Babel plugin to convert simple React components to PHP

plug.js

module.exports = function( babel ) {
	const t = babel.types;
	let insertedPhp = false;

	const updateParamNameVisitor = {
		Identifier( path ) {
			if ( path.node.name.startsWith( '$' ) ) {
				return;
			}
			// Transform VariableDeclarator Identifiers to PHP style
			path.replaceWith( t.identifier( '$' + path.node.name ) );
		},

		MemberExpression( path ) {
			// Transform point reference syntax to thin arrow syntax
			path.replaceWith( t.expressionStatement( t.identifier( `${path.node.object.name}->${path.node.property.name};` ) ) );
		}
	};

	return {
		visitor: {
			BinaryExpression( path ) {
				if ( t.isStringLiteral( path.node.left ) && path.node.operator === '+' ) {
					// Transform string concat operator to PHP style
					path.node.operator = '.';
				}
				path.traverse( updateParamNameVisitor );
			},

			VariableDeclaration( path ) {
				if ( ! insertedPhp ) {
					// Add `<?php` expression
					path.insertBefore( t.expressionStatement( t.identifier( '<?php ' ) ) );
					insertedPhp = true;
					return;
				}
				// Replace VariableDeclaration with PHP VariableDeclaration
				path.replaceWith( path.node.declarations[0] );
			},

			VariableDeclarator( path ) {
				// Transform VariableDeclarator into PHP style
				if ( path.node.id.name.startsWith( '$' ) ) {
					return;
				}
				if ( t.isFunctionExpression( path.node.init ) ) {
					return;
				}
				path.replaceWith( t.variableDeclarator( t.identifier( '$' + path.node.id.name ), path.node.init ) );
				path.traverse( updateParamNameVisitor );
			},

			FunctionExpression( path ) {
				// Transform FunctionExpression to FunctionDeclaration
				// Also remove VariableDeclaration for FunctionExpression
				path.parentPath.parentPath.replaceWith( t.functionDeclaration( path.parentPath.node.id, path.node.params, path.node.body ) );
			},

			FunctionDeclaration( path ) {
				// Transform FunctionDeclaration variables to PHP style
				path.node.params = path.node.params.map( function( param ) {
					param.name = '$' + param.name;
					return param;
				} );
			}
		}
	};
}