6 +437,34 @@ uint String::hash() const {
 	return hashit(c_str());
 }
 
+// static
+String String::printf(const char *fmt, ...)
+{
+	String output;
+	assert(output.isStorageIntern());
+
+	va_list va;
+	va_start(va, fmt);
+	int len = vsnprintf(output._str, _builtinCapacity, fmt, va);
+	va_end(va);
+
+	if (len < (int)_builtinCapacity) {
+		// vsnprintf succeeded
+		output._size = len;
+	} else {
+		// vsnprintf didn't have enough space, so grow buffer
+		output.ensureCapacity(len, false);
+		va_start(va, fmt);
+		int len2 = vsnprintf(output._str, len+1, fmt, va);
+		va_end(va);
+		assert(len == len2);
+		output._size = len2;
+	}
+
+	return output;
+}
+
+
 #pragma mark -
 
 bool String::operator ==(const String &x) const {
diff --git a/common/str.h b/common/str.h
index b7dbd6535a..2fc88e9c91 100644
--- a/common/str.h
+++ b/common/str.h
@@ -218,6 +218,11 @@ public:
 
 	uint hash() const;
 
+	/**
+	 * Printf-like function. Returns a formatted String.
+	 */
+	static Common::String printf(const char *fmt, ...) GCC_PRINTF(1,2);
+
 public:
 	typedef char *        iterator;
 	typedef const char *  const_iterator;
diff --git a/test/common/str.h b/test/common/str.h
index bf0db98b09..f65b078bdc 100644
--- a/test/common/str.h
+++ b/test/common/str.h
@@ -285,4 +285,12 @@ class StringTestSuite : public CxxTest::TestSuite
 		TS_ASSERT(!Common::matchString("monkey.s99",  "monkey.s*1"));
 		TS_ASSERT(Common::matchString("monkey.s101", "monkey.s*1"));
 	}
+
+	void test_string_printf() {
+		TS_ASSERT( Common::String::printf("") == "" );
+		TS_ASSERT( Common::String::printf("%s", "test") == "test" );
+		TS_ASSERT( Common::String::printf("%s.s%.02d", "monkey", 1) == "monkey.s01" );
+		TS_ASSERT( Common::String::printf("%s%X", "test", 1234) == "test4D2" );
+		TS_ASSERT( Common::String::printf("Some %s to make this string longer than the default built-in %s %d", "text", "capacity", 123456) == "Some text to make this string longer than the default built-in capacity 123456" );
+	}
 };