fn visit_mut()

in serde-reflection/src/format.rs [549:598]
45 lines of code
2 McCabe index (conditional complexity)

    fn visit_mut(&mut self, f: &mut dyn FnMut(&mut Format) -> Result<()>) -> Result<()> {
        match self {
            Self::Variable(variable) => {
                variable.visit_mut(f)?;
                // At this point, `variable` is known and points to variable-free content.
                // Remove the variable.
                *self = std::mem::take(variable)
                    .into_inner()
                    .expect("variable is known");
            }
            Self::TypeName(_)
            | Self::Unit
            | Self::Bool
            | Self::I8
            | Self::I16
            | Self::I32
            | Self::I64
            | Self::I128
            | Self::U8
            | Self::U16
            | Self::U32
            | Self::U64
            | Self::U128
            | Self::F32
            | Self::F64
            | Self::Char
            | Self::Str
            | Self::Bytes => (),

            Self::Option(format)
            | Self::Seq(format)
            | Self::TupleArray {
                content: format, ..
            } => {
                format.visit_mut(f)?;
            }

            Self::Map { key, value } => {
                key.visit_mut(f)?;
                value.visit_mut(f)?;
            }

            Self::Tuple(formats) => {
                for format in formats {
                    format.visit_mut(f)?;
                }
            }
        }
        f(self)
    }