util: Add function FormatParagraph to format paragraph to fixed-width

This is to be used for the `-version` and `-help` messages.

src/test/util_tests.cpp

@@ -351,4 +351,15 @@ BOOST_AUTO_TEST_CASE(test_ParseInt32)
     BOOST_CHECK(!ParseInt32("32482348723847471234", NULL));
 }
 
+BOOST_AUTO_TEST_CASE(test_FormatParagraph)
+{
+    BOOST_CHECK_EQUAL(FormatParagraph("", 79, 0), "");
+    BOOST_CHECK_EQUAL(FormatParagraph("test", 79, 0), "test");
+    BOOST_CHECK_EQUAL(FormatParagraph(" test", 79, 0), "test");
+    BOOST_CHECK_EQUAL(FormatParagraph("test test", 79, 0), "test test");
+    BOOST_CHECK_EQUAL(FormatParagraph("test test", 4, 0), "test\ntest");
+    BOOST_CHECK_EQUAL(FormatParagraph("testerde test ", 4, 0), "testerde\ntest");
+    BOOST_CHECK_EQUAL(FormatParagraph("test test", 4, 4), "test\n    test");
+}
+
 BOOST_AUTO_TEST_SUITE_END()

src/util.cpp

@@ -1407,3 +1407,38 @@ std::string DateTimeStrFormat(const char* pszFormat, int64_t nTime)
     ss << boost::posix_time::from_time_t(nTime);
     return ss.str();
 }
+
+std::string FormatParagraph(const std::string in, size_t width, size_t indent)
+{
+    std::stringstream out;
+    size_t col = 0;
+    size_t ptr = 0;
+    while(ptr < in.size())
+    {
+        // Find beginning of next word
+        ptr = in.find_first_not_of(' ', ptr);
+        if (ptr == std::string::npos)
+            break;
+        // Find end of next word
+        size_t endword = in.find_first_of(' ', ptr);
+        if (endword == std::string::npos)
+            endword = in.size();
+        // Add newline and indentation if this wraps over the allowed width
+        if (col > 0)
+        {
+            if ((col + endword - ptr) > width)
+            {
+                out << '\n';
+                for(size_t i=0; i<indent; ++i)
+                    out << ' ';
+                col = 0;
+            } else
+                out << ' ';
+        }
+        // Append word
+        out << in.substr(ptr, endword - ptr);
+        col += endword - ptr;
+        ptr = endword;
+    }
+    return out.str();
+}

src/util.h

@@ -286,6 +286,11 @@ inline std::string HexStr(const T& vch, bool fSpaces=false)
     return HexStr(vch.begin(), vch.end(), fSpaces);
 }
 
+/** Format a paragraph of text to a fixed width, adding spaces for
+ * indentation to any added line.
+ */
+std::string FormatParagraph(const std::string in, size_t width=79, size_t indent=0);
+
 inline int64_t GetPerformanceCounter()
 {
     int64_t nCounter = 0;