firebase-ios-sdk/GeminiLanguageModel/scripts/typegen

Swift type generation (typegen)

This directory contains the OpenAPI 3.1.0 upgrade and Swift code generation pipeline used to generate the data models in GeminiLanguageModel/Sources/GeminiAPIDataModels/GenerateContent.

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Architecture and code generation workflow

graph TD
    A["Google Discovery Document JSON"] -->|Upgraded by| B("upgrade_spec.py")
    E["firebasevertexai-overrides.yaml"] -->|Merged by| B
    B -->|Produces| F["firebasevertexai-openapi.yaml"]
    F -->|Parsed by| C("generate_types.py")
    E -->|Configures| C
    D["Jinja2 Swift Templates"] -->|Rendered by| C
    C -->|Generates Swift Models| G["Sources/GeminiAPIDataModels/GenerateContent"]

Setup

From GeminiLanguageModel/scripts/typegen:

python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

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1. Upgrading the specification (upgrade_spec.py)

Before generating types, convert the Google Discovery Document to an OpenAPI 3.1.0 specification and apply manual overrides:

python upgrade_spec.py

If discovery_documents/firebasevertexai_discovery_v1beta.json is not cached locally, upgrade_spec.py automatically downloads it from Google APIs. To force a fresh download of the latest Discovery Document even when cached:

python upgrade_spec.py --fetch

This script loads firebasevertexai_discovery_v1beta.json, normalizes schema references, extracts shared standalone enums (such as HarmCategory, Modality, and DataType), infers required fields, merges manual overrides from firebasevertexai-overrides.yaml, and writes discovery_documents/firebasevertexai-openapi.yaml (both the fetched .json and generated -openapi.yaml files are gitignored).

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2. Generating Swift types (generate_types.py)

Use generate_types.py to parse the upgraded OpenAPI 3.1.0 specification and write Swift types directly into GeminiLanguageModel/Sources/GeminiAPIDataModels/GenerateContent:

python generate_types.py

Command-line arguments reference

Argument	Default	Description
--openapi-spec	discovery_documents/firebasevertexai-openapi.yaml	Upgraded spec YAML path.
--overrides-file	discovery_documents/firebasevertexai-overrides.yaml	YAML overrides file path.
--output-dir	../../Sources/GeminiAPIDataModels/GenerateContent	Output directory.
--roots	["GenerateContentRequest", ...]	Roots to resolve.
--access-level	package	Swift access control: public, package, or internal.
--strip-prefix	all generatorConfig.backends	Backend prefixes to strip and merge (pass with no values to disable).
--namespace	""	Swift root namespace.
--shared-models-target	""	Shared models target.
--templates-dir	templates	Jinja2 templates folder.
--doc-wrap-width	100	Maximum column width for DocC comments.
--verbose	false	Enable verbose output.

The overrides file is required: the generator exits with an error if it is missing, rather than generating a much smaller type set and pruning existing output. Each --strip-prefix value must be listed in generatorConfig.backends. If no backends are configured, the generator exits with an error unless --strip-prefix is passed with no values. Backends are always merged Developer API (gl-developer) first, regardless of argument or config order.

Code layout

generate_types.py is a thin entry point. The implementation lives in the swift_typegen package:

Module	Responsibility
cli.py	Argument parsing; builds PipelineOptions.
pipeline.py	Orchestration: load → per-backend preprocess → merge → cycle check → process → write.
config.py	GeneratorConfig, loaded from the overrides YAML generatorConfig block (including backends prefixes/tags and preservedFiles).
merge.py	Backend prefix stripping, schema renaming, and cross-backend schema merging.
graph.py	$ref traversal, reachability from roots, and cycle detection.
processor.py	SchemaProcessor: OpenAPI schemas → SwiftType models.
models.py	SwiftType, SwiftProperty, SwiftEnumCase.
naming.py	Swift identifier casing, acronyms, and keyword escaping.
docc.py	DocC comment extraction, cleanup, and wrapping.
render.py	Jinja2 rendering to (filename, source) with no file I/O.
output.py	Writing files, swift format, and pruning stale outputs.

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3. Running unit tests

From GeminiLanguageModel/scripts/typegen/:

python -m unittest discover -s tests -t .

Or from anywhere in the repository:

python -m unittest discover \
  -s GeminiLanguageModel/scripts/typegen/tests \
  -t GeminiLanguageModel/scripts/typegen

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4. Formatting

Python sources are formatted with pyink using the settings in pyproject.toml. From GeminiLanguageModel/scripts/typegen/:

pip install pyink
pyink .