use std::{borrow::Cow, collections::HashMap, ops::DerefMut}; use bstr::{BStr, BString, ByteVec}; use crate::{    file::{        self,        mutable::{escape_value, Whitespace},        Section, SectionId,    },    lookup,    parse::{section, Event},    value::{normalize_bstr, normalize_bstring},}; /// Internal data structure for [`MutableMultiValue`]#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]pub(crate) struct EntryData {    pub(crate) section_id: SectionId,    pub(crate) offset_index: usize,} /// An intermediate representation of a mutable multivar obtained from a [`File`][crate::File].#[derive(PartialEq, Eq, Debug)]pub struct MultiValueMut<'borrow, 'lookup, 'event> {    pub(crate) section: &'borrow mut HashMap<SectionId, Section<'event>>,    pub(crate) key: section::Key<'lookup>,    /// Each entry data struct provides sufficient information to index into    /// [`Self::offsets`]. This layer of indirection is used for users to index    /// into the offsets rather than leaking the internal data structures.    pub(crate) indices_and_sizes: Vec<EntryData>,    /// Each offset represents the size of a event slice and whether or not the    /// event slice is significant or not. This is used to index into the    /// actual section.    pub(crate) offsets: HashMap<SectionId, Vec<usize>>,} impl<'borrow, 'lookup, 'event> MultiValueMut<'borrow, 'lookup, 'event> {    /// Returns the actual values.    pub fn get(&self) -> Result<Vec<Cow<'_, BStr>>, lookup::existing::Error> {        let mut expect_value = false;        let mut values = Vec::new();        let mut concatenated_value = BString::default();         for EntryData {            section_id,            offset_index,        } in &self.indices_and_sizes        {            let (offset, size) = MultiValueMut::index_and_size(&self.offsets, *section_id, *offset_index);            for event in &self.section.get(section_id).expect("known section id").as_ref()[offset..offset + size] {                match event {                    Event::SectionKey(section_key) if *section_key == self.key => expect_value = true,                    Event::Value(v) if expect_value => {                        expect_value = false;                        values.push(normalize_bstr(v.as_ref()));                    }                    Event::ValueNotDone(v) if expect_value => concatenated_value.push_str(v.as_ref()),                    Event::ValueDone(v) if expect_value => {                        expect_value = false;                        concatenated_value.push_str(v.as_ref());                        values.push(normalize_bstring(std::mem::take(&mut concatenated_value)));                    }                    _ => (),                }            }        }         if values.is_empty() {            return Err(lookup::existing::Error::KeyMissing);        }         Ok(values)    }     /// Returns the amount of values within this multivar.    #[must_use]    pub fn len(&self) -> usize {        self.indices_and_sizes.len()    }     /// Returns true if the multivar does not have any values.    /// This might occur if the value was deleted but wasn't yet set with a new value.    #[must_use]    pub fn is_empty(&self) -> bool {        self.indices_and_sizes.is_empty()    }     /// Sets the value at the given index.    ///    /// # Safety    ///    /// This will panic if the index is out of range.    pub fn set_string_at(&mut self, index: usize, value: impl AsRef<str>) {        self.set_at(index, value.as_ref());    }     /// Sets the value at the given index.    ///    /// # Safety    ///    /// This will panic if the index is out of range.    pub fn set_at<'a>(&mut self, index: usize, value: impl Into<&'a BStr>) {        let EntryData {            section_id,            offset_index,        } = self.indices_and_sizes[index];        MultiValueMut::set_value_inner(            &self.key,            &mut self.offsets,            &mut self.section.get_mut(&section_id).expect("known section id").body,            section_id,            offset_index,            value.into(),        );    }     /// Sets all values to the provided ones. Note that this follows [`zip`]    /// logic: if the number of values in the input is less than the number of    /// values currently existing, then only the first `n` values are modified.    /// If more values are provided than there currently are, then the    /// remaining values are ignored.    ///    /// [`zip`]: std::iter::Iterator::zip    pub fn set_values<'a, Iter, Item>(&mut self, values: Iter)    where        Iter: IntoIterator<Item = Item>,        Item: Into<&'a BStr>,    {        for (            EntryData {                section_id,                offset_index,            },            value,        ) in self.indices_and_sizes.iter().zip(values)        {            Self::set_value_inner(                &self.key,                &mut self.offsets,                &mut self.section.get_mut(section_id).expect("known section id").body,                *section_id,                *offset_index,                value.into(),            );        }    }     /// Sets all values in this multivar to the provided one without owning the    /// provided input.    pub fn set_all<'a>(&mut self, input: impl Into<&'a BStr>) {        let input = input.into();        for EntryData {            section_id,            offset_index,        } in &self.indices_and_sizes        {            Self::set_value_inner(                &self.key,                &mut self.offsets,                &mut self.section.get_mut(section_id).expect("known section id").body,                *section_id,                *offset_index,                input,            );        }    }     fn set_value_inner<'a: 'event>(        key: &section::Key<'lookup>,        offsets: &mut HashMap<SectionId, Vec<usize>>,        section: &mut file::section::Body<'event>,        section_id: SectionId,        offset_index: usize,        value: &BStr,    ) {        let (offset, size) = MultiValueMut::index_and_size(offsets, section_id, offset_index);        let whitespace = Whitespace::from_body(section);        let section = section.as_mut();        section.drain(offset..offset + size);         let key_sep_events = whitespace.key_value_separators();        MultiValueMut::set_offset(offsets, section_id, offset_index, 2 + key_sep_events.len());        section.insert(offset, Event::Value(escape_value(value).into()));        section.insert_many(offset, key_sep_events.into_iter().rev());        section.insert(offset, Event::SectionKey(key.to_owned()));    }     /// Removes the value at the given index. Does nothing when called multiple    /// times in succession.    ///    /// # Safety    ///    /// This will panic if the index is out of range.    pub fn delete(&mut self, index: usize) {        let EntryData {            section_id,            offset_index,        } = &self.indices_and_sizes[index];        let (offset, size) = MultiValueMut::index_and_size(&self.offsets, *section_id, *offset_index);        if size == 0 {            return;        }        self.section            .get_mut(section_id)            .expect("known section id")            .body            .as_mut()            .drain(offset..offset + size);         Self::set_offset(&mut self.offsets, *section_id, *offset_index, 0);        self.indices_and_sizes.remove(index);    }     /// Removes all values. Does nothing when called multiple times in    /// succession.    pub fn delete_all(&mut self) {        for EntryData {            section_id,            offset_index,        } in &self.indices_and_sizes        {            let (offset, size) = MultiValueMut::index_and_size(&self.offsets, *section_id, *offset_index);            if size == 0 {                continue;            }            self.section                .get_mut(section_id)                .expect("known section id")                .body                .as_mut()                .drain(offset..offset + size);            Self::set_offset(&mut self.offsets, *section_id, *offset_index, 0);        }        self.indices_and_sizes.clear();    }     fn index_and_size(        offsets: &'lookup HashMap<SectionId, Vec<usize>>,        section_id: SectionId,        offset_index: usize,    ) -> (usize, usize) {        offsets            .get(&section_id)            .expect("known section id")            .iter()            .take(offset_index + 1)            .fold((0, 0), |(total_ofs, ofs), size| (total_ofs + ofs, *size))    }     // This must be an associated function rather than a method to allow Rust    // to split mutable borrows.    fn set_offset(        offsets: &mut HashMap<SectionId, Vec<usize>>,        section_id: SectionId,        offset_index: usize,        value: usize,    ) {        *offsets            .get_mut(&section_id)            .expect("known section id")            .get_mut(offset_index)            .unwrap()            .deref_mut() = value;    }}