string-le 0.3.1

//! Quoted runs, for every format this does not parse.
//!
//! **This is the extractor that does the audit.** A `.ts`, `.py`, `.go`
//! or `.java` file is not a format with a parser here, so it lands
//! exactly here — and the quoted strings in a source file are the
//! user-facing copy a reviewer came looking for.
//!
//! It is deliberately naive: it takes what is between quotes and does
//! not resolve escapes, because that is what the extension does. A
//! backslash in the source survives into the value.

use std::sync::LazyLock;

use regex::Regex;

/// The extension's `QUOTED_STRING_REGEX`, ported rather than re-derived.
///
/// JavaScript spells it as a backreference to the opening quote with a
/// lookahead that lets an escaped character count as one unit —
/// `regex` has neither, so the
/// three quote styles are written out as three alternatives, each with
/// its own "escaped anything, or one non-quote character" body.
///
/// **Newlines are excluded on purpose.** JavaScript's `.` does not match
/// one without the `s` flag, so a quoted run there cannot span lines and
/// a multi-line template literal is simply missed. Rust's character
/// classes match newlines happily, so leaving them in found a value the
/// extension never reports — the corpus caught it on the first run.
/// The same pattern with newlines allowed inside a run — what
/// JavaScript would spell with the `s` flag, which the extension does
/// not set and cannot easily add without changing what its editor
/// surface reports.
///
/// **Opt-in, and a deliberate divergence.** A multi-line template
/// literal in a source file is an email body, a help paragraph, a
/// consent notice — the copy an audit least wants to miss — and the
/// terminal has no reason to inherit a limit that exists because a
/// regex in an editor did not set a flag. Off by default, so the corpus
/// still pins the two frontends against each other.
static QUOTED_MULTILINE: LazyLock<Regex> = LazyLock::new(|| {
    Regex::new(r#"(?s)"(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'|`(?:\\.|[^`\\])*`"#)
        .expect("a constant pattern compiles")
});

static QUOTED: LazyLock<Regex> = LazyLock::new(|| {
    Regex::new(
        r#""(?:\\[^\r\n]|[^"\\\r\n])*"|'(?:\\[^\r\n]|[^'\\\r\n])*'|`(?:\\[^\r\n]|[^`\\\r\n])*`"#,
    )
    .expect("a constant pattern compiles")
});

#[cfg(test)]
pub(crate) fn extract(text: &str) -> Vec<String> {
    extract_with(text, false)
}

/// The inside of every quoted run, exactly as the source spells it.
///
/// Separate from `extract_with` so `source` can reuse the pattern
/// without reusing the trimming: what counts as a string is
/// `collect`'s question, and answering it twice is how two frontends
/// start to disagree.
pub(crate) fn runs(text: &str, multiline: bool) -> Vec<&str> {
    let pattern = if multiline {
        &*QUOTED_MULTILINE
    } else {
        &*QUOTED
    };
    pattern
        .find_iter(text)
        .map(|found| {
            let matched = found.as_str();
            &matched[1..matched.len() - 1]
        })
        .collect()
}

pub(crate) fn extract_with(text: &str, multiline: bool) -> Vec<String> {
    runs(text, multiline)
        .into_iter()
        .map(super::text::trim)
        .filter(|value| !value.is_empty())
        .map(str::to_string)
        .collect()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn all_three_quote_styles_are_read() {
        assert_eq!(
            extract("a = \"double\"; b = 'single'; c = `backtick`;"),
            ["double", "single", "backtick"]
        );
    }

    #[test]
    fn the_quotes_themselves_are_not_part_of_the_value() {
        assert_eq!(extract("'hello'"), ["hello"]);
    }

    #[test]
    fn empty_and_whitespace_only_runs_are_dropped() {
        assert_eq!(extract("a=''; b='  '; c='kept'"), ["kept"]);
    }

    /// The naivety is the ported behaviour: an escape is matched as one
    /// unit so the run does not end early, but it is left in the value.
    #[test]
    fn an_escaped_quote_does_not_end_the_run_and_is_not_resolved() {
        assert_eq!(extract(r"'It\'s fine'"), [r"It\'s fine"]);
        assert_eq!(extract(r#""say \"hi\"""#), [r#"say \"hi\""#]);
    }

    /// Unquoted prose is not a string here. A reviewer pointing this at
    /// a README gets nothing, which is the honest answer.
    #[test]
    fn unquoted_text_yields_nothing() {
        assert!(extract("just some words with no quotes").is_empty());
    }

    /// Ported behaviour, not an oversight: JavaScript's `.` stops at a
    /// newline, so by default a run that spans lines is not a run and a
    /// multi-line template literal is missed by both frontends.
    #[test]
    fn a_run_cannot_span_lines_by_default() {
        assert!(extract("`first\nsecond`").is_empty());
    }

    /// Asked for, it can. The copy an audit least wants to miss lives in
    /// exactly this shape.
    #[test]
    fn a_run_may_span_lines_on_request() {
        assert_eq!(extract_with("`first\nsecond`", true), ["first\nsecond"]);
        assert_eq!(
            extract_with("const body = `Dear reader,\n\nWelcome.`;", true),
            ["Dear reader,\n\nWelcome."]
        );
    }

    /// Turning it on must not change anything that already worked.
    #[test]
    fn the_multiline_pattern_agrees_on_single_line_runs() {
        let source = "a = \"one\"; b = 'two'; c = `three`;";
        assert_eq!(extract(source), extract_with(source, true));
    }

    #[test]
    fn quotes_of_another_style_inside_a_run_are_kept() {
        assert_eq!(extract(r#""it's here""#), ["it's here"]);
    }

    /// A comment is text like any other. Filtering by syntactic role
    /// would be this crate deciding which strings matter.
    #[test]
    fn a_quoted_run_inside_a_comment_is_still_a_run() {
        assert_eq!(extract("// see \"the docs\""), ["the docs"]);
    }
}