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use super::Context;
use super::LintRule;
use swc_ecmascript::ast::{ArrowExpr, Expr, Function, Pat, VarDecl};
use swc_ecmascript::visit::noop_visit_type;
use swc_ecmascript::visit::Node;
use swc_ecmascript::visit::Visit;
pub struct NoThisAlias;
impl LintRule for NoThisAlias {
fn new() -> Box<Self> {
Box::new(NoThisAlias)
}
fn tags(&self) -> &[&'static str] {
&["recommended"]
}
fn code(&self) -> &'static str {
"no-this-alias"
}
fn lint_module(
&self,
context: &mut Context,
module: &swc_ecmascript::ast::Module,
) {
let mut visitor = NoThisAliasVisitor::new(context);
visitor.visit_module(module, module);
}
}
struct NoThisAliasVisitor<'c> {
context: &'c mut Context,
}
impl<'c> NoThisAliasVisitor<'c> {
fn new(context: &'c mut Context) -> Self {
Self { context }
}
}
impl<'c> Visit for NoThisAliasVisitor<'c> {
noop_visit_type!();
fn visit_var_decl(&mut self, var_decl: &VarDecl, _parent: &dyn Node) {
for decl in &var_decl.decls {
if let Some(init) = &decl.init {
if let Expr::Arrow(arrow) = &**init {
self.visit_arrow_expr(&arrow, _parent);
} else if let Expr::This(_) = &**init {
if let Pat::Ident(_ident) = &decl.name {
self.context.add_diagnostic(
var_decl.span,
"no-this-alias",
"assign `this` to declare a value is not allowed",
);
}
}
}
}
}
fn visit_arrow_expr(&mut self, arrow_expr: &ArrowExpr, _parent: &dyn Node) {
self.visit_block_stmt_or_expr(&arrow_expr.body, _parent);
}
fn visit_expr_stmt(
&mut self,
expr: &swc_ecmascript::ast::ExprStmt,
_parent: &dyn Node,
) {
if let Expr::Arrow(arrow) = &*expr.expr {
self.visit_arrow_expr(arrow, _parent);
}
}
fn visit_function(&mut self, function: &Function, _parent: &dyn Node) {
if let Some(stmt) = &function.body {
self.visit_block_stmt(stmt, _parent);
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::test_util::*;
#[test]
fn no_this_alias_valid() {
assert_lint_ok::<NoThisAlias>("const self = foo(this);");
assert_lint_ok::<NoThisAlias>("const self = 'this';");
assert_lint_ok::<NoThisAlias>("const { props, state } = this;");
assert_lint_ok::<NoThisAlias>("const [foo] = this;");
}
#[test]
fn no_this_alias_invalid() {
assert_lint_err::<NoThisAlias>("const self = this;", 0);
assert_lint_err_on_line_n::<NoThisAlias>(
"
var unscoped = this;
function testFunction() {
let inFunction = this;
}
const testLambda = () => {
const inLambda = this;
};",
vec![(2, 0), (5, 2), (9, 2)],
);
assert_lint_err_on_line_n::<NoThisAlias>(
"
class TestClass {
constructor() {
const inConstructor = this;
const asThis: this = this;
const asString = 'this';
const asArray = [this];
const asArrayString = ['this'];
}
public act(scope: this = this) {
const inMemberFunction = this;
}
}",
vec![(4, 4), (5, 4), (13, 4)],
);
}
}