Add schema tree node gathering for cleaning in pydantic GenerateSchema

Author: MarkusSintonen

.github/workflows/ci.yml

@@ -212,7 +212,8 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          repository: pydantic/pydantic
+          repository: MarkusSintonen/pydantic  # TODO remove before merging
+          ref: optimized-schema-building
           path: pydantic
 
       - uses: actions/checkout@v4

pyproject.toml

@@ -53,6 +53,7 @@ python-source = "python"
 module-name = "pydantic_core._pydantic_core"
 bindings = 'pyo3'
 features = ["pyo3/extension-module"]
+profile = "release"  # TEMPORARY: remove this
 
 [tool.ruff]
 line-length = 120

python/pydantic_core/__init__.py

@@ -23,11 +23,12 @@
     ValidationError,
     __version__,
     from_json,
+    gather_schemas_for_cleaning,
     to_json,
     to_jsonable_python,
     validate_core_schema,
 )
-from .core_schema import CoreConfig, CoreSchema, CoreSchemaType, ErrorType
+from .core_schema import CoreConfig, CoreSchema, CoreSchemaType, DefinitionReferenceSchema, ErrorType
 
 if _sys.version_info < (3, 11):
     from typing_extensions import NotRequired as _NotRequired
@@ -67,6 +68,7 @@
     'from_json',
     'to_jsonable_python',
     'validate_core_schema',
+    'gather_schemas_for_cleaning',
 ]
 
 
@@ -137,3 +139,11 @@ class MultiHostHost(_TypedDict):
     """The host part of this host, or `None`."""
     port: int | None
     """The port part of this host, or `None`."""
+
+
+class GatherResult(_TypedDict):
+    """Internal result of gathering schemas for cleaning."""
+
+    definition_refs: dict[str, list[DefinitionReferenceSchema]]
+    recursive_refs: set[str]
+    deferred_discriminators: list[tuple[CoreSchema, _Any]]

python/pydantic_core/_pydantic_core.pyi

@@ -5,7 +5,7 @@ from typing import Any, Callable, Generic, Literal, TypeVar, final
 from _typeshed import SupportsAllComparisons
 from typing_extensions import LiteralString, Self, TypeAlias
 
-from pydantic_core import ErrorDetails, ErrorTypeInfo, InitErrorDetails, MultiHostHost
+from pydantic_core import ErrorDetails, ErrorTypeInfo, GatherResult, InitErrorDetails, MultiHostHost
 from pydantic_core.core_schema import CoreConfig, CoreSchema, ErrorType
 
 __all__ = [
@@ -35,6 +35,7 @@ __all__ = [
     'list_all_errors',
     'TzInfo',
     'validate_core_schema',
+    'gather_schemas_for_cleaning',
 ]
 __version__: str
 build_profile: str
@@ -1164,3 +1165,7 @@ def validate_core_schema(schema: CoreSchema, *, strict: bool | None = None) -> C
     We may also remove this function altogether, do not rely on it being present if you are
     using pydantic-core directly.
     """
+
+def gather_schemas_for_cleaning(schema: CoreSchema, definitions: dict[str, CoreSchema]) -> GatherResult:
+    """Used internally for schema cleaning when schemas are generated.
+    Gathers information from the schema tree for the cleaning."""

src/lib.rs

@@ -22,6 +22,7 @@ mod errors;
 mod input;
 mod lookup_key;
 mod recursion_guard;
+mod schema_traverse;
 mod serializers;
 mod tools;
 mod url;
@@ -35,6 +36,7 @@ pub use build_tools::SchemaError;
 pub use errors::{
     list_all_errors, PydanticCustomError, PydanticKnownError, PydanticOmit, PydanticUseDefault, ValidationError,
 };
+pub use schema_traverse::gather_schemas_for_cleaning;
 pub use serializers::{
     to_json, to_jsonable_python, PydanticSerializationError, PydanticSerializationUnexpectedValue, SchemaSerializer,
     WarningsArg,
@@ -133,6 +135,7 @@ fn _pydantic_core(py: Python, m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(from_json, m)?)?;
     m.add_function(wrap_pyfunction!(to_jsonable_python, m)?)?;
     m.add_function(wrap_pyfunction!(list_all_errors, m)?)?;
+    m.add_function(wrap_pyfunction!(gather_schemas_for_cleaning, m)?)?;
     m.add_function(wrap_pyfunction!(validate_core_schema, m)?)?;
     Ok(())
 }

src/schema_traverse.rs

@@ -0,0 +1,194 @@
+use crate::tools::py_err;
+use pyo3::exceptions::PyKeyError;
+use pyo3::prelude::*;
+use pyo3::types::{PyDict, PyList, PySet, PyString, PyTuple};
+use pyo3::{intern, Bound, PyResult};
+use std::collections::HashSet;
+
+const CORE_SCHEMA_METADATA_DISCRIMINATOR_PLACEHOLDER_KEY: &str = "pydantic.internal.union_discriminator";
+
+macro_rules! get {
+    ($dict: expr, $key: expr) => {
+        $dict.get_item(intern!($dict.py(), $key))?
+    };
+}
+
+macro_rules! traverse_key_fn {
+    ($key: expr, $func: expr, $dict: expr, $ctx: expr) => {{
+        if let Some(v) = get!($dict, $key) {
+            $func(v.downcast_exact()?, $ctx)?
+        }
+    }};
+}
+
+macro_rules! traverse {
+    ($($key:expr => $func:expr),*; $dict: expr, $ctx: expr) => {{
+        $(traverse_key_fn!($key, $func, $dict, $ctx);)*
+        gather_serialization($dict, $ctx)?;
+        gather_meta($dict, $ctx)?;
+    }}
+}
+
+macro_rules! defaultdict_list_append {
+    ($dict: expr, $key: expr, $value: expr) => {{
+        match $dict.get_item($key)? {
+            None => {
+                let list = PyList::empty_bound($dict.py());
+                list.append($value)?;
+                $dict.set_item($key, list)?;
+            }
+            // Safety: we know that the value is a PyList as we just created it above
+            Some(list) => unsafe { list.downcast_unchecked::<PyList>() }.append($value)?,
+        };
+    }};
+}
+
+fn gather_definition_ref(schema_ref_dict: &Bound<'_, PyDict>, ctx: &mut GatherCtx) -> PyResult<()> {
+    if let Some(schema_ref) = get!(schema_ref_dict, "schema_ref") {
+        let schema_ref_pystr = schema_ref.downcast_exact::<PyString>()?;
+        let schema_ref_str = schema_ref_pystr.to_str()?;
+
+        if !ctx.recursively_seen_refs.contains(schema_ref_str) {
+            defaultdict_list_append!(&ctx.def_refs, schema_ref_pystr, schema_ref_dict);
+
+            // TODO should py_err! when not found. That error can be used to detect the missing defs in cleaning side
+            if let Some(definition) = ctx.definitions_dict.get_item(schema_ref_pystr)? {
+                ctx.recursively_seen_refs.insert(schema_ref_str.to_string());
+
+                gather_schema(definition.downcast_exact::<PyDict>()?, ctx)?;
+                gather_serialization(schema_ref_dict, ctx)?;
+                gather_meta(schema_ref_dict, ctx)?;
+
+                ctx.recursively_seen_refs.remove(schema_ref_str);
+            }
+        } else {
+            ctx.recursive_def_refs.add(schema_ref_pystr)?;
+            for seen_ref in &ctx.recursively_seen_refs {
+                let seen_ref_pystr = PyString::new_bound(schema_ref.py(), seen_ref);
+                ctx.recursive_def_refs.add(seen_ref_pystr)?;
+            }
+        }
+        Ok(())
+    } else {
+        py_err!(PyKeyError; "Invalid definition-ref, missing schema_ref")
+    }
+}
+
+fn gather_serialization(schema: &Bound<'_, PyDict>, ctx: &mut GatherCtx) -> PyResult<()> {
+    if let Some(ser) = get!(schema, "serialization") {
+        let ser_dict = ser.downcast_exact::<PyDict>()?;
+        traverse!("schema" => gather_schema, "return_schema" => gather_schema; ser_dict, ctx);
+    }
+    Ok(())
+}
+
+fn gather_meta(schema: &Bound<'_, PyDict>, ctx: &mut GatherCtx) -> PyResult<()> {
+    if let Some(meta) = get!(schema, "metadata") {
+        let meta_dict = meta.downcast_exact::<PyDict>()?;
+        if let Some(discriminator) = get!(meta_dict, CORE_SCHEMA_METADATA_DISCRIMINATOR_PLACEHOLDER_KEY) {
+            let schema_discriminator = PyTuple::new_bound(schema.py(), vec![schema.as_any(), &discriminator]);
+            ctx.discriminators.append(schema_discriminator)?;
+        }
+    }
+    Ok(())
+}
+
+fn gather_list(schema_list: &Bound<'_, PyList>, ctx: &mut GatherCtx) -> PyResult<()> {
+    for v in schema_list.iter() {
+        gather_schema(v.downcast_exact()?, ctx)?;
+    }
+    Ok(())
+}
+
+fn gather_dict(schemas_by_key: &Bound<'_, PyDict>, ctx: &mut GatherCtx) -> PyResult<()> {
+    for (_, v) in schemas_by_key.iter() {
+        gather_schema(v.downcast_exact()?, ctx)?;
+    }
+    Ok(())
+}
+
+fn gather_union_choices(schema_list: &Bound<'_, PyList>, ctx: &mut GatherCtx) -> PyResult<()> {
+    for v in schema_list.iter() {
+        if let Ok(tup) = v.downcast_exact::<PyTuple>() {
+            gather_schema(tup.get_item(0)?.downcast_exact()?, ctx)?;
+        } else {
+            gather_schema(v.downcast_exact()?, ctx)?;
+        }
+    }
+    Ok(())
+}
+
+fn gather_arguments(arguments: &Bound<'_, PyList>, ctx: &mut GatherCtx) -> PyResult<()> {
+    for v in arguments.iter() {
+        traverse_key_fn!("schema", gather_schema, v.downcast_exact::<PyDict>()?, ctx);
+    }
+    Ok(())
+}
+
+// Has 100% coverage in Pydantic side. This is exclusively used there
+#[cfg_attr(has_coverage_attribute, coverage(off))]
+fn gather_schema(schema: &Bound<'_, PyDict>, ctx: &mut GatherCtx) -> PyResult<()> {
+    let type_ = get!(schema, "type");
+    if type_.is_none() {
+        return py_err!(PyKeyError; "Schema type missing");
+    }
+    match type_.unwrap().downcast_exact::<PyString>()?.to_str()? {
+        "definition-ref" => gather_definition_ref(schema, ctx)?,
+        "definitions" => traverse!("schema" => gather_schema, "definitions" => gather_list; schema, ctx),
+        "list" | "set" | "frozenset" | "generator" => traverse!("items_schema" => gather_schema; schema, ctx),
+        "tuple" => traverse!("items_schema" => gather_list; schema, ctx),
+        "dict" => traverse!("keys_schema" => gather_schema, "values_schema" => gather_schema; schema, ctx),
+        "union" => traverse!("choices" => gather_union_choices; schema, ctx),
+        "tagged-union" => traverse!("choices" => gather_dict; schema, ctx),
+        "chain" => traverse!("steps" => gather_list; schema, ctx),
+        "lax-or-strict" => traverse!("lax_schema" => gather_schema, "strict_schema" => gather_schema; schema, ctx),
+        "json-or-python" => traverse!("json_schema" => gather_schema, "python_schema" => gather_schema; schema, ctx),
+        "model-fields" | "typed-dict" => traverse!(
+            "extras_schema" => gather_schema, "computed_fields" => gather_list, "fields" => gather_dict; schema, ctx
+        ),
+        "dataclass-args" => traverse!("computed_fields" => gather_list, "fields" => gather_list; schema, ctx),
+        "arguments" => traverse!(
+            "arguments_schema" => gather_arguments,
+            "var_args_schema" => gather_schema,
+            "var_kwargs_schema" => gather_schema;
+            schema, ctx
+        ),
+        "call" => traverse!("arguments_schema" => gather_schema, "return_schema" => gather_schema; schema, ctx),
+        "computed-field" | "function-plain" => traverse!("return_schema" => gather_schema; schema, ctx),
+        "function-wrap" => traverse!("return_schema" => gather_schema, "schema" => gather_schema; schema, ctx),
+        _ => traverse!("schema" => gather_schema; schema, ctx),
+    };
+    Ok(())
+}
+
+pub struct GatherCtx<'a, 'py> {
+    pub definitions_dict: &'a Bound<'py, PyDict>,
+    pub def_refs: Bound<'py, PyDict>,
+    pub recursive_def_refs: Bound<'py, PySet>,
+    pub discriminators: Bound<'py, PyList>,
+    recursively_seen_refs: HashSet<String>,
+}
+
+#[pyfunction(signature = (schema, definitions))]
+pub fn gather_schemas_for_cleaning<'py>(
+    schema: &Bound<'py, PyAny>,
+    definitions: &Bound<'py, PyAny>,
+) -> PyResult<Bound<'py, PyDict>> {
+    let py = schema.py();
+    let schema_dict = schema.downcast_exact::<PyDict>()?;
+
+    let mut ctx = GatherCtx {
+        definitions_dict: definitions.downcast_exact()?,
+        def_refs: PyDict::new_bound(definitions.py()),
+        recursive_def_refs: PySet::empty_bound(definitions.py())?,
+        discriminators: PyList::empty_bound(definitions.py()),
+        recursively_seen_refs: HashSet::new(),
+    };
+    gather_schema(schema_dict, &mut ctx)?;
+
+    let res = PyDict::new_bound(py);
+    res.set_item(intern!(py, "definition_refs"), ctx.def_refs)?;
+    res.set_item(intern!(py, "recursive_refs"), ctx.recursive_def_refs)?;
+    res.set_item(intern!(py, "deferred_discriminators"), ctx.discriminators)?;
+    Ok(res)
+}