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simplify cyclomatic complexity auxiliarly value computation

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previously the HIR was unnecessarily traversed twice
This commit is contained in:
Oliver Schneider 2016-03-04 16:27:03 +01:00
parent c0c2f61d7d
commit e7fa117ff8
1 changed files with 23 additions and 26 deletions
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49
src/cyclomatic_complexity.rs
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@ -48,18 +48,22 @@ impl CyclomaticComplexity {
let n = cfg.graph.len_nodes() as u64;
let e = cfg.graph.len_edges() as u64;
let cc = e + 2 - n;
let mut arm_counter = MatchArmCounter(0);
arm_counter.visit_block(block);
let narms = arm_counter.0;
let mut helper = CCHelper {
match_arms: 0,
divergence: 0,
tcx: &cx.tcx,
};
helper.visit_block(block);
let CCHelper {
match_arms,
divergence,
..
} = helper;
let mut diverge_counter = DivergenceCounter(0, &cx.tcx);
diverge_counter.visit_block(block);
let divergence = diverge_counter.0;
if cc + divergence < narms {
report_cc_bug(cx, cc, narms, divergence, span);
if cc + divergence < match_arms {
report_cc_bug(cx, cc, match_arms, divergence, span);
} else {
let rust_cc = cc + divergence - narms;
let rust_cc = cc + divergence - match_arms;
if rust_cc > self.limit.limit() {
span_help_and_lint(cx,
CYCLOMATIC_COMPLEXITY,
@ -98,35 +102,28 @@ impl LateLintPass for CyclomaticComplexity {
}
}
struct MatchArmCounter(u64);
struct CCHelper<'a, 'tcx: 'a> {
match_arms: u64,
divergence: u64,
tcx: &'a ty::TyCtxt<'tcx>,
}
impl<'a> Visitor<'a> for MatchArmCounter {
impl<'a, 'b, 'tcx> Visitor<'a> for CCHelper<'b, 'tcx> {
fn visit_expr(&mut self, e: &'a Expr) {
match e.node {
ExprMatch(_, ref arms, _) => {
walk_expr(self, e);
let arms_n: u64 = arms.iter().map(|arm| arm.pats.len() as u64).sum();
if arms_n > 1 {
self.0 += arms_n - 2;
self.match_arms += arms_n - 2;
}
}
ExprClosure(..) => {}
_ => walk_expr(self, e),
}
}
}
struct DivergenceCounter<'a, 'tcx: 'a>(u64, &'a ty::TyCtxt<'tcx>);
impl<'a, 'b, 'tcx> Visitor<'a> for DivergenceCounter<'b, 'tcx> {
fn visit_expr(&mut self, e: &'a Expr) {
match e.node {
ExprCall(ref callee, _) => {
walk_expr(self, e);
let ty = self.1.node_id_to_type(callee.id);
let ty = self.tcx.node_id_to_type(callee.id);
if let ty::TyBareFn(_, ty) = ty.sty {
if ty.sig.skip_binder().output.diverges() {
self.0 += 1;
self.divergence += 1;
}
}
}