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use super::{Context, LintRule};
use swc_common::Span;
use swc_ecmascript::ast::Expr;
use swc_ecmascript::ast::Expr::{Assign, Bin, Paren};
use swc_ecmascript::ast::Module;
use swc_ecmascript::visit::{noop_visit_type, Node, Visit};
use std::sync::Arc;
pub struct NoCondAssign;
impl LintRule for NoCondAssign {
fn new() -> Box<Self> {
Box::new(NoCondAssign)
}
fn code(&self) -> &'static str {
"no-cond-assign"
}
fn lint_module(&self, context: Arc<Context>, module: &Module) {
let mut visitor = NoCondAssignVisitor::new(context);
visitor.visit_module(module, module);
}
}
struct NoCondAssignVisitor {
context: Arc<Context>,
}
impl NoCondAssignVisitor {
pub fn new(context: Arc<Context>) -> Self {
Self { context }
}
fn add_diagnostic(&self, span: Span) {
self.context.add_diagnostic(
span,
"no-cond-assign",
"Expected a conditional expression and instead saw an assignment",
);
}
fn check_condition(&self, condition: &Expr) {
match condition {
Assign(assign) => {
self.add_diagnostic(assign.span);
}
Bin(bin) => {
if bin.op == swc_ecmascript::ast::BinaryOp::LogicalOr {
self.check_condition(&bin.left);
self.check_condition(&bin.right);
}
}
_ => {}
}
}
}
impl Visit for NoCondAssignVisitor {
noop_visit_type!();
fn visit_if_stmt(
&mut self,
if_stmt: &swc_ecmascript::ast::IfStmt,
_parent: &dyn Node,
) {
self.check_condition(&if_stmt.test);
}
fn visit_while_stmt(
&mut self,
while_stmt: &swc_ecmascript::ast::WhileStmt,
_parent: &dyn Node,
) {
self.check_condition(&while_stmt.test);
}
fn visit_do_while_stmt(
&mut self,
do_while_stmt: &swc_ecmascript::ast::DoWhileStmt,
_parent: &dyn Node,
) {
self.check_condition(&do_while_stmt.test);
}
fn visit_for_stmt(
&mut self,
for_stmt: &swc_ecmascript::ast::ForStmt,
_parent: &dyn Node,
) {
if let Some(for_test) = &for_stmt.test {
self.check_condition(&for_test);
}
}
fn visit_cond_expr(
&mut self,
cond_expr: &swc_ecmascript::ast::CondExpr,
_parent: &dyn Node,
) {
if let Paren(paren) = &*cond_expr.test {
self.check_condition(&paren.expr);
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::test_util::*;
#[test]
fn it_passes_using_equality_operator() {
assert_lint_ok::<NoCondAssign>("if (x === 0) { };");
}
#[test]
fn it_passes_with_bracketed_assignment() {
assert_lint_ok::<NoCondAssign>("if ((x = y)) { }");
}
#[test]
fn it_fails_using_assignment_in_if_stmt() {
assert_lint_err::<NoCondAssign>("if (x = 0) { }", 4);
}
#[test]
fn it_fails_using_assignment_in_while_stmt() {
assert_lint_err::<NoCondAssign>("while (x = 0) { }", 7);
}
#[test]
fn it_fails_using_assignment_in_do_while_stmt() {
assert_lint_err::<NoCondAssign>("do { } while (x = 0);", 14);
}
#[test]
fn it_fails_using_assignment_in_for_stmt() {
assert_lint_err::<NoCondAssign>("for (let i = 0; i = 10; i++) { }", 16);
}
#[test]
fn no_cond_assign_valid() {
assert_lint_ok::<NoCondAssign>("const x = 0; if (x == 0) { const b = 1; }");
assert_lint_ok::<NoCondAssign>("const x = 5; while (x < 5) { x = x + 1; }");
assert_lint_ok::<NoCondAssign>("while ((a = b));");
assert_lint_ok::<NoCondAssign>("do {} while ((a = b));");
assert_lint_ok::<NoCondAssign>("for (;(a = b););");
assert_lint_ok::<NoCondAssign>("for (;;) {}");
assert_lint_ok::<NoCondAssign>(
"if (someNode || (someNode = parentNode)) { }",
);
assert_lint_ok::<NoCondAssign>(
"while (someNode || (someNode = parentNode)) { }",
);
assert_lint_ok::<NoCondAssign>(
"do { } while (someNode || (someNode = parentNode));",
);
assert_lint_ok::<NoCondAssign>(
"for (;someNode || (someNode = parentNode););",
);
assert_lint_ok::<NoCondAssign>(
"if ((function(node) { return node = parentNode; })(someNode)) { }",
);
assert_lint_ok::<NoCondAssign>(
"if ((node => node = parentNode)(someNode)) { }",
);
assert_lint_ok::<NoCondAssign>(
"if (function(node) { return node = parentNode; }) { }",
);
assert_lint_ok::<NoCondAssign>("const x; const b = (x === 0) ? 1 : 0;");
assert_lint_ok::<NoCondAssign>("switch (foo) { case a = b: bar(); }");
}
#[test]
fn no_cond_assign_invalid() {
assert_lint_err::<NoCondAssign>("const x; if (x = 0) { const b = 1; }", 13);
assert_lint_err::<NoCondAssign>(
"const x; while (x = 0) { const b = 1; }",
16,
);
assert_lint_err::<NoCondAssign>(
"const x = 0, y; do { y = x; } while (x = x + 1);",
37,
);
assert_lint_err::<NoCondAssign>("let x; for(; x+=1 ;){};", 13);
assert_lint_err::<NoCondAssign>("let x; if ((x) = (0));", 11);
assert_lint_err::<NoCondAssign>("let x; let b = (x = 0) ? 1 : 0;", 16);
assert_lint_err::<NoCondAssign>(
"(((123.45)).abcd = 54321) ? foo : bar;",
1,
);
}
}