Method add_or_modify

crates/kernel_cmdline/src/bytes.rs:251–296

Add or modify a parameter to the command line Returns `Action::Added` if the parameter did not exist before and was added. Returns `Action::Modified` if the parameter existed before, but contained a different value. The value was updated to the newly-requested value. Returns `Action::Existed` if the parameter existed before, and contained the same value as the newly-requested value. No modifi

(&mut self, param: &Parameter)

    /// contained the same value as the newly-requested value.  No
    /// modification was made.
    pub fn add_or_modify(&mut self, param: &Parameter) -> Action {
        let mut new_params = Vec::new();
        let mut modified = false;
        let mut seen_key = false;

        for p in self.iter() {
            if p.key == param.key {
                if !seen_key {
                    // This is the first time we've seen this key.
                    // We will replace it with the new parameter.
                    if p != *param {
                        modified = true;
                    }
                    new_params.push(param.parameter);
                } else {
                    // This is a subsequent parameter with the same key.
                    // We will remove it, which constitutes a modification.
                    modified = true;
                }
                seen_key = true;
            } else {
                new_params.push(p.parameter);
            }
        }

        if !seen_key {
            // The parameter was not found, so we append it.
            let self_mut = self.0.to_mut();
            if self_mut
                .last()
                .filter(|v| !v.is_ascii_whitespace())
                .is_some()
            {
                self_mut.push(b' ');
            }
            self_mut.extend_from_slice(param.parameter);
            return Action::Added;
        }
        if modified {
            self.0 = Cow::Owned(new_params.join(b" ".as_slice()));
            Action::Modified
        } else {
            // The parameter already existed with the same content, and there were no duplicates.
            Action::Existed
        }
    }

    /// Remove parameter(s) with the given key from the command line
    ///