Efficient Integer Array Parser

Based on the efficient float parsing implementation in ../parse_fp, this is an optimized integer array parser that can handle large arrays with multithreading support.

Features

Fast lexing: Efficient tokenization of integer arrays in [1,2,3,...] format
Multithreaded parsing: Uses std::from_chars with thread pool for large arrays
Memory efficient: Zero-copy lexing using spans pointing to original input
Robust error handling: Comprehensive validation and error reporting
Configurable: Support for trailing delimiters and custom separators

Usage

make
./parse_int [num_elements] [delim_at_end] [num_threads]

Parameters

num_elements: Number of integers to generate and parse (default: 33554432)
delim_at_end: Allow trailing comma (1=yes, 0=no, default: 1)
num_threads: Number of threads for parsing (default: 1)

Examples

# Parse 1M integers with 4 threads
./parse_int 1000000 1 4

# Parse 10M integers, no trailing comma, single-threaded
./parse_int 10000000 0 1

Architecture

Two-Phase Parsing

Lexing Phase: Fast scan through input to identify integer boundaries
- Returns int_lex_span objects with pointer + length
- Handles whitespace, delimiters, and validation
- O(n) single pass through input
Parsing Phase: Convert lexed spans to actual integers
- Uses fast std::from_chars for conversion
- Automatic multithreading for arrays > 128K elements
- Thread-safe with atomic counters

Key Data Structures

int_lex_span: Zero-copy span representing an integer token
Lexer: Stateful lexer with position tracking and error reporting
Thread pool with work stealing for parsing phase

Performance Notes

Optimized for large integer arrays (millions of elements)
Multithreading kicks in automatically for arrays > 131,072 elements
Uses std::from_chars which is typically faster than std::stoi or atoi
Memory usage scales linearly with input size

TODO

Add support for different integer types (int32, uint64, etc.)
Implement vector parsing (e.g., [(1,2), (3,4)])
Add SIMD optimizations for lexing phase
Support for hexadecimal and binary integer formats