fix: improved leading comments in front of a type as well as extensible interface keys

examples/commons/extensible_metadata.cddl

@@ -0,0 +1,11 @@
+MetadataScalar = null / bool / int / float / text
+MessageMetadata = {
+  ? provider: text,
+  ? model: text,
+  ? modelType: text,
+  ? runId: text,
+  ? threadId: text,
+  ? systemFingerprint: text,
+  ? serviceTier: text,
+  * text => MetadataScalar,
+}

packages/cddl2py/src/index.ts

@@ -28,6 +28,8 @@ interface ResolveTypeOptions {
     quoteForwardReferences?: boolean
 }
 
+const STRING_RECORD_KEY_TYPES = new Set(['str', 'text', 'tstr'])
+
 export function transform (assignments: Assignment[], options?: TransformOptions): string {
     const ctx: Context = {
         pydantic: options?.pydantic ?? false,
@@ -135,6 +137,7 @@ function generateGroup (group: Group, ctx: Context): string {
     }
 
     const props = properties as Property[]
+    const extraItemsType = getExtraItemsType(props, ctx)
 
     if (props.length === 1) {
         const prop = props[0]
@@ -150,7 +153,7 @@ function generateGroup (group: Group, ctx: Context): string {
     }
 
     const mixins = props.filter(isUnNamedProperty)
-    const ownProps = props.filter(p => !isUnNamedProperty(p))
+    const ownProps = props.filter(p => !isUnNamedProperty(p) && !isExtensibleRecordProperty(p))
 
     const simpleMixinBases: string[] = []
     const unionMixinGroups: string[][] = []
@@ -186,10 +189,10 @@ function generateGroup (group: Group, ctx: Context): string {
     }
 
     if (unionMixinGroups.length > 0) {
-        return comments + generateGroupWithUnionMixins(name, simpleMixinBases, unionMixinGroups, ownProps, ctx)
+        return comments + generateGroupWithUnionMixins(name, simpleMixinBases, unionMixinGroups, ownProps, extraItemsType, ctx)
     }
 
-    return comments + generateClass(name, simpleMixinBases, ownProps, ctx)
+    return comments + generateClass(name, simpleMixinBases, ownProps, ctx, extraItemsType)
 }
 
 function generateGroupWithChoices (name: string, properties: (Property | Property[])[], ctx: Context): string {
@@ -259,6 +262,7 @@ function generateGroupWithUnionMixins (
     simpleBases: string[],
     unionGroups: string[][],
     ownProps: Property[],
+    extraItemsType: string | undefined,
     ctx: Context
 ): string {
     if (ownProps.length === 0 && simpleBases.length === 0) {
@@ -278,7 +282,7 @@ function generateGroupWithUnionMixins (
 
         if (ownProps.length > 0) {
             const baseName = `_${name}Fields`
-            blocks.push(generateClass(baseName, [], ownProps, ctx))
+            blocks.push(generateClass(baseName, [], ownProps, ctx, extraItemsType))
 
             for (let i = 0; i < unionTypes.length; i++) {
                 const variantName = `_${name}Variant${i}`
@@ -291,7 +295,7 @@ function generateGroupWithUnionMixins (
                 const variantName = `_${name}Variant${i}`
                 variantNames.push(variantName)
                 const bases = [unionTypes[i], ...simpleBases]
-                blocks.push(generateClass(variantName, bases, [], ctx))
+                blocks.push(generateClass(variantName, bases, [], ctx, extraItemsType))
             }
         }
     } else {
@@ -366,7 +370,13 @@ function generateArrayAssignment (arr: CDDLArray, ctx: Context): string {
 // Class generation (TypedDict or Pydantic BaseModel)
 // ---------------------------------------------------------------------------
 
-function generateClass (name: string, bases: string[], props: Property[], ctx: Context): string {
+function generateClass (
+    name: string,
+    bases: string[],
+    props: Property[],
+    ctx: Context,
+    extraItemsType?: string
+): string {
     const lines: string[] = []
 
     let classDecl: string
@@ -381,17 +391,25 @@ function generateClass (name: string, bases: string[], props: Property[], ctx: C
     } else {
         ctx.typingExtensionsImports.add('TypedDict')
         const typedDictBases = bases.filter((base) => isModelCompatibleBase(base, ctx))
-        if (typedDictBases.length > 0) {
-            classDecl = `class ${name}(${typedDictBases.join(', ')}):`
-        } else {
-            classDecl = `class ${name}(TypedDict):`
-        }
+        const baseList = typedDictBases.length > 0 ? typedDictBases.join(', ') : 'TypedDict'
+        classDecl = extraItemsType
+            ? `class ${name}(${baseList}, extra_items=${extraItemsType}):`
+            : `class ${name}(${baseList}):`
     }
 
     lines.push(classDecl)
 
+    if (ctx.pydantic && extraItemsType) {
+        ctx.pydanticImports.add('ConfigDict')
+        ctx.pydanticImports.add('Field')
+        lines.push(`    __pydantic_extra__: dict[str, ${extraItemsType}] = Field(init=False)`)
+        lines.push(`    model_config = ConfigDict(extra='allow')`)
+    }
+
     if (props.length === 0) {
-        lines.push('    pass')
+        if (lines.length === 1) {
+            lines.push('    pass')
+        }
         return lines.join('\n')
     }
 
@@ -470,6 +488,34 @@ function generateField (prop: Property, ctx: Context): string | null {
     return `    ${propName}: ${typeStr}${commentSuffix}`
 }
 
+function isExtensibleRecordProperty (prop: Property): boolean {
+    return !isUnNamedProperty(prop) &&
+        prop.Occurrence.m === Infinity &&
+        !prop.HasCut &&
+        STRING_RECORD_KEY_TYPES.has(prop.Name)
+}
+
+function getExtraItemsType (props: Property[], ctx: Context): string | undefined {
+    const types = props
+        .filter(isExtensibleRecordProperty)
+        .flatMap((prop) => {
+            const cddlTypes = Array.isArray(prop.Type) ? prop.Type : [prop.Type]
+            return cddlTypes.map((type) => resolveType(type, ctx))
+        })
+
+    if (types.length === 0) {
+        return
+    }
+
+    const uniqueTypes = [...new Set(types)]
+    if (uniqueTypes.length === 1) {
+        return uniqueTypes[0]
+    }
+
+    ctx.typingImports.add('Union')
+    return `Union[${uniqueTypes.join(', ')}]`
+}
+
 // ---------------------------------------------------------------------------
 // Type resolution
 // ---------------------------------------------------------------------------

packages/cddl2py/tests/__snapshots__/extensible_metadata.test.ts.snap

@@ -0,0 +1,22 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`extensible metadata > should render extensible metadata as a TypedDict with extra_items 1`] = `
+"# compiled with https://www.npmjs.com/package/cddl2py
+
+from __future__ import annotations
+
+from typing import Union
+from typing_extensions import NotRequired, TypedDict
+
+MetadataScalar = Union[None, bool, int, float, str]
+
+class MessageMetadata(TypedDict, extra_items=MetadataScalar):
+    provider: NotRequired[str]
+    model: NotRequired[str]
+    model_type: NotRequired[str]
+    run_id: NotRequired[str]
+    thread_id: NotRequired[str]
+    system_fingerprint: NotRequired[str]
+    service_tier: NotRequired[str]
+"
+`;

packages/cddl2py/tests/extensible_metadata.test.ts

@@ -0,0 +1,71 @@
+import url from 'node:url'
+import path from 'node:path'
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
+
+import cli from '../src/cli.js'
+import { normalizeSnapshotOutput } from './snapshot.js'
+
+const __dirname = url.fileURLToPath(new URL('.', import.meta.url))
+const cddlFile = path.join(__dirname, '..', '..', '..', 'examples', 'commons', 'extensible_metadata.cddl')
+
+vi.mock('../src/constants', () => ({
+    pkg: {
+        name: 'cddl2py',
+        version: '0.1.0',
+        author: 'Test Author',
+        description: 'Generate Python types from CDDL'
+    },
+    NATIVE_TYPE_MAP: {
+        any: 'Any',
+        number: 'Union[int, float]',
+        int: 'int',
+        uint: 'int',
+        nint: 'int',
+        float: 'float',
+        float16: 'float',
+        float32: 'float',
+        float64: 'float',
+        bool: 'bool',
+        bstr: 'bytes',
+        bytes: 'bytes',
+        tstr: 'str',
+        text: 'str',
+        str: 'str',
+        nil: 'None',
+        null: 'None',
+    }
+}))
+
+describe('extensible metadata', () => {
+    let exitOrig = process.exit
+    let logOrig = console.log
+    let errorOrig = console.error
+
+    beforeEach(() => {
+        process.exit = vi.fn() as any
+        console.log = vi.fn()
+        console.error = vi.fn()
+    })
+
+    afterEach(() => {
+        process.exit = exitOrig
+        console.log = logOrig
+        console.error = errorOrig
+    })
+
+    it('should render extensible metadata as a TypedDict with extra_items', async () => {
+        await cli([cddlFile])
+
+        expect(process.exit).not.toHaveBeenCalledWith(1)
+        expect(console.error).not.toHaveBeenCalled()
+
+        const output = vi.mocked(console.log).mock.calls.flat().join('\n')
+
+        expect(output).toContain('class MessageMetadata(TypedDict, extra_items=MetadataScalar):')
+        expect(output).toContain('provider: NotRequired[str]')
+        expect(output).toContain('model_type: NotRequired[str]')
+        expect(output).toContain('system_fingerprint: NotRequired[str]')
+        expect(output).not.toContain('text: NotRequired[MetadataScalar]')
+        expect(normalizeSnapshotOutput(output)).toMatchSnapshot()
+    })
+})

packages/cddl2py/tests/transform_edge_cases.test.ts

@@ -281,6 +281,48 @@ describe('transform edge cases', () => {
         expect(output).toContain('maybe_enabled: Optional[bool] = Field(default=False)')
     })
 
+    it('should emit extensible TypedDict properties as extra_items', () => {
+        const output = transform([
+            variable('metadata-scalar', ['null', 'bool', 'int', 'float', 'text']),
+            group('message-metadata', [
+                property('provider', 'text', {
+                    Occurrence: { n: 0, m: 1 }
+                }),
+                property('model', 'text', {
+                    Occurrence: { n: 0, m: 1 }
+                }),
+                property('text', groupRef('metadata-scalar'), {
+                    Occurrence: { n: 0, m: Infinity }
+                })
+            ])
+        ])
+
+        expect(output).toContain('class MessageMetadata(TypedDict, extra_items=MetadataScalar):')
+        expect(output).toContain('provider: NotRequired[str]')
+        expect(output).toContain('model: NotRequired[str]')
+        expect(output).not.toContain('text: NotRequired[MetadataScalar]')
+    })
+
+    it('should emit typed extra fields for pydantic models', () => {
+        const output = transform([
+            variable('metadata-scalar', ['null', 'bool', 'int', 'float', 'text']),
+            group('message-metadata', [
+                property('provider', 'text', {
+                    Occurrence: { n: 0, m: 1 }
+                }),
+                property('text', groupRef('metadata-scalar'), {
+                    Occurrence: { n: 0, m: Infinity }
+                })
+            ])
+        ], { pydantic: true })
+
+        expect(output).toContain('from pydantic import BaseModel, ConfigDict, Field')
+        expect(output).toContain('class MessageMetadata(BaseModel):')
+        expect(output).toContain('__pydantic_extra__: dict[str, MetadataScalar] = Field(init=False)')
+        expect(output).toContain(`model_config = ConfigDict(extra='allow')`)
+        expect(output).not.toContain('text: MetadataScalar')
+    })
+
     it('should cover direct type-resolution edge cases', () => {
         const output = transform([
             variable('direct-range', {