Updates to some BURT related functions in the EPICS sequencer.

• Remove plain char arrays from writeTable2File, replace with fixed_string.
• Rework encodeBURTString to take fixed_string inputs
  • Update it to have no failure cases. This is done by replacing pointers with references and putting compile time checks in on input lengths.
  • Put encodeBURTString under test.
• Minor updates to fixed_string
  • introduce begin()/end() for range for loop support and empty() to clarify code.
  • introduce an operator+=(char) for appending a character at a time.
• Updates to the parseLine function
  • put parseLine under test
  • Fixed an overflow issue in parseLine when there is a quoted word that is longer than the output buffers.
  • Fixed an issue with parsing where the quotes were returned in the output if the first word was quote escaped.
  • Reworked it to use fixed strings and vectors instead of 6 char* out parameters.
• Moved encodeBURTString and parseLine to burt_file.hh
  • Put them in a BURT namespace
  • Renamed BURT::encodeBURTString -> BURT::encodeString

src/epics/seq/test/test_burtfile.cc

+//
+// Created by jonathan.hanks on 4/2/22.
+//
+#include "catch.hpp"
+#include "burt_file.hh"
+#include <string>
+#include <vector>
+
+TEST_CASE( "Test encodeString" )
+{
+    struct TestCase
+    {
+        const char* input;
+        const char* expected_output;
+    };
+    std::vector< TestCase > test_cases{
+        { nullptr, "\\0" },
+        { "", "\\0" },
+        { "abc", "abc" },
+        { "abc def", "\"abc def\"" },
+        { "abc\"d\"ef", "\"abc\"d\"ef\"" },
+        { "abc\"def", "\"abc\"def\"" },
+        { "abc\ndef", "\"abc\ndef\"" },
+        { "abc\tdef", "\"abc\tdef\"" },
+    };
+    for ( const auto& test_case : test_cases )
+    {
+        embedded::fixed_string< 18 > src( test_case.input );
+        embedded::fixed_string< 20 > dest;
+        BURT::encodeString( src, dest );
+        REQUIRE( strcmp( test_case.expected_output, dest.c_str( ) ) == 0 );
+    }
+}
+#include <iostream>
+TEST_CASE( "Test parseLine" )
+{
+    struct TestCase
+    {
+        const char*                input;
+        std::vector< std::string > expected_output;
+    };
+    std::vector< TestCase > test_cases{
+        { "", {} },
+        { "\\0", { "" } },
+        { "abc", { "abc" } },
+        { "abc def", { "abc", "def" } },
+        { "abc\tdef", { "abc", "def" } },
+        /* newline ends the parsing */
+        { "abc\ndef", { "abc" } },
+        { "0 1 2 3 4 5", { "0", "1", "2", "3", "4", "5" } },
+        { "0 1 2 \\0 4 5", { "0", "1", "2", "", "4", "5" } },
+        /* shouldn't include the quote in the output */
+        { "\"0\" 1 2 3 4 5", { "0", "1", "2", "3", "4", "5" } },
+        { "0 1 2 3 4 5 6", { "0", "1", "2", "3", "4", "5" } },
+        { "0 1 2 3 4 5 6 7 8 9 10", { "0", "1", "2", "3", "4", "5" } },
+        { "0 \" 1 2 3 4 5 \" 6 7 8 9 10",
+          { "0", " 1 2 3 4 5 ", "6", "7", "8", "9" } },
+        { "0 \" 1\t2\t3 4 5 \" 6 7 8 9 10",
+          { "0", " 1\t2\t3 4 5 ", "6", "7", "8", "9" } },
+        { "0 \" 1\t2\n\t3 4 5 \" 6 7 8 9 10", { "0", " 1\t2" } },
+        { "012345678901234567890", { "01234567890123" } },
+        { "012345678901234567890 012345678901234567890",
+          { "01234567890123", "01234567890123" } },
+        /* Make sure the quote is not in the output */
+        { "\"012345678901234567890\" 012345678901234567890",
+          { "01234567890123", "01234567890123" } },
+        /* truncate, and do not overflow */
+        { "012345678901234567890 \"abcdefghijklmnop\" ABC",
+          { "01234567890123", "abcdefghijklmn", "ABC" } },
+    };
+    for ( const auto& test_case : test_cases )
+    {
+        embedded::fixed_size_vector< embedded::fixed_string< 15 >, 6 > out{ };
+
+        std::cout << test_case.input << "\n";
+        int wc = BURT::parseLine( test_case.input, out );
+        REQUIRE( wc == test_case.expected_output.size( ) );
+        REQUIRE( wc == out.size( ) );
+        for ( auto i = 0; i < wc; ++i )
+        {
+            REQUIRE( out[ i ] == test_case.expected_output[ i ].c_str( ) );
+        }
+    }
+}
\ No newline at end of file