feat(rome_js_analyze): useExponentiationOperator rule (#3848)

Co-authored-by: Micha Reiser <[email protected]>

crates/rome_diagnostics_categories/src/categories.rs

@@ -100,6 +100,7 @@ define_dategories! {
     "lint/nursery/useDefaultSwitchClauseLast":"https://docs.rome.tools/lint/rules/useDefaultSwitchClauseLast",
     "lint/nursery/useEnumInitializers":"https://docs.rome.tools/lint/rules/useEnumInitializers",
     "lint/nursery/useExhaustiveDependencies": "https://docs.rome.tools/lint/rules/useExhaustiveDependencies",
+    "lint/nursery/useExponentiationOperator": "https://docs.rome.tools/lint/rules/useExponentiationOperator",
     "lint/nursery/useFlatMap": "https://docs.rome.tools/lint/rules/useFlatMap",
     "lint/nursery/useNumericLiterals": "https://docs.rome.tools/lint/rules/useNumericLiterals",
     "lint/nursery/useValidForDirection": "https://docs.rome.tools/lint/rules/useValidForDirection",

crates/rome_js_analyze/src/analyzers/nursery/use_exponentiation_operator.rs

@@ -0,0 +1,316 @@
+use crate::semantic_services::Semantic;
+use crate::JsRuleAction;
+use rome_analyze::context::RuleContext;
+use rome_analyze::{declare_rule, ActionCategory, Rule, RuleDiagnostic};
+use rome_console::markup;
+use rome_diagnostics::Applicability;
+use rome_js_factory::{make, syntax::T};
+use rome_js_syntax::{
+    AnyJsExpression, JsBinaryOperator, JsCallExpression, JsClassDeclaration, JsClassExpression,
+    JsExtendsClause, JsInExpression, OperatorPrecedence,
+};
+use rome_rowan::{AstNode, AstSeparatedList, BatchMutationExt};
+
+declare_rule! {
+    /// Disallow the use of `Math.pow` in favor of the `**` operator.
+    ///
+    /// > Introduced in ES2016, the infix exponentiation operator ** is an alternative for the standard Math.pow function.
+    /// > Infix notation is considered to be more readable and thus more preferable than the function notation.
+    ///
+    /// Source: https://eslint.org/docs/latest/rules/prefer-exponentiation-operator
+    ///
+    /// ## Examples
+    ///
+    /// ### Invalid
+    ///
+    /// ```js,expect_diagnostic
+    /// const foo = Math.pow(2, 8);
+    /// ```
+    ///
+    /// ```js,expect_diagnostic
+    /// const bar = Math.pow(a, b);
+    /// ```
+    ///
+    /// ```js,expect_diagnostic
+    /// let baz = Math.pow(a + b, c + d);
+    /// ```
+    ///
+    /// ```js,expect_diagnostic
+    /// let quux = Math.pow(-1, n);
+    /// ```
+    ///
+    /// ### Valid
+    ///
+    /// ```js
+    /// const foo = 2 ** 8;
+    ///
+    /// const bar = a ** b;
+    ///
+    /// let baz = (a + b) ** (c + d);
+    ///
+    /// let quux = (-1) ** n;
+    /// ```
+    ///
+    pub(crate) UseExponentiationOperator {
+        version: "11.0.0",
+        name: "useExponentiationOperator",
+        recommended: false,
+    }
+}
+
+pub struct MathPowCall {
+    base: AnyJsExpression,
+    exponent: AnyJsExpression,
+}
+
+impl MathPowCall {
+    fn make_base(&self) -> Option<AnyJsExpression> {
+        Some(if self.does_base_need_parens()? {
+            parenthesize_any_js_expression(&self.base)
+        } else {
+            self.base.clone()
+        })
+    }
+
+    fn make_exponent(&self) -> Option<AnyJsExpression> {
+        Some(if self.does_exponent_need_parens()? {
+            parenthesize_any_js_expression(&self.exponent)
+        } else {
+            self.exponent.clone()
+        })
+    }
+
+    /// Determines whether the base expression needs parens in an exponentiation binary expression.
+    fn does_base_need_parens(&self) -> Option<bool> {
+        Some(
+            // '**' is right-associative, parens are needed when Math.pow(a ** b, c) is converted to (a ** b) ** c
+            self.base.precedence().ok()? <= OperatorPrecedence::Exponential
+				// An unary operator cannot be used immediately before an exponentiation expression
+				|| self.base.as_js_unary_expression().is_some()
+				|| self.base.as_js_await_expression().is_some(),
+        )
+    }
+
+    /// Determines whether the exponent expression needs parens in an exponentiation binary expression.
+    fn does_exponent_need_parens(&self) -> Option<bool> {
+        Some(self.exponent.precedence().ok()? < OperatorPrecedence::Exponential)
+    }
+}
+
+impl Rule for UseExponentiationOperator {
+    type Query = Semantic<JsCallExpression>;
+    type State = ();
+    type Signals = Option<Self::State>;
+    type Options = ();
+
+    fn run(ctx: &RuleContext<Self>) -> Self::Signals {
+        let node = ctx.query();
+        let model = ctx.model();
+
+        let object = match node.callee().ok()?.omit_parentheses() {
+            AnyJsExpression::JsStaticMemberExpression(static_member_expr) => {
+                if static_member_expr
+                    .member()
+                    .ok()?
+                    .as_js_name()?
+                    .value_token()
+                    .ok()?
+                    .token_text_trimmed()
+                    != "pow"
+                {
+                    return None;
+                }
+
+                static_member_expr.object()
+            }
+            AnyJsExpression::JsComputedMemberExpression(computed_member_expr) => {
+                if !computed_member_expr
+                    .member()
+                    .ok()?
+                    .is_string_constant("pow")
+                {
+                    return None;
+                }
+
+                computed_member_expr.object()
+            }
+            _ => return None,
+        };
+
+        let reference = object.ok()?.omit_parentheses().as_reference_identifier()?;
+
+        // verifies that the Math reference is not a local variable
+        let has_math_pow = reference.has_name("Math") && model.binding(&reference).is_none();
+        has_math_pow.then_some(())
+    }
+
+    fn diagnostic(ctx: &RuleContext<Self>, _: &Self::State) -> Option<RuleDiagnostic> {
+        let diagnostic = RuleDiagnostic::new(
+            rule_category!(),
+            ctx.query().range(),
+            "Use the '**' operator instead of 'Math.pow'.",
+        );
+
+        Some(diagnostic)
+    }
+
+    fn action(ctx: &RuleContext<Self>, _: &Self::State) -> Option<JsRuleAction> {
+        let node = ctx.query();
+
+        if !should_suggest_fix(node)? {
+            return None;
+        }
+
+        let mut mutation = ctx.root().begin();
+        let [base, exponent] = node.get_arguments_by_index([0, 1]);
+
+        let math_pow_call = MathPowCall {
+            base: base?.as_any_js_expression()?.clone().omit_parentheses(),
+            exponent: exponent?.as_any_js_expression()?.clone().omit_parentheses(),
+        };
+
+        let new_node = make::js_binary_expression(
+            math_pow_call.make_base()?,
+            make::token(T![**]),
+            math_pow_call.make_exponent()?,
+        );
+
+        if let Some((needs_parens, parent)) = does_exponentiation_expression_need_parens(node) {
+            if needs_parens && parent.is_some() {
+                mutation.replace_node(parent.clone()?, parenthesize_any_js_expression(&parent?));
+            }
+
+            mutation.replace_node(
+                AnyJsExpression::from(node.clone()),
+                parenthesize_any_js_expression(&AnyJsExpression::from(new_node)),
+            );
+        } else {
+            mutation.replace_node(
+                AnyJsExpression::from(node.clone()),
+                AnyJsExpression::from(new_node),
+            );
+        }
+
+        Some(JsRuleAction {
+            category: ActionCategory::QuickFix,
+            applicability: Applicability::MaybeIncorrect,
+            message: markup! { "Use the '**' operator instead of 'Math.pow'." }.to_owned(),
+            mutation,
+        })
+    }
+}
+
+/// Verify if the autofix is safe to be applied and won't remove comments.
+/// Argument list is considered valid if there's no spread arg and leading/trailing comments.
+fn should_suggest_fix(node: &JsCallExpression) -> Option<bool> {
+    let arguments = node.arguments().ok()?;
+    let args_count = arguments.args().len();
+
+    Some(
+        args_count == 2
+            && !arguments.l_paren_token().ok()?.has_leading_comments()
+            && !arguments.l_paren_token().ok()?.has_trailing_comments()
+            && !arguments.r_paren_token().ok()?.has_leading_comments()
+            && !arguments.r_paren_token().ok()?.has_trailing_comments()
+            && arguments.args().into_iter().flatten().all(|arg| {
+                !arg.syntax().has_leading_comments()
+                    && !arg.syntax().has_trailing_comments()
+                    && arg.as_js_spread().is_none()
+            }),
+    )
+}
+
+/// Wraps a [AnyJsExpression] in paretheses
+fn parenthesize_any_js_expression(expr: &AnyJsExpression) -> AnyJsExpression {
+    AnyJsExpression::from(make::js_parenthesized_expression(
+        make::token(T!['(']),
+        expr.clone(),
+        make::token(T![')']),
+    ))
+}
+
+/// Determines whether the given parent node needs parens if used as the exponent in an exponentiation binary expression.
+fn does_exponentiation_expression_need_parens(
+    node: &JsCallExpression,
+) -> Option<(bool, Option<AnyJsExpression>)> {
+    if let Some(parent) = node.parent::<AnyJsExpression>() {
+        if does_expression_need_parens(node, &parent)? {
+            return Some((true, Some(parent)));
+        }
+    } else if let Some(extends_clause) = node.parent::<JsExtendsClause>() {
+        if extends_clause.parent::<JsClassDeclaration>().is_some() {
+            return Some((true, None));
+        }
+
+        if let Some(class_expr) = extends_clause.parent::<JsClassExpression>() {
+            let class_expr = AnyJsExpression::from(class_expr);
+            if does_expression_need_parens(node, &class_expr)? {
+                return Some((true, Some(class_expr)));
+            }
+        }
+    }
+
+    None
+}
+
+/// Determines whether the given expression needs parens when used in an exponentiation binary expression.
+fn does_expression_need_parens(
+    node: &JsCallExpression,
+    expression: &AnyJsExpression,
+) -> Option<bool> {
+    let needs_parentheses = match &expression {
+        // Skips already parenthesized expressions
+        AnyJsExpression::JsParenthesizedExpression(_) => return None,
+        AnyJsExpression::JsBinaryExpression(bin_expr) => {
+            if bin_expr.parent::<JsInExpression>().is_some() {
+                return Some(true);
+            }
+
+            let binding = bin_expr.right().ok()?;
+            let call_expr = binding.as_js_call_expression();
+
+            bin_expr.operator().ok()? != JsBinaryOperator::Exponent
+                || call_expr.is_none()
+                || call_expr? != node
+        }
+        AnyJsExpression::JsCallExpression(call_expr) => !call_expr
+            .arguments()
+            .ok()?
+            .args()
+            .iter()
+            .filter_map(|arg| {
+                let binding = arg.ok()?;
+                return binding
+                    .as_any_js_expression()?
+                    .as_js_call_expression()
+                    .cloned();
+            })
+            .any(|arg| &arg == node),
+        AnyJsExpression::JsNewExpression(new_expr) => !new_expr
+            .arguments()?
+            .args()
+            .iter()
+            .filter_map(|arg| {
+                let binding = arg.ok()?;
+                return binding
+                    .as_any_js_expression()?
+                    .as_js_call_expression()
+                    .cloned();
+            })
+            .any(|arg| &arg == node),
+        AnyJsExpression::JsComputedMemberExpression(member_expr) => {
+            let binding = member_expr.member().ok()?;
+            let call_expr = binding.as_js_call_expression();
+
+            call_expr.is_none() || call_expr? != node
+        }
+        AnyJsExpression::JsInExpression(_) => return Some(true),
+        AnyJsExpression::JsClassExpression(_)
+        | AnyJsExpression::JsStaticMemberExpression(_)
+        | AnyJsExpression::JsUnaryExpression(_)
+        | AnyJsExpression::JsTemplateExpression(_) => true,
+        _ => false,
+    };
+
+    Some(needs_parentheses && expression.precedence().ok()? >= OperatorPrecedence::Exponential)
+}

crates/rome_js_analyze/tests/specs/nursery/useExponentiationOperator/invalid.js

@@ -0,0 +1,60 @@
+Math.pow(a, b);
+(Math).pow(a, b);
+
+// able to catch some workarounds
+Math[`pow`](a, b);
+(Math)['pow'](a, b);
+(Math)["pow"](a, b);
+(Math)[`pow`](a, b);
+
+// non-expression parents that don't require parens
+var x = Math.pow(a, b);
+if(Math.pow(a, b)){}
+for(;Math.pow(a, b);){}
+switch(foo){ case Math.pow(a, b): break; }
+{ foo: Math.pow(a, b) }
+function foo(bar, baz = Math.pow(a, b), quux){}
+`${Math.pow(a, b)}`
+
+// non-expression parents that do require parens
+class C extends Math.pow(a, b) {}
+
+// already parenthesised, shouldn't insert extra parens
++(Math.pow(a, b))
+(Math.pow(a, b)).toString()
+(class extends (Math.pow(a, b)) {})
+class C extends (Math.pow(a, b)) {}
+
+// '**' is right-associative, that applies to both parent and child nodes
+a ** Math.pow(b, c);
+Math.pow(a, b) ** c;
+Math.pow(a, b ** c);
+Math.pow(a ** b, c);
+a ** Math.pow(b ** c, d ** e) ** f;
+
+// doesn't remove already existing unnecessary parens around the whole expression
+(Math.pow(a, b));
+foo + (Math.pow(a, b));
+(Math.pow(a, b)) + foo;
+`${(Math.pow(a, b))}`;
+
+// doesn't preserve unnecessary parens around base and exponent
+Math.pow((a), (b))
+Math.pow(((a)), ((b)))
+Math.pow((a.foo), b)
+Math.pow(a, (b.foo))
+Math.pow((a()), b)
+Math.pow(a, (b()))
+
+// Optional chaining
+Math.pow?.(a, b)
+Math?.pow(a, b)
+Math?.pow?.(a, b)
+;(Math?.pow)(a, b)
+;(Math?.pow)?.(a, b)
+
+// doesn't put extra parens
+Math.pow((a + b), (c + d))
+
+// tokens that can be adjacent
+a+Math.pow(b, c)+d