Bump dependencies

1 files changed, 0 insertions, 814 deletions

diff --git a/src/export/subset.rs b/src/export/subset.rs
deleted file mode 100644
index e688d9cc..00000000
--- a/src/export/subset.rs
+++ /dev/null
@@ -1,814 +0,0 @@
-//! OpenType font subsetting.
-
-use std::borrow::Cow;
-use std::collections::HashSet;
-use std::iter;
-use std::ops::Range;
-
-use ttf_parser::parser::{
-    FromData, LazyArray16, LazyArray32, Offset, Offset16, Offset32, Stream, F2DOT14,
-};
-use ttf_parser::Tag;
-
-/// Subset a font face for PDF embedding.
-///
-/// This will remove the outlines of all glyphs that are not part of the given
-/// slice. Furthmore, all character mapping and layout tables are dropped as
-/// shaping has already happened.
-///
-/// Returns `None` if the font data is fatally broken (in which case
-/// `ttf-parser` would probably already have rejected the font, so this
-/// shouldn't happen if the font data has already passed through `ttf-parser`).
-pub fn subset(data: &[u8], index: u32, glyphs: &HashSet<u16>) -> Option<Vec<u8>> {
-    Some(Subsetter::new(data, index, glyphs)?.subset())
-}
-
-struct Subsetter<'a> {
-    data: &'a [u8],
-    magic: Magic,
-    records: LazyArray16<'a, TableRecord>,
-    num_glyphs: u16,
-    glyphs: &'a HashSet<u16>,
-    tables: Vec<(Tag, Cow<'a, [u8]>)>,
-}
-
-impl<'a> Subsetter<'a> {
-    /// Parse the font header and create a new subsetter.
-    fn new(data: &'a [u8], index: u32, glyphs: &'a HashSet<u16>) -> Option<Self> {
-        let mut s = Stream::new(data);
-
-        let mut magic = s.read::<Magic>()?;
-        if magic == Magic::Collection {
-            // Parse font collection header if necessary.
-            s.skip::<u32>();
-            let num_faces = s.read::<u32>()?;
-            let offsets = s.read_array32::<Offset32>(num_faces)?;
-            let offset = offsets.get(index)?.to_usize();
-
-            s = Stream::new_at(data, offset)?;
-            magic = s.read::<Magic>()?;
-            if magic == Magic::Collection {
-                return None;
-            }
-        }
-
-        // Read number of table records.
-        let count = s.read::<u16>()?;
-
-        // Skip boring parts of header.
-        s.skip::<u16>();
-        s.skip::<u16>();
-        s.skip::<u16>();
-
-        // Read the table records.
-        let records = s.read_array16::<TableRecord>(count)?;
-        let mut subsetter = Self {
-            data,
-            magic,
-            records,
-            num_glyphs: 0,
-            glyphs,
-            tables: vec![],
-        };
-
-        // Find out number of glyphs.
-        let maxp = subsetter.table_data(MAXP)?;
-        subsetter.num_glyphs = Stream::read_at::<u16>(maxp, 4)?;
-
-        Some(subsetter)
-    }
-
-    /// Encode the subsetted font file.
-    fn subset(mut self) -> Vec<u8> {
-        self.subset_tables();
-
-        // Start writing a brand new font.
-        let mut w = Vec::new();
-        w.write(self.magic);
-
-        // Write table directory.
-        let count = self.tables.len() as u16;
-        let entry_selector = (count as f32).log2().floor() as u16;
-        let search_range = 2u16.pow(u32::from(entry_selector)) * 16;
-        let range_shift = count * 16 - search_range;
-        w.write(count);
-        w.write(search_range);
-        w.write(entry_selector);
-        w.write(range_shift);
-
-        // Tables shall be sorted by tag.
-        self.tables.sort_by_key(|&(tag, _)| tag);
-
-        // This variable will hold the offset to the checksum adjustment field
-        // in the head table, which we'll have to write in the end (after
-        // checksumming the whole font).
-        let mut checksum_adjustment_offset = None;
-
-        // Write table records.
-        let mut offset = 12 + self.tables.len() * TableRecord::SIZE;
-        for (tag, data) in &mut self.tables {
-            if *tag == HEAD {
-                // Zero out checksum field in head table.
-                data.to_mut()[8 .. 12].fill(0);
-                checksum_adjustment_offset = Some(offset + 8);
-            }
-
-            let len = data.len();
-            w.write(TableRecord {
-                tag: *tag,
-                checksum: checksum(data),
-                offset: offset as u32,
-                length: len as u32,
-            });
-
-            // Increase offset, plus padding zeros to align to 4 bytes.
-            offset += len;
-            while offset % 4 != 0 {
-                offset += 1;
-            }
-        }
-
-        // Write tables.
-        for (_, data) in &self.tables {
-            // Write data plus padding zeros to align to 4 bytes.
-            w.extend(data.as_ref());
-            while w.len() % 4 != 0 {
-                w.push(0);
-            }
-        }
-
-        // Write checksumAdjustment field in head table.
-        if let Some(i) = checksum_adjustment_offset {
-            let sum = checksum(&w);
-            let val = 0xB1B0AFBA_u32.wrapping_sub(sum);
-            w[i .. i + 4].copy_from_slice(&val.to_be_bytes());
-        }
-
-        w
-    }
-
-    /// Subset, drop and copy tables.
-    fn subset_tables(&mut self) {
-        // Remove unnecessary name information.
-        let handled_post = post::subset(self).is_some();
-
-        // Remove unnecessary glyph outlines.
-        let handled_glyf_loca = glyf::subset(self).is_some();
-        let handled_cff1 = cff::subset_v1(self).is_some();
-
-        for record in self.records {
-            // If `handled` is true, we don't take any further action, if it's
-            // false, we copy the table.
-            #[rustfmt::skip]
-            let handled = match &record.tag.to_bytes() {
-                // Drop: Glyphs are already mapped.
-                b"cmap" => true,
-
-                // Drop: Layout is already finished.
-                b"GPOS" | b"GSUB" | b"BASE" | b"JSTF" | b"MATH" |
-                b"ankr" | b"kern" | b"kerx" | b"mort" | b"morx" |
-                b"trak" | b"bsln" | b"just" | b"feat" | b"prop" => true,
-
-                // Drop: They don't render in PDF viewers anyway.
-                // TODO: We probably have to convert fonts with one of these
-                // tables into Type 3 fonts where glyphs are described by either
-                // PDF graphics operators or XObject images.
-                b"CBDT" | b"CBLC" | b"COLR" | b"CPAL" | b"sbix" | b"SVG " => true,
-
-                // Subsetted: Subsetting happens outside the loop, but if it
-                // failed, we simply copy the affected table(s).
-                b"post" => handled_post,
-                b"loca" | b"glyf" => handled_glyf_loca,
-                b"CFF " => handled_cff1,
-
-                // Copy: All other tables are simply copied.
-                _ => false,
-            };
-
-            if !handled {
-                if let Some(data) = self.table_data(record.tag) {
-                    self.push_table(record.tag, data);
-                }
-            }
-        }
-    }
-
-    /// Retrieve the table data for a table.
-    fn table_data(&mut self, tag: Tag) -> Option<&'a [u8]> {
-        let (_, record) = self.records.binary_search_by(|record| record.tag.cmp(&tag))?;
-        let start = record.offset as usize;
-        let end = start + (record.length as usize);
-        self.data.get(start .. end)
-    }
-
-    /// Push a new table.
-    fn push_table(&mut self, tag: Tag, data: impl Into<Cow<'a, [u8]>>) {
-        self.tables.push((tag, data.into()));
-    }
-}
-
-// Some common tags.
-const HEAD: Tag = Tag::from_bytes(b"head");
-const MAXP: Tag = Tag::from_bytes(b"maxp");
-const POST: Tag = Tag::from_bytes(b"post");
-const LOCA: Tag = Tag::from_bytes(b"loca");
-const GLYF: Tag = Tag::from_bytes(b"glyf");
-const CFF1: Tag = Tag::from_bytes(b"CFF ");
-
-/// Calculate a checksum over the sliced data as a sum of u32s. If the data
-/// length is not a multiple of four, it is treated as if padded with zero to a
-/// length that is a multiple of four.
-fn checksum(data: &[u8]) -> u32 {
-    let mut sum = 0u32;
-    for chunk in data.chunks(4) {
-        let mut bytes = [0; 4];
-        bytes[.. chunk.len()].copy_from_slice(chunk);
-        sum = sum.wrapping_add(u32::from_be_bytes(bytes));
-    }
-    sum
-}
-
-/// Zero all bytes in a slice.
-fn memzero(slice: &mut [u8]) {
-    for byte in slice {
-        *byte = 0;
-    }
-}
-
-/// Convenience trait for writing into a byte buffer.
-trait BufExt {
-    fn write<T: ToData>(&mut self, v: T);
-}
-
-impl BufExt for Vec<u8> {
-    fn write<T: ToData>(&mut self, v: T) {
-        v.write(self);
-    }
-}
-
-/// A trait for writing raw binary data.
-trait ToData {
-    fn write(&self, data: &mut Vec<u8>);
-}
-
-impl ToData for u8 {
-    fn write(&self, data: &mut Vec<u8>) {
-        data.push(*self);
-    }
-}
-
-impl ToData for u16 {
-    fn write(&self, data: &mut Vec<u8>) {
-        data.extend(&self.to_be_bytes());
-    }
-}
-
-impl ToData for Offset16 {
-    fn write(&self, data: &mut Vec<u8>) {
-        self.0.write(data);
-    }
-}
-
-impl ToData for u32 {
-    fn write(&self, data: &mut Vec<u8>) {
-        data.extend(&self.to_be_bytes());
-    }
-}
-
-impl ToData for Offset32 {
-    fn write(&self, data: &mut Vec<u8>) {
-        self.0.write(data);
-    }
-}
-
-impl ToData for Tag {
-    fn write(&self, data: &mut Vec<u8>) {
-        self.as_u32().write(data);
-    }
-}
-
-/// Font magic number.
-#[derive(Debug, Copy, Clone, Eq, PartialEq)]
-enum Magic {
-    TrueType,
-    OpenType,
-    Collection,
-}
-
-impl FromData for Magic {
-    const SIZE: usize = 4;
-
-    fn parse(data: &[u8]) -> Option<Self> {
-        match u32::parse(data)? {
-            0x00010000 | 0x74727565 => Some(Magic::TrueType),
-            0x4F54544F => Some(Magic::OpenType),
-            0x74746366 => Some(Magic::Collection),
-            _ => None,
-        }
-    }
-}
-
-impl ToData for Magic {
-    fn write(&self, data: &mut Vec<u8>) {
-        let value: u32 = match self {
-            Magic::TrueType => 0x00010000,
-            Magic::OpenType => 0x4F54544F,
-            Magic::Collection => 0x74746366,
-        };
-        value.write(data);
-    }
-}
-
-/// Locates a table in the font file.
-#[derive(Debug, Copy, Clone, Eq, PartialEq)]
-struct TableRecord {
-    tag: Tag,
-    checksum: u32,
-    offset: u32,
-    length: u32,
-}
-
-impl FromData for TableRecord {
-    const SIZE: usize = 16;
-
-    fn parse(data: &[u8]) -> Option<Self> {
-        let mut s = Stream::new(data);
-        Some(TableRecord {
-            tag: s.read::<Tag>()?,
-            checksum: s.read::<u32>()?,
-            offset: s.read::<u32>()?,
-            length: s.read::<u32>()?,
-        })
-    }
-}
-
-impl ToData for TableRecord {
-    fn write(&self, data: &mut Vec<u8>) {
-        self.tag.write(data);
-        self.checksum.write(data);
-        self.offset.write(data);
-        self.length.write(data);
-    }
-}
-
-mod post {
-    use super::*;
-
-    /// Subset the post table by removing the name information.
-    pub(super) fn subset(subsetter: &mut Subsetter) -> Option<()> {
-        // Table version three is the one without names.
-        let mut new = 0x00030000_u32.to_be_bytes().to_vec();
-        new.extend(subsetter.table_data(POST)?.get(4 .. 32)?);
-        subsetter.push_table(POST, new);
-        Some(())
-    }
-}
-
-mod glyf {
-    use super::*;
-
-    /// Subset the glyf and loca tables by clearing out glyph data for
-    /// unused glyphs.
-    pub(super) fn subset(subsetter: &mut Subsetter) -> Option<()> {
-        let head = subsetter.table_data(HEAD)?;
-        let short = Stream::read_at::<i16>(head, 50)? == 0;
-        if short {
-            subset_impl::<Offset16>(subsetter)
-        } else {
-            subset_impl::<Offset32>(subsetter)
-        }
-    }
-
-    fn subset_impl<T>(subsetter: &mut Subsetter) -> Option<()>
-    where
-        T: LocaOffset,
-    {
-        let loca = subsetter.table_data(LOCA)?;
-        let glyf = subsetter.table_data(GLYF)?;
-
-        let offsets = LazyArray32::<T>::new(loca);
-        let glyph_data = |id: u16| {
-            let from = offsets.get(u32::from(id))?.loca_to_usize();
-            let to = offsets.get(u32::from(id) + 1)?.loca_to_usize();
-            glyf.get(from .. to)
-        };
-
-        // The set of all glyphs we will include in the subset.
-        let mut subset = HashSet::new();
-
-        // Because glyphs may depend on other glyphs as components (also with
-        // multiple layers of nesting), we have to process all glyphs to find
-        // their components. For notdef and all requested glyphs we simply use
-        // an iterator, but to track other glyphs that need processing we create
-        // a work stack.
-        let mut iter = iter::once(0).chain(subsetter.glyphs.iter().copied());
-        let mut work = vec![];
-
-        // Find composite glyph descriptions.
-        while let Some(id) = work.pop().or_else(|| iter.next()) {
-            if subset.insert(id) {
-                let mut s = Stream::new(glyph_data(id)?);
-                if let Some(num_contours) = s.read::<i16>() {
-                    // Negative means this is a composite glyph.
-                    if num_contours < 0 {
-                        // Skip min/max metrics.
-                        s.read::<i16>();
-                        s.read::<i16>();
-                        s.read::<i16>();
-                        s.read::<i16>();
-
-                        // Read component glyphs.
-                        work.extend(component_glyphs(s));
-                    }
-                }
-            }
-        }
-
-        let mut sub_loca = vec![];
-        let mut sub_glyf = vec![];
-
-        for id in 0 .. subsetter.num_glyphs {
-            // If the glyph shouldn't be contained in the subset, it will
-            // still get a loca entry, but the glyf data is simply empty.
-            sub_loca.write(T::usize_to_loca(sub_glyf.len())?);
-            if subset.contains(&id) {
-                sub_glyf.extend(glyph_data(id)?);
-            }
-        }
-
-        sub_loca.write(T::usize_to_loca(sub_glyf.len())?);
-
-        subsetter.push_table(LOCA, sub_loca);
-        subsetter.push_table(GLYF, sub_glyf);
-
-        Some(())
-    }
-
-    trait LocaOffset: Sized + FromData + ToData {
-        fn loca_to_usize(self) -> usize;
-        fn usize_to_loca(offset: usize) -> Option<Self>;
-    }
-
-    impl LocaOffset for Offset16 {
-        fn loca_to_usize(self) -> usize {
-            2 * usize::from(self.0)
-        }
-
-        fn usize_to_loca(offset: usize) -> Option<Self> {
-            if offset % 2 == 0 {
-                (offset / 2).try_into().ok().map(Self)
-            } else {
-                None
-            }
-        }
-    }
-
-    impl LocaOffset for Offset32 {
-        fn loca_to_usize(self) -> usize {
-            self.0 as usize
-        }
-
-        fn usize_to_loca(offset: usize) -> Option<Self> {
-            offset.try_into().ok().map(Self)
-        }
-    }
-
-    /// Returns an iterator over the component glyphs referenced by the given
-    /// `glyf` table composite glyph description.
-    fn component_glyphs(mut s: Stream) -> impl Iterator<Item = u16> + '_ {
-        const ARG_1_AND_2_ARE_WORDS: u16 = 0x0001;
-        const WE_HAVE_A_SCALE: u16 = 0x0008;
-        const MORE_COMPONENTS: u16 = 0x0020;
-        const WE_HAVE_AN_X_AND_Y_SCALE: u16 = 0x0040;
-        const WE_HAVE_A_TWO_BY_TWO: u16 = 0x0080;
-
-        let mut done = false;
-        iter::from_fn(move || {
-            if done {
-                return None;
-            }
-
-            let flags = s.read::<u16>()?;
-            let component = s.read::<u16>()?;
-
-            if flags & ARG_1_AND_2_ARE_WORDS != 0 {
-                s.skip::<i16>();
-                s.skip::<i16>();
-            } else {
-                s.skip::<u16>();
-            }
-
-            if flags & WE_HAVE_A_SCALE != 0 {
-                s.skip::<F2DOT14>();
-            } else if flags & WE_HAVE_AN_X_AND_Y_SCALE != 0 {
-                s.skip::<F2DOT14>();
-                s.skip::<F2DOT14>();
-            } else if flags & WE_HAVE_A_TWO_BY_TWO != 0 {
-                s.skip::<F2DOT14>();
-                s.skip::<F2DOT14>();
-                s.skip::<F2DOT14>();
-                s.skip::<F2DOT14>();
-            }
-
-            done = flags & MORE_COMPONENTS == 0;
-            Some(component)
-        })
-    }
-}
-
-mod cff {
-    use super::*;
-
-    /// Subset the CFF table by zeroing glyph data for unused glyphs.
-    pub(super) fn subset_v1(subsetter: &mut Subsetter) -> Option<()> {
-        let cff = subsetter.table_data(CFF1)?;
-        let mut s = Stream::new(cff);
-
-        let (major, _) = (s.read::<u8>()?, s.skip::<u8>());
-        if major != 1 {
-            return None;
-        }
-
-        let header_size = s.read::<u8>()?;
-        s = Stream::new_at(cff, usize::from(header_size))?;
-
-        // Skip the name index.
-        Index::parse_stream(&mut s);
-
-        // Read the top dict. The index should contain only one item.
-        let top_dict_index = Index::parse_stream(&mut s)?;
-        let top_dict = Dict::parse(top_dict_index.get(0)?);
-
-        let mut sub_cff = cff.to_vec();
-
-        // Because completely rebuilding the CFF structure would be pretty
-        // complex, for now, we employ a peculiar strategy for CFF subsetting:
-        // We simply replace unused data with zeros. This way, the font
-        // structure and offsets can stay the same. And while the CFF table
-        // itself doesn't shrink, the actual embedded font is compressed and
-        // greatly benefits from the repeated zeros.
-        zero_char_strings(subsetter, cff, &top_dict, &mut sub_cff);
-        zero_subr_indices(subsetter, cff, &top_dict, &mut sub_cff);
-
-        subsetter.push_table(CFF1, sub_cff);
-
-        Some(())
-    }
-
-    /// Zero unused char strings.
-    fn zero_char_strings(
-        subsetter: &Subsetter,
-        cff: &[u8],
-        top_dict: &Dict,
-        sub_cff: &mut [u8],
-    ) -> Option<()> {
-        let char_strings_offset = top_dict.get_offset(Op::CHAR_STRINGS)?;
-        let char_strings = Index::parse(cff.get(char_strings_offset ..)?)?;
-
-        for (id, _, range) in char_strings.iter() {
-            if !subsetter.glyphs.contains(&id) {
-                let start = char_strings_offset + range.start;
-                let end = char_strings_offset + range.end;
-                memzero(sub_cff.get_mut(start .. end)?);
-            }
-        }
-
-        Some(())
-    }
-
-    /// Zero unused local subroutine indices. We don't currently remove
-    /// individual subroutines because finding out which ones are used is
-    /// complicated.
-    fn zero_subr_indices(
-        subsetter: &Subsetter,
-        cff: &[u8],
-        top_dict: &Dict,
-        sub_cff: &mut [u8],
-    ) -> Option<()> {
-        // Parse FD Select data structure, which maps from glyph ids to find
-        // dict indices.
-        let fd_select_offset = top_dict.get_offset(Op::FD_SELECT)?;
-        let fd_select =
-            parse_fd_select(cff.get(fd_select_offset ..)?, subsetter.num_glyphs)?;
-
-        // Clear local subrs from unused font dicts.
-        let fd_array_offset = top_dict.get_offset(Op::FD_ARRAY)?;
-        let fd_array = Index::parse(cff.get(fd_array_offset ..)?)?;
-
-        // Determine which font dict's subrs to keep.
-        let mut sub_fds = HashSet::new();
-        for &glyph in subsetter.glyphs {
-            sub_fds.insert(fd_select.get(usize::from(glyph))?);
-        }
-
-        for (i, data, _) in fd_array.iter() {
-            if !sub_fds.contains(&(i as u8)) {
-                let font_dict = Dict::parse(data);
-                if let Some(private_range) = font_dict.get_range(Op::PRIVATE) {
-                    let private_dict = Dict::parse(cff.get(private_range.clone())?);
-                    if let Some(subrs_offset) = private_dict.get_offset(Op::SUBRS) {
-                        let start = private_range.start + subrs_offset;
-                        let index = Index::parse(cff.get(start ..)?)?;
-                        let end = start + index.data.len();
-                        memzero(sub_cff.get_mut(start .. end)?);
-                    }
-                }
-            }
-        }
-
-        Some(())
-    }
-
-    /// Returns the font dict index for each glyph.
-    fn parse_fd_select(data: &[u8], num_glyphs: u16) -> Option<Cow<'_, [u8]>> {
-        let mut s = Stream::new(data);
-        let format = s.read::<u8>()?;
-        Some(match format {
-            0 => Cow::Borrowed(s.read_bytes(usize::from(num_glyphs))?),
-            3 => {
-                let count = usize::from(s.read::<u16>()?);
-                let mut fds = vec![];
-                let mut start = s.read::<u16>()?;
-                for _ in 0 .. count {
-                    let fd = s.read::<u8>()?;
-                    let end = s.read::<u16>()?;
-                    for _ in start .. end {
-                        fds.push(fd);
-                    }
-                    start = end;
-                }
-                Cow::Owned(fds)
-            }
-            _ => Cow::Borrowed(&[]),
-        })
-    }
-
-    struct Index<'a> {
-        /// The data of the whole index (including its header).
-        data: &'a [u8],
-        /// The data ranges for the actual items.
-        items: Vec<Range<usize>>,
-    }
-
-    impl<'a> Index<'a> {
-        fn parse(data: &'a [u8]) -> Option<Self> {
-            let mut s = Stream::new(data);
-
-            let count = usize::from(s.read::<u16>()?);
-
-            let mut items = Vec::with_capacity(count);
-            let mut len = 2;
-
-            if count > 0 {
-                let offsize = usize::from(s.read::<u8>()?);
-                if !matches!(offsize, 1 ..= 4) {
-                    return None;
-                }
-
-                // Read an offset and transform it to be relative to the start
-                // of the index.
-                let data_offset = 3 + offsize * (count + 1);
-                let mut read_offset = || {
-                    let mut bytes = [0u8; 4];
-                    bytes[4 - offsize .. 4].copy_from_slice(s.read_bytes(offsize)?);
-                    Some(data_offset - 1 + u32::from_be_bytes(bytes) as usize)
-                };
-
-                let mut last = read_offset()?;
-                for _ in 0 .. count {
-                    let offset = read_offset()?;
-                    data.get(last .. offset)?;
-                    items.push(last .. offset);
-                    last = offset;
-                }
-
-                len = last;
-            }
-
-            Some(Self { data: data.get(.. len)?, items })
-        }
-
-        fn parse_stream(s: &'a mut Stream) -> Option<Self> {
-            let index = Index::parse(s.tail()?)?;
-            s.advance(index.data.len());
-            Some(index)
-        }
-
-        fn get(&self, idx: usize) -> Option<&'a [u8]> {
-            self.data.get(self.items.get(idx)?.clone())
-        }
-
-        fn iter(&self) -> impl Iterator<Item = (u16, &'a [u8], Range<usize>)> + '_ {
-            self.items
-                .iter()
-                .enumerate()
-                .map(move |(i, item)| (i as u16, &self.data[item.clone()], item.clone()))
-        }
-    }
-
-    struct Dict<'a>(Vec<Pair<'a>>);
-
-    impl<'a> Dict<'a> {
-        fn parse(data: &'a [u8]) -> Self {
-            let mut s = Stream::new(data);
-            Self(iter::from_fn(|| Pair::parse(&mut s)).collect())
-        }
-
-        fn get(&self, op: Op) -> Option<&[Operand<'a>]> {
-            self.0
-                .iter()
-                .find(|pair| pair.op == op)
-                .map(|pair| pair.operands.as_slice())
-        }
-
-        fn get_offset(&self, op: Op) -> Option<usize> {
-            match self.get(op)? {
-                &[Operand::Int(offset)] if offset > 0 => usize::try_from(offset).ok(),
-                _ => None,
-            }
-        }
-
-        fn get_range(&self, op: Op) -> Option<Range<usize>> {
-            match self.get(op)? {
-                &[Operand::Int(len), Operand::Int(offset)] if offset > 0 => {
-                    let offset = usize::try_from(offset).ok()?;
-                    let len = usize::try_from(len).ok()?;
-                    Some(offset .. offset + len)
-                }
-                _ => None,
-            }
-        }
-    }
-
-    #[derive(Debug)]
-    struct Pair<'a> {
-        operands: Vec<Operand<'a>>,
-        op: Op,
-    }
-
-    impl<'a> Pair<'a> {
-        fn parse(s: &mut Stream<'a>) -> Option<Self> {
-            let mut operands = vec![];
-            while s.clone().read::<u8>()? > 21 {
-                operands.push(Operand::parse(s)?);
-            }
-            Some(Self { operands, op: Op::parse(s)? })
-        }
-    }
-
-    #[derive(Debug, Eq, PartialEq)]
-    struct Op(u8, u8);
-
-    impl Op {
-        const CHAR_STRINGS: Self = Self(17, 0);
-        const PRIVATE: Self = Self(18, 0);
-        const SUBRS: Self = Self(19, 0);
-        const FD_ARRAY: Self = Self(12, 36);
-        const FD_SELECT: Self = Self(12, 37);
-
-        fn parse(s: &mut Stream) -> Option<Self> {
-            let b0 = s.read::<u8>()?;
-            match b0 {
-                12 => Some(Self(b0, s.read::<u8>()?)),
-                0 ..= 21 => Some(Self(b0, 0)),
-                _ => None,
-            }
-        }
-    }
-
-    #[derive(Debug)]
-    enum Operand<'a> {
-        Int(i32),
-        Real(&'a [u8]),
-    }
-
-    impl<'a> Operand<'a> {
-        fn parse(s: &mut Stream<'a>) -> Option<Self> {
-            let b0 = i32::from(s.read::<u8>()?);
-            Some(match b0 {
-                30 => {
-                    let mut len = 0;
-                    for &byte in s.tail()? {
-                        len += 1;
-                        if byte & 0x0f == 0x0f {
-                            break;
-                        }
-                    }
-                    Self::Real(s.read_bytes(len)?)
-                }
-                32 ..= 246 => Self::Int(b0 - 139),
-                247 ..= 250 => {
-                    let b1 = i32::from(s.read::<u8>()?);
-                    Self::Int((b0 - 247) * 256 + b1 + 108)
-                }
-                251 ..= 254 => {
-                    let b1 = i32::from(s.read::<u8>()?);
-                    Self::Int(-(b0 - 251) * 256 - b1 - 108)
-                }
-                28 => Self::Int(i32::from(s.read::<i16>()?)),
-                29 => Self::Int(s.read::<i32>()?),
-                _ => return None,
-            })
-        }
-    }
-}