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//! `Cognitive` implementation for Elixir.
#![allow(
clippy::enum_glob_use,
clippy::match_same_arms,
clippy::needless_pass_by_value,
clippy::wildcard_imports
)]
#![allow(
clippy::cast_precision_loss,
clippy::cast_possible_truncation,
clippy::cast_sign_loss
)]
use super::*;
use crate::lang_helpers::elixir::{
elixir_applying_remote_call, elixir_short_circuit_kind, elixir_short_circuit_name,
};
use crate::metrics::elixir_decisions::{elixir_pair_section, elixir_receive_dispatches};
/// Whether a Call spelling `keyword` takes `try`'s sections — `else`,
/// `rescue`, `catch` — in its keyword form: `try` itself, and the
/// method-defining macros, whose body is an implicit `try`
/// (`def f, do: g(), rescue: (e -> e)`).
fn elixir_takes_try_sections(keyword: &str) -> bool {
keyword == "try" || elixir_is_method_macro(keyword)
}
/// The cost a keyword-form section carries, matching its block form.
enum ElixirSection {
/// `else:`, which adds +1 as the `Else` token does.
Else,
/// `rescue:` / `catch:`, which add +nesting as `RescueBlock` /
/// `CatchBlock` do.
Handler,
}
/// The section `pair` spells, when its Call takes it (#1574). Only such
/// a Call scores it, because `else:` is an ordinary option name to any
/// other function; a `with`'s `else:` is that construct's clause
/// dispatch, which its own +nesting already paid.
fn elixir_section<'a>(
pair: &Node<'a>,
code: &'a [u8],
ancestors: Ancestors<'a, '_>,
) -> Option<ElixirSection> {
let (key, call) = elixir_pair_section(pair, code, ancestors)?;
let keyword = elixir_call_keyword(&call, code)?;
match key {
"else" if matches!(keyword, "if" | "unless") || elixir_takes_try_sections(keyword) => {
Some(ElixirSection::Else)
}
"rescue" | "catch" if elixir_takes_try_sections(keyword) => Some(ElixirSection::Handler),
_ => None,
}
}
/// Folds an Elixir `BinaryOperator`'s short-circuit operator children
/// into the boolean-sequence counter — Elixir has four (`&&`, `||`,
/// `and`, `or`). Each word form is keyed to its symbol (see
/// [`compute_booleans_keyed`] and [`elixir_short_circuit_kind`]).
fn compute_elixir_booleans(node: &Node, stats: &mut Stats) {
compute_booleans_keyed(node, stats, |id| {
elixir_short_circuit_kind(id).map(|key| key as u16)
});
}
/// [`compute_elixir_booleans`] for a short-circuit `Kernel` remote call
/// (`Kernel.||(a, b)`, `Kernel.or(a, b)`), whose operator sits in the
/// call's name rather than among a `binary_operator`'s children. The
/// sequence is keyed on the call's span, as a `binary_operator`'s is on
/// its own, and on the same symbol, so `a or Kernel.||(b, c)` is one run.
fn compute_elixir_remote_booleans<'a>(
op: &Node<'a>,
code: &'a [u8],
ancestors: Ancestors<'a, '_>,
stats: &mut Stats,
) {
if let Some(remote) = elixir_applying_remote_call(op, code, ancestors)
&& let Some(key) = elixir_short_circuit_name(op, code)
{
stats.structural = stats.boolean_seq.eval_based_on_prev(
key as u16,
remote.call.end_byte(),
stats.structural,
);
}
}
impl Cognitive for ElixirCode {
// Elixir control flow is macro-shaped: `if`, `unless`, `case`,
// `cond`, `with`, `receive`, `for`, `while`, and `try` each surface as a
// `Call` node whose `target` Identifier text spells the keyword.
// We classify the Call once on entry (raising nesting), then let
// the structural `Else` token and `Rescue` / `Catch` blocks inside
// the do_block contribute their own cost without double-counting.
//
// Mapping (mirrors the Java/Kotlin SonarSource interpretation for
// switch-like constructs):
// - `if` / `unless` / `for` / `while`: single-branch control flow,
// `+nesting`. Their `else` (token `Elixir::Else` inside an
// `ElseBlock`) adds `+1` without nesting, matching Java.
// - `case` / `cond` / `with` / `receive`: switch-/multi-arm,
// `+nesting` once on the container. Individual `stab_clause` arms
// do NOT add extra cost (matches Java `SwitchBlock` / `case:`
// rule).
// - `try`: `+0` on the container itself — it is a wrapper, and its
// `rescue` / `catch` arms surface as `RescueBlock` / `CatchBlock`
// and each one adds `+nesting`, matching Java's `CatchClause`
// treatment. See the arm comment below.
// - `def` / `defp` / `defmacro` / `defmacrop`: method-defining
// macros. Nesting resets at the boundary, as in Bash's
// `FunctionDefinition` rule, but the function depth deliberately
// does NOT bump — see the arm comment below for why.
// - `AnonymousFunction` (`fn x -> y end`): lambda nesting bumps.
// - `&&` / `||` / `and` / `or`: boolean sequence cost, as is a
// `Kernel.&&` / `Kernel.||` / `Kernel.and` / `Kernel.or` remote
// call.
//
// Limitations:
// - `Enum.reduce` / `Enum.map` and friends are higher-order function
// calls (`RemoteCallWithParentheses`), not syntactic control flow.
// Cognitive complexity per the SonarSource spec does NOT count
// function calls; we follow suit.
// - Recursion detection is intentionally omitted. The SonarSource
// spec scores recursion at +1, but reliably detecting recursion
// needs symbol-table awareness (the body of `def foo do foo() end`
// must compare names) which is out of scope for this fix. See
// the issue body's explicit "skip if too complex" guidance.
fn compute<'a>(
node: &Node<'a>,
code: &'a [u8],
ancestors: Ancestors<'a, '_>,
stats: &mut Stats,
nesting_map: &mut NestingMap,
) {
// bca: suppress(cyclomatic, halstead) — kind dispatch table; each gated arm is one rule
use Elixir as E;
let mut nesting = get_nesting_from_map(node, nesting_map);
match node.kind_id().into() {
E::Call => match elixir_call_keyword(node, code) {
Some("if" | "unless" | "for" | "while" | "case" | "cond" | "with") => {
increase_nesting(stats, &mut nesting);
}
// A `case` over the mailbox, paying as one (#1581) when
// it has message clauses; one holding only an `after`
// timeout is a timed wait, the idiomatic sleep, and
// branches on nothing. The `after` adds nothing either
// way: like `case`, the container pays and its arms do
// not, a timeout beside a bare `_ ->` included.
Some("receive") if elixir_receive_dispatches(node, code) => {
increase_nesting(stats, &mut nesting);
}
// `try` is intentionally absent: it is a wrapper for
// `rescue` / `catch` arms (each of which earns its own
// +nesting via `RescueBlock` / `CatchBlock`). Adding the
// `try` itself would double-count, matching Java /
// C#'s "try is a wrapper, only catch counts" rule.
Some(kw) if elixir_is_method_macro(kw) => {
// Method-defining macros reset nesting at the
// function boundary, mirroring Bash's
// `FunctionDefinition` rule. We deliberately do
// NOT call `increment_function_depth` here: that
// helper matches `Call` ancestors by `kind_id`
// alone, and EVERY `def` inside a `defmodule` has
// a `Call` ancestor (the defmodule Call) which
// would falsely raise the function depth. Elixir
// does not allow `def` nested inside another
// `def` (defs only live at module top level), so
// truly nested method definitions are not a
// concern — the lambda channel via
// `AnonymousFunction` handles the analogous
// higher-order case. Elixir is therefore the one
// language that takes the resets without the depth
// bump, so it resets inline instead of calling the
// shared `enter_function_boundary` the other
// eighteen modules use (#1103).
//
// Both channels, not just the conditional one. `def`
// inside `fn` is invalid Elixir but the grammar
// parses it, and skipping the lambda reset here is
// exactly the accidental opt-out that #1187 moved
// the line into the shared helper to prevent — so
// the one language that cannot use the helper has to
// stay in step by hand.
nesting.conditional = 0;
nesting.lambda = 0;
}
_ => {}
},
// `else` keyword inside an `else_block` (else arm of `if`
// / `unless` / `try`). Matches Java/Kotlin's `Else` rule: +1
// without raising nesting.
//
// Not a `with`'s: its `else` holds the clauses that dispatch
// over the value a `<-` failed to match, the arms of the
// `case` the construct is in all but spelling, and `case`'s
// arms add nothing past the +nesting its container paid.
// Ruby draws the same line for the `else` of `case/when`
// (#451); the `if` alternative and `try`'s no-exception
// branch, which no container paid for, keep their +1. The
// keyword form `with(…, do: …, else: (…))` scored 1 all
// along; this puts the block form level with it (#1574).
// The `else` token's parents are the `else_block`, then the
// `do_block`, then the Call.
E::Else
if ancestors
.iter(node)
.nth(2)
.is_none_or(|(call, _)| elixir_call_keyword(&call, code) != Some("with")) =>
{
increment_by_one(stats);
}
// The keyword spellings of the sections above, for the
// owners `elixir_section` names: `if(c, do: 1, else: 2)`,
// `try(do: f(), rescue: (…))`, bare or in brackets. A user
// macro's `foo(do: 1, else: 2)` scores nothing here while
// its `foo do 1 else 2 end` scores the `Else` arm above.
E::Pair => match elixir_section(node, code, ancestors) {
Some(ElixirSection::Else) => increment_by_one(stats),
Some(ElixirSection::Handler) => increase_nesting(stats, &mut nesting),
None => {}
},
// `rescue` / `catch` arms of a `try` Call each add +nesting,
// matching Java's `CatchClause` treatment.
E::RescueBlock | E::CatchBlock => {
increase_nesting(stats, &mut nesting);
}
// Anonymous functions are Elixir's lambdas. Increment the
// lambda depth so the cost of control flow inside them is
// amplified, matching Kotlin's `LambdaLiteral` rule.
E::AnonymousFunction => {
nesting.lambda += 1;
}
// Short-circuit booleans (token-form `&&` / `||` and word-
// form `and` / `or`) contribute one structural cost per
// operator sequence. Single-pass helper (see
// `compute_elixir_booleans`) collapses the four operator
// kinds in one walk of `node.children()` — the previous
// shape called `compute_booleans` twice, walking children
// twice per BinaryOperator.
E::BinaryOperator | E::BinaryOperator2 | E::BinaryOperator3 => {
compute_elixir_booleans(node, stats);
}
// A short-circuit `Kernel` remote call applies the operator
// as `a || b` does, so it opens or continues a sequence the
// same way (#1574), keyed on the call's span as a
// `binary_operator`'s operator is keyed on the operator's.
// `Foo.||(a, b)` is an ordinary call and is not matched; the
// token inside a `binary_operator` is the arm above's.
// `Kernel.and` / `Kernel.or` name the operator with an
// `identifier` instead of a token (#1582).
E::AMPAMP | E::PIPEPIPE | E::Identifier => {
compute_elixir_remote_booleans(node, code, ancestors, stats);
}
_ => {}
}
nesting_map.insert(node.id(), nesting);
}
}