use once_cell::sync::OnceCell;
use rustc_middle::ty::TyCtxt;
use crate::{
analysis::{
core::dataflow::{graph::Graph, *},
opt::OptCheck,
utils::def_path::DefPath,
},
utils::log::{relative_pos_range, span_to_filename, span_to_line_number, span_to_source_code},
};
use annotate_snippets::{Level, Renderer, Snippet};
use rustc_span::Span;
static DEFPATHS: OnceCell<DefPaths> = OnceCell::new();
struct DefPaths {
flat_map: DefPath,
flatten: DefPath,
collect: DefPath,
}
impl DefPaths {
fn new(tcx: &TyCtxt<'_>) -> Self {
Self {
flat_map: DefPath::new("std::iter::Iterator::flat_map", tcx),
flatten: DefPath::new("std::iter::Iterator::flatten", tcx),
collect: DefPath::new("std::iter::Iterator::collect", tcx),
}
}
}
pub struct FlattenCollectCheck {
record: Vec<Span>,
}
fn is_flatten_node(node: &GraphNode) -> bool {
let def_paths = &DEFPATHS.get().unwrap();
for op in node.ops.iter() {
if let NodeOp::Call(def_id) = op {
if *def_id == def_paths.flat_map.last_def_id()
|| *def_id == def_paths.flatten.last_def_id()
{
return true;
}
}
}
false
}
fn is_collect_node(node: &GraphNode) -> bool {
let def_paths = &DEFPATHS.get().unwrap();
for op in node.ops.iter() {
if let NodeOp::Call(def_id) = op {
if *def_id == def_paths.collect.last_def_id() {
return true;
}
}
}
false
}
impl OptCheck for FlattenCollectCheck {
fn new() -> Self {
Self { record: Vec::new() }
}
fn check(&mut self, graph: &Graph, tcx: &TyCtxt) {
let _ = &DEFPATHS.get_or_init(|| DefPaths::new(tcx));
for node in graph.nodes.iter() {
if is_flatten_node(node) {
for edge_idx in node.out_edges.iter() {
let dst_idx = graph.edges[*edge_idx].dst;
let dst_node = &graph.nodes[dst_idx];
if is_collect_node(dst_node) {
self.record.push(dst_node.span);
}
}
}
}
}
fn report(&self, graph: &Graph) {
for span in self.record.iter() {
report_flatten_collect(graph, *span);
}
}
fn cnt(&self) -> usize {
self.record.len()
}
}
fn report_flatten_collect(graph: &Graph, span: Span) {
let code_source = span_to_source_code(graph.span);
let filename = span_to_filename(span);
let snippet: Snippet<'_> = Snippet::source(&code_source)
.line_start(span_to_line_number(graph.span))
.origin(&filename)
.fold(true)
.annotation(
Level::Error
.span(relative_pos_range(graph.span, span))
.label("Flatten then collect."),
);
let message = Level::Error
.title("Data collection inefficiency detected")
.snippet(snippet)
.footer(Level::Help.title("Use extend manually."));
let renderer = Renderer::styled();
println!("{}", renderer.render(message));
}