16239454628

Committed 12 Jul 2025 03:29PM UTC coverage: 94.234% (+0.5%) from 93.685%

Build # 16239454628

Build Type

Pull #53

github

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web-flow

Commit Message

Merge a5de05240 into 1db0180ce

Pull Request Pull Request #53: Big refactor step 1

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87.98

/picojson/src/stream_parser.rs

// SPDX-License-Identifier: Apache-2.0

use crate::escape_processor::UnicodeEscapeCollector;
use crate::event_processor::{
    clear_events, create_tokenizer_callback, have_events, process_begin_events,
    process_simple_escape_event, process_simple_events, process_unicode_escape_events,
    take_first_event, ContentExtractor, EscapeHandler, EventResult, ParserContext,
};
use crate::parse_error::ParseError;
use crate::shared::{ContentRange, Event, ParserState, UnexpectedState};
use crate::stream_buffer::StreamBuffer;
use crate::{ujson, PullParser};
use ujson::{EventToken, Tokenizer};

use ujson::{BitStackConfig, DefaultConfig};

/// Trait for input sources that can provide data to the streaming parser.
pub trait Reader {
    /// The error type returned by read operations
    type Error;

    /// Read data into the provided buffer.
    /// Returns the number of bytes read, or an error.
    ///
    /// # Contract
    /// - A return value of 0 **MUST** indicate true end of stream
    /// - Implementations **MUST NOT** return 0 unless no more data will ever be available
    /// - Returning 0 followed by non-zero reads in subsequent calls violates this contract
    fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error>;
}

/// Represents the processing state of the StreamParser
/// Enforces logical invariants: once Finished, no other processing states are possible
#[derive(Debug)]
enum ProcessingState {
    /// Normal active processing
    Active {
        unescaped_reset_queued: bool,
        in_escape_sequence: bool,
    },
    /// All input consumed, tokenizer finished
    Finished,
}

/// A pull parser that parses JSON from a stream.
///
/// Generic over BitStackConfig for configurable nesting depth.
/// It is designed to be used with the [Reader] trait, which is used to read data from a stream.
///
pub struct StreamParser<'b, R: Reader, C: BitStackConfig = DefaultConfig> {
    /// The tokenizer that processes JSON tokens
    tokenizer: Tokenizer<C::Bucket, C::Counter>,
    /// Parser state tracking
    parser_state: ParserState,
    /// Reader for streaming input
    reader: R,
    /// StreamBuffer for single-buffer input and escape processing
    stream_buffer: StreamBuffer<'b>,

    /// Processing state machine that enforces logical invariants
    processing_state: ProcessingState,

    /// Shared Unicode escape collector for \uXXXX sequences
    unicode_escape_collector: UnicodeEscapeCollector,
}

/// Methods for StreamParser using DefaultConfig
impl<'b, R: Reader> StreamParser<'b, R, DefaultConfig> {
    /// Create a new StreamParser with default configuration
    ///
    /// Uses the default BitStack configuration (u32 bucket, u8 counter)
    /// for most common use cases.
    pub fn new(reader: R, buffer: &'b mut [u8]) -> Self {
        Self::with_config(reader, buffer)
    }
}

/// Methods for StreamParser with custom BitStackConfig
impl<'b, R: Reader, C: BitStackConfig> StreamParser<'b, R, C> {
    /// Create a new StreamParser with custom configuration
    ///
    /// Use this when you need custom BitStack storage types for specific
    /// memory or nesting depth requirements.
    ///
    /// # Example
    /// ```
    /// use picojson::{StreamParser, BitStackStruct, ChunkReader};
    ///
    /// let json = b"{\"test\": 42}";
    /// // For testing, ChunkReader is a convenient Reader implementation
    /// let reader = ChunkReader::new(json, 10);
    /// let mut buffer = [0u8; 256];
    ///
    /// // Custom configuration: u64 bucket + u16 counter for deeper nesting
    /// let mut parser = StreamParser::<_, BitStackStruct<u64, u16>>::with_config(reader, &mut buffer);
    /// ```
    pub fn with_config(reader: R, buffer: &'b mut [u8]) -> Self {
        Self {
            tokenizer: Tokenizer::new(),
            parser_state: ParserState::new(),
            reader,
            stream_buffer: StreamBuffer::new(buffer),

            // Initialize new state machine to Active with default values
            processing_state: ProcessingState::Active {
                unescaped_reset_queued: false,
                in_escape_sequence: false,
            },

            unicode_escape_collector: UnicodeEscapeCollector::new(),
        }
    }
}

/// Shared methods for StreamParser with any BitStackConfig
impl<R: Reader, C: BitStackConfig> StreamParser<'_, R, C> {
    /// Get the next JSON event from the stream
    fn next_event_impl(&mut self) -> Result<Event<'_, '_>, ParseError> {
        // Apply any queued unescaped content reset from previous call
        self.apply_unescaped_reset_if_queued();

        loop {
            // Pull events from tokenizer until we have some
            while !self.have_events() {
                // Only fill buffer when we actually need more data
                if self.stream_buffer.is_empty() {
                    self.fill_buffer_from_reader()?;
                }

                if self.stream_buffer.is_empty() {
                    // Handle end of data with tokenizer finish
                    if !matches!(self.processing_state, ProcessingState::Finished) {
                        self.processing_state = ProcessingState::Finished;

                        // Clear events and try to finish tokenizer
                        clear_events(&mut self.parser_state.evts);
                        {
                            let mut callback =
                                create_tokenizer_callback(&mut self.parser_state.evts);
                            if let Err(e) = self.tokenizer.finish(&mut callback) {
                                return Err(ParseError::TokenizerError(e));
                            }
                        }
                    }

                    if !self.have_events() {
                        return Ok(Event::EndDocument);
                    }
                    // Continue to process any events generated by finish()
                } else {
                    // Get byte and advance
                    let byte = self.stream_buffer.current_byte()?;
                    self.stream_buffer.advance()?;

                    // Process byte through tokenizer
                    clear_events(&mut self.parser_state.evts);
                    {
                        let mut callback = create_tokenizer_callback(&mut self.parser_state.evts);
                        if let Err(e) = self.tokenizer.parse_chunk(&[byte], &mut callback) {
                            return Err(ParseError::TokenizerError(e));
                        }
                    }

                    // Special case processing removed - let all escape handling go through event system

                    // Handle byte accumulation if no event was generated
                    if !self.have_events() {
                        self.handle_byte_accumulation(byte)?;
                    }
                }
            }

            // Now we have events - process ONE event
            let taken_event = take_first_event(&mut self.parser_state.evts);

            if let Some(taken_event) = taken_event {
                // Process the event directly in the main loop
                // First, try the shared simple event processor
                if let Some(simple_result) = process_simple_events(taken_event.clone()) {
                    match simple_result {
                        EventResult::Complete(event) => return Ok(event),
                        EventResult::ExtractString => return self.validate_and_extract_string(),
                        EventResult::ExtractKey => return self.validate_and_extract_key(),
                        EventResult::ExtractNumber(from_container_end) => {
                            return self.validate_and_extract_number(from_container_end)
                        }
                        EventResult::Continue => {
                            // Continue to next iteration for more events
                        }
                    }
                } else if let Some(begin_result) = process_begin_events(&taken_event, self) {
                    match begin_result {
                        EventResult::Continue => {
                            // Continue to next iteration for more events
                        }
                        _ => unreachable!("process_begin_events only returns Continue"),
                    }
                } else {
                    // Handle parser-specific events
                    match taken_event {
                        // Escape sequence handling
                        ujson::Event::Begin(EventToken::EscapeSequence) => {
                            // Start of escape sequence - we'll handle escapes by unescaping to buffer
                            self.start_escape_processing()?;
                            // Continue processing
                        }
                        ujson::Event::End(
                            escape_token @ (EventToken::EscapeQuote
                            | EventToken::EscapeBackslash
                            | EventToken::EscapeSlash
                            | EventToken::EscapeBackspace
                            | EventToken::EscapeFormFeed
                            | EventToken::EscapeNewline
                            | EventToken::EscapeCarriageReturn
                            | EventToken::EscapeTab),
                        ) => {
                            // Handle simple escape sequences using shared function
                            process_simple_escape_event(&escape_token, self)?;
                            // Continue processing
                        }
                        _ if process_unicode_escape_events(&taken_event, self)? => {
                            // Unicode escape events handled by shared function
                            // Continue processing
                        }

                        // All other events - continue processing
                        _ => {
                            // Continue to next byte
                        }
                    }
                }
            }
            // If no event was processed, continue the outer loop to get more events
        }
    }

    /// Check if we have events waiting to be processed
    fn have_events(&self) -> bool {
        have_events(&self.parser_state.evts)
    }

    /// Helper to create an unescaped string from StreamBuffer
    fn create_unescaped_string(&mut self) -> Result<Event<'_, '_>, ParseError> {
        self.queue_unescaped_reset();
        let unescaped_slice = self.stream_buffer.get_unescaped_slice()?;
        let str_content = crate::shared::from_utf8(unescaped_slice)?;
        Ok(Event::String(crate::String::Unescaped(str_content)))
    }

    /// Helper to create a borrowed string from StreamBuffer
    fn create_borrowed_string(
        &mut self,
        content_start: usize,
    ) -> Result<Event<'_, '_>, ParseError> {
        let current_pos = self.stream_buffer.current_position();
        let (content_start, content_end) =
            ContentRange::string_content_bounds_from_content_start(content_start, current_pos);

        let bytes = self
            .stream_buffer
            .get_string_slice(content_start, content_end)?;
        let str_content = crate::shared::from_utf8(bytes)?;
        Ok(Event::String(crate::String::Borrowed(str_content)))
    }

    /// Helper to create an unescaped key from StreamBuffer
    fn create_unescaped_key(&mut self) -> Result<Event<'_, '_>, ParseError> {
        self.queue_unescaped_reset();
        let unescaped_slice = self.stream_buffer.get_unescaped_slice()?;
        let str_content = crate::shared::from_utf8(unescaped_slice)?;
        Ok(Event::Key(crate::String::Unescaped(str_content)))
    }

    /// Helper to create a borrowed key from StreamBuffer
    fn create_borrowed_key(&mut self, content_start: usize) -> Result<Event<'_, '_>, ParseError> {
        let current_pos = self.stream_buffer.current_position();
        let (content_start, content_end) =
            ContentRange::string_content_bounds_from_content_start(content_start, current_pos);

        let bytes = self
            .stream_buffer
            .get_string_slice(content_start, content_end)?;
        let str_content = crate::shared::from_utf8(bytes)?;
        Ok(Event::Key(crate::String::Borrowed(str_content)))
    }

    /// Fill buffer from reader
    fn fill_buffer_from_reader(&mut self) -> Result<(), ParseError> {
        if let Some(fill_slice) = self.stream_buffer.get_fill_slice() {
            let bytes_read = self
                .reader
                .read(fill_slice)
                .map_err(|_| ParseError::ReaderError)?;

            self.stream_buffer.mark_filled(bytes_read)?;
        } else {
            // Buffer is full - ALWAYS attempt compaction
            let compact_start_pos = match self.parser_state.state {
                crate::shared::State::Number(start_pos) => start_pos,
                crate::shared::State::Key(start_pos) => start_pos,
                crate::shared::State::String(start_pos) => start_pos,
                _ => self.stream_buffer.current_position(),
            };

            let offset = self.stream_buffer.compact_from(compact_start_pos)?;

            if offset == 0 {
                // SOL: Buffer too small for current token
                return Err(ParseError::ScratchBufferFull);
            }

            // Update parser state positions
            self.update_positions_after_compaction(offset)?;

            // Try to fill again after compaction
            if let Some(fill_slice) = self.stream_buffer.get_fill_slice() {
                let bytes_read = self
                    .reader
                    .read(fill_slice)
                    .map_err(|_| ParseError::ReaderError)?;

                self.stream_buffer.mark_filled(bytes_read)?;
            }
        }
        Ok(())
    }

    /// Update parser state positions after buffer compaction
    fn update_positions_after_compaction(&mut self, offset: usize) -> Result<(), ParseError> {
        // Check for positions that would be discarded and need escape mode
        // CRITICAL: Position 0 is never discarded, regardless of offset
        let needs_escape_mode = match &self.parser_state.state {
            crate::shared::State::Key(pos) if *pos > 0 && *pos < offset => Some((*pos, true)), // true = is_key
            crate::shared::State::String(pos) if *pos > 0 && *pos < offset => Some((*pos, false)), // false = is_string
            crate::shared::State::Number(pos) if *pos > 0 && *pos < offset => {
                return Err(ParseError::ScratchBufferFull);
            }
            _ => None,
        };

        // Handle escape mode transition if needed
        if let Some((original_pos, is_key)) = needs_escape_mode {
            if is_key {
                self.switch_key_to_escape_mode(original_pos, offset)?;
            } else {
                self.switch_string_to_escape_mode(original_pos, offset)?;
            }
        }

        // Update positions
        match &mut self.parser_state.state {
            crate::shared::State::None => {
                // No position-based state to update
            }
            crate::shared::State::Key(pos) => {
                if *pos > 0 && *pos < offset {
                    *pos = 0; // Reset for escape mode
                } else if *pos >= offset {
                    *pos = pos.checked_sub(offset).unwrap_or(0); // Safe position adjustment
                }
                // else: *pos == 0 or *pos < offset with pos == 0, keep as-is
            }
            crate::shared::State::String(pos) => {
                if *pos > 0 && *pos < offset {
                    *pos = 0; // Reset for escape mode
                } else if *pos >= offset {
                    *pos = pos.checked_sub(offset).unwrap_or(0); // Safe position adjustment
                }
                // else: *pos == 0 or *pos < offset with pos == 0, keep as-is
            }
            crate::shared::State::Number(pos) => {
                if *pos >= offset {
                    *pos = pos.checked_sub(offset).unwrap_or(0); // Safe position adjustment
                } else {
                    *pos = 0; // Reset for discarded number start
                }
            }
        }

        Ok(())
    }

    /// Switch key processing to escape/copy mode when original position was discarded
    fn switch_key_to_escape_mode(
        &mut self,
        original_pos: usize,
        offset: usize,
    ) -> Result<(), ParseError> {
        // The key start position was in the discarded portion of the buffer

        // For keys, the original_pos now points to the content start (after opening quote)
        // If offset > original_pos, it means some actual content was discarded

        // Calculate how much actual key content was discarded
        let content_start = original_pos; // Key content starts at original_pos (now tracks content directly)
        let discarded_content = offset.saturating_sub(content_start);

        if discarded_content > 0 {
            // We lost some actual key content - this would require content recovery
            // For now, this is unsupported
            return Err(ParseError::ScratchBufferFull);
        }

        // No actual content was discarded, we can continue parsing
        // We can continue parsing the key from the current position
        Ok(())
    }

    /// Switch string processing to escape/copy mode when original position was discarded
    fn switch_string_to_escape_mode(
        &mut self,
        original_pos: usize,
        offset: usize,
    ) -> Result<(), ParseError> {
        // The string start position was in the discarded portion of the buffer

        // For strings, the original_pos now points to the content start (after opening quote)
        // If offset > original_pos, it means some actual content was discarded

        // Calculate how much actual string content was discarded
        let content_start = original_pos; // String content starts at original_pos (now tracks content directly)
        let discarded_content = offset.saturating_sub(content_start);

        if discarded_content > 0 {
            // We lost some actual string content - this would require content recovery
            // For now, this is unsupported
            return Err(ParseError::ScratchBufferFull);
        }

        // No actual content was discarded, we can continue parsing
        // We can continue parsing the string from the current position
        Ok(())
    }

    /// Handle byte accumulation for strings/keys and Unicode escape sequences
    fn handle_byte_accumulation(&mut self, byte: u8) -> Result<(), ParseError> {
        // Check if we're in a string or key state
        let in_string_mode = matches!(
            self.parser_state.state,
            crate::shared::State::String(_) | crate::shared::State::Key(_)
        );

        if in_string_mode {
            // Access escape state from enum
            let in_escape = if let ProcessingState::Active {
                in_escape_sequence, ..
            } = &self.processing_state
            {
                *in_escape_sequence
            } else {
                false
            };

            // Normal byte accumulation - all escape processing now goes through event system
            // Skip writing bytes to escape buffer when we have a pending high surrogate
            // (prevents literal \uD801 text from being included in final string)
            if !in_escape
                && self.stream_buffer.has_unescaped_content()
                && !self.unicode_escape_collector.has_pending_high_surrogate()
            {
                self.append_byte_to_escape_buffer(byte)?;
            }
        }

        Ok(())
    }

    /// Start escape processing using StreamBuffer
    fn start_escape_processing(&mut self) -> Result<(), ParseError> {
        // Update escape state in enum
        if let ProcessingState::Active {
            ref mut in_escape_sequence,
            ..
        } = self.processing_state
        {
            *in_escape_sequence = true;
        }

        // Initialize escape processing with StreamBuffer if not already started
        if !self.stream_buffer.has_unescaped_content() {
            if let crate::shared::State::String(start_pos) | crate::shared::State::Key(start_pos) =
                self.parser_state.state
            {
                let current_pos = self.stream_buffer.current_position();

                // With content tracking, start_pos is the content_start
                let content_start = start_pos;
                // Content to copy ends right before the escape character
                let content_end = if self.unicode_escape_collector.has_pending_high_surrogate() {
                    // Skip copying high surrogate text when processing low surrogate
                    content_start
                } else {
                    ContentRange::end_position_excluding_delimiter(current_pos)
                };

                // Estimate max length needed for unescaping (content so far + remaining buffer)
                let content_len = content_end.wrapping_sub(content_start);
                let max_escaped_len = self
                    .stream_buffer
                    .remaining_bytes()
                    .checked_add(content_len)
                    .ok_or(ParseError::NumericOverflow)?;

                // Start unescaping with StreamBuffer and copy existing content
                self.stream_buffer.start_unescaping_with_copy(
                    max_escaped_len,
                    content_start,
                    content_end,
                )?;
            }
        }

        Ok(())
    }

    /// Append a byte to the StreamBuffer's unescaped content
    fn append_byte_to_escape_buffer(&mut self, byte: u8) -> Result<(), ParseError> {
        self.stream_buffer
            .append_unescaped_byte(byte)
            .map_err(|e| e.into())
    }

    /// Queue a reset of unescaped content for the next next_event() call
    fn queue_unescaped_reset(&mut self) {
        // Set the reset flag in the Active state
        if let ProcessingState::Active {
            ref mut unescaped_reset_queued,
            ..
        } = self.processing_state
        {
            *unescaped_reset_queued = true;
        }
    }

    /// Apply queued unescaped content reset if flag is set
    fn apply_unescaped_reset_if_queued(&mut self) {
        // Check the enum field first
        let should_reset = if let ProcessingState::Active {
            ref mut unescaped_reset_queued,
            ..
        } = self.processing_state
        {
            let needs_reset = *unescaped_reset_queued;
            *unescaped_reset_queued = false; // Clear the flag
            needs_reset
        } else {
            false
        };

        if should_reset {
            self.stream_buffer.clear_unescaped();
        }
    }
}

impl<'b, R: Reader, C: BitStackConfig> ParserContext for StreamParser<'b, R, C> {
    fn current_position(&self) -> usize {
        self.stream_buffer.current_position()
    }

    fn begin_string_content(&mut self, _pos: usize) {
        // StreamParser doesn't need explicit string begin setup like SliceParser
        // String processing is handled automatically by the StreamBuffer
    }

    fn set_parser_state(&mut self, state: crate::shared::State) {
        self.parser_state.state = state;
    }
}

impl<'b, R: Reader, C: BitStackConfig> ContentExtractor for StreamParser<'b, R, C> {
    fn parser_state_mut(&mut self) -> &mut crate::shared::State {
        &mut self.parser_state.state
    }

    fn extract_string_content(&mut self, start_pos: usize) -> Result<Event<'_, '_>, ParseError> {
        if self.stream_buffer.has_unescaped_content() {
            self.create_unescaped_string()
        } else {
            self.create_borrowed_string(start_pos)
        }
    }

    fn extract_key_content(&mut self, start_pos: usize) -> Result<Event<'_, '_>, ParseError> {
        if self.stream_buffer.has_unescaped_content() {
            self.create_unescaped_key()
        } else {
            self.create_borrowed_key(start_pos)
        }
    }

    fn extract_number_content(
        &mut self,
        start_pos: usize,
        from_container_end: bool,
    ) -> Result<Event<'_, '_>, ParseError> {
        let number_token_start = start_pos;

        // StreamParser determines correct delimiter handling:
        // Only exclude delimiter when NOT at document end for standalone numbers
        let buffer_current_pos = self.stream_buffer.current_position();
        let corrected_pos =
            if !from_container_end && matches!(self.processing_state, ProcessingState::Finished) {
                // End(Number) at document end - no delimiter to exclude
                buffer_current_pos
            } else {
                // All other cases - exclude delimiter
                buffer_current_pos.saturating_sub(1)
            };

        // Use the position-controlled API - StreamParser handles all position logic
        crate::number_parser::parse_number_event(
            &self.stream_buffer,
            number_token_start,
            corrected_pos,
        )
    }
}

impl<'b, R: Reader, C: BitStackConfig> EscapeHandler for StreamParser<'b, R, C> {
    fn parser_state(&self) -> &crate::shared::State {
        &self.parser_state.state
    }

    fn reset_unicode_collector_all(&mut self) {
        self.unicode_escape_collector.reset_all();
    }

    fn reset_unicode_collector(&mut self) {
        self.unicode_escape_collector.reset();
    }

    fn has_pending_high_surrogate(&self) -> bool {
        self.unicode_escape_collector.has_pending_high_surrogate()
    }

    fn process_unicode_escape_with_collector(&mut self) -> Result<(), crate::ParseError> {
        // Update escape state in enum - Unicode escape processing is complete
        if let ProcessingState::Active {
            ref mut in_escape_sequence,
            ..
        } = self.processing_state
        {
            *in_escape_sequence = false;
        }

        // Process Unicode escape sequence, making a copy of the bytes to avoid borrow conflicts
        let utf8_bytes_copy = {
            let current_pos = self.stream_buffer.current_position();
            let hex_slice_provider = |start, end| {
                self.stream_buffer
                    .get_string_slice(start, end)
                    .map_err(Into::into)
            };

            let mut utf8_buf = [0u8; 4];
            let (utf8_bytes_opt, _escape_start_pos) =
                crate::escape_processor::process_unicode_escape_sequence(
                    current_pos,
                    &mut self.unicode_escape_collector,
                    hex_slice_provider,
                    &mut utf8_buf,
                )?;

            if let Some(utf8_bytes) = utf8_bytes_opt {
                let mut copy = [0u8; 4];
                let len = utf8_bytes.len();
                if let Some(dest) = copy.get_mut(..len) {
                    dest.copy_from_slice(utf8_bytes);
                }
                (copy, len)
            } else {
                // High surrogate waiting for low surrogate - no UTF-8 bytes to process
                ([0u8; 4], 0)
            }
        };

        // Now append the copied bytes to avoid borrow conflicts
        if let Some(bytes_to_copy) = utf8_bytes_copy.0.get(..utf8_bytes_copy.1) {
            for &byte in bytes_to_copy {
                self.append_byte_to_escape_buffer(byte)?;
            }
        }

        Ok(())
    }

    fn handle_simple_escape_char(&mut self, escape_char: u8) -> Result<(), crate::ParseError> {
        // Update escape state in enum
        if let ProcessingState::Active {
            ref mut in_escape_sequence,
            ..
        } = self.processing_state
        {
            *in_escape_sequence = false;
        }

        self.append_byte_to_escape_buffer(escape_char)?;
        Ok(())
    }
}

impl<'b, R: Reader, C: BitStackConfig> PullParser for StreamParser<'b, R, C> {
    fn next_event(&mut self) -> Result<Event<'_, '_>, ParseError> {
        self.next_event_impl()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Simple test reader that reads from a byte slice
    pub struct SliceReader<'a> {
        data: &'a [u8],
        position: usize,
    }

    impl<'a> SliceReader<'a> {
        pub fn new(data: &'a [u8]) -> Self {
            Self { data, position: 0 }
        }
    }

    impl Reader for SliceReader<'_> {
        type Error = ();

        fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
            let remaining = self.data.len().saturating_sub(self.position);
            if remaining == 0 {
                return Ok(0); // EOF
            }

            let to_copy = remaining.min(buf.len());
            let end_pos = self.position.saturating_add(to_copy);
            if let (Some(dest), Some(src)) = (
                buf.get_mut(..to_copy),
                self.data.get(self.position..end_pos),
            ) {
                dest.copy_from_slice(src);
                self.position = end_pos;
                Ok(to_copy)
            } else {
                Err(())
            }
        }
    }

    type TestStreamParser<'b> = StreamParser<'b, SliceReader<'static>>;

    #[test]
    fn test_direct_parser_simple_object() {
        let json = b"{}";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        // Should get ObjectStart
        let event = parser.next_event().unwrap();
        assert!(matches!(event, Event::StartObject));

        // Should get ObjectEnd
        let event = parser.next_event().unwrap();
        assert!(matches!(event, Event::EndObject));

        // Should get EndDocument
        let event = parser.next_event().unwrap();
        assert!(matches!(event, Event::EndDocument));
    }

    #[test]
    fn test_direct_parser_simple_array() {
        let json = b"[]";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        // Should get ArrayStart
        let event = parser.next_event().unwrap();
        assert!(matches!(event, Event::StartArray));

        // Should get ArrayEnd
        let event = parser.next_event().unwrap();
        assert!(matches!(event, Event::EndArray));

        // Should get EndDocument
        let event = parser.next_event().unwrap();
        assert!(matches!(event, Event::EndDocument));
    }

    #[test]
    fn test_direct_parser_simple_escape() {
        let json = b"\"hello\\nworld\"";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        if let Event::String(json_string) = parser.next_event().unwrap() {
            assert_eq!(json_string.as_str(), "hello\nworld");
        } else {
            panic!("Expected String event");
        }
    }

    #[test]
    fn test_pending_state_edge_cases() {
        // Test 1: Complex nested container endings
        let json1 = br#"{"a": {"b": [{"c": 123}]}}"#;
        let reader1 = SliceReader::new(json1);
        let mut buffer1 = [0u8; 256];
        let mut parser1 = TestStreamParser::new(reader1, &mut buffer1);

        let mut events = Vec::new();
        loop {
            match parser1.next_event() {
                Ok(Event::EndDocument) => break,
                Ok(event) => events.push(format!("{:?}", event)),
                Err(e) => panic!("Nested containers failed: {:?}", e),
            }
        }

        // Should contain all expected events
        assert!(events.len() >= 8); // StartObject, Key, StartObject, Key, StartArray, StartObject, Key, Number, EndObject, EndArray, EndObject, EndObject

        // Test 2: Mixed types after numbers in array
        let json2 = br#"[123, "string", true, null, 456]"#;
        let reader2 = SliceReader::new(json2);
        let mut buffer2 = [0u8; 256];
        let mut parser2 = TestStreamParser::new(reader2, &mut buffer2);

        let mut number_count = 0;
        loop {
            match parser2.next_event() {
                Ok(Event::EndDocument) => break,
                Ok(Event::Number(_)) => number_count += 1,
                Ok(_) => {}
                Err(e) => panic!("Mixed types failed: {:?}", e),
            }
        }
        assert_eq!(number_count, 2); // Should find both 123 and 456

        // Test 3: Empty containers
        let json3 = br#"[[], {}, [{}], {"empty": []}]"#;
        let reader3 = SliceReader::new(json3);
        let mut buffer3 = [0u8; 256];
        let mut parser3 = TestStreamParser::new(reader3, &mut buffer3);

        loop {
            match parser3.next_event() {
                Ok(Event::EndDocument) => break,
                Ok(_) => {}
                Err(e) => panic!("Empty containers failed: {:?}", e),
            }
        }

        // Test 4: Multiple consecutive numbers
        let json4 = br#"[1, 2, 3, 4, 5]"#;
        let reader4 = SliceReader::new(json4);
        let mut buffer4 = [0u8; 256];
        let mut parser4 = TestStreamParser::new(reader4, &mut buffer4);

        let mut consecutive_numbers = Vec::new();
        loop {
            match parser4.next_event() {
                Ok(Event::EndDocument) => break,
                Ok(Event::Number(n)) => consecutive_numbers.push(n.as_str().to_string()),
                Ok(_) => {}
                Err(e) => panic!("Consecutive numbers failed: {:?}", e),
            }
        }
        assert_eq!(consecutive_numbers, vec!["1", "2", "3", "4", "5"]);
    }

    #[test]
    fn test_error_recovery_with_pending_state() {
        // Test error handling - this should fail gracefully without hanging onto pending state
        let invalid_json = br#"{"key": 123,"#; // Missing closing brace
        let reader = SliceReader::new(invalid_json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        // Parse until we hit an error or EOF
        loop {
            match parser.next_event() {
                Ok(Event::EndDocument) => break, // EOF reached
                Ok(_) => {}
                Err(_) => break, // Error occurred - this is expected
            }
        }

        // The important thing is that we don't panic or hang
        // The specific error behavior may vary
    }

    #[test]
    fn test_multiple_rapid_container_ends() {
        // Test deeply nested structures that end with numbers
        // This tests whether we can handle multiple rapid container ends correctly

        // Test 1: Deeply nested arrays ending with number
        let json1 = br#"[[[123]]]"#;
        let reader1 = SliceReader::new(json1);
        let mut buffer1 = [0u8; 256];
        let mut parser1 = TestStreamParser::new(reader1, &mut buffer1);

        let mut events1 = Vec::new();
        loop {
            match parser1.next_event() {
                Ok(Event::EndDocument) => break,
                Ok(event) => events1.push(format!("{:?}", event)),
                Err(e) => panic!("Deeply nested arrays failed: {:?}", e),
            }
        }

        // Should have: StartArray, StartArray, StartArray, Number(123), EndArray, EndArray, EndArray
        assert_eq!(events1.len(), 7);
        assert!(events1[3].contains("Number"));
        assert_eq!(&events1[4], "EndArray");
        assert_eq!(&events1[5], "EndArray");
        assert_eq!(&events1[6], "EndArray");

        // Test 2: Mixed nested containers ending with number
        let json2 = br#"{"a": [{"b": 456}]}"#;
        let reader2 = SliceReader::new(json2);
        let mut buffer2 = [0u8; 256];
        let mut parser2 = TestStreamParser::new(reader2, &mut buffer2);

        let mut events2 = Vec::new();
        loop {
            match parser2.next_event() {
                Ok(Event::EndDocument) => break,
                Ok(event) => events2.push(format!("{:?}", event)),
                Err(e) => panic!("Mixed nested containers failed: {:?}", e),
            }
        }

        // Should properly handle the sequence of: number -> EndObject -> EndArray -> EndObject
        assert!(events2.len() >= 8);

        // Test 3: Multiple numbers at different nesting levels
        let json3 = br#"[123, [456, [789]]]"#;
        let reader3 = SliceReader::new(json3);
        let mut buffer3 = [0u8; 256];
        let mut parser3 = TestStreamParser::new(reader3, &mut buffer3);

        let mut number_count = 0;
        let mut events3 = Vec::new();
        loop {
            match parser3.next_event() {
                Ok(Event::EndDocument) => break,
                Ok(Event::Number(n)) => {
                    number_count += 1;
                    events3.push(format!("Number({})", n.as_str()));
                }
                Ok(event) => events3.push(format!("{:?}", event)),
                Err(e) => panic!("Multiple nested numbers failed: {:?}", e),
            }
        }

        assert_eq!(number_count, 3); // Should find all three numbers: 123, 456, 789
    }

    #[test]
    fn test_pending_flag_priority() {
        // Defensive test: ensure that if both pending flags were somehow set,
        // we handle it gracefully (this shouldn't happen in normal operation)

        let json = br#"[{"key": 123}]"#;
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        // Parse normally - this should work fine and never set both flags
        let mut events = Vec::new();
        loop {
            match parser.next_event() {
                Ok(Event::EndDocument) => break,
                Ok(event) => events.push(format!("{:?}", event)),
                Err(e) => panic!("Flag priority test failed: {:?}", e),
            }
        }

        // Should successfully parse: StartArray, StartObject, Key, Number, EndObject, EndArray
        assert_eq!(events.len(), 6);
        assert!(events[3].contains("Number"));
        assert_eq!(&events[4], "EndObject");
        assert_eq!(&events[5], "EndArray");
    }

    #[test]
    fn test_direct_parser_array_of_strings() {
        let json = b"[\"first\", \"second\"]";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        assert!(matches!(parser.next_event().unwrap(), Event::StartArray));

        if let Event::String(s1) = parser.next_event().unwrap() {
            assert_eq!(s1.as_str(), "first");
        } else {
            panic!("Expected String event");
        }

        if let Event::String(s2) = parser.next_event().unwrap() {
            assert_eq!(s2.as_str(), "second");
        } else {
            panic!("Expected String event");
        }

        assert!(matches!(parser.next_event().unwrap(), Event::EndArray));
    }

    #[test]
    fn test_direct_parser_object_with_keys() {
        let json = b"{\"name\": \"value\", \"count\": \"42\"}";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        assert!(matches!(parser.next_event().unwrap(), Event::StartObject));

        // First key-value pair
        if let Event::Key(key1) = parser.next_event().unwrap() {
            assert_eq!(key1.as_str(), "name");
        } else {
            panic!("Expected Key event");
        }

        if let Event::String(val1) = parser.next_event().unwrap() {
            assert_eq!(val1.as_str(), "value");
        } else {
            panic!("Expected String event");
        }

        // Second key-value pair
        if let Event::Key(key2) = parser.next_event().unwrap() {
            assert_eq!(key2.as_str(), "count");
        } else {
            panic!("Expected Key event");
        }

        if let Event::String(val2) = parser.next_event().unwrap() {
            assert_eq!(val2.as_str(), "42");
        } else {
            panic!("Expected String event");
        }

        assert!(matches!(parser.next_event().unwrap(), Event::EndObject));
    }

    #[test]
    fn test_direct_parser_multiple_escapes() {
        let json = b"\"line1\\nline2\\ttab\\\"quote\"";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        if let Event::String(json_string) = parser.next_event().unwrap() {
            let content = json_string.as_str();
            // Check that escape sequences were properly processed
            let has_newline = content.contains('\n');
            let has_tab = content.contains('\t');
            let has_quote = content.contains('"');

            // These should be real control characters, not literal \n \t \"
            assert!(has_newline, "Should contain actual newline character");
            assert!(has_tab, "Should contain actual tab character");
            assert!(has_quote, "Should contain actual quote character");
        } else {
            panic!("Expected String event");
        }
    }

    #[test]
    fn test_direct_parser_unicode_escape() {
        let json = b"\"Hello \\u0041\\u03B1\""; // Hello A(alpha)
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        if let Event::String(json_string) = parser.next_event().unwrap() {
            let content = json_string.as_str();
            // Should be "Hello A⍺" (with actual A and alpha characters)
            assert!(content.contains('A'));
            // Note: This test will initially fail until we implement Unicode escapes
        } else {
            panic!("Expected String event");
        }
    }

    #[test]
    fn test_direct_parser_boolean_true() {
        let json = b"true";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        let event = parser.next_event().unwrap();
        assert_eq!(event, Event::Bool(true));

        let event = parser.next_event().unwrap();
        assert_eq!(event, Event::EndDocument);
    }

    #[test]
    fn test_direct_parser_boolean_false() {
        let json = b"false";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        let event = parser.next_event().unwrap();
        assert_eq!(event, Event::Bool(false));

        let event = parser.next_event().unwrap();
        assert_eq!(event, Event::EndDocument);
    }

    #[test]
    fn test_direct_parser_null() {
        let json = b"null";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        let event = parser.next_event().unwrap();
        assert_eq!(event, Event::Null);

        let event = parser.next_event().unwrap();
        assert_eq!(event, Event::EndDocument);
    }

    #[test]
    fn test_direct_parser_booleans_in_array() {
        let json = b"[true, false, null]";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        assert_eq!(parser.next_event().unwrap(), Event::StartArray);
        assert_eq!(parser.next_event().unwrap(), Event::Bool(true));
        assert_eq!(parser.next_event().unwrap(), Event::Bool(false));
        assert_eq!(parser.next_event().unwrap(), Event::Null);
        assert_eq!(parser.next_event().unwrap(), Event::EndArray);
        assert_eq!(parser.next_event().unwrap(), Event::EndDocument);
    }

    #[test]
    fn test_direct_parser_number_simple() {
        let json = b"42";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        let event = parser.next_event().unwrap();
        if let Event::Number(json_number) = event {
            assert_eq!(json_number.as_str(), "42");
        } else {
            panic!("Expected Number event, got: {:?}", event);
        }

        let event = parser.next_event().unwrap();
        assert_eq!(event, Event::EndDocument);
    }

    #[test]
    fn test_direct_parser_number_negative() {
        let json = b"-123";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        let event = parser.next_event().unwrap();
        if let Event::Number(json_number) = event {
            assert_eq!(json_number.as_str(), "-123");
        } else {
            panic!("Expected Number event, got: {:?}", event);
        }

        let event = parser.next_event().unwrap();
        assert_eq!(event, Event::EndDocument);
    }

    #[test]
    fn test_direct_parser_number_float() {
        let json = b"3.14159";
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        #[cfg(feature = "float-error")]
        {
            // float-error configuration should return an error for float values
            let result = parser.next_event();
            assert!(
                result.is_err(),
                "Expected error for float with float-error configuration"
            );
            return;
        }

        #[cfg(not(feature = "float-error"))]
        {
            let event = parser.next_event().unwrap();
            if let Event::Number(json_number) = event {
                assert_eq!(json_number.as_str(), "3.14159");
            } else {
                panic!("Expected Number event, got: {:?}", event);
            }

            let event = parser.next_event().unwrap();
            assert_eq!(event, Event::EndDocument);
        }
    }

    #[test]
    fn test_direct_parser_numbers_in_array() {
        #[cfg(feature = "float-error")]
        let json = b"[42, -7]"; // No floats for float-error config
        #[cfg(not(feature = "float-error"))]
        let json = b"[42, -7, 3.14]"; // Include float for other configs

        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        assert_eq!(parser.next_event().unwrap(), Event::StartArray);

        let event = parser.next_event().unwrap();
        if let Event::Number(json_number) = event {
            assert_eq!(json_number.as_str(), "42");
        } else {
            panic!("Expected Number event, got: {:?}", event);
        }

        let event = parser.next_event().unwrap();
        if let Event::Number(json_number) = event {
            assert_eq!(json_number.as_str(), "-7");
        } else {
            panic!("Expected Number event, got: {:?}", event);
        }

        #[cfg(not(feature = "float-error"))]
        {
            let event = parser.next_event().unwrap();
            if let Event::Number(json_number) = event {
                assert_eq!(json_number.as_str(), "3.14");
            } else {
                panic!("Expected Number event, got: {:?}", event);
            }
        }

        assert_eq!(parser.next_event().unwrap(), Event::EndArray);
        assert_eq!(parser.next_event().unwrap(), Event::EndDocument);
    }

    #[test]
    fn test_direct_parser_numbers_in_object() {
        #[cfg(feature = "float-error")]
        let json = b"{\"count\": 42, \"score\": -7}"; // No floats for float-error config
        #[cfg(not(feature = "float-error"))]
        let json = b"{\"count\": 42, \"score\": -7.5}"; // Include float for other configs

        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        assert_eq!(parser.next_event().unwrap(), Event::StartObject);

        // First key-value pair
        if let Event::Key(key1) = parser.next_event().unwrap() {
            assert_eq!(key1.as_str(), "count");
        } else {
            panic!("Expected Key event");
        }

        if let Event::Number(val1) = parser.next_event().unwrap() {
            assert_eq!(val1.as_str(), "42");
        } else {
            panic!("Expected Number event");
        }

        // Second key-value pair
        if let Event::Key(key2) = parser.next_event().unwrap() {
            assert_eq!(key2.as_str(), "score");
        } else {
            panic!("Expected Key event");
        }

        if let Event::Number(val2) = parser.next_event().unwrap() {
            #[cfg(feature = "float-error")]
            assert_eq!(val2.as_str(), "-7");
            #[cfg(not(feature = "float-error"))]
            assert_eq!(val2.as_str(), "-7.5");
        } else {
            panic!("Expected Number event");
        }

        assert_eq!(parser.next_event().unwrap(), Event::EndObject);
        assert_eq!(parser.next_event().unwrap(), Event::EndDocument);
    }

    #[test]
    fn test_direct_parser_no_float_configuration() {
        // Test that StreamParser properly uses unified number parsing with no-float config
        let json = br#"{"integer": 42, "float": 3.14, "scientific": 1e3}"#;
        let reader = SliceReader::new(json);
        let mut buffer = [0u8; 256];
        let mut parser = TestStreamParser::new(reader, &mut buffer);

        // Parse through the JSON and verify number handling
        assert_eq!(parser.next_event().unwrap(), Event::StartObject);

        // Integer key-value
        assert_eq!(
            parser.next_event().unwrap(),
            Event::Key(crate::String::Borrowed("integer"))
        );
        if let Event::Number(num) = parser.next_event().unwrap() {
            assert_eq!(num.as_str(), "42");
            match num.parsed() {
                crate::NumberResult::Integer(i) => assert_eq!(*i, 42),
                _ => panic!("Expected integer parsing"),
            }
        } else {
            panic!("Expected Number event");
        }

        // Float key-value - behavior varies by configuration
        assert_eq!(
            parser.next_event().unwrap(),
            Event::Key(crate::String::Borrowed("float"))
        );

        #[cfg(feature = "float-error")]
        {
            // float-error should return an error when encountering floats
            let result = parser.next_event();
            assert!(
                result.is_err(),
                "Expected error for float with float-error configuration"
            );
            // Test ends here for float-error - no more processing needed
        }

        #[cfg(not(feature = "float-error"))]
        {
            if let Event::Number(num) = parser.next_event().unwrap() {
                assert_eq!(num.as_str(), "3.14");
                // In no-float configuration, this should be FloatDisabled
                match num.parsed() {
                    #[cfg(not(feature = "float"))]
                    crate::NumberResult::FloatDisabled => {
                        // This is expected in no-float build
                    }
                    #[cfg(feature = "float")]
                    crate::NumberResult::Float(f) => {
                        // This is expected in float-enabled build
                        assert!((f - 3.14).abs() < 0.01);
                    }
                    #[cfg(feature = "float-skip")]
                    crate::NumberResult::FloatSkipped => {
                        // This is expected in float-skip build
                    }
                    #[cfg(feature = "float-truncate")]
                    crate::NumberResult::FloatTruncated(i) => {
                        // This is expected in float-truncate build (3.14 -> 3)
                        assert_eq!(*i, 3);
                    }
                    _ => panic!("Unexpected number parsing result for float"),
                }
            } else {
                panic!("Expected Number event");
            }

            // Scientific notation handling varies by float configuration
            assert_eq!(
                parser.next_event().unwrap(),
                Event::Key(crate::String::Borrowed("scientific"))
            );

            // float-truncate rejects scientific notation, so test should end early for that config
            #[cfg(feature = "float-truncate")]
            {
                // float-truncate rejects scientific notation since it would require float math
                let result = parser.next_event();
                assert!(
                    result.is_err(),
                    "Expected error for scientific notation with float-truncate"
                );
                // Test ends here for float-truncate - no more processing needed
            }

            #[cfg(not(feature = "float-truncate"))]
            {
                if let Event::Number(num) = parser.next_event().unwrap() {
                    assert_eq!(num.as_str(), "1e3");
                    match num.parsed() {
                        #[cfg(not(feature = "float"))]
                        crate::NumberResult::FloatDisabled => {
                            // This is expected in no-float build - raw string preserved for manual parsing
                        }
                        #[cfg(feature = "float-skip")]
                        crate::NumberResult::FloatSkipped => {
                            // This is expected in float-skip build
                        }
                        #[cfg(feature = "float")]
                        crate::NumberResult::Float(f) => {
                            // This is expected in float-enabled build
                            assert!((f - 1000.0).abs() < f64::EPSILON);
                        }
                        _ => panic!("Unexpected number parsing result for scientific notation"),
                    }
                } else {
                    panic!("Expected Number event");
                }

                assert_eq!(parser.next_event().unwrap(), Event::EndObject);
                assert_eq!(parser.next_event().unwrap(), Event::EndDocument);
            }
        }
    }

    #[test]
    fn test_number_parsing_delimiter_exclusion() {
        // Test that numbers don't include trailing delimiters in various contexts

        // Test 1: Number followed by array end
        let json1 = b"[123]";
        let reader1 = SliceReader::new(json1);
        let mut buffer1 = [0u8; 256];
        let mut parser1 = TestStreamParser::new(reader1, &mut buffer1);

        assert!(matches!(parser1.next_event().unwrap(), Event::StartArray));
        if let Event::Number(num) = parser1.next_event().unwrap() {
            assert_eq!(
                num.as_str(),
                "123",
                "Number should not include trailing delimiter ']'"
            );
        } else {
            panic!("Expected Number event");
        }
        assert!(matches!(parser1.next_event().unwrap(), Event::EndArray));

        // Test 2: Number followed by object end
        let json2 = b"{\"key\":456}";
        let reader2 = SliceReader::new(json2);
        let mut buffer2 = [0u8; 256];
        let mut parser2 = TestStreamParser::new(reader2, &mut buffer2);

        assert!(matches!(parser2.next_event().unwrap(), Event::StartObject));
        assert!(matches!(parser2.next_event().unwrap(), Event::Key(_)));
        if let Event::Number(num) = parser2.next_event().unwrap() {
            assert_eq!(
                num.as_str(),
                "456",
                "Number should not include trailing delimiter '}}'"
            );
        } else {
            panic!("Expected Number event");
        }
        assert!(matches!(parser2.next_event().unwrap(), Event::EndObject));

        // Test 3: Number followed by comma in array
        let json3 = b"[789,10]";
        let reader3 = SliceReader::new(json3);
        let mut buffer3 = [0u8; 256];
        let mut parser3 = TestStreamParser::new(reader3, &mut buffer3);

        assert!(matches!(parser3.next_event().unwrap(), Event::StartArray));
        if let Event::Number(num1) = parser3.next_event().unwrap() {
            assert_eq!(
                num1.as_str(),
                "789",
                "First number should not include trailing delimiter ','"
            );
        } else {
            panic!("Expected first Number event");
        }
        if let Event::Number(num2) = parser3.next_event().unwrap() {
            assert_eq!(
                num2.as_str(),
                "10",
                "Second number should not include trailing delimiter ']'"
            );
        } else {
            panic!("Expected second Number event");
        }
        assert!(matches!(parser3.next_event().unwrap(), Event::EndArray));

        // Test 4: Number followed by comma in object
        let json4 = b"{\"a\":11,\"b\":22}";
        let reader4 = SliceReader::new(json4);
        let mut buffer4 = [0u8; 256];
        let mut parser4 = TestStreamParser::new(reader4, &mut buffer4);

        assert!(matches!(parser4.next_event().unwrap(), Event::StartObject));
        assert!(matches!(parser4.next_event().unwrap(), Event::Key(_)));
        if let Event::Number(num1) = parser4.next_event().unwrap() {
            assert_eq!(
                num1.as_str(),
                "11",
                "First number should not include trailing delimiter ','"
            );
        } else {
            panic!("Expected first Number event");
        }
        assert!(matches!(parser4.next_event().unwrap(), Event::Key(_)));
        if let Event::Number(num2) = parser4.next_event().unwrap() {
            assert_eq!(
                num2.as_str(),
                "22",
                "Second number should not include trailing delimiter '}}'"
            );
        } else {
            panic!("Expected second Number event");
        }
        assert!(matches!(parser4.next_event().unwrap(), Event::EndObject));

        // Test 5: Standalone number at end of document (should include full content)
        let json5 = b"999";
        let reader5 = SliceReader::new(json5);
        let mut buffer5 = [0u8; 256];
        let mut parser5 = TestStreamParser::new(reader5, &mut buffer5);

        if let Event::Number(num) = parser5.next_event().unwrap() {
            assert_eq!(
                num.as_str(),
                "999",
                "Standalone number should include full content"
            );
        } else {
            panic!("Expected Number event");
        }
        assert!(matches!(parser5.next_event().unwrap(), Event::EndDocument));

        // Test 6: Negative numbers with delimiters
        let json6 = b"[-42,33]";
        let reader6 = SliceReader::new(json6);
        let mut buffer6 = [0u8; 256];
        let mut parser6 = TestStreamParser::new(reader6, &mut buffer6);

        assert!(matches!(parser6.next_event().unwrap(), Event::StartArray));
        if let Event::Number(num1) = parser6.next_event().unwrap() {
            assert_eq!(
                num1.as_str(),
                "-42",
                "Negative number should not include trailing delimiter ','"
            );
        } else {
            panic!("Expected first Number event");
        }
        if let Event::Number(num2) = parser6.next_event().unwrap() {
            assert_eq!(
                num2.as_str(),
                "33",
                "Second number should not include trailing delimiter ']'"
            );
        } else {
            panic!("Expected second Number event");
        }
        assert!(matches!(parser6.next_event().unwrap(), Event::EndArray));

        // Test 7: Decimal numbers with delimiters (if float enabled)
        #[cfg(not(feature = "float-error"))]
        {
            let json7 = b"[3.14,2.71]";
            let reader7 = SliceReader::new(json7);
            let mut buffer7 = [0u8; 256];
            let mut parser7 = TestStreamParser::new(reader7, &mut buffer7);

            assert!(matches!(parser7.next_event().unwrap(), Event::StartArray));
            if let Event::Number(num1) = parser7.next_event().unwrap() {
                assert_eq!(
                    num1.as_str(),
                    "3.14",
                    "Decimal number should not include trailing delimiter ','"
                );
            } else {
                panic!("Expected first Number event");
            }
            if let Event::Number(num2) = parser7.next_event().unwrap() {
                assert_eq!(
                    num2.as_str(),
                    "2.71",
                    "Second decimal number should not include trailing delimiter ']'"
                );
            } else {
                panic!("Expected second Number event");
            }
            assert!(matches!(parser7.next_event().unwrap(), Event::EndArray));
        }
    }

    #[test]
    fn test_escape_buffer_functions() {
        // Test the uncovered escape processing functions
        let json_stream = br#"{"escaped": "test\nstring"}"#;
        let mut buffer = [0u8; 1024];
        let mut parser = StreamParser::new(SliceReader::new(json_stream), &mut buffer);

        // These functions are private but we can test them through the public API
        // The escape processing should trigger the uncovered functions
        assert_eq!(parser.next_event().unwrap(), Event::StartObject);
        assert_eq!(
            parser.next_event().unwrap(),
            Event::Key(crate::String::Borrowed("escaped"))
        );

        // This should trigger append_byte_to_escape_buffer and queue_unescaped_reset
        if let Event::String(s) = parser.next_event().unwrap() {
            assert_eq!(s.as_ref(), "test\nstring"); // Escape sequence should be processed
        } else {
            panic!("Expected String event with escape sequence");
        }

        assert_eq!(parser.next_event().unwrap(), Event::EndObject);
        assert_eq!(parser.next_event().unwrap(), Event::EndDocument);
    }

    #[test]
    fn test_slice_reader_constructor() {
        // Test the uncovered SliceReader::new function
        let data = b"test data";
        let reader = SliceReader::new(data);
        assert_eq!(reader.data, data);
        assert_eq!(reader.position, 0);
    }

    #[test]
    fn test_complex_escape_sequences() {
        // Test more complex escape processing to cover the escape buffer functions
        let json_stream = br#"{"multi": "line1\nline2\ttab\r\n"}"#;
        let mut buffer = [0u8; 1024];
        let mut parser = StreamParser::new(SliceReader::new(json_stream), &mut buffer);

        assert_eq!(parser.next_event().unwrap(), Event::StartObject);
        assert_eq!(
            parser.next_event().unwrap(),
            Event::Key(crate::String::Borrowed("multi"))
        );

        // This should exercise the escape buffer processing extensively
        if let Event::String(s) = parser.next_event().unwrap() {
            assert_eq!(s.as_ref(), "line1\nline2\ttab\r\n");
        } else {
            panic!("Expected String event");
        }

        assert_eq!(parser.next_event().unwrap(), Event::EndObject);
        assert_eq!(parser.next_event().unwrap(), Event::EndDocument);
    }

    /// Helper function to test escape sequence parsing with specific buffer size
    fn test_simple_escape_with_buffer_size(buffer_size: usize) -> Result<(), crate::ParseError> {
        // DEBUG TEST: Simple escape sequence should need minimal buffer
        // JSON: ["hello\\"] = 10 bytes total, should work with ~7 byte buffer
        let json_stream = br#"["hello\\"]"#;

        println!("Testing escape sequence with buffer size: {}", buffer_size);
        println!(
            "JSON input: {:?}",
            core::str::from_utf8(json_stream).unwrap()
        );
        let mut buffer = vec![0u8; buffer_size];
        let mut parser = StreamParser::new(SliceReader::new(json_stream), &mut buffer);

        // Array start
        match parser.next_event()? {
            Event::StartArray => println!("  ✅ StartArray OK"),
            other => panic!("Expected StartArray, got: {:?}", other),
        }

        // String with escape
        match parser.next_event()? {
            Event::String(s) => {
                println!("  ✅ String OK: '{}'", s.as_str());
                assert_eq!(s.as_str(), "hello\\");
            }
            other => panic!("Expected String, got: {:?}", other),
        }

        // Array end
        match parser.next_event()? {
            Event::EndArray => println!("  ✅ EndArray OK"),
            other => panic!("Expected EndArray, got: {:?}", other),
        }

        // End document
        match parser.next_event()? {
            Event::EndDocument => println!("  ✅ EndDocument OK"),
            other => panic!("Expected EndDocument, got: {:?}", other),
        }

        println!("  🎉 SUCCESS with buffer size: {}", buffer_size);
        Ok(())
    }

    #[test]
    fn test_minimal_buffer_simple_escape_1() {
        // Buffer size 4 - clearly not enough
        match test_simple_escape_with_buffer_size(4) {
            Ok(()) => panic!("Expected failure with 4-byte buffer, but succeeded!"),
            Err(e) => println!("Expected failure with 4-byte buffer: {:?}", e),
        }
    }

    #[test]
    fn test_minimal_buffer_simple_escape_2() {
        // Buffer size 12 - test if larger buffer avoids compaction bugs
        test_simple_escape_with_buffer_size(12)
            .expect("12-byte buffer should be sufficient for simple escape");
    }

    #[test]
    fn test_minimal_buffer_simple_escape_3() {
        // Buffer size 24 - known working boundary from stress tests
        test_simple_escape_with_buffer_size(24).expect("24-byte buffer should definitely work");
    }

    #[test]
    fn test_surrogate_pair_buffer_boundary_cases() {
        // Test 7: Surrogate pair split across very small buffer chunks
        let input7 = r#"["\uD801\uDC37"]"#;
        let mut buffer7 = [0u8; 16]; // Small buffer
        let reader7 = crate::chunk_reader::ChunkReader::new(input7.as_bytes(), 3); // Tiny chunks
        let mut parser7 = StreamParser::<_, DefaultConfig>::with_config(reader7, &mut buffer7);
        assert_eq!(parser7.next_event(), Ok(Event::StartArray));
        match parser7.next_event() {
            Ok(Event::String(s)) => {
                let content = match s {
                    crate::String::Borrowed(c) => c,
                    crate::String::Unescaped(c) => c,
                };
                assert_eq!(content, "𐐷");
            }
            other => panic!(
                "Expected String with surrogate pair across buffer boundary, got: {:?}",
                other
            ),
        }

        // Test 8: Surrogate pair with small buffer (still needs minimum space)
        let input8 = r#"["\uD801\uDC37"]"#;
        let mut buffer8 = [0u8; 32]; // Small but sufficient buffer
        let reader8 = crate::chunk_reader::ChunkReader::new(input8.as_bytes(), 6); // Split at surrogate boundary
        let mut parser8 = StreamParser::<_, DefaultConfig>::with_config(reader8, &mut buffer8);
        assert_eq!(parser8.next_event(), Ok(Event::StartArray));
        match parser8.next_event() {
            Ok(Event::String(s)) => {
                let content = match s {
                    crate::String::Borrowed(c) => c,
                    crate::String::Unescaped(c) => c,
                };
                assert_eq!(content, "𐐷");
            }
            other => panic!(
                "Expected String with surrogate pair at small buffer, got: {:?}",
                other
            ),
        }
    }
}

kaidokert / picojson-rs / 16239454628

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