Adds enum support to Picoschema.

docs/dotprompt.md

@@ -71,6 +71,7 @@ schema:
   title: string # string, number, and boolean types are defined like this
   subtitle?: string # optional fields are marked with a `?`
   draft?: boolean, true when in draft state
+  status?(enum, approval status): [PENDING, APPROVED]
   date: string, the date of publication e.g. '2024-04-09' # descriptions follow a comma
   tags(array, relevant tags for article): string # arrays are denoted via parentheses
   authors(array):
@@ -89,6 +90,8 @@ interface Article {
   subtitle?: string;
   /** true when in draft state */
   draft?: boolean;
+  /** approval status */
+  status?: 'PENDING' | 'APPROVED';
   /** the date of publication e.g. '2024-04-09' */
   date: string;
   /** relevant tags for article */
@@ -107,7 +110,7 @@ interface Article {
 ```
 
 Picoschema supports scalar types `string`, `integer`, `number`, and `boolean`. For
-objects and arrays, they are denoted by a parenthetical after the field name.
+objects, arrays, and enums they are denoted by a parenthetical after the field name.
 
 Objects defined by Picoschema have all properties as required unless denoted optional
 by `?`, and do not allow additional properties.

js/dotprompt/src/picoschema.ts

@@ -93,6 +93,8 @@ function parsePico(obj: any, path: string[] = []): JSONSchema {
       };
     } else if (type === 'object') {
       schema.properties[propertyName] = parsePico(obj[key], [...path, key]);
+    } else if (type === 'enum') {
+      schema.properties[propertyName] = { enum: obj[key] };
     } else {
       throw new Error(
         "Picoschema: parenthetical types must be 'object' or 'array', got: " +

js/dotprompt/tests/picoschema_test.ts

@@ -147,6 +147,18 @@ describe('picoschema()', () => {
     foo: {type: string}`,
       want: { type: 'object', properties: { foo: { type: 'string' } } },
     },
+    {
+      description: 'enum field',
+      yaml: `schema:
+  color?(enum, the enum): [RED, BLUE, GREEN]`,
+      want: {
+        type: 'object',
+        properties: {
+          color: { description: 'the enum', enum: ['RED', 'BLUE', 'GREEN'] },
+        },
+        additionalProperties: false,
+      },
+    },
   ];
 
   for (const test of tests) {