Move classNamer to a separate function

Author: Andrii Kirmas

src/ctx.ts

@@ -1,62 +1,80 @@
 import type { Falsy, ToggleMap, ClassValue, ClassNamer, ClassNamed } from "./defs"
 import { emptize, stringifyClassNamed, truthyKeys } from "./utils"
 
+interface tClassNaming<ClassKeys extends string> {
+  /**
+   * @example classes(true) === props.className
+   * @example classes({class1: true, class2: false}) === "class1"
+   * @example classes("class3", false && "class4") === "class3"
+   * @example classes(true, {class1: true, class2: false}, "class3", false && "class4") === `${props.className} class1 class3`
+  */
+ // Using overloads will make error not in certain argument but on all call - 'No overload found'
+  (
+    propagate_or_map_or_expression: true | ToggleMap<ClassKeys> | ClassKeys | Falsy,
+    map_or_expression?: (
+      [Extract<typeof propagate_or_map_or_expression, true>] extends [never]
+      ? never
+      : ToggleMap<ClassKeys>
+    ) | ClassKeys | Falsy,
+    ...expressions: (ClassKeys | Falsy)[]
+  ) : ClassNamed
+}
+
 export default classNamingCtx
 
-function classNamingCtx<ClassKeys extends string>(ctx: ClassNamer<ClassKeys>) {
+/**
+ * @example const classes = classNamingCtx(this.props)
+ * @example const classes = classNamingCtx({className, classNames})
+ * @example const classes = classNamingCtx({classNames})
+ */
+function classNamingCtx<ClassKeys extends string>(ctx: ClassNamer<ClassKeys>): tClassNaming<ClassKeys> {
   emptize(ctx.classNames)
-  
-  const {classNames, className} = ctx
 
-  const classNamer = function classNamer/*<ClassKeys extends string>*/(
-    // this: ClassNamer<ClassKeys>,
-    //TODO (typeof className extends string ? true : never)
-    arg0: ToggleMap<ClassKeys> | ClassKeys | true,
-    arg1?: [Extract<typeof arg0, boolean>] extends [never]
-    ? (ClassKeys | Falsy)
-    : (ToggleMap<ClassKeys> | ClassKeys | Falsy),
-    ...args: (ClassKeys | Falsy)[]
-  ): ClassNamed {
-    // const {className, classNames} = this
-    const withPropagation = arg0 === true
-    , allowed: ClassKeys[] = truthyKeys(arg0 === true ? false : arg0)
-    //@ts-expect-error
-    .concat(truthyKeys(arg1))
+  return classNamer.bind(ctx) as tClassNaming<ClassKeys>
+}
+
+function classNamer<ClassKeys extends string>(
+  this: ClassNamer<ClassKeys>,
+  arg0: true | ToggleMap<ClassKeys> | ClassKeys,
+  arg1?: ToggleMap<ClassKeys> | ClassKeys,
+  ...args: (ClassKeys | Falsy)[]
+): ClassNamed {
+  const {className, classNames} = this
+  const withPropagation = arg0 === true
+  , allowed: ClassKeys[] = truthyKeys(arg0 === true ? false : arg0)
+  //@ts-expect-error
+  .concat(truthyKeys(arg1))
+  //@ts-expect-error
+  .concat(args)
+  .filter<ClassKeys>(
     //@ts-expect-error
-    .concat(args)
-    .filter<ClassKeys>(
-      //@ts-expect-error
-      Boolean
-    )
-    
-    for (let i = allowed.length; i--;) {
-      const key = allowed[i]
-      , hash: ClassValue = classNames[key]
-      
-      if (hash !== undefined)
-        //@ts-expect-error
-        allowed[i] = hash
-    }
+    Boolean
+  )
+  
+  for (let i = allowed.length; i--;) {
+    const key = allowed[i]
+    , hash: ClassValue = classNames[key]
 
-    const allowedString = allowed.join(" ")
-    , propagated = withPropagation && className || ""
-    , $return = {
-      className: `${
-        propagated
-      }${
-        propagated && allowedString
-        ? " "
-        : ""
-      }${
-        allowedString
-      }`
-    }
-
-    stringifyClassNamed($return)
-
-    return $return
-  }   
+    if (hash !== undefined)
+      //@ts-expect-error
+      allowed[i] = hash
+  }
 
-  return classNamer
-}
+  const allowedString = allowed.join(" ")
+  , propagated = withPropagation && className || ""
+  , $return = {
+    className: `${
+      propagated
+    }${
+      propagated && allowedString
+      ? " "
+      : ""
+    }${
+      allowedString
+    }`
+  }
+
+  stringifyClassNamed($return)
 
+  return $return
+}