Doxygen @code line numbers

Question

Is there a way to display code line numbers inside a @code ... @endcode block? From the screenshots in the doxygen manual it would seem that there is, but I was unable to find an option for doxygen itself, or a tag syntax to accomplish this.

I need this to be able to write something like "In the above code, line 3" after a code block.

Tested also for fenced code blocks, still getting no numbers.

Answer 1

Short Answer

It seems that at least in the current version (1.8.9) line numbers are added:

• to C code only when using \includelineno tag
• to any Python code

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Details

Python code formatter

Python code formatter includes line numbers if g_sourceFileDef evaluates as TRUE:

/*! start a new line of code, inserting a line number if g_sourceFileDef
 * is TRUE. If a definition starts at the current line, then the line
 * number is linked to the documentation of that definition.
 */
static void startCodeLine()
{
  //if (g_currentFontClass) { g_code->endFontClass(); }
  if (g_sourceFileDef)

( https://github.com/doxygen/doxygen/blob/Release_1_8_9/src/pycode.l#L356 )

It's initialized from FileDef *fd passed into parseCode/parsePythonCode if it was provided (non-zero) or from new FileDef(<...>) otherwise:

g_sourceFileDef = fd;
<...>
if (fd==0)
{
  // create a dummy filedef for the example
  g_sourceFileDef = new FileDef("",(exName?exName:"generated"));
  cleanupSourceDef = TRUE;
}

( https://github.com/doxygen/doxygen/blob/Release_1_8_9/src/pycode.l#L1458 ) so it seems all Python code is having line numbers included

C code formatter

C code formatter has an additional variable g_lineNumbers and includes line numbers if both g_sourceFileDef and g_lineNumbers evaluate as TRUE:

/*! start a new line of code, inserting a line number if g_sourceFileDef
 * is TRUE. If a definition starts at the current line, then the line
 * number is linked to the documentation of that definition.
 */
static void startCodeLine()
{
  //if (g_currentFontClass) { g_code->endFontClass(); }
  if (g_sourceFileDef && g_lineNumbers)

( https://github.com/doxygen/doxygen/blob/Release_1_8_9/src/code.l#L486 )

They are initialized in the following way:

g_sourceFileDef = fd;
g_lineNumbers = fd!=0 && showLineNumbers;
<...>
if (fd==0)
{
  // create a dummy filedef for the example
  g_sourceFileDef = new FileDef("",(exName?exName:"generated"));
  cleanupSourceDef = TRUE;
}

( https://github.com/doxygen/doxygen/blob/Release_1_8_9/src/code.l#L3623 )

Note that g_lineNumbers remains FALSE if provided fd value was 0

HtmlDocVisitor

Among parseCode calls in HtmlDocVisitor::visit there is only one (for DocInclude::IncWithLines, what corresponds to \includelineno) which passes non-zero fd: https://github.com/doxygen/doxygen/blob/Release_1_8_9/src/htmldocvisitor.cpp#L540 so this seems to be the only command which will result in line numbers included into C code listing

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