/// Enables the use of the mark field when matching the compiled regular expression. The
/// pattern must have been previously studied and an extra block must have been created.
///
/// To ensure that an extra block has been created, call [study_with_options()](#method.study_with_options)
/// passing the [`StudyExtraNeeded`](enum.StudyOption.html#variant.StudyExtraNeeded) study option.
///
/// # Return value
/// `true` if the use of the mark field could be enabled. `false` otherwise, which signifies
/// that an extra block needs to be created.
Enables the use of the mark field when matching the compiled regular expression. The
pattern must have been previously studied and an extra block must have been created.


Enables the use of the mark field when matching the compiled regular expression . The pattern must have been previously studied and an extra block must have been created .
pub fn enable_mark(&mut self) -> bool {
        unsafe {
            if self.extra.is_null() {
                false
            } else {
                (*self.extra).set_mark(&mut self.mark_);
                true
            }
        }
    }
pub fn enable_mark ( & mut self ) -> bool { unsafe { if self . extra . is_null ( ) { false } else { ( * self . extra ) . set_mark ( & mut self . mark_ ) ; true } } }
Enables the use of the mark field when matching the compiled regular expression.
Enables the use of the mark field when matching the compiled regular expression .
&mut self
return value
`true` if the use of the mark field could be enabled. `false` otherwise, which signifies
that an extra block needs to be created.
` true ` if the use of the mark field could be enabled . ` false ` otherwise which signifies that an extra block needs to be created .