fix: better type checking for strings arguments of decorators

src/decorators/__tests__/condition.test.ts

@@ -101,7 +101,7 @@ describe('@Condition: basic testing', () => {
       foo: number = 1
       bar: number = 2
       @Choice('foo', {
-        1: [TestArg, 'foo, bar'],
+        1: [TestArg, 'foo,bar'],
       })
       field: TestArg
     }

src/decorators/__tests__/controller.test.ts

@@ -347,18 +347,6 @@ describe('@Controller: errors', () => {
       testControllerCursor(TestClass, 'field', () => cur.read(PrimitiveSymbol.u8), [], cur)
     }).toThrow(EOFError)
   })
-  it('@Count: recursiveGet should throw an error for non existing property', () => {
-    expect(() => {
-      class TestClass {
-        child = { count: 2 }
-
-        @Count('child.x', { primitiveCheck: false })
-        field: number
-      }
-
-      testController(TestClass, 'field', () => 1, [1, 1])
-    }).toThrow(ReferenceError)
-  })
   it('@Count: recursiveGet should throw an error when referencing a string in an arithmetic expression', () => {
     expect(() => {
       class TestClass {

src/decorators/common.ts

@@ -67,6 +67,42 @@ export function createClassMetaDescriptor (type: symbol, name: string, metadata:
   }
 }
 
+type RecursiveKeyOf<TObj extends object> = {
+  [TKey in keyof TObj & (string | number)]:
+    TObj[TKey] extends any[] 
+      ? `${TKey}`
+      : TObj[TKey] extends object
+        ? `${TKey}.${RecursiveKeyOf<TObj[TKey]>}`
+        : `${TKey}`
+}[keyof TObj & (string | number)];
+
+type NumericalString = `${number}`
+
+type RecursiveKeyWithOperations<TObj extends object, T extends string, U extends string = RecursiveKeyOf<TObj> | NumericalString> = 
+  T extends U 
+    ? T 
+    : T extends `${U} + ${infer R}` 
+      ? T extends `${infer F} + ${R}` 
+        ? `${F} + ${RecursiveKeyWithOperations<TObj, R, Exclude<U, F>>}` 
+        : never 
+      : T extends `${U} - ${infer R}`
+        ? T extends `${infer F} - ${R}` 
+          ? `${F} - ${RecursiveKeyWithOperations<TObj, R, Exclude<U, F>>}` 
+          : never 
+        : U
+
+type CommaSeparetedRecursiveKey<TObj extends object, T extends string, U extends string = RecursiveKeyOf<TObj>> = 
+  T extends U 
+    ? T 
+    : T extends `${U},${infer R}` 
+      ? T extends `${infer F},${R}` 
+        ? `${F},${CommaSeparetedRecursiveKey<TObj, R, Exclude<U, F>>}` 
+        : never 
+      : U;
+
+export type StringFormattedRecursiveKeyOf<T extends object, Args extends string> = Args extends RecursiveKeyWithOperations<T, Args> ? Args : RecursiveKeyWithOperations<T, Args>
+export type StringFormattedCommaSepRecursiveKeyOf<T extends object, Args extends string> = Args extends CommaSeparetedRecursiveKey<T, Args> ? Args : CommaSeparetedRecursiveKey<T, Args>
+
 /**
  * Chained accessor to get the value of `expr` for `obj`.
  *
@@ -77,7 +113,7 @@ export function createClassMetaDescriptor (type: symbol, name: string, metadata:
  * @throws {ReferenceError} if you attempt to access a non existing property.
  *
  */
-export function recursiveGet (obj: any, expr: string): any {
+export function recursiveGet<T extends object, Args extends string> (obj: T, expr: RecursiveKeyWithOperations<T, Args>): any {
   const _isOperation = (x: string): boolean => ['+', '-'].includes(x)
 
   const _get = (path: string): any => path.split('.').reduce((acc: any, key: string) => {
@@ -109,7 +145,7 @@ export function recursiveGet (obj: any, expr: string): any {
   }
 }
 
-export function commaSeparetedRecursiveGet (obj: any, args: string): any[] {
+export function commaSeparetedRecursiveGet<T extends object, Args extends string> (obj: T, args: CommaSeparetedRecursiveKey<T, Args>): any[] {
   const keys = args.split(',')
-  return keys.map(key => recursiveGet(obj, key.trim()))
+  return keys.map(key => recursiveGet(obj, key.trim() as RecursiveKeyWithOperations<T, typeof key>))
 }

src/decorators/condition.ts

@@ -40,7 +40,7 @@
  *
  * @module Condition
  */
-import { recursiveGet, type PropertyMetaDescriptor, createPropertyMetaDescriptor } from './common'
+import { recursiveGet, type PropertyMetaDescriptor, createPropertyMetaDescriptor, StringFormattedRecursiveKeyOf } from './common'
 import { type PrimitiveTypeProperty, type RelationTypeProperty, type RelationParameters, Relation, createPrimitiveTypeProperty, createRelationTypeProperty } from './primitive'
 import { isPrimitiveSymbol, type DecoratorType, type Primitive, type Context } from '../types'
 import { NoConditionMatched } from '../error'
@@ -87,7 +87,7 @@ export interface Condition<This> extends PropertyMetaDescriptor<This> {
  *
  * @category Advanced Use
  */
-export function conditionDecoratorFactory<This, Target, Value> (name: string, cond: ConditionFunction<This>, then?: Primitive<Target>, args?: RelationParameters<This>): DecoratorType<This, Value> {
+export function conditionDecoratorFactory<This extends object, Target, Value, Args extends string> (name: string, cond: ConditionFunction<This>, then?: Primitive<Target>, args?: RelationParameters<This, Args>): DecoratorType<This, Value> {
   return function (_: undefined, context: Context<This, Value>) {
     const propertyName = context.name as keyof This
     function createRelation (relationOrPrimitive: Primitive<Target>): PrimitiveTypeProperty<This> | RelationTypeProperty<This, Target> {
@@ -125,7 +125,7 @@ export function conditionDecoratorFactory<This, Target, Value> (name: string, co
  *
  * @category Advanced Use
  */
-export function dynamicConditionDecoratorFactory<This, Target, Value> (name: string, func: DynamicGetterFunction<This, Target>, args?: RelationParameters<This>): DecoratorType<This, Value> {
+export function dynamicConditionDecoratorFactory<This extends object, Target, Value, Args extends string> (name: string, func: DynamicGetterFunction<This, Target>, args?: RelationParameters<This, Args>): DecoratorType<This, Value> {
   return function (_: undefined, context: Context<This, Value>) {
     const propertyName = context.name as keyof This
     function createRelation (relationOrPrimitive: Primitive<Target>): PrimitiveTypeProperty<This> | RelationTypeProperty<This, Target> {
@@ -204,7 +204,7 @@ export function dynamicConditionDecoratorFactory<This, Target, Value> (name: str
  *
  * @category Decorators
  */
-export function IfThen<This, Target, Value> (cond: ConditionFunction<This>, then?: Primitive<Target>, args?: RelationParameters<This>): DecoratorType<This, Value> {
+export function IfThen<This extends object, Target, Value, Args extends string> (cond: ConditionFunction<This>, then?: Primitive<Target>, args?: RelationParameters<This, Args>): DecoratorType<This, Value> {
   return conditionDecoratorFactory('ifthen', cond, then, args)
 }
 
@@ -251,7 +251,7 @@ export function IfThen<This, Target, Value> (cond: ConditionFunction<This>, then
  *
  * @category Decorators
  */
-export function Else<This, Target, Value> (then?: Primitive<Target>, args?: RelationParameters<This>): DecoratorType<This, Value> {
+export function Else<This extends object, Target, Value, Args extends string> (then?: Primitive<Target>, args?: RelationParameters<This, Args>): DecoratorType<This, Value> {
   return conditionDecoratorFactory('else', () => true, then, args)
 }
 
@@ -430,7 +430,7 @@ export function Else<This, Target, Value> (then?: Primitive<Target>, args?: Rela
  *
  * @category Decorators
  */
-export function Choice<This, Value> (cmp: string | ((targetInstance: This) => any), match: Record<any, Primitive<any> | [Primitive<any>, RelationParameters<This>] | undefined>, args?: RelationParameters<This>): DecoratorType<This, Value> {
+export function Choice<This extends object, Value, Args extends string> (cmp: StringFormattedRecursiveKeyOf<This, Args> | ((targetInstance: This) => any), match: Record<any, Primitive<any> | [Primitive<any>, RelationParameters<This, Args>] | undefined>, args?: RelationParameters<This, Args>): DecoratorType<This, Value> {
   const valueToCompare = typeof cmp === 'string' ? (targetInstance: This) => recursiveGet(targetInstance, cmp) : cmp
   // Mandatory to cast to String because the key is always a string even though you declare it as a number
   const decorators = Object.keys(match).map((key: keyof typeof match) => {
@@ -500,7 +500,7 @@ export function Choice<This, Value> (cmp: string | ((targetInstance: This) => an
  * @returns {DecoratorType<This, Value>} The property decorator function.
  * @category Decorators
  */
-export function Select<This, Value> (getter: ((targetInstance: This) => Primitive<any>), args?: RelationParameters<This>): DecoratorType<This, Value> {
+export function Select<This extends object, Value, Args extends string> (getter: ((targetInstance: This) => Primitive<any>), args?: RelationParameters<This, Args>): DecoratorType<This, Value> {
   return dynamicConditionDecoratorFactory('select', getter, args)
 }
 

src/decorators/controller.ts

@@ -50,7 +50,7 @@
  *
  * @module Controller
  */
-import { createPropertyMetaDescriptor, type PropertyMetaDescriptor, recursiveGet } from './common'
+import { createPropertyMetaDescriptor, type PropertyMetaDescriptor, recursiveGet, StringFormattedRecursiveKeyOf } from './common'
 import { type Cursor } from '../cursor'
 import { EOF, type DecoratorType, type InstantiableObject, type Context } from '../types'
 import { relationExistsOrThrow, EOFError } from '../error'
@@ -98,6 +98,8 @@ export const ControllerOptionsDefault = {
 export type ControllerFunction<This> = (targetInstance: This, cursor: Cursor, read: ControllerReader, opt: ControllerOptions) => any
 export type OptionlessControllerFunction = (targetInstance: any, cursor: Cursor, read: ControllerReader) => any
 
+type NumberOrRecursiveKey<This extends object, Args extends string> = number | StringFormattedRecursiveKeyOf<This, Args>
+
 /**
  * Controller type interface structure definition.
  *
@@ -500,7 +502,7 @@ export function NullTerminatedString<This, Value> (opt?: Partial<ControllerOptio
  *
  * @category Decorators
  */
-export function Count<This, Value> (arg: number | string, opt?: Partial<ControllerOptions>): DecoratorType<This, Value> {
+export function Count<This extends object, Value, Args extends string> (arg: NumberOrRecursiveKey<This, Args>, opt?: Partial<ControllerOptions>): DecoratorType<This, Value> {
   function countController (
     currStateObject: This,
     cursor: Cursor,
@@ -542,14 +544,14 @@ export function Count<This, Value> (arg: number | string, opt?: Partial<Controll
  *
  * @category Decorators
  */
-export function Matrix<This, Value> (width: number | string, height: number | string, opt?: Partial<ControllerOptions>): DecoratorType<This, Value> {
+export function Matrix<This extends object, Value, Args extends string> (width: NumberOrRecursiveKey<This, Args>, height: NumberOrRecursiveKey<This, Args>, opt?: Partial<ControllerOptions>): DecoratorType<This, Value> {
   function matrixController (
     currStateObject: This,
     cursor: Cursor,
     read: ControllerReader,
     opt: ControllerOptions,
   ): any {
-    const getArg = (x: number | string): number => typeof x === 'string'
+    const getArg = (x: NumberOrRecursiveKey<This, Args>): number => typeof x === 'string'
       ? recursiveGet(currStateObject, x)
       : x
     const finalWidth = getArg(width)
@@ -614,7 +616,7 @@ export function Matrix<This, Value> (width: number | string, height: number | st
  *
  * @category Decorators
  */
-export function Size<This, Value> (size: number | string, opt?: Partial<ControllerOptions>): DecoratorType<This, Value> {
+export function Size<This extends object, Value, Args extends string> (size: NumberOrRecursiveKey<This, Args>, opt?: Partial<ControllerOptions>): DecoratorType<This, Value> {
   return controllerDecoratorFactory(
     'size',
     (currStateObject: This, cursor: Cursor, read: ControllerReader, opt: ControllerOptions) => {
@@ -669,7 +671,7 @@ export function Size<This, Value> (size: number | string, opt?: Partial<Controll
  *
  * @category Decorators
  */
-export function MapTo<This, Value> (arr: string | any[] | ((_: This) => any[]), opt?: Partial<ControllerOptions>): DecoratorType<This, Value> {
+export function MapTo<This extends object, Value, Args extends string> (arr: StringFormattedRecursiveKeyOf<This, Args> | any[] | ((_: This) => any[]), opt?: Partial<ControllerOptions>): DecoratorType<This, Value> {
   return controllerDecoratorFactory(
     'map',
     (currStateObject: This, cursor: Cursor, read: ControllerReader, opt: ControllerOptions) => {

src/decorators/prepost.ts

@@ -47,7 +47,7 @@
  *
  * @module PrePost
  */
-import { ClassMetaDescriptor, type PropertyMetaDescriptor, createClassMetaDescriptor, createPropertyMetaDescriptor, recursiveGet } from './common'
+import { ClassMetaDescriptor, type PropertyMetaDescriptor, StringFormattedRecursiveKeyOf, createClassMetaDescriptor, createPropertyMetaDescriptor, recursiveGet } from './common'
 import { relationExistsOrThrow } from '../error'
 import { ExecutionScope, type ClassAndPropertyDecoratorType, type ClassAndPropertyDecoratorContext, type DecoratorType, type Context } from '../types'
 import { type Cursor, type BinaryCursorEndianness, BinaryCursor } from '../cursor'
@@ -400,7 +400,7 @@ export function Post<This> (func: PrePostFunction<This>, opt?: Partial<PrePostOp
  *
  * @category Decorators
  */
-export function Offset<This> (offset: number | string | ((instance: This, cursor: Cursor) => number), opt?: Partial<PrePostOptions>): ClassAndPropertyDecoratorType<This> {
+export function Offset<This extends object, Args extends string> (offset: number | StringFormattedRecursiveKeyOf<This, Args> | ((instance: This, cursor: Cursor) => number), opt?: Partial<PrePostOptions>): ClassAndPropertyDecoratorType<This> {
   return preFunctionDecoratorFactory('offset', (targetInstance, cursor) => {
     const offCompute = typeof offset === 'string'
       ? recursiveGet(targetInstance, offset) as number
@@ -483,7 +483,7 @@ export function Offset<This> (offset: number | string | ((instance: This, cursor
  *
  * @category Decorators
  */
-export function Peek<This> (offset?: number | string | ((instance: This, cursor: Cursor) => number), opt?: Partial<PrePostOptions>): ClassAndPropertyDecoratorType<This> {
+export function Peek<This extends object, Args extends string> (offset?: number | StringFormattedRecursiveKeyOf<This, Args> | ((instance: This, cursor: Cursor) => number), opt?: Partial<PrePostOptions>): ClassAndPropertyDecoratorType<This> {
   return function (_: undefined, context: ClassAndPropertyDecoratorContext<This>) {
     preFunctionDecoratorFactory<This>('pre-peek', (targetInstance, cursor) => {
       const preOff = cursor.offset()
@@ -667,7 +667,7 @@ type ValueSetFunction<This, Value> = (instance: This) => Value
  *
  * @throws {@link Primitive.RelationAlreadyDefinedError} if a relation metadata is found.
  */
-export function ValueSet<This, Value extends This[keyof This]> (setter: ValueSetFunction<This, Value>, opt?: Partial<PrePostOptions>): DecoratorType<This, Value> {
+export function ValueSet<This extends object, Value extends This[keyof This]> (setter: ValueSetFunction<This, Value>, opt?: Partial<PrePostOptions>): DecoratorType<This, Value> {
   return function (_: any, context: Context<This, Value>) {
     const propertyName = context.name as keyof This
     if (!Meta.isFieldDecorated(context.metadata, propertyName)) {

src/decorators/primitive.ts

@@ -33,7 +33,7 @@
  *
  * @module Primitive
  */
-import { type PropertyMetaDescriptor, createPropertyMetaDescriptor, commaSeparetedRecursiveGet } from './common'
+import { type PropertyMetaDescriptor, createPropertyMetaDescriptor, commaSeparetedRecursiveGet, StringFormattedCommaSepRecursiveKeyOf } from './common'
 import { RelationAlreadyDefinedError, WrongBitfieldClassImplementation } from '../error'
 import Meta from '../metadatas'
 import { type PrimitiveSymbol, isPrimitiveSymbol, type InstantiableObject, type DecoratorType, type Context, type DecoratorMetadataObject } from '../types'
@@ -111,8 +111,7 @@ export interface PrimitiveTypeProperty<This> extends PropertyMetaDescriptor<This
  *
  * @typeParam This The type of the class the decorator is applied to.
  */
-export type RelationParameters<This> = ((targetInstance: This) => any[]) | string
-
+export type RelationParameters<This extends object, Args extends string> = ((targetInstance: This) => any[]) | StringFormattedCommaSepRecursiveKeyOf<This, Args>
 /**
  * `RelationTypeProperty` are primitive type that holds information about
  * another binary type definition.
@@ -225,7 +224,7 @@ export function createPrimitiveTypeProperty<This> (metadata: DecoratorMetadataOb
  *
  * @category Advanced Use
  */
-export function createRelationTypeProperty<This, Target> (metadata: DecoratorMetadataObject, propertyKey: keyof This, relation: InstantiableObject<Target>, args?: RelationParameters<This>): RelationTypeProperty<This, Target> {
+export function createRelationTypeProperty<This extends object, Target, Args extends string> (metadata: DecoratorMetadataObject, propertyKey: keyof This, relation: InstantiableObject<Target>, args?: RelationParameters<This, Args>): RelationTypeProperty<This, Target> {
   const argsFunc = typeof args === 'string'
     ? (targetInstance: This) => commaSeparetedRecursiveGet(targetInstance, args)
     : args as ((targetInstance: This) => any[]) | undefined
@@ -344,7 +343,7 @@ export function createRelationTypeProperty<This, Target> (metadata: DecoratorMet
  *
  * @category Decorators
  */
-export function Relation<This, Target, Value> (relation?: InstantiableObject<Target> | PrimitiveSymbol, args?: RelationParameters<This>): DecoratorType<This, Value> {
+export function Relation<This extends object, Target, Value, Args extends string> (relation?: InstantiableObject<Target> | PrimitiveSymbol, args?: RelationParameters<This, Args>): DecoratorType<This, Value> {
   return function (_: undefined, context: Context<This, Value>): void {
     if (Meta.getBitFields(context.metadata).length > 0) {
       throw new WrongBitfieldClassImplementation(String(context.name))
@@ -360,7 +359,7 @@ export function Relation<This, Target, Value> (relation?: InstantiableObject<Tar
     } else if (isPrimitiveSymbol(relation)) {
       Meta.setField(context.metadata, createPrimitiveTypeProperty<This>(context.metadata, propertyName, relation))
     } else {
-      Meta.setField(context.metadata, createRelationTypeProperty<This, Target>(context.metadata, propertyName, relation, args))
+      Meta.setField(context.metadata, createRelationTypeProperty<This, Target, Args>(context.metadata, propertyName, relation, args))
     }
   }
 }