qmd/dist/ast.js

/**
 * AST-aware chunking support via web-tree-sitter.
 *
 * Provides language detection, AST break point extraction for supported
 * code file types, and a stub for future symbol extraction.
 *
 * All functions degrade gracefully: parse failures or unsupported languages
 * return empty arrays, falling back to regex-only chunking.
 *
 * ## Dependency Note
 *
 * Grammar packages (tree-sitter-typescript, etc.) are listed as
 * optionalDependencies with pinned versions. They ship native prebuilds
 * and source files (~72 MB total) but QMD only uses the .wasm files
 * (~5 MB). If install size becomes a concern, the .wasm files can be
 * bundled directly in the repo (e.g. assets/grammars/) and resolved
 * via import.meta.url instead of require.resolve(), eliminating the
 * grammar packages entirely.
 */
import { createRequire } from "node:module";
import { extname } from "node:path";
const EXTENSION_MAP = {
    ".ts": "typescript",
    ".tsx": "tsx",
    ".js": "javascript",
    ".jsx": "tsx",
    ".mts": "typescript",
    ".cts": "typescript",
    ".mjs": "javascript",
    ".cjs": "javascript",
    ".py": "python",
    ".go": "go",
    ".rs": "rust",
};
/**
 * Detect language from file path extension.
 * Returns null for unsupported or unknown extensions (including .md).
 */
export function detectLanguage(filepath) {
    const ext = extname(filepath).toLowerCase();
    return EXTENSION_MAP[ext] ?? null;
}
// =============================================================================
// Grammar Resolution
// =============================================================================
/**
 * Maps language to the npm package and wasm filename for the grammar.
 */
const GRAMMAR_MAP = {
    typescript: { pkg: "tree-sitter-typescript", wasm: "tree-sitter-typescript.wasm" },
    tsx: { pkg: "tree-sitter-typescript", wasm: "tree-sitter-tsx.wasm" },
    javascript: { pkg: "tree-sitter-typescript", wasm: "tree-sitter-typescript.wasm" },
    python: { pkg: "tree-sitter-python", wasm: "tree-sitter-python.wasm" },
    go: { pkg: "tree-sitter-go", wasm: "tree-sitter-go.wasm" },
    rust: { pkg: "tree-sitter-rust", wasm: "tree-sitter-rust.wasm" },
};
// =============================================================================
// Per-Language Query Definitions
// =============================================================================
/**
 * Tree-sitter S-expression queries for each language.
 * Each capture name maps to a break point score via SCORE_MAP.
 *
 * For TypeScript/JavaScript, we match export_statement wrappers to get the
 * correct start position (before `export`), plus bare declarations for
 * non-exported code.
 */
const LANGUAGE_QUERIES = {
    typescript: `
    (export_statement) @export
    (class_declaration) @class
    (function_declaration) @func
    (method_definition) @method
    (interface_declaration) @iface
    (type_alias_declaration) @type
    (enum_declaration) @enum
    (import_statement) @import
    (lexical_declaration (variable_declarator value: (arrow_function))) @func
    (lexical_declaration (variable_declarator value: (function_expression))) @func
  `,
    tsx: `
    (export_statement) @export
    (class_declaration) @class
    (function_declaration) @func
    (method_definition) @method
    (interface_declaration) @iface
    (type_alias_declaration) @type
    (enum_declaration) @enum
    (import_statement) @import
    (lexical_declaration (variable_declarator value: (arrow_function))) @func
    (lexical_declaration (variable_declarator value: (function_expression))) @func
  `,
    javascript: `
    (export_statement) @export
    (class_declaration) @class
    (function_declaration) @func
    (method_definition) @method
    (import_statement) @import
    (lexical_declaration (variable_declarator value: (arrow_function))) @func
    (lexical_declaration (variable_declarator value: (function_expression))) @func
  `,
    python: `
    (class_definition) @class
    (function_definition) @func
    (decorated_definition) @decorated
    (import_statement) @import
    (import_from_statement) @import
  `,
    go: `
    (type_declaration) @type
    (function_declaration) @func
    (method_declaration) @method
    (import_declaration) @import
  `,
    rust: `
    (struct_item) @struct
    (impl_item) @impl
    (function_item) @func
    (trait_item) @trait
    (enum_item) @enum
    (use_declaration) @import
    (type_item) @type
    (mod_item) @mod
  `,
};
/**
 * Score mapping from capture names to break point scores.
 * Aligned with the markdown BREAK_PATTERNS scale (h1=100, h2=90, etc.)
 * so findBestCutoff() decay works unchanged.
 */
const SCORE_MAP = {
    class: 100,
    iface: 100,
    struct: 100,
    trait: 100,
    impl: 100,
    mod: 100,
    export: 90,
    func: 90,
    method: 90,
    decorated: 90,
    type: 80,
    enum: 80,
    import: 60,
};
// =============================================================================
// Parser Caching & Initialization
// =============================================================================
let ParserClass = null;
let LanguageClass = null;
let QueryClass = null;
let initPromise = null;
/** Languages that have already failed to load — warn only once per process. */
const failedLanguages = new Set();
/** Cached grammar load promises. */
const grammarCache = new Map();
/** Cached compiled queries per language. */
const queryCache = new Map();
/**
 * Initialize web-tree-sitter. Called once and cached.
 */
async function ensureInit() {
    if (!initPromise) {
        initPromise = (async () => {
            const mod = await import("web-tree-sitter");
            ParserClass = mod.Parser;
            LanguageClass = mod.Language;
            QueryClass = mod.Query;
            await ParserClass.init();
        })();
    }
    return initPromise;
}
/**
 * Resolve the filesystem path to a grammar .wasm file.
 * Uses createRequire to resolve from installed dependency packages.
 */
function resolveGrammarPath(language) {
    const { pkg, wasm } = GRAMMAR_MAP[language];
    const require = createRequire(import.meta.url);
    return require.resolve(`${pkg}/${wasm}`);
}
/**
 * Load and cache a grammar for the given language.
 * Returns null on failure (logs once per language).
 */
async function loadGrammar(language) {
    if (failedLanguages.has(language))
        return null;
    const wasmKey = GRAMMAR_MAP[language].wasm;
    if (!grammarCache.has(wasmKey)) {
        grammarCache.set(wasmKey, (async () => {
            const path = resolveGrammarPath(language);
            return LanguageClass.load(path);
        })());
    }
    try {
        return await grammarCache.get(wasmKey);
    }
    catch (err) {
        failedLanguages.add(language);
        grammarCache.delete(wasmKey);
        console.warn(`[qmd] Failed to load tree-sitter grammar for ${language}: ${err}`);
        return null;
    }
}
/**
 * Get or create a compiled query for the given language.
 */
function getQuery(language, grammar) {
    if (!queryCache.has(language)) {
        const source = LANGUAGE_QUERIES[language];
        const query = new QueryClass(grammar, source);
        queryCache.set(language, query);
    }
    return queryCache.get(language);
}
// =============================================================================
// AST Break Point Extraction
// =============================================================================
/**
 * Parse a source file and return break points at AST node boundaries.
 *
 * Returns an empty array for unsupported languages, parse failures,
 * or grammar loading failures. Never throws.
 *
 * @param content - The file content to parse.
 * @param filepath - The file path (used for language detection).
 * @returns Array of BreakPoint objects suitable for merging with regex break points.
 */
export async function getASTBreakPoints(content, filepath) {
    const language = detectLanguage(filepath);
    if (!language)
        return [];
    try {
        await ensureInit();
        const grammar = await loadGrammar(language);
        if (!grammar)
            return [];
        const parser = new ParserClass();
        parser.setLanguage(grammar);
        const tree = parser.parse(content);
        if (!tree) {
            parser.delete();
            return [];
        }
        const query = getQuery(language, grammar);
        const captures = query.captures(tree.rootNode);
        // Deduplicate: at each byte position, keep the highest-scoring capture.
        // This handles cases like export_statement wrapping a class_declaration
        // at different offsets — we want the outermost (earliest) position.
        const seen = new Map();
        for (const cap of captures) {
            const pos = cap.node.startIndex;
            const score = SCORE_MAP[cap.name] ?? 20;
            const type = `ast:${cap.name}`;
            const existing = seen.get(pos);
            if (!existing || score > existing.score) {
                seen.set(pos, { pos, score, type });
            }
        }
        tree.delete();
        parser.delete();
        return Array.from(seen.values()).sort((a, b) => a.pos - b.pos);
    }
    catch (err) {
        console.warn(`[qmd] AST parse failed for ${filepath}, falling back to regex: ${err instanceof Error ? err.message : err}`);
        return [];
    }
}
// =============================================================================
// Health / Status
// =============================================================================
/**
 * Check which tree-sitter grammars are available.
 * Returns a status object for each supported language.
 */
export async function getASTStatus() {
    const languages = [];
    try {
        await ensureInit();
    }
    catch (err) {
        return {
            available: false,
            languages: Object.keys(GRAMMAR_MAP).map(lang => ({
                language: lang,
                available: false,
                error: `web-tree-sitter init failed: ${err instanceof Error ? err.message : err}`,
            })),
        };
    }
    for (const lang of Object.keys(GRAMMAR_MAP)) {
        try {
            const grammar = await loadGrammar(lang);
            if (grammar) {
                // Also verify the query compiles
                getQuery(lang, grammar);
                languages.push({ language: lang, available: true });
            }
            else {
                languages.push({ language: lang, available: false, error: "grammar failed to load" });
            }
        }
        catch (err) {
            languages.push({
                language: lang,
                available: false,
                error: err instanceof Error ? err.message : String(err),
            });
        }
    }
    return {
        available: languages.some(l => l.available),
        languages,
    };
}
/**
 * Extract symbol metadata for code within a byte range.
 * Stubbed for Phase 2 — returns empty array.
 */
export function extractSymbols(_content, _language, _startPos, _endPos) {
    return [];
}