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use super::Context;
use super::LintRule;
use swc_ecmascript::ast::ClassMethod;
use swc_ecmascript::ast::FnDecl;
use swc_ecmascript::ast::FnExpr;
use swc_ecmascript::ast::Function;
use swc_ecmascript::ast::MethodProp;
use swc_ecmascript::ast::PrivateMethod;
use swc_ecmascript::ast::YieldExpr;
use swc_ecmascript::visit::noop_visit_type;
use swc_ecmascript::visit::Node;
use swc_ecmascript::visit::Visit;
use std::sync::Arc;
pub struct RequireYield;
impl LintRule for RequireYield {
fn new() -> Box<Self> {
Box::new(RequireYield)
}
fn code(&self) -> &'static str {
"require-yield"
}
fn lint_module(
&self,
context: Arc<Context>,
module: &swc_ecmascript::ast::Module,
) {
let mut visitor = RequireYieldVisitor::new(context);
visitor.visit_module(module, module);
}
}
struct RequireYieldVisitor {
context: Arc<Context>,
yield_stack: Vec<u32>,
}
impl RequireYieldVisitor {
pub fn new(context: Arc<Context>) -> Self {
Self {
context,
yield_stack: vec![],
}
}
fn enter_function(&mut self, function: &Function) {
if function.is_generator {
self.yield_stack.push(0);
}
}
fn exit_function(&mut self, function: &Function) {
if function.is_generator {
let yield_count = self.yield_stack.pop().unwrap();
if let Some(body) = &function.body {
if !body.stmts.is_empty() && yield_count == 0 {
self.context.add_diagnostic(
function.span,
"require-yield",
"Generator function has no `yield`",
);
}
}
}
}
}
impl Visit for RequireYieldVisitor {
noop_visit_type!();
fn visit_yield_expr(&mut self, _yield_expr: &YieldExpr, _parent: &dyn Node) {
if let Some(last) = self.yield_stack.last_mut() {
*last += 1;
}
}
fn visit_fn_decl(&mut self, fn_decl: &FnDecl, parent: &dyn Node) {
self.enter_function(&fn_decl.function);
swc_ecmascript::visit::visit_fn_decl(self, fn_decl, parent);
self.exit_function(&fn_decl.function);
}
fn visit_fn_expr(&mut self, fn_expr: &FnExpr, parent: &dyn Node) {
self.enter_function(&fn_expr.function);
swc_ecmascript::visit::visit_fn_expr(self, fn_expr, parent);
self.exit_function(&fn_expr.function);
}
fn visit_class_method(
&mut self,
class_method: &ClassMethod,
parent: &dyn Node,
) {
self.enter_function(&class_method.function);
swc_ecmascript::visit::visit_class_method(self, class_method, parent);
self.exit_function(&class_method.function);
}
fn visit_private_method(
&mut self,
private_method: &PrivateMethod,
parent: &dyn Node,
) {
self.enter_function(&private_method.function);
swc_ecmascript::visit::visit_private_method(self, private_method, parent);
self.exit_function(&private_method.function);
}
fn visit_method_prop(&mut self, method_prop: &MethodProp, parent: &dyn Node) {
self.enter_function(&method_prop.function);
swc_ecmascript::visit::visit_method_prop(self, method_prop, parent);
self.exit_function(&method_prop.function);
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::test_util::*;
#[test]
fn require_yield_ok() {
assert_lint_ok::<RequireYield>(
r#"
function foo() {}
function* bar() {
yield "bar";
}
function* emptyBar() {}
class Fizz {
*fizz() {
yield "fizz";
}
*#buzz() {
yield "buzz";
}
}
const obj = {
*foo() {
yield "foo";
}
};
"#,
);
}
#[test]
fn require_yield() {
assert_lint_err::<RequireYield>(r#"function* bar() { return "bar"; }"#, 0);
assert_lint_err::<RequireYield>(
r#"(function* foo() { return "foo"; })();"#,
1,
);
assert_lint_err::<RequireYield>(
r#"function* nested() { function* gen() { yield "gen"; } }"#,
0,
);
assert_lint_err_on_line_n::<RequireYield>(
r#"
class Fizz {
*fizz() {
return "fizz";
}
*#buzz() {
return "buzz";
}
}
"#,
vec![(3, 2), (7, 2)],
);
assert_lint_err::<RequireYield>(
r#"const obj = { *foo() { return "foo"; } };"#,
14,
);
}
}