From 9d4ac46513c17bc37300baba834c7eb72de3f605 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20Unneb=C3=A4ck?= <linus@folkdatorn.se>
Date: Thu, 9 Aug 2018 19:43:20 +0100
Subject: [PATCH 1/6] Add toJSON to TypeScript typings

---
 index.d.ts      | 18 ++++++++++++++----
 test/typings.ts |  3 +++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index 53507a4..005c146 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -67,11 +67,21 @@ declare namespace factory {
   }
 }
 
-declare function createValidator<T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): ((input: unknown, options?: any) => input is { [K in keyof T]: (K extends R ? ExtractSchemaType<T[K]> : ExtractSchemaType<T[K]> | undefined) }) & { errors: factory.ValidationError[] }
-declare function createValidator<T extends GenericSchema> (schema: T, options?: any): ((input: unknown, options?: any) => input is ExtractSchemaType<T>) & { errors: factory.ValidationError[] }
+declare interface Validator<Schema, Output = ExtractSchemaType<Schema>> {
+  (input: unknown, options?: any): input is Output
+  errors: factory.ValidationError[]
+  toJSON(): Schema
+}
+
+declare function createValidator<T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Validator<ObjectSchema<T, R>>
+declare function createValidator<T extends GenericSchema> (schema: T, options?: any): Validator<T>
+
+declare interface Filter<Output> {
+  (input: Output, options?: any): Output
+}
 
-declare function createFilter<T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): ((input: { [K in keyof T]: (K extends R ? ExtractSchemaType<T[K]> : ExtractSchemaType<T[K]> | undefined) }, options?: any) => { [K in keyof T]: (K extends R ? ExtractSchemaType<T[K]> : ExtractSchemaType<T[K]> | undefined) })
-declare function createFilter<T extends GenericSchema> (schema: T, options?: any): ((input: ExtractSchemaType<T>, options?: any) => ExtractSchemaType<T>)
+declare function createFilter<T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Filter<ExtractedSchemaObject<T, R>>
+declare function createFilter<T extends GenericSchema> (schema: T, options?: any): Filter<ExtractSchemaType<T>>
 
 declare type Factory = (typeof createValidator) & { filter: typeof createFilter }
 declare const factory: Factory
diff --git a/test/typings.ts b/test/typings.ts
index 425578d..2f96408 100644
--- a/test/typings.ts
+++ b/test/typings.ts
@@ -9,6 +9,7 @@ function assertType<T>(value: T): void {}
 const input = null as unknown
 
 const nullValidator = createValidator({ type: 'null' })
+assertType<{ type: 'null' }>(nullValidator.toJSON())
 
 if (nullValidator(input)) {
   assertType<null>(input)
@@ -22,12 +23,14 @@ assertType<string>(nullValidator.errors[0].type)
 assertType<unknown>(nullValidator.errors[0].value)
 
 const numberValidator = createValidator({ type: 'number' })
+assertType<{ type: 'number' }>(numberValidator.toJSON())
 
 if (numberValidator(input)) {
   assertType<number>(input)
 }
 
 const stringValidator = createValidator({ type: 'string' })
+assertType<{ type: 'string' }>(stringValidator.toJSON())
 
 if (stringValidator(input)) {
   assertType<string>(input)

From 8ecbe380d053d6ba6d149a2b0038c00b58b736cb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20Unneb=C3=A4ck?= <linus@folkdatorn.se>
Date: Thu, 9 Aug 2018 21:44:59 +0100
Subject: [PATCH 2/6] Refactor Factory definition

---
 index.d.ts | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index 005c146..246f50f 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -73,17 +73,18 @@ declare interface Validator<Schema, Output = ExtractSchemaType<Schema>> {
   toJSON(): Schema
 }
 
-declare function createValidator<T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Validator<ObjectSchema<T, R>>
-declare function createValidator<T extends GenericSchema> (schema: T, options?: any): Validator<T>
-
 declare interface Filter<Output> {
   (input: Output, options?: any): Output
 }
 
-declare function createFilter<T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Filter<ExtractedSchemaObject<T, R>>
-declare function createFilter<T extends GenericSchema> (schema: T, options?: any): Filter<ExtractSchemaType<T>>
+declare interface Factory {
+  <T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Validator<ObjectSchema<T, R>>
+  <T extends GenericSchema> (schema: T, options?: any): Validator<T>
+
+  createFilter<T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Filter<ExtractedSchemaObject<T, R>>
+  createFilter<T extends GenericSchema> (schema: T, options?: any): Filter<ExtractSchemaType<T>>
+}
 
-declare type Factory = (typeof createValidator) & { filter: typeof createFilter }
 declare const factory: Factory
 
 export = factory

From 3da57a4fb7c3c83da5f8ba9660ebf116cd0ebfe0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20Unneb=C3=A4ck?= <linus@folkdatorn.se>
Date: Thu, 9 Aug 2018 21:51:01 +0100
Subject: [PATCH 3/6] Refactor away LeafSchema and GenericSchema

---
 index.d.ts | 28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index 246f50f..79e4554 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,3 +1,5 @@
+type AnySchema = NullSchema | BooleanSchema | NumberSchema | StringSchema | AnyEnumSchema | AnyArraySchema | AnyObjectSchema
+
 interface NullSchema {
   type: 'null'
 }
@@ -14,20 +16,19 @@ interface StringSchema {
   type: 'string'
 }
 
-type LeafSchema = NullSchema | BooleanSchema | NumberSchema | StringSchema
-
+interface AnyEnumSchema extends EnumSchema<any> {}
 interface EnumSchema<T> {
   enum: T[]
 }
 
-interface ArraySchema<T extends LeafSchema | EnumSchema<any> | ArraySchema<LeafSchema | EnumSchema<any> | ObjectSchema<ObjectProps, any>> | ObjectSchema<ObjectProps, any>> {
+interface AnyArraySchema extends ArraySchema<AnySchema> {}
+interface ArraySchema<T extends AnySchema> {
   type: 'array'
   items: T
 }
 
-type ObjectProps = { [K in string]: LeafSchema | EnumSchema<any> | ArraySchema<LeafSchema | EnumSchema<any> | ArraySchema<LeafSchema | EnumSchema<any> | ObjectSchema<ObjectProps, any>> | ObjectSchema<ObjectProps, any>> | ObjectSchema<ObjectProps, any> }
-
-interface ObjectSchema<T extends ObjectProps, R extends keyof T> {
+interface AnyObjectSchema extends ObjectSchema<Record<string, AnySchema>, string> {}
+interface ObjectSchema<T extends Record<string, AnySchema>, R extends keyof T> {
   additionalProperties?: boolean
   type: 'object'
   properties: T
@@ -51,13 +52,6 @@ declare type ExtractSchemaType<Type> = (
   : never
 )
 
-declare type GenericSchema = (
-  { enum: any[] } |
-  { type: 'string' | 'number' | 'boolean' | 'null' } |
-  { type: 'array', items: GenericSchema } |
-  { type: 'object', properties: ObjectProps }
-)
-
 declare namespace factory {
   interface ValidationError {
     field: string
@@ -78,11 +72,11 @@ declare interface Filter<Output> {
 }
 
 declare interface Factory {
-  <T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Validator<ObjectSchema<T, R>>
-  <T extends GenericSchema> (schema: T, options?: any): Validator<T>
+  <T extends Record<string, AnySchema>, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Validator<ObjectSchema<T, R>>
+  <T extends AnySchema> (schema: T, options?: any): Validator<T>
 
-  createFilter<T extends ObjectProps, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Filter<ExtractedSchemaObject<T, R>>
-  createFilter<T extends GenericSchema> (schema: T, options?: any): Filter<ExtractSchemaType<T>>
+  createFilter<T extends Record<string, AnySchema>, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Filter<ExtractedSchemaObject<T, R>>
+  createFilter<T extends AnySchema> (schema: T, options?: any): Filter<ExtractSchemaType<T>>
 }
 
 declare const factory: Factory

From c634f4b15837d3ce90829c47db8ab6915ab2c5c3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20Unneb=C3=A4ck?= <linus@folkdatorn.se>
Date: Thu, 9 Aug 2018 21:56:34 +0100
Subject: [PATCH 4/6] Refactor to more verbose naming

---
 index.d.ts | 44 ++++++++++++++++++++++----------------------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index 79e4554..9c7b940 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -17,38 +17,38 @@ interface StringSchema {
 }
 
 interface AnyEnumSchema extends EnumSchema<any> {}
-interface EnumSchema<T> {
-  enum: T[]
+interface EnumSchema<Enum> {
+  enum: Enum[]
 }
 
 interface AnyArraySchema extends ArraySchema<AnySchema> {}
-interface ArraySchema<T extends AnySchema> {
+interface ArraySchema<ItemSchema extends AnySchema> {
   type: 'array'
-  items: T
+  items: ItemSchema
 }
 
 interface AnyObjectSchema extends ObjectSchema<Record<string, AnySchema>, string> {}
-interface ObjectSchema<T extends Record<string, AnySchema>, R extends keyof T> {
+interface ObjectSchema<Properties extends Record<string, AnySchema>, Required extends keyof Properties> {
   additionalProperties?: boolean
   type: 'object'
-  properties: T
-  required: R[]
+  properties: Properties
+  required: Required[]
 }
 
-interface ExtractedSchemaArray<T> extends Array<ExtractSchemaType<T>> {}
+interface ExtractedSchemaArray<Schema> extends Array<ExtractSchemaType<Schema>> {}
 
-declare type ExtractedSchemaObject<T, R> = {
-  [K in keyof T]: (K extends R ? ExtractSchemaType<T[K]> : ExtractSchemaType<T[K]> | undefined)
+declare type ExtractedSchemaObject<Properties, Required> = {
+  [Key in keyof Properties]: (Key extends Required ? ExtractSchemaType<Properties[Key]> : ExtractSchemaType<Properties[Key]> | undefined)
 }
 
-declare type ExtractSchemaType<Type> = (
-  Type extends EnumSchema<infer T> ? T
-  : Type extends NullSchema ? null
-  : Type extends BooleanSchema ? boolean
-  : Type extends NumberSchema ? number
-  : Type extends StringSchema ? string
-  : Type extends ArraySchema<infer T> ? ExtractedSchemaArray<T>
-  : Type extends ObjectSchema<infer T, infer R> ? ExtractedSchemaObject<T, R>
+declare type ExtractSchemaType<Schema> = (
+    Schema extends EnumSchema<infer Enum> ? Enum
+  : Schema extends NullSchema ? null
+  : Schema extends BooleanSchema ? boolean
+  : Schema extends NumberSchema ? number
+  : Schema extends StringSchema ? string
+  : Schema extends ArraySchema<infer ItemSchema> ? ExtractedSchemaArray<ItemSchema>
+  : Schema extends ObjectSchema<infer Properties, infer Required> ? ExtractedSchemaObject<Properties, Required>
   : never
 )
 
@@ -72,11 +72,11 @@ declare interface Filter<Output> {
 }
 
 declare interface Factory {
-  <T extends Record<string, AnySchema>, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Validator<ObjectSchema<T, R>>
-  <T extends AnySchema> (schema: T, options?: any): Validator<T>
+  <Properties extends Record<string, AnySchema>, Required extends keyof Properties> (schema: ObjectSchema<Properties, Required>, options?: any): Validator<ObjectSchema<Properties, Required>>
+  <Schema extends AnySchema> (schema: Schema, options?: any): Validator<Schema>
 
-  createFilter<T extends Record<string, AnySchema>, R extends keyof T> (schema: ObjectSchema<T, R>, options?: any): Filter<ExtractedSchemaObject<T, R>>
-  createFilter<T extends AnySchema> (schema: T, options?: any): Filter<ExtractSchemaType<T>>
+  createFilter<Properties extends Record<string, AnySchema>, Required extends keyof Properties> (schema: ObjectSchema<Properties, Required>, options?: any): Filter<ExtractedSchemaObject<Properties, Required>>
+  createFilter<Schema extends AnySchema> (schema: Schema, options?: any): Filter<ExtractSchemaType<Schema>>
 }
 
 declare const factory: Factory

From feed73c1f1f3370c5f7c3bd3d0b73b87153dbf08 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20Unneb=C3=A4ck?= <linus@folkdatorn.se>
Date: Thu, 9 Aug 2018 22:02:33 +0100
Subject: [PATCH 5/6] Improve type names

---
 index.d.ts | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index 9c7b940..2d234c2 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -35,20 +35,20 @@ interface ObjectSchema<Properties extends Record<string, AnySchema>, Required ex
   required: Required[]
 }
 
-interface ExtractedSchemaArray<Schema> extends Array<ExtractSchemaType<Schema>> {}
+interface ArrayFromSchema<Schema> extends Array<TypeFromSchema<Schema>> {}
 
-declare type ExtractedSchemaObject<Properties, Required> = {
-  [Key in keyof Properties]: (Key extends Required ? ExtractSchemaType<Properties[Key]> : ExtractSchemaType<Properties[Key]> | undefined)
+declare type ObjectFromSchema<Properties, Required> = {
+  [Key in keyof Properties]: (Key extends Required ? TypeFromSchema<Properties[Key]> : TypeFromSchema<Properties[Key]> | undefined)
 }
 
-declare type ExtractSchemaType<Schema> = (
+declare type TypeFromSchema<Schema> = (
     Schema extends EnumSchema<infer Enum> ? Enum
   : Schema extends NullSchema ? null
   : Schema extends BooleanSchema ? boolean
   : Schema extends NumberSchema ? number
   : Schema extends StringSchema ? string
-  : Schema extends ArraySchema<infer ItemSchema> ? ExtractedSchemaArray<ItemSchema>
-  : Schema extends ObjectSchema<infer Properties, infer Required> ? ExtractedSchemaObject<Properties, Required>
+  : Schema extends ArraySchema<infer ItemSchema> ? ArrayFromSchema<ItemSchema>
+  : Schema extends ObjectSchema<infer Properties, infer Required> ? ObjectFromSchema<Properties, Required>
   : never
 )
 
@@ -61,7 +61,7 @@ declare namespace factory {
   }
 }
 
-declare interface Validator<Schema, Output = ExtractSchemaType<Schema>> {
+declare interface Validator<Schema, Output = TypeFromSchema<Schema>> {
   (input: unknown, options?: any): input is Output
   errors: factory.ValidationError[]
   toJSON(): Schema
@@ -75,8 +75,8 @@ declare interface Factory {
   <Properties extends Record<string, AnySchema>, Required extends keyof Properties> (schema: ObjectSchema<Properties, Required>, options?: any): Validator<ObjectSchema<Properties, Required>>
   <Schema extends AnySchema> (schema: Schema, options?: any): Validator<Schema>
 
-  createFilter<Properties extends Record<string, AnySchema>, Required extends keyof Properties> (schema: ObjectSchema<Properties, Required>, options?: any): Filter<ExtractedSchemaObject<Properties, Required>>
-  createFilter<Schema extends AnySchema> (schema: Schema, options?: any): Filter<ExtractSchemaType<Schema>>
+  createFilter<Properties extends Record<string, AnySchema>, Required extends keyof Properties> (schema: ObjectSchema<Properties, Required>, options?: any): Filter<ObjectFromSchema<Properties, Required>>
+  createFilter<Schema extends AnySchema> (schema: Schema, options?: any): Filter<TypeFromSchema<Schema>>
 }
 
 declare const factory: Factory

From 4c39294798cc90142cc56274e0bb20b8e752aaa7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20Unneb=C3=A4ck?= <linus@folkdatorn.se>
Date: Thu, 9 Aug 2018 22:14:21 +0100
Subject: [PATCH 6/6] Tighten up generic input types

---
 index.d.ts | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index 2d234c2..da692e4 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,4 +1,5 @@
 type AnySchema = NullSchema | BooleanSchema | NumberSchema | StringSchema | AnyEnumSchema | AnyArraySchema | AnyObjectSchema
+type StringKeys<T> = (keyof T) & string
 
 interface NullSchema {
   type: 'null'
@@ -28,20 +29,20 @@ interface ArraySchema<ItemSchema extends AnySchema> {
 }
 
 interface AnyObjectSchema extends ObjectSchema<Record<string, AnySchema>, string> {}
-interface ObjectSchema<Properties extends Record<string, AnySchema>, Required extends keyof Properties> {
+interface ObjectSchema<Properties extends Record<string, AnySchema>, Required extends StringKeys<Properties>> {
   additionalProperties?: boolean
   type: 'object'
   properties: Properties
   required: Required[]
 }
 
-interface ArrayFromSchema<Schema> extends Array<TypeFromSchema<Schema>> {}
+interface ArrayFromSchema<ItemSchema extends AnySchema> extends Array<TypeFromSchema<ItemSchema>> {}
 
-declare type ObjectFromSchema<Properties, Required> = {
+type ObjectFromSchema<Properties extends Record<string, AnySchema>, Required extends StringKeys<Properties>> = {
   [Key in keyof Properties]: (Key extends Required ? TypeFromSchema<Properties[Key]> : TypeFromSchema<Properties[Key]> | undefined)
 }
 
-declare type TypeFromSchema<Schema> = (
+type TypeFromSchema<Schema extends AnySchema> = (
     Schema extends EnumSchema<infer Enum> ? Enum
   : Schema extends NullSchema ? null
   : Schema extends BooleanSchema ? boolean
@@ -61,21 +62,21 @@ declare namespace factory {
   }
 }
 
-declare interface Validator<Schema, Output = TypeFromSchema<Schema>> {
+interface Validator<Schema extends AnySchema, Output = TypeFromSchema<Schema>> {
   (input: unknown, options?: any): input is Output
   errors: factory.ValidationError[]
   toJSON(): Schema
 }
 
-declare interface Filter<Output> {
+interface Filter<Output> {
   (input: Output, options?: any): Output
 }
 
-declare interface Factory {
-  <Properties extends Record<string, AnySchema>, Required extends keyof Properties> (schema: ObjectSchema<Properties, Required>, options?: any): Validator<ObjectSchema<Properties, Required>>
+interface Factory {
+  <Properties extends Record<string, AnySchema>, Required extends StringKeys<Properties>> (schema: ObjectSchema<Properties, Required>, options?: any): Validator<ObjectSchema<Properties, Required>>
   <Schema extends AnySchema> (schema: Schema, options?: any): Validator<Schema>
 
-  createFilter<Properties extends Record<string, AnySchema>, Required extends keyof Properties> (schema: ObjectSchema<Properties, Required>, options?: any): Filter<ObjectFromSchema<Properties, Required>>
+  createFilter<Properties extends Record<string, AnySchema>, Required extends StringKeys<Properties>> (schema: ObjectSchema<Properties, Required>, options?: any): Filter<ObjectFromSchema<Properties, Required>>
   createFilter<Schema extends AnySchema> (schema: Schema, options?: any): Filter<TypeFromSchema<Schema>>
 }