Fifth version of our transform, which moves the casting calls from the decorator to the getter and setter

transform-value.v5.ts

// Constants:
// ...
const CASTERS_QUERY = 'CallExpression[expression.name!="Value"], CallExpression[expression.name="Value"] > Identifier[name!="Value"], CallExpression[expression.name="Value"] > ArrayLiteralExpression > Identifier[name!="Value"]';
const CAST_RESULT_EXPRESSION_QUERY = 'ExpressionStatement';
const GETTER_CAST_QUERY = 'Identifier[name="isNotNull"]';

const CAST_CALL_TEMPLATE = tstemplate.compile(`
    val = <%= name %>(val,  <%= propertyName %>);
`);

export function transformer (source: SourceFile): TransformerFactory<Node> {
    // ...
}

export function valueDecoratorToGetterAndSetterFactory (nodes: Array<Node>): TransformerFactory<Node> {
    return function (context: TransformationContext): Transformer<Node> {
        // ...
        function visit (node: Node): Node | Array<Node> {
            if (nodes.includes(node)) {
                // Create the base structure of the new getter/setter:
                // ...

                // Re-attach any other decorators:
                // ...
  
                // Find caster function names:
                const casterNodes = tsquery(node, CASTERS_QUERY);

                // Create the CallExpressions for each cast call:
                const castCalls = casterNodes.map(casterNode => {
                    const [call] = tsquery(CAST_CALL_TEMPLATE({
                        name: casterNode,
                        propertyName: createLiteral(propertyName),
                    }), CAST_RESULT_EXPRESSION_QUERY);
                    return call;
                });
                const getters = castCalls.filter(call => tsquery(call, GETTER_CAST_QUERY).length);
                const setters = castCalls.filter(call => !getters.includes(call));

                // Insert the cast calls into the getter and setter bodies:
                getter.body.statements.splice(1, 0, ...getters);
                setter.body.statements.splice(1, 0, ...setters);

                // Return the new AST nodes to replace the old one:
                // ...
            }
        }
    };
}