feat: custom schema extension

src/applySchemaTyping.ts

@@ -1,9 +1,10 @@
 import type {LinkedJSONSchema} from './types/JSONSchema'
 import {Intersection, Parent, Types} from './types/JSONSchema'
 import {typesOfSchema} from './typesOfSchema'
+import {Options} from './'
 
-export function applySchemaTyping(schema: LinkedJSONSchema) {
-  const types = typesOfSchema(schema)
+export function applySchemaTyping(schema: LinkedJSONSchema, options?: Options) {
+  const types = typesOfSchema(schema, options)
 
   Object.defineProperty(schema, Types, {
     enumerable: false,

src/index.ts

@@ -85,6 +85,13 @@ export interface Options {
    * Generate unknown type instead of any
    */
   unknownAny: boolean
+  /**
+   * Custom parser extensions for unsupported schema types
+   */
+  parserExtensions?: Record<
+    string,
+    (schema: Record<string, unknown>, compileSchema: (schema: Record<string, unknown>) => string) => string
+  >
 }
 
 export const DEFAULT_OPTIONS: Options = {

src/normalizer.ts

@@ -242,9 +242,9 @@ rules.set('Add tsEnumNames to enum types', (schema, _, options) => {
 // the intersection schema needs to participate in the schema cache during
 // the parsing step, so it cannot be re-calculated every time the schema
 // is encountered.
-rules.set('Pre-calculate schema types and intersections', schema => {
+rules.set('Pre-calculate schema types and intersections', (schema, _fileName, options) => {
   if (schema !== null && typeof schema === 'object') {
-    applySchemaTyping(schema)
+    applySchemaTyping(schema, options)
   }
 })
 

src/parser.ts

@@ -15,6 +15,7 @@ import type {
 } from './types/JSONSchema'
 import {Intersection, Types, getRootSchema, isBoolean, isPrimitive} from './types/JSONSchema'
 import {generateName, log, maybeStripDefault} from './utils'
+import {generateType} from './generator'
 
 export type Processed = Map<NormalizedJSONSchema, Map<SchemaType, AST>>
 
@@ -157,15 +158,42 @@ function parseNonLiteral(
         standaloneName: standaloneName(schema, keyNameFromDefinition, usedNames, options),
         type: 'BOOLEAN',
       }
-    case 'CUSTOM_TYPE':
+    case 'CUSTOM_TYPE': {
+      let customType: string
+
+      if (schema.tsType) {
+        customType = schema.tsType
+      } else if (options.parserExtensions && schema.type && typeof schema.type === 'string') {
+        const extension = options.parserExtensions[schema.type]
+        if (extension) {
+          // Create a compilation callback for nested schemas
+          const compileSchema = (nestedSchema: any): string => {
+            // Clone the schema to avoid modifying the original
+            const clonedSchema = {...nestedSchema}
+            if (!clonedSchema[Types]) {
+              applySchemaTyping(clonedSchema, options)
+            }
+            const ast = parse(clonedSchema, options, undefined, processed, usedNames)
+            return generateType(ast, options)
+          }
+
+          customType = extension(schema, compileSchema)
+        } else {
+          customType = 'any'
+        }
+      } else {
+        customType = 'any'
+      }
+
       return {
         comment: schema.description,
         deprecated: schema.deprecated,
         keyName,
-        params: schema.tsType!,
+        params: customType,
         standaloneName: standaloneName(schema, keyNameFromDefinition, usedNames, options),
         type: 'CUSTOM_TYPE',
       }
+    }
     case 'NAMED_ENUM':
       return {
         comment: schema.description,
@@ -271,7 +299,7 @@ function parseNonLiteral(
         params: (schema.type as JSONSchema4TypeName[]).map(type => {
           const member: LinkedJSONSchema = {...omit(schema, '$id', 'description', 'title'), type}
           maybeStripDefault(member)
-          applySchemaTyping(member)
+          applySchemaTyping(member, options)
           return parse(member, options, undefined, processed, usedNames)
         }),
         type: 'UNION',

src/typesOfSchema.ts

@@ -1,5 +1,6 @@
 import {isPlainObject} from 'lodash'
 import {isCompound, JSONSchema, SchemaType} from './types/JSONSchema'
+import {Options} from './'
 
 /**
  * Duck types a JSONSchema schema or property to determine which kind of AST node to parse it into.
@@ -9,12 +10,18 @@ import {isCompound, JSONSchema, SchemaType} from './types/JSONSchema'
  * types). The spec leaves it up to implementations to decide what to do with this
  * loosely-defined behavior.
  */
-export function typesOfSchema(schema: JSONSchema): Set<SchemaType> {
+export function typesOfSchema(schema: JSONSchema, options?: Options): Set<SchemaType> {
   // tsType is an escape hatch that supercedes all other directives
   if (schema.tsType) {
     return new Set(['CUSTOM_TYPE'])
   }
 
+  if (options?.parserExtensions && schema.type && typeof schema.type === 'string') {
+    if (schema.type in options.parserExtensions) {
+      return new Set(['CUSTOM_TYPE'])
+    }
+  }
+
   // Collect matched types
   const matchedTypes = new Set<SchemaType>()
   for (const [schemaType, f] of Object.entries(matchers)) {