swc-plugin-dev-expression 0.2.11

/* This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option)
 * any later version.

 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.

 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <https://www.gnu.org/licenses/>.
*/

use swc_core::plugin::{plugin_transform, proxies::TransformPluginProgramMetadata};
use swc_core::{
    common::{util::take::Take, DUMMY_SP},
    ecma::{
        ast::{
            op, BinExpr, BlockStmt, CallExpr, CondExpr, Expr, ExprOrSpread, ExprStmt, Ident,
            IfStmt, Lit, MemberExpr, ParenExpr, Program, Stmt, UnaryExpr, UnaryOp,
        },
        transforms::testing::test,
        visit::{as_folder, FoldWith, VisitMut, VisitMutWith},
    },
};

pub struct TransformVisitor;

// Returns the __DEV__ transformation `"production" !== process.env.NODE_ENV`
fn dev_expression() -> Box<Expr> {
    BinExpr {
        span: DUMMY_SP,
        op: op!("!=="),
        left: Lit::Str("production".into()).into(),
        right: MemberExpr {
            span: DUMMY_SP,
            obj: MemberExpr {
                span: DUMMY_SP,
                obj: Ident::new("process".into(), DUMMY_SP).into(),
                prop: Ident::new("env".into(), DUMMY_SP).into(),
            }
            .into(),
            prop: Ident::new("NODE_ENV".into(), DUMMY_SP).into(),
        }
        .into(),
    }
    .into()
}

// Transforms
// `warning(condition, "argument", argument);"`
// into
// `if ("production" !== process.env.NODE_ENV) {
//    warning(condition, "argument", argument);
//  }`
fn wrap_in_if_not_prod(stmt: Stmt, alt: Option<Stmt>) -> Stmt {
    let boxed_alt = alt.map(|s| {
        Box::new(Stmt::from(BlockStmt {
            span: DUMMY_SP,
            stmts: vec![s],
        }))
    });
    Stmt::from(IfStmt {
        span: DUMMY_SP,
        test: dev_expression(),
        cons: Box::new(Stmt::from(BlockStmt {
            span: DUMMY_SP,
            stmts: vec![stmt],
        })),
        alt: boxed_alt,
    })
}

// Transforms
//  `invariant(condition, argument, argument);`
// into
//  `if (!condition) {
//    if ("production" !== process.env.NODE_ENV) {
//      invariant(false, argument, argument);
//    } else {
//      invariant(false);
//    }
//  }`
fn wrap_invariant(invariant: &mut CallExpr) -> Stmt {
    if invariant.args.is_empty() {
        return Stmt::dummy();
    }
    if invariant.args[0].spread.is_some() {
        return Stmt::dummy();
    }
    let condition = match invariant.args.len() {
        0 => return Stmt::dummy(),
        _ => match invariant.args[0].spread {
            Some(_) => return Stmt::dummy(),
            None => invariant.args[0].expr.take(),
        },
    };

    let not_condition = UnaryExpr {
        span: DUMMY_SP,
        op: op!("!"),
        arg: condition,
    };

    let false_expr = ExprOrSpread {
        spread: None,
        expr: false.into(),
    };

    let invariant_no_args = ExprStmt {
        span: DUMMY_SP,
        expr: CallExpr {
            span: DUMMY_SP,
            callee: invariant.callee.clone(),
            args: vec![false_expr.clone()],
            type_args: None,
        }
        .into(),
    }
    .into();

    let mut args = invariant.args.take();
    args[0] = false_expr;
    let invariant_with_args = ExprStmt {
        span: DUMMY_SP,
        expr: CallExpr {
            span: DUMMY_SP,
            callee: invariant.callee.take(),
            args,
            type_args: None,
        }
        .into(),
    }
    .into();

    let inner_if = wrap_in_if_not_prod(invariant_with_args, Some(invariant_no_args));

    Stmt::from(IfStmt {
        span: DUMMY_SP,
        test: not_condition.into(),
        cons: Box::new(Stmt::from(BlockStmt {
            span: DUMMY_SP,
            stmts: vec![inner_if],
        })),
        alt: None,
    })
}

impl VisitMut for TransformVisitor {
    // Visits statements, matching function calls to invariant or warning
    fn visit_mut_stmt(&mut self, stmt: &mut Stmt) {
        stmt.visit_mut_children_with(self);

        let expr_stmt = match stmt.as_mut_expr() {
            Some(es) => es,
            None => return,
        };

        let call_expr = match expr_stmt.expr.as_mut_call() {
            Some(ce) => ce,
            None => return,
        };

        let callee_expr = match call_expr.callee.as_expr() {
            Some(be) => be,
            None => return,
        };

        let ident = match callee_expr.as_ident() {
            Some(i) => i,
            None => return,
        };

        let sym = &*ident.sym;

        match sym {
            "warning" => {
                *stmt = wrap_in_if_not_prod(stmt.take(), None);
            }
            "invariant" => {
                *stmt = wrap_invariant(call_expr);
            }
            _ => {}
        }
    }

    // Visits !unary expressions, looking for __DEV__
    fn visit_mut_unary_expr(&mut self, expr: &mut UnaryExpr) {
        expr.visit_mut_children_with(self);

        match expr.op {
            UnaryOp::Bang => {}
            _ => return,
        }

        let ident = match expr.arg.as_ident() {
            Some(i) => i,
            None => return,
        };

        let sym = &*ident.sym;

        if let "__DEV__" = sym {
            expr.arg = ParenExpr {
                span: DUMMY_SP,
                expr: dev_expression(),
            }
            .into();
        };
    }

    // Visits binary (`&&`,`||`) expressions, looking for __DEV__
    fn visit_mut_bin_expr(&mut self, expr: &mut BinExpr) {
        expr.visit_mut_children_with(self);

        match expr.op {
            swc_core::ecma::ast::BinaryOp::LogicalOr => {}
            swc_core::ecma::ast::BinaryOp::LogicalAnd => {}
            _ => return,
        }

        if let Some(ident) = expr.left.as_ident() {
            let sym = &*ident.sym;

            if let "__DEV__" = sym {
                *expr.left = ParenExpr {
                    span: DUMMY_SP,
                    expr: dev_expression(),
                }
                .into();
            };
        };

        if let Some(ident) = expr.right.as_ident() {
            let sym = &*ident.sym;

            if let "__DEV__" = sym {
                *expr.right = ParenExpr {
                    span: DUMMY_SP,
                    expr: dev_expression(),
                }
                .into();
            };
        };
    }

    // Visits conditional expressions `cond ? true : false`, looking for __DEV__
    fn visit_mut_cond_expr(&mut self, expr: &mut CondExpr) {
        expr.visit_mut_children_with(self);

        let ident = match expr.test.as_ident() {
            Some(i) => i,
            None => return,
        };

        let sym = &*ident.sym;

        if let "__DEV__" = sym {
            expr.test = dev_expression();
        };
    }

    // Visits if statements, looking for __DEV__
    fn visit_mut_if_stmt(&mut self, stmt: &mut IfStmt) {
        stmt.visit_mut_children_with(self);

        let ident = match stmt.test.as_ident() {
            Some(i) => i,
            None => return,
        };

        let sym = &*ident.sym;

        if let "__DEV__" = sym {
            stmt.test = dev_expression();
        };
    }
}

#[plugin_transform]
pub fn process_transform(program: Program, _metadata: TransformPluginProgramMetadata) -> Program {
    program.fold_with(&mut as_folder(TransformVisitor))
}

test!(
    Default::default(),
    |_| as_folder(TransformVisitor),
    warning_substitution,
    // Input codes
    r#"warning(condition, "argument", argument);"#,
    // Output codes after transformed with plugin
    r#"if ("production" !== process.env.NODE_ENV) {warning(condition, "argument", argument);}"#
);

test!(
    Default::default(),
    |_| as_folder(TransformVisitor),
    invariant_substitution,
    // Input codes
    r#"invariant(condition, argument, argument);"#,
    // Output codes after transformed with plugin
    r#"if (!condition) {
    if ("production" !== process.env.NODE_ENV) {
      invariant(false, argument, argument);
    } else {
      invariant(false);
    }
    }"#
);

test!(
    Default::default(),
    |_| as_folder(TransformVisitor),
    cond_dev_expr,
    // Input codes
    r#"const x = __DEV__ ? 'a' : 'b';"#,
    // Output codes after transformed with plugin
    r#"const x = "production" !== process.env.NODE_ENV ? 'a' : 'b';"#
);

test!(
    Default::default(),
    |_| as_folder(TransformVisitor),
    if_dev_expr,
    // Input codes
    r#"if (__DEV__) {toot()}"#,
    // Output codes after transformed with plugin
    r#"if ("production" !== process.env.NODE_ENV) {toot();}"#
);

test!(
    Default::default(),
    |_| as_folder(TransformVisitor),
    unary_dev_expr_not,
    // Input codes
    r#"if (!__DEV__) {dont_toot()}"#,
    // Output codes after transformed with plugin
    r#"if (!("production" !== process.env.NODE_ENV)) {dont_toot();}"#
);

test!(
    Default::default(),
    |_| as_folder(TransformVisitor),
    binary_dev_expr_and,
    // Input codes
    r#"__DEV__ && true"#,
    // Output codes after transformed with plugin
    r#""production" !== process.env.NODE_ENV && true;"#
);

test!(
    Default::default(),
    |_| as_folder(TransformVisitor),
    binary_dev_expr_or,
    // Input codes
    r#"__DEV__ || false"#,
    // Output codes after transformed with plugin
    r#""production" !== process.env.NODE_ENV || false;"#
);