424 lines
15 KiB
Rust
424 lines
15 KiB
Rust
use std::ops::Index;
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use phf::Set;
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use crate::err::{ErrorType, ProcessingResult};
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use crate::pattern::SinglePattern;
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macro_rules! chain {
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($proc:ident $($tail:tt)+) => ({
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chain!(@line $proc, last, $($tail)+);
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last
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});
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// Match `?` operator before a call without `?`.
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(@line $proc:ident, $last:ident, . $method:ident($($arg:expr),*)? $($tail:tt)+) => {
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$proc.$method($($arg),*)?;
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chain!(@line $proc, $last, $($tail)*);
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};
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(@line $proc:ident, $last:ident, . $method:ident($($arg:expr),*) $($tail:tt)+) => {
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$proc.$method($($arg),*);
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chain!(@line $proc, $last, $($tail)*);
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};
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(@line $proc:ident, $last:ident, . $method:ident($($arg:expr),*)?) => {
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let $last = $proc.$method($($arg),*)?;
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};
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(@line $proc:ident, $last:ident, . $method:ident($($arg:expr),*)) => {
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let $last = $proc.$method($($arg),*);
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};
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}
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#[derive(Copy, Clone)]
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pub enum RequireReason {
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Custom,
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ExpectedNotChar(u8),
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ExpectedMatch(&'static [u8]),
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ExpectedChar(u8),
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}
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#[derive(Copy, Clone)]
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pub struct Checkpoint {
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read_next: usize,
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write_next: usize,
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}
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// TODO DOC
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#[derive(Copy, Clone)]
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pub struct ProcessorRange {
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start: usize,
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end: usize,
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}
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impl ProcessorRange {
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pub fn len(&self) -> usize {
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self.end - self.start
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}
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pub fn empty(&self) -> bool {
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self.start >= self.end
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}
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}
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// Processing state of a file. Most fields are used internally and set during
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// processing. Single use only; create one per processing.
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pub struct Processor<'d> {
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code: &'d mut [u8],
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// Index of the next character to read.
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read_next: usize,
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// Index of the next unwritten space.
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write_next: usize,
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// Match.
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// Need to record start as we might get slice after keeping or skipping.
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match_start: usize,
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// Position in output match has been written to. Useful for long term slices where source would already be overwritten.
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match_dest: usize,
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// Guaranteed amount of characters that exist from `start` at time of creation of this struct.
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match_len: usize,
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// Character matched, if any. Only exists for single-character matches and if matched.
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match_char: Option<u8>,
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match_reason: RequireReason,
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}
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impl<'d> Index<ProcessorRange> for Processor<'d> {
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type Output = [u8];
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fn index(&self, index: ProcessorRange) -> &Self::Output {
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&self.code[index.start..index.end]
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}
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}
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impl<'d> Processor<'d> {
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// Constructor.
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pub fn new(code: &mut [u8]) -> Processor {
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Processor { write_next: 0, read_next: 0, code, match_start: 0, match_dest: 0, match_len: 0, match_char: None, match_reason: RequireReason::Custom }
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}
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// INTERNAL APIs.
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// Bounds checking.
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fn _in_bounds(&self, offset: usize) -> bool {
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self.read_next + offset < self.code.len()
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}
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// Reading.
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/// Get the `offset` character from next.
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/// When `offset` is 0, the next character is returned.
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/// Panics. Does not check bounds for performance (e.g. already checked).
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fn _read_offset(&self, offset: usize) -> u8 {
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self.code[self.read_next + offset]
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}
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fn _maybe_read_offset(&self, offset: usize) -> Option<u8> {
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if self._in_bounds(offset) {
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Some(self._read_offset(offset))
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} else {
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None
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}
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}
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// Shifting.
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/// Move next `amount` characters to output.
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/// Panics. Does not check bounds for performance (e.g. already checked).
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fn _shift(&mut self, amount: usize) -> () {
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// Optimisation: Don't shift if already there (but still update offsets).
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if self.read_next != self.write_next {
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self.code.copy_within(self.read_next..self.read_next + amount, self.write_next);
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};
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self.read_next += amount;
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self.write_next += amount;
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}
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// Matching.
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// Set match.
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fn _new_match(&mut self, count: usize, char: Option<u8>, reason: RequireReason) -> () {
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// Don't assert match doesn't exist, as otherwise we would need to clear match on every use
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// which would slow down performance and require mutable methods for querying match.
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self.match_start = self.read_next;
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self.match_len = count;
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self.match_char = char;
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self.match_reason = reason;
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}
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fn _match_one<C: FnOnce(u8) -> bool>(&mut self, cond: C, reason: RequireReason) -> () {
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match self._maybe_read_offset(0).filter(|n| cond(*n)) {
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Some(c) => self._new_match(1, Some(c), reason),
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None => self._new_match(0, None, reason),
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}
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}
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fn _match_greedy<C: Fn(u8) -> bool>(&mut self, cond: C) -> () {
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let mut count = 0usize;
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while self._in_bounds(count) && cond(self._read_offset(count)) {
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count += 1;
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};
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self._new_match(count, None, RequireReason::Custom)
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}
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// Ensure that match is nonempty or return error.
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fn _match_require(&self, custom_reason: Option<&'static str>) -> ProcessingResult<()> {
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if self.match_len > 0 {
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Ok(())
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} else {
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match self.match_reason {
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RequireReason::Custom => Err(ErrorType::NotFound(custom_reason.unwrap())),
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RequireReason::ExpectedNotChar(c) => Err(ErrorType::CharNotFound { need: c, got: self.match_char.unwrap() }),
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RequireReason::ExpectedChar(c) => Err(ErrorType::UnexpectedChar(c)),
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RequireReason::ExpectedMatch(m) => Err(ErrorType::MatchNotFound(m)),
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}
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}
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}
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// PUBLIC APIs.
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// Bounds checking
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pub fn at_end(&self) -> bool {
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!self._in_bounds(0)
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}
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/// Get how many characters have been consumed from source.
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pub fn read_len(&self) -> usize {
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self.read_next
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}
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/// Get how many characters have been written to output.
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pub fn written_len(&self) -> usize {
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self.write_next
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}
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// Consume match APIs.
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// Query match.
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pub fn matched(&self) -> bool {
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self.match_len > 0
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}
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pub fn length(&self) -> usize {
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self.match_len
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}
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pub fn char(&self) -> u8 {
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self.match_char.unwrap()
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}
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pub fn maybe_char(&self) -> Option<u8> {
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self.match_char
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}
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pub fn range(&self) -> ProcessorRange {
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ProcessorRange { start: self.match_start, end: self.match_start + self.match_len }
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}
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pub fn out_range(&self) -> ProcessorRange {
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ProcessorRange { start: self.match_dest, end: self.match_dest + self.match_len }
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}
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pub fn slice(&self) -> &[u8] {
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&self.code[self.match_start..self.match_start + self.match_len]
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}
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pub fn out_slice(&self) -> &[u8] {
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&self.code[self.match_dest..self.match_dest + self.match_len]
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}
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// Assert match.
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pub fn require(&self) -> ProcessingResult<()> {
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self._match_require(None)
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}
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pub fn require_with_reason(&self, reason: &'static str) -> ProcessingResult<()> {
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self._match_require(Some(reason))
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}
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// TODO Document
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pub fn expect(&self) -> () {
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debug_assert!(self.match_len > 0);
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}
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// Take action on match.
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// Note that match_len has already been verified to be valid, so don't need to bounds check again.
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pub fn keep(&mut self) -> () {
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self.match_dest = self.write_next;
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self._shift(self.match_len);
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}
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pub fn discard(&mut self) -> () {
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self.read_next = self.match_start + self.match_len;
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}
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// Single-char matching APIs.
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pub fn match_char(&mut self, c: u8) -> () {
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self._match_one(|n| n == c, RequireReason::ExpectedChar(c))
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}
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pub fn match_not_char(&mut self, c: u8) -> () {
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self._match_one(|n| n != c, RequireReason::ExpectedNotChar(c))
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}
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pub fn match_member(&mut self, set: Set<u8>) -> () {
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self._match_one(|n| set.contains(&n), RequireReason::Custom)
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}
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pub fn match_not_member(&mut self, set: Set<u8>) -> () {
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self._match_one(|n| !set.contains(&n), RequireReason::Custom)
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}
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pub fn match_pred(&mut self, pred: fn(u8) -> bool) -> () {
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self._match_one(|n| pred(n), RequireReason::Custom)
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}
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pub fn match_not_pred(&mut self, pred: fn(u8) -> bool) -> () {
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self._match_one(|n| !pred(n), RequireReason::Custom)
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}
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// Sequence matching APIs.
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pub fn match_seq(&mut self, pat: &'static [u8]) -> () {
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// For faster short-circuiting matching, compare char-by-char instead of slices.
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let len = pat.len();
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let mut count = 0;
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if len > 0 && self._in_bounds(len - 1) {
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for i in 0..len {
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if self._read_offset(i) != pat[i] {
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count = 0;
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break;
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};
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count += 1;
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};
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};
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self._new_match(count, None, RequireReason::Custom)
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}
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pub fn match_line_terminator(&mut self) -> () {
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self._new_match(match self._maybe_read_offset(0) {
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Some(b'\n') => 1,
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Some(b'\r') => 1 + self._maybe_read_offset(1).filter(|c| *c == b'\n').is_some() as usize,
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_ => 0,
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}, None, RequireReason::Custom)
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}
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// Multi-char matching APIs.
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pub fn match_while_char(&mut self, c: u8) -> () {
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self._match_greedy(|n| n == c)
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}
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pub fn match_while_not_char(&mut self, c: u8) -> () {
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self._match_greedy(|n| n != c)
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}
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pub fn match_while_member(&mut self, set: Set<u8>) -> () {
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self._match_greedy(|n| set.contains(&n))
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}
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pub fn match_while_not_member(&mut self, set: Set<u8>) -> () {
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self._match_greedy(|n| !set.contains(&n))
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}
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pub fn match_while_pred(&mut self, pred: fn(u8) -> bool) -> () {
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self._match_greedy(pred)
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}
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pub fn match_while_not_seq(&mut self, s: &SinglePattern) -> () {
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// TODO Test
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// TODO Document
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let count = match s.match_against(&self.code[self.read_next..]) {
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Some(idx) => idx,
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None => self.code.len() - self.read_next,
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};
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self._new_match(count, None, RequireReason::Custom)
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}
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// Checkpoints.
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pub fn checkpoint(&self) -> Checkpoint {
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Checkpoint {
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read_next: self.read_next,
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write_next: self.write_next,
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}
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}
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/// Restore to previously set checkpoint.
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pub fn restore(&mut self, checkpoint: Checkpoint) -> () {
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self.read_next = checkpoint.read_next;
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self.write_next = checkpoint.write_next;
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}
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/// Write characters skipped from source since checkpoint. Must not have written anything since checkpoint.
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pub fn write_skipped(&mut self, checkpoint: Checkpoint) -> () {
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// Make sure that nothing has been written since checkpoint (which would be lost).
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debug_assert_eq!(self.write_next, checkpoint.write_next);
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// Get src code from checkpoint until last consumed character (inclusive).
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let src_start = checkpoint.read_next;
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let src_end = self.read_next;
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self.code.copy_within(src_start..src_end, checkpoint.write_next);
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self.read_next = src_end;
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self.write_next += src_end - src_start;
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}
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/// Discard characters written since checkpoint but keep source position.
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pub fn erase_written(&mut self, checkpoint: Checkpoint) -> () {
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self.write_next = checkpoint.write_next;
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}
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/// Get consumed characters since checkpoint as range.
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pub fn consumed_range(&self, checkpoint: Checkpoint) -> ProcessorRange {
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ProcessorRange { start: checkpoint.read_next, end: self.read_next }
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}
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/// Get written characters since checkpoint as range.
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pub fn written_range(&self, checkpoint: Checkpoint) -> ProcessorRange {
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ProcessorRange { start: checkpoint.write_next, end: self.write_next }
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}
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/// Get amount of source characters consumed since checkpoint.
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pub fn consumed_count(&self, checkpoint: Checkpoint) -> usize {
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self.read_next - checkpoint.read_next
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}
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/// Get amount of output characters written since checkpoint.
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pub fn written_count(&self, checkpoint: Checkpoint) -> usize {
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self.write_next - checkpoint.write_next
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}
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// Looking ahead.
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/// Get the `offset` character from next.
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/// When `offset` is 0, the next character is returned.
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pub fn peek_offset_eof(&self, offset: usize) -> Option<u8> {
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self._maybe_read_offset(offset)
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}
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pub fn peek_offset(&self, offset: usize) -> ProcessingResult<u8> {
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self._maybe_read_offset(offset).ok_or(ErrorType::UnexpectedEnd)
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}
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pub fn peek_eof(&self) -> Option<u8> {
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self._maybe_read_offset(0)
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}
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pub fn peek(&self) -> ProcessingResult<u8> {
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self._maybe_read_offset(0).ok_or(ErrorType::UnexpectedEnd)
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}
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// Consuming source characters.
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/// Skip the next `count` characters (can be zero).
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/// Will result in an error if exceeds bounds.
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pub fn skip_amount(&mut self, count: usize) -> ProcessingResult<()> {
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// Check for zero to prevent underflow as type is usize.
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if count == 0 || self._in_bounds(count - 1) {
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self.read_next += count;
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Ok(())
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} else {
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Err(ErrorType::UnexpectedEnd)
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}
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}
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/// Skip and return the next character.
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/// Will result in an error if exceeds bounds.
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pub fn skip(&mut self) -> ProcessingResult<u8> {
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if !self.at_end() {
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let c = self._read_offset(0);
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self.read_next += 1;
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Ok(c)
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} else {
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Err(ErrorType::UnexpectedEnd)
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}
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}
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// Writing characters directly.
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/// Write `c` to output. Will panic if exceeds bounds.
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pub fn write(&mut self, c: u8) -> () {
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self.code[self.write_next] = c;
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self.write_next += 1;
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}
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pub fn write_range(&mut self, s: ProcessorRange) -> () {
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self.code.copy_within(s.start..s.end, self.write_next);
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self.write_next += s.len();
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}
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/// Write `s` to output. Will panic if exceeds bounds.
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pub fn write_slice(&mut self, s: &[u8]) -> () {
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self.code[self.write_next..self.write_next + s.len()].copy_from_slice(s);
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self.write_next += s.len();
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}
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pub fn write_utf8(&mut self, c: char) -> () {
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let mut encoded = [0u8; 4];
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c.encode_utf8(&mut encoded);
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self.write_slice(&encoded);
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}
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// Shifting characters.
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pub fn accept(&mut self) -> ProcessingResult<u8> {
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if !self.at_end() {
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let c = self._read_offset(0);
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self._shift(1);
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Ok(c)
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} else {
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Err(ErrorType::UnexpectedEnd)
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}
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}
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pub fn accept_amount(&mut self, count: usize) -> ProcessingResult<()> {
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// Check for zero to prevent underflow as type is usize.
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if count == 0 || self._in_bounds(count - 1) {
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self._shift(count);
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Ok(())
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} else {
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Err(ErrorType::UnexpectedEnd)
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}
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}
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}
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