const replPlugin = ({ types: t }) => ({
visitor: {
ModuleDeclaration(path) {
throw path.buildCodeFrameError("Modules aren't supported in the REPL");
},
VariableDeclaration(path) {
if (path.node.kind !== "var") {
throw path.buildCodeFrameError(
"Only `var` variables are supported in the REPL",
);
}
},
Program(path) {
if (path.get("body").some(child => child.isExpressionStatement())) return;
// If the executed code doesn't evaluate to a value,
// prevent implicit strict mode from printing 'use strict'.
path.pushContainer(
"body",
t.expressionStatement(t.identifier("undefined")),
);
},
},
});
function pushPlugin(str) {
return {
visitor: {
Program(path) {
path.pushContainer(
"body",
babel.types.expressionStatement(babel.types.identifier(str)),
);
},
},
};
}