readseek 0.2.12

structural source reader with stable line hashes
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// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (c) 2026 Jarkko Sakkinen

const HASHLINE_MODULUS: u32 = 0x1000;

/// Compute a stable locality-preserving hash for a source line.
///
/// The line text is whitespace-normalized before hashing so that minor
/// whitespace changes do not invalidate the hash.  The result is a 3-digit
/// hex string in `[000, fff]`.
pub(crate) fn hash_line(_line: usize, text: &str) -> String {
    let text = text.strip_suffix('\r').unwrap_or(text);
    let normalized = text.split_whitespace().collect::<String>();
    format!(
        "{:03x}",
        xxhash_rust::xxh32::xxh32(normalized.as_bytes(), 0) % HASHLINE_MODULUS
    )
}

/// Compute a BLAKE3 content hash for the full source text.
pub(crate) fn hash_text(text: &str) -> String {
    blake3::hash(text.as_bytes()).to_hex().to_string()
}