sva_core/

lib.rs

// Concern: the parse->tempo->render pipeline shared by both front ends | Non-concern: argv (sva-cli), JS bindings (sva-wasm) | IO: (a Source, a target) -> Rendered, a Stream or CliError

mod analyze;
mod answer;
mod builtins;
mod cli_error;
mod decode;
pub mod encode;
pub mod json;
mod lint_code;
mod outline;
mod output;
mod query;
mod set;
pub mod solve;
mod song;
mod target;
mod until;

pub use analyze::{analyzable, analyzed};
pub use answer::{
    Played, Printed, Report, SAMPLE_LIMIT, answer_json, counters_json, engine_stats_json,
    label_json, query_data, resampled_json, stats_json, stream_stats_json, value_json, work_json,
};
pub use builtins::{Builtins, Callable, Crossing, builtins, builtins_data};
pub use cli_error::{CliError, LintViolation, lint_diagnostic, warning_diagnostic};
pub use lint_code::LintCode;
pub use outline::{events_data, outline_data, song_data};
pub use output::{
    Diagnostic, Severity, diagnostics_json, error_envelope, error_envelope_with, success_envelope,
};
pub use query::{
    Asked, Call, Destination, RETIRED, Spelled, Taken, asked, asked_all, call, calls, is_wav,
    retired, seconds,
};
pub use set::{overlaid, set};
pub use song::{as_lane, sung};
pub use sva_ast::RESERVED_VARIABLES;
pub use target::{Edge, Target, target};
pub use until::until;

use std::cell::RefCell;
use std::num::NonZeroUsize;
use std::path::Path;

use sva_ast::song::Song;
use sva_ast::{Dir, Graph, Refusal, Source};
use sva_engine::{
    Ask, Change, Changed, DEFAULT_SAMPLE_RATE, EngineError, Kind, PSYCHOACOUSTIC_V1, Phase, Range,
    RenderConfig, StreamConfig, render, render_called,
};

pub use sva_engine::{Abandon, Handle, Hear, Never, Out, Placed, Session, Stream, Until};

pub use sva_engine::{Answer, Extent, Label, Output, Representation};
pub use sva_engine::{
    Backend, CacheStats, Counters, DEFAULT_CACHE_BYTES, DEFAULT_STORE_BYTES, EngineStats,
    FETCH_READS, Nothing, Persisted, Store, Tier,
};

pub const ROOT: &str = "master";
pub const PROBE: &str = "probe";
pub const RECORDING_UNREADABLE: &str = "recording.unreadable";

pub struct Rendered {
    pub config: RenderConfig,
    /// What the song's files earn: each prints, and the render goes on.
    pub warnings: Vec<sva_ast::song::Warning>,
    pub expression: String,
    pub target: String,
    pub render: sva_engine::Render,
    /// So a structural check needs no second parse, and an ad-hoc target is the same `probe`.
    pub graph: Graph,
}

impl Rendered {
    pub fn answer(&self, node: &str, representation: Representation) -> Result<Answer, CliError> {
        let written = |e| CliError::Engine(as_written(e, &self.expression));
        let id = self.render.node(node).map_err(written)?;
        let mut answer = sva_engine::answer(&self.render, id, representation).map_err(written)?;
        self.attribute(&mut answer)?;
        Ok(answer)
    }

    /// What a bar lasts in this render's tempo; `None` where it has none.
    pub fn seconds_per_bar(&self) -> Option<f64> {
        self.graph.tempo().map(|tempo| tempo.seconds_per_bar())
    }

    /// `asked`'s reading, its bars in this render's tempo.
    pub fn answered(&self, asked: &Asked) -> Result<Answer, CliError> {
        let representation = asked.representation(self.config.rate, self.seconds_per_bar())?;
        self.answer(
            asked.node.as_deref().unwrap_or(&self.target),
            representation,
        )
    }

    /// An alias score reads beside how many instances the render holds.
    fn attribute(&self, answer: &mut Answer) -> Result<(), CliError> {
        let Output::Alias(alias) = &mut answer.value else {
            return Ok(());
        };
        alias.instances = self.render.tys.paths().count();
        Ok(())
    }

    pub fn label(&self) -> Option<&sva_engine::Label> {
        self.render.labels.get(&self.render.root)
    }
}

/// One render: `target` an expression over the composition `source` holds, its own ref
/// read over an interval where it writes one.
pub struct Job<'a> {
    pub source: &'a dyn Source,
    pub target: &'a str,
    /// `None` ends the render where the interval or the target's support ends.
    pub until: Option<&'a str>,
    pub rate: Option<u32>,
    pub bits: Option<i32>,
    pub asked: &'a [Asked],
    pub volatile: &'a [String],
    pub out: Out,
    pub abandon: &'a dyn Abandon,
    pub hear: Option<&'a dyn Hear>,
    /// The most threads it computes on; `None` takes every core the platform reports.
    pub threads: Option<NonZeroUsize>,
}

impl<'a> Job<'a> {
    pub fn over(source: &'a dyn Source, target: &'a str) -> Job<'a> {
        Job {
            source,
            target,
            until: None,
            rate: None,
            bits: None,
            asked: &[],
            volatile: &[],
            out: Out::Kept,
            abandon: &Never,
            hear: None,
            threads: None,
        }
    }
}

fn settle(job: &Job) -> Result<(Graph, RenderConfig, Song), CliError> {
    let Target { expr, interval } = target(job.target)?;
    let roots = roots_of(job.source, &expr)?;
    let hinted = |e| solve::hinted(e, job.source, Some(job.target));
    let mut graph = settled(sva_ast::load_reaching(
        job.source,
        &roots.iter().map(String::as_str).collect::<Vec<_>>(),
    ))
    .map_err(hinted)?;
    let parsed = sva_ast::parse_expr(&expr)
        .map_err(|d| {
            CliError::BadProbe(format!(
                "`{}` does not parse as an expression: {}",
                job.target, d.message
            ))
        })
        .map_err(hinted)?;
    let parsed =
        sva_ast::resolve_recordings(&parsed, job.source).map_err(|unheld| match unheld.why {
            None => CliError::NotFound(unheld.message()),
            Some(_) => CliError::usage(RECORDING_UNREADABLE, unheld.message()),
        })?;
    define_probe(&mut graph, parsed)?;
    let rate = job.rate.unwrap_or(DEFAULT_SAMPLE_RATE);
    let per_bar = graph.tempo().map(|tempo| tempo.seconds_per_bar());
    let range = match interval {
        None => Range::default(),
        Some((start, end)) => Range {
            start: start.sample(rate, per_bar)?,
            end: end.sample(rate, per_bar)?,
        },
    };
    if let Range {
        start: Some(start),
        end: Some(end),
    } = range
        && end <= start
    {
        return Err(CliError::usage(
            "render.empty_interval",
            format!(
                "`{}` reads an interval from sample {start} to {end}, which holds none",
                job.target
            ),
        ));
    }
    let until = match job.until {
        Some(text) => Some(until(text, rate, per_bar)?),
        None => None,
    };
    let mut config = RenderConfig {
        range,
        until,
        ..RenderConfig::at(rate)
    };
    config.profile.precision_bits = precision_bits(job.bits)?;
    config.volatile = job.volatile.to_vec();
    config.out = job.out;
    if let Some(threads) = job.threads {
        config.threads = threads;
    }
    config.asks = job
        .asked
        .iter()
        .map(|asked| {
            Ok(Ask {
                node: asked.node.clone().unwrap_or_else(|| PROBE.to_string()),
                representation: asked.representation(rate, per_bar)?,
            })
        })
        .collect::<Result<_, CliError>>()?;
    let song = sung(&mut graph, PROBE, rate)?;
    Ok((graph, config, song))
}

/// An engine refusal as the song names it where a moving lane reaches it, else as written.
fn refused(song: &Song, graph: &Graph, e: EngineError, target: &str) -> CliError {
    match as_lane(song, graph, e) {
        CliError::Engine(e) => CliError::Engine(as_written(e, target)),
        other => other,
    }
}

/// `trace` names one instance of a parameterized file as `<path>(<name>=<value>, ..)`.
fn instance_call(text: &str) -> Option<(&str, &str)> {
    let (path, rest) = text.split_once('(')?;
    let binds = rest.strip_suffix(')')?.trim();
    (!binds.is_empty() && all_named(binds)).then_some((path, binds))
}

/// Only commas and equals outside a bind's own parens count: a bind's value may be a call.
fn all_named(binds: &str) -> bool {
    let mut depth = 0i32;
    let mut named = false;
    for c in binds.chars() {
        match c {
            '(' => depth += 1,
            ')' if depth == 0 => return false,
            ')' => depth -= 1,
            '=' if depth == 0 => named = true,
            ',' if depth == 0 && !std::mem::take(&mut named) => return false,
            _ => {}
        }
    }
    named && depth == 0
}

/// The ref an instance name stands for, so `lint` and `trace` answer for the same node.
fn instance_read(graph: &Graph, text: &str) -> Option<sva_ast::Expr> {
    let (path, binds) = instance_call(text)?;
    if !graph.defines(path) {
        return None;
    }
    sva_ast::parse_expr(&format!("@{path}(t, {binds})")).ok()
}

pub fn execute(job: Job, tier: &Tier) -> Result<Rendered, CliError> {
    let (graph, config, song) = settle(&job)?;
    let render = render(&graph, PROBE, config, tier);
    rendered(&job, (graph, song), render)
}

/// `job` over `tier`, typing anew only what `session` typed otherwise; only `persist` commits
/// what it offers a disk beneath.
pub async fn execute_over<B: Backend>(
    job: Job<'_>,
    tier: &Tier<B>,
    session: &mut Session,
) -> Result<Rendered, CliError> {
    let call = tier.call(Kind::Render, job.target, Phase::Parsing);
    let (graph, config, song) = settle(&job)?;
    let hooks = (job.abandon, job.hear);
    let render = render_called(session, &graph, PROBE, config, tier, hooks, call).await;
    rendered(&job, (graph, song), render)
}

fn rendered(
    job: &Job,
    (graph, song): (Graph, Song),
    render: Result<sva_engine::Render, EngineError>,
) -> Result<Rendered, CliError> {
    let render = render.map_err(|e| refused(&song, &graph, e, job.target))?;
    Ok(Rendered {
        warnings: song.warnings().to_vec(),
        config: render.config.clone(),
        expression: job.target.to_string(),
        target: PROBE.to_string(),
        render,
        graph,
    })
}

/// The render a job would run, and the warnings its song earns.
pub fn plan(job: &Job) -> Result<(sva_engine::Render, Vec<sva_ast::song::Warning>), CliError> {
    let (planned, song, _) = planned(job)?;
    Ok((planned, song.warnings().to_vec()))
}

/// The render a job would run, its song, and the seconds a bar of its tempo lasts.
pub(crate) fn planned(job: &Job) -> Result<(sva_engine::Render, Song, Option<f64>), CliError> {
    let (graph, config, song) = settle(job)?;
    let per_bar = graph.tempo().map(|tempo| tempo.seconds_per_bar());
    let planned = sva_engine::plan(&graph, PROBE, config);
    let planned = planned.map_err(|e| refused(&song, &graph, e, job.target))?;
    Ok((planned, song, per_bar))
}

/// Every refusal typing the target reaches, and no render's; the warnings its song earns.
pub fn types(job: &Job) -> Result<Vec<sva_ast::song::Warning>, CliError> {
    let (graph, config, song) = settle(job)?;
    sva_engine::types_at(&graph, PROBE, config.rate)
        .map_err(|e| refused(&song, &graph, e, job.target))?;
    Ok(song.warnings().to_vec())
}

/// `root`'s song derived and laid over `graph`, as `outline` reads it.
pub fn song_of(source: &dyn Source, target: &str) -> Result<(Graph, Song), CliError> {
    let job = Job::over(source, target);
    let (graph, _, song) = settle(&job)?;
    Ok((graph, song))
}

/// `channels`: what it plays, the target's own where `None`.
pub async fn stream<B: Backend>(
    job: &Job<'_>,
    (block, channels): (usize, Option<usize>),
    tier: &Tier<B>,
) -> Result<Stream, CliError> {
    let call = tier.call(Kind::Stream, job.target, Phase::Parsing);
    let (graph, config, _) = settle(job)?;
    let target = graph
        .expr(PROBE)
        .cloned()
        .expect("the target was defined as the probe");
    let config = StreamConfig {
        block,
        channels,
        render: config,
    };
    Stream::open_called(&graph, &target, config, tier, call)
        .await
        .map_err(|e| CliError::Engine(as_written(e, job.target)))
}

/// `target`, an expression over `source` with no interval of its own, in place of what
/// `stream` plays. Each edit here is `sva_engine::change`'s: the stream plays on meanwhile.
pub async fn edit<B: Backend>(
    stream: &RefCell<Stream>,
    source: &dyn Source,
    target: &str,
    tier: &Tier<B>,
) -> Result<(), CliError> {
    let build = |s: &Stream| {
        let (graph, expr) = streamed(s, source, target, None)?;
        Ok(Change::Target(graph, expr))
    };
    changed(stream, build, Some(target), tier).await.map(|_| ())
}

/// `term` summed into the stream's `@notes`, its sample 0 placed `at`.
pub async fn add<B: Backend>(
    stream: &RefCell<Stream>,
    source: &dyn Source,
    (term, at): (&str, Placed),
    tier: &Tier<B>,
) -> Result<Handle, CliError> {
    let build = |s: &Stream| {
        let (graph, expr) = streamed(s, source, term, Some(at))?;
        Ok(Change::Add(graph, expr, at))
    };
    match changed(stream, build, Some(term), tier).await? {
        Changed::Added(handle) => Ok(handle),
        _ => unreachable!("an add answers its handle"),
    }
}

/// False where the stream no longer holds `handle`.
pub async fn replace<B: Backend>(
    stream: &RefCell<Stream>,
    source: &dyn Source,
    (handle, term, at): (Handle, &str, Placed),
    tier: &Tier<B>,
) -> Result<bool, CliError> {
    let build = |s: &Stream| {
        let (graph, expr) = streamed(s, source, term, Some(at))?;
        Ok(Change::Replace(handle, graph, expr, at))
    };
    Ok(changed(stream, build, Some(term), tier).await? == Changed::Held(true))
}

/// False where the stream no longer holds `handle`.
pub async fn remove<B: Backend>(
    stream: &RefCell<Stream>,
    handle: Handle,
    tier: &Tier<B>,
) -> Result<bool, CliError> {
    let build = |_: &Stream| Ok(Change::Remove(handle));
    Ok(changed(stream, build, None, tier).await? == Changed::Held(true))
}

async fn changed<B: Backend>(
    stream: &RefCell<Stream>,
    build: impl FnMut(&Stream) -> Result<Change, CliError>,
    text: Option<&str>,
    tier: &Tier<B>,
) -> Result<Changed, CliError> {
    let changed = sva_engine::change(stream, build, tier).await;
    changed.map_err(|e| match (e, text) {
        (CliError::Engine(e), Some(text)) => CliError::Engine(as_written(e, text)),
        (e, _) => e,
    })
}

pub async fn fetch<B: Backend>(stream: &RefCell<Stream>, tier: &Tier<B>) {
    sva_engine::fetch(stream, tier).await;
}

/// `text` with no interval, and each node it reads that `stream` does not hold, or holds at an
/// earlier edit of `source`, read and parsed off `source`: an edit is a version the stream plays.
fn streamed(
    stream: &Stream,
    source: &dyn Source,
    text: &str,
    term: Option<Placed>,
) -> Result<(Graph, sva_ast::Expr), CliError> {
    let Target { expr, interval } = target(text)?;
    if interval.is_some() {
        return Err(CliError::usage(
            "stream.interval",
            format!("`{text}` reads an interval, and a stream keeps its own"),
        ));
    }
    let held = stream.graph();
    let roots = roots_of(source, &expr)?;
    let roots: Vec<&str> = roots.iter().map(String::as_str).collect();
    let mut delta = sva_ast::load_beside(source, &roots, held).map_err(CliError::Refusals)?;
    delta
        .lower_reserved(Some(held))
        .map_err(CliError::Refusals)?;
    let parsed = sva_ast::parse_expr(&expr).map_err(|d| {
        CliError::BadProbe(format!(
            "`{text}` does not parse as an expression: {}",
            d.message
        ))
    })?;
    let mut view = held.sourced();
    for path in delta.paths() {
        view.set(path, delta.held(path));
    }
    let rate = stream.config().render.rate;
    let lowered = match term {
        None => {
            view.set(PROBE, None);
            define_probe(&mut view, parsed)?;
            sung(&mut view, PROBE, rate)?;
            view.expr(PROBE)
                .cloned()
                .expect("the target was defined as the probe")
        }
        Some(placed) => termed(&mut view, parsed, placed, rate)?,
    };
    let mut out = delta;
    let changed: Vec<String> = view
        .paths()
        .filter(|path| !held.holds_as(path, &view) || !held.read_as(path, &view))
        .map(str::to_string)
        .collect();
    for path in changed {
        out.set(&path, view.held(&path));
    }
    Ok((out, lowered))
}

/// A stream term lowered beside the stream's song: its instances read the song's lanes at
/// their position, and a term reaching a move of its own refuses, since lanes derive from the
/// song's files.
fn termed(
    view: &mut Graph,
    term: sva_ast::Expr,
    placed: Placed,
    rate: u32,
) -> Result<sva_ast::Expr, CliError> {
    const ALONE: &str = "#term";
    const BESIDE: &str = "#song";
    let mut alone = view.clone();
    alone
        .define_settled(None, ALONE, term)
        .map_err(CliError::Refusals)?;
    let written = alone.expr(ALONE).cloned().expect("just defined");
    let own = alone.song(ALONE).map_err(CliError::Refusals)?;
    if let Some(lane) = own.lanes().first() {
        let first = &lane.moves[0].reached;
        return Err(CliError::Refusals(vec![Refusal::new(
            format!("{}{}", first.score, sva_ast::score::EXTENSION),
            sva_ast::ByteSpan::at(0),
            sva_ast::DiagCode::BadLane,
            format!(
                "a stream term reaches this move on `{}`; a term adds sound and never moves, \
                 since lanes derive from the song's files: move it in one",
                lane.id.name()
            ),
        )]));
    }
    let target = view.source_expr(PROBE).expect("a stream holds its target");
    let both = sva_ast::Expr::Bin(
        sva_ast::BinOp::Add,
        Box::new(target),
        Box::new(written.clone()),
    );
    view.define_settled(None, BESIDE, both)
        .map_err(CliError::Refusals)?;
    sung(view, BESIDE, rate)?;
    let Some(sva_ast::Expr::Bin(_, _, lowered)) = view.expr(BESIDE).cloned() else {
        unreachable!("a sum lowers to a sum")
    };
    view.set(BESIDE, None);
    if placed == Placed::Landing && *lowered != written {
        return Err(CliError::Refusals(vec![Refusal::new(
            ALONE,
            sva_ast::ByteSpan::at(0),
            sva_ast::DiagCode::BadLane,
            "this term lands where the stream is when it arrives, so it has no song time, and a \
             lane of the song moves what it plays; a lane reaches an instance at its song \
             position, so add it at a written time"
                .to_string(),
        )]));
    }
    Ok(*lowered)
}

/// The precision a render writes every sample to: `bits`, else the profile's own.
pub fn precision_bits(bits: Option<i32>) -> Result<i32, CliError> {
    bits.map_or(Ok(PSYCHOACOUSTIC_V1.precision_bits), precision)
}

/// A double holds no bit past its own mantissa, and one bit writes only zero.
fn precision(bits: i32) -> Result<i32, CliError> {
    match (2..=52).contains(&bits) {
        true => Ok(bits),
        false => Err(CliError::usage(
            "cli.bad_value",
            format!("`--bits` takes a precision from 2 to 52 bits, not {bits}"),
        )),
    }
}

/// The engine knows a target only as the node it was defined as, so a refusal that names
/// that node names the target as the caller wrote it instead.
fn as_written(refused: EngineError, target: &str) -> EngineError {
    match refused {
        EngineError::Refused(mut d) => {
            if d.location.node == PROBE {
                d.location.node = target.to_string();
            }
            d.message = d
                .message
                .replace(&format!("`{PROBE}`"), &format!("`{target}`"));
            EngineError::Refused(d)
        }
        EngineError::Binding { node, span, fault } if node == PROBE => EngineError::Binding {
            node: target.to_string(),
            span,
            fault,
        },
        other => other,
    }
}

pub fn probe(dir: &Path, expression: &str) -> Result<Rendered, CliError> {
    execute(Job::over(&Dir::at(dir), expression), &Tier::default())
}

pub fn cwd() -> Result<std::path::PathBuf, CliError> {
    std::env::current_dir()
        .map_err(|e| CliError::Io(format!("could not read the current directory: {e}")))
}

/// Every node `source` holds; a solve's `fits/` costs are no nodes, so the load never sees them.
pub fn prepared(source: &dyn Source) -> Result<Graph, CliError> {
    settled(sva_ast::load(&Unfitted(source))).map_err(|e| solve::hinted(e, source, None))
}

struct Unfitted<'a>(&'a dyn Source);

impl Source for Unfitted<'_> {
    fn paths(&self) -> Result<sva_ast::Listing, String> {
        let fits = format!("{}/", solve::FITS);
        let mut listing = self.0.paths()?;
        listing.found.retain(|path| !path.starts_with(&fits));
        listing.unreadable.retain(|path| !path.starts_with(&fits));
        Ok(listing)
    }

    fn get(&self, path: &str) -> Result<Option<std::borrow::Cow<'_, str>>, String> {
        self.0.get(path)
    }

    fn generation(&self, path: &str) -> Option<u64> {
        self.0.generation(path)
    }

    fn name(&self) -> String {
        self.0.name()
    }

    fn recording(&self, path: &str) -> Result<Option<std::sync::Arc<sva_ast::Recording>>, String> {
        self.0.recording(path)
    }
}

/// Argv math: `trace` and `lint` each refuse a target no node answers for here, under one
/// code and one message.
pub fn define_probe_for(graph: &mut Graph, text: &str) -> Result<(), CliError> {
    let expr = match instance_read(graph, text) {
        Some(read) => read,
        None if names_a_missing_node(text) => {
            return Err(CliError::NotFound(format!(
                "`{text}` is not a node this composition defines"
            )));
        }
        None => sva_ast::parse_expr(text).map_err(|d| {
            CliError::BadProbe(format!(
                "`{text}` is not a node in this composition, and does not parse as an \
                 expression: {}",
                d.message
            ))
        })?,
    };
    define_probe(graph, expr)
}

/// Only a path, or instance syntax, is a node; the rest is math the parser and engine answer
/// for. `t` and `A4` are spelled like paths and read as values.
fn names_a_missing_node(text: &str) -> bool {
    match instance_call(text) {
        Some((path, _)) => sva_ast::names_a_node(path),
        None => !text.contains('(') && sva_ast::names_a_node(text) && !reads_as_a_value(text),
    }
}

fn reads_as_a_value(text: &str) -> bool {
    match sva_ast::parse_expr(text) {
        Ok(sva_ast::Expr::Lit(_)) => true,
        Ok(sva_ast::Expr::Var(name)) => sva_ast::is_reserved(&name),
        _ => false,
    }
}

/// Argv math settled the way a file is; `concat` is no file-only dialect.
fn define_probe(graph: &mut Graph, expr: sva_ast::Expr) -> Result<(), CliError> {
    let defined = graph
        .define_settled(None, PROBE, expr)
        .map_err(CliError::Refusals)?;
    if !defined {
        return Err(CliError::BadProbe(format!(
            "this composition already has a node named `{PROBE}`"
        )));
    }
    Ok(())
}

/// Loaded with its reserved variables lowered; a song lowers its scores once a root is named.
pub fn settled(loaded: Result<Graph, Vec<Refusal>>) -> Result<Graph, CliError> {
    let mut graph = loaded.map_err(CliError::Refusals)?;
    graph.lower_reserved(None).map_err(CliError::Refusals)?;
    Ok(graph)
}

/// A node path the source answers for is a node; anything else is math, and its reads are
/// roots. Only a node path is asked of the source: math is never looked up as a file.
pub fn roots_of(source: &dyn Source, target: &str) -> Result<Vec<String>, CliError> {
    let mut roots: Vec<String> = RESERVED_VARIABLES.map(sva_ast::variable).to_vec();
    let listed = source.paths().map_err(CliError::Io)?.found;
    let variables = format!("{}/", sva_ast::VARIABLES);
    roots.extend(listed.into_iter().filter(|p| p.starts_with(&variables)));
    roots.sort();
    roots.dedup();
    let held = |path: &str| -> Result<bool, CliError> {
        let file = format!("{path}{}", sva_ast::score::EXTENSION);
        let get = |at: &str| {
            source
                .get(at)
                .map(|text| text.is_some())
                .map_err(CliError::Io)
        };
        Ok(sva_ast::whole_ref_path(path) && (get(path)? || get(&file)?))
    };
    match target {
        target if held(target)? => {
            roots.push(target.to_string());
        }
        text => match instance_call(text).map(|(path, _)| path) {
            Some(path) if held(path)? => {
                roots.push(path.to_string());
            }
            _ => {
                if let Ok(expr) = sva_ast::parse_expr(text) {
                    roots.extend(sva_ast::reads_of(PROBE, &expr));
                }
            }
        },
    }
    Ok(roots)
}