Function compileRef

packages/db/src/query/compiler/evaluators.ts:139–211

* Compiles a reference expression into an optimized evaluator

(ref: PropRef)

 * Compiles a reference expression into an optimized evaluator
 */
function compileRef(ref: PropRef): CompiledExpression {
  const [namespace, ...propertyPath] = ref.path

  if (!namespace) {
    throw new EmptyReferencePathError()
  }

  // Handle $selected namespace - references SELECT result fields
  if (namespace === `$selected`) {
    // Access $selected directly
    if (propertyPath.length === 0) {
      // Just $selected - return entire $selected object
      return (namespacedRow) => (namespacedRow as any).$selected
    } else if (propertyPath.length === 1) {
      // Single property access - most common case
      const prop = propertyPath[0]!
      return (namespacedRow) => {
        const selectResults = (namespacedRow as any).$selected
        return selectResults?.[prop]
      }
    } else {
      // Multiple property navigation (nested SELECT fields)
      return (namespacedRow) => {
        const selectResults = (namespacedRow as any).$selected
        if (selectResults === undefined) {
          return undefined
        }

        let value: any = selectResults
        for (const prop of propertyPath) {
          if (value == null) {
            return value
          }
          value = value[prop]
        }
        return value
      }
    }
  }

  // Handle table alias namespace (existing logic)
  const tableAlias = namespace

  // Pre-compile the property path navigation
  if (propertyPath.length === 0) {
    // Simple table reference
    return (namespacedRow) => namespacedRow[tableAlias]
  } else if (propertyPath.length === 1) {
    // Single property access - most common case
    const prop = propertyPath[0]!
    return (namespacedRow) => {
      const tableData = namespacedRow[tableAlias]
      return tableData?.[prop]
    }
  } else {
    // Multiple property navigation
    return (namespacedRow) => {
      const tableData = namespacedRow[tableAlias]