codetether-rlm 0.1.0

//! Semantic boundary detection for chunk splitting.

use std::collections::HashMap;

use super::types::ChunkType;

/// Find semantic boundaries in `lines`.
pub fn find_boundaries(lines: &[&str]) -> HashMap<usize, (ChunkType, u8)> {
    let mut boundaries = HashMap::new();
    for (i, line) in lines.iter().enumerate() {
        let t = line.trim();
        if t.starts_with("[User]:") || t.starts_with("[Assistant]:") {
            boundaries.insert(i, (ChunkType::Conversation, 5));
            continue;
        }
        if t.starts_with("[Tool ") {
            let pri = if t.contains("FAILED") || t.contains("error") {
                7
            } else {
                3
            };
            boundaries.insert(i, (ChunkType::ToolOutput, pri));
            continue;
        }
        classify_syntax_boundary(t, i, &mut boundaries);
    }
    boundaries
}

fn classify_syntax_boundary(t: &str, i: usize, b: &mut HashMap<usize, (ChunkType, u8)>) {
    if t.starts_with("```") {
        b.insert(i, (ChunkType::Code, 4));
        return;
    }
    if t.starts_with('/') || t.starts_with("./") || t.starts_with("~/") {
        b.insert(i, (ChunkType::Code, 4));
        return;
    }
    let defs = [
        "function",
        "class ",
        "def ",
        "async function",
        "export",
        "fn ",
        "impl ",
        "struct ",
        "enum ",
    ];
    if defs.iter().any(|p| t.starts_with(p)) {
        b.insert(i, (ChunkType::Code, 5));
        return;
    }
    let low = t.to_lowercase();
    if low.starts_with("error")
        || low.contains("error:")
        || t.starts_with("Exception")
        || t.contains("FAILED")
    {
        b.insert(i, (ChunkType::Text, 8));
        return;
    }
    if t.starts_with('#') && t.len() > 2 && t.chars().nth(1) == Some(' ') {
        b.insert(i, (ChunkType::Text, 6));
    }
}