fallow_core/duplicates/tokenize/

mod.rs

use std::path::Path;

use oxc_allocator::Allocator;
use oxc_ast_visit::Visit;
use oxc_parser::Parser;
use oxc_span::{SourceType, Span};

// Re-export all public types so existing `use ... tokenize::X` paths continue to work.
pub use super::token_types::{
    FileTokens, KeywordType, OperatorType, PunctuationType, SourceToken, TokenKind,
};
use super::token_visitor::TokenExtractor;

/// Tokenize a source file into a sequence of normalized tokens.
///
/// For Vue/Svelte SFC files, extracts `<script>` blocks first and tokenizes
/// their content, mirroring the main analysis pipeline's SFC handling.
/// For Astro files, extracts frontmatter. For MDX files, extracts import/export statements.
///
/// When `strip_types` is true, TypeScript type annotations, interfaces, and type
/// aliases are stripped from the token stream. This enables cross-language clone
/// detection between `.ts` and `.js` files.
#[must_use]
pub fn tokenize_file(path: &Path, source: &str) -> FileTokens {
    tokenize_file_inner(path, source, false)
}

/// Tokenize a source file with optional type stripping for cross-language detection.
#[must_use]
pub fn tokenize_file_cross_language(path: &Path, source: &str, strip_types: bool) -> FileTokens {
    tokenize_file_inner(path, source, strip_types)
}

fn tokenize_file_inner(path: &Path, source: &str, strip_types: bool) -> FileTokens {
    use crate::extract::{extract_astro_frontmatter, extract_mdx_statements, is_sfc_file};

    let ext = path.extension().and_then(|e| e.to_str()).unwrap_or("");

    if is_sfc_file(path) {
        return tokenize_sfc(source, strip_types);
    }
    if ext == "astro" {
        return tokenize_astro(source, strip_types, extract_astro_frontmatter);
    }
    if ext == "mdx" {
        return tokenize_mdx(source, strip_types, extract_mdx_statements);
    }
    if ext == "css" || ext == "scss" {
        return empty_tokens(source);
    }

    tokenize_js_ts(path, source, strip_types)
}

/// Tokenize Vue/Svelte SFC `<script>` blocks.
#[expect(
    clippy::cast_possible_truncation,
    reason = "byte offsets are bounded by source size"
)]
fn tokenize_sfc(source: &str, strip_types: bool) -> FileTokens {
    let scripts = crate::extract::extract_sfc_scripts(source);
    let mut all_tokens = Vec::new();

    for script in &scripts {
        let source_type = match (script.is_typescript, script.is_jsx) {
            (true, true) => SourceType::tsx(),
            (true, false) => SourceType::ts(),
            (false, true) => SourceType::jsx(),
            (false, false) => SourceType::mjs(),
        };
        let allocator = Allocator::default();
        let parser_return = Parser::new(&allocator, &script.body, source_type).parse();

        let mut extractor = TokenExtractor::with_strip_types(strip_types);
        extractor.visit_program(&parser_return.program);

        let offset = script.byte_offset as u32;
        for token in &mut extractor.tokens {
            token.span = Span::new(token.span.start + offset, token.span.end + offset);
        }
        all_tokens.extend(extractor.tokens);
    }

    FileTokens {
        tokens: all_tokens,
        source: source.to_string(),
        line_count: source.lines().count().max(1),
    }
}

/// Tokenize Astro frontmatter between `---` delimiters.
#[expect(
    clippy::cast_possible_truncation,
    reason = "byte offsets are bounded by source size"
)]
fn tokenize_astro(
    source: &str,
    strip_types: bool,
    extract_fn: fn(&str) -> Option<fallow_extract::sfc::SfcScript>,
) -> FileTokens {
    if let Some(script) = extract_fn(source) {
        let allocator = Allocator::default();
        let parser_return = Parser::new(&allocator, &script.body, SourceType::ts()).parse();

        let mut extractor = TokenExtractor::with_strip_types(strip_types);
        extractor.visit_program(&parser_return.program);

        let offset = script.byte_offset as u32;
        for token in &mut extractor.tokens {
            token.span = Span::new(token.span.start + offset, token.span.end + offset);
        }

        return FileTokens {
            tokens: extractor.tokens,
            source: source.to_string(),
            line_count: source.lines().count().max(1),
        };
    }
    empty_tokens(source)
}

/// Tokenize MDX import/export statements.
fn tokenize_mdx(source: &str, strip_types: bool, extract_fn: fn(&str) -> String) -> FileTokens {
    let statements = extract_fn(source);
    if !statements.is_empty() {
        let allocator = Allocator::default();
        let parser_return = Parser::new(&allocator, &statements, SourceType::jsx()).parse();

        let mut extractor = TokenExtractor::with_strip_types(strip_types);
        extractor.visit_program(&parser_return.program);

        return FileTokens {
            tokens: extractor.tokens,
            source: source.to_string(),
            line_count: source.lines().count().max(1),
        };
    }
    empty_tokens(source)
}

/// Return empty tokens for a source file (CSS, no-frontmatter Astro, empty MDX).
fn empty_tokens(source: &str) -> FileTokens {
    FileTokens {
        tokens: Vec::new(),
        source: source.to_string(),
        line_count: source.lines().count().max(1),
    }
}

/// Tokenize a standard JS/TS file, with JSX fallback for parse errors.
fn tokenize_js_ts(path: &Path, source: &str, strip_types: bool) -> FileTokens {
    let source_type = SourceType::from_path(path).unwrap_or_default();
    let allocator = Allocator::default();
    let parser_return = Parser::new(&allocator, source, source_type).parse();

    let mut extractor = TokenExtractor::with_strip_types(strip_types);
    extractor.visit_program(&parser_return.program);

    // If parsing produced very few tokens relative to source size (likely parse errors
    // from Flow types or JSX in .js files), retry with JSX/TSX source type as a fallback.
    if extractor.tokens.len() < 5 && source.len() > 100 && !source_type.is_jsx() {
        let jsx_type = if source_type.is_typescript() {
            SourceType::tsx()
        } else {
            SourceType::jsx()
        };
        let allocator2 = Allocator::default();
        let retry_return = Parser::new(&allocator2, source, jsx_type).parse();
        let mut retry_extractor = TokenExtractor::with_strip_types(strip_types);
        retry_extractor.visit_program(&retry_return.program);
        if retry_extractor.tokens.len() > extractor.tokens.len() {
            extractor = retry_extractor;
        }
    }

    FileTokens {
        tokens: extractor.tokens,
        source: source.to_string(),
        line_count: source.lines().count().max(1),
    }
}

#[cfg(test)]
mod tests;