Adds parsing / validation of JSON configuration, for I19 transmission hardware.

src/dodal/devices/beamlines/i19/transmission/spec_from_config/__init__.py

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+"""Utility library that captures system specification state from JSON.
+
+Beamline scientists have the freedom to edit the JSON files.
+
+The latest state of JSON at system start up should convert to instances of the Spec(ification) classes,
+( which are pydantic (v2) BaseModel classes ).
+For these validated BaseModels the absorber instrumentation classes are built, that the transmission system logic will govern.
+"""

src/dodal/devices/beamlines/i19/transmission/spec_from_config/energy_interval_spec.py

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+from typing import Literal
+
+from pydantic import BaseModel, ConfigDict, Field, StrictFloat, model_validator
+
+
+class EnergyIntervalSpec(BaseModel):
+    """JSON built sub-dict of one energy range, used in specifying material absorption spectra.
+
+    Note:
+        The range of energies is a closed interval, so inclusive of end values.
+
+    Attributes:
+        units: At present only 'keV' (or 'kiloelectronvolts') are supported.
+        lower: The lower end of the energy interval (range) for specific absorption fit curve.
+        upper: The upper end of the energy interval (range) for specific absorption fit curve.
+    """
+
+    units: Literal["keV", "kiloelectronvolts"]
+    lower: StrictFloat = Field(gt=0.0)
+    upper: StrictFloat = Field(gt=0.0)
+
+    # Base Model internal setting to make this class immutable
+    model_config = ConfigDict(frozen=True, extra="forbid")
+
+    @model_validator(mode="after")
+    def validate_attributes(self) -> "EnergyIntervalSpec":
+        if 0.0 < self.lower < self.upper:
+            return self
+        _msg = f"Energy interval lower {self.lower} and upper {self.upper} bounds are in wrong order."
+        raise ValueError(_msg)

src/dodal/devices/beamlines/i19/transmission/spec_from_config/fitted_absorption_curve_spec.py

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+from typing import Final
+
+from pydantic import BaseModel, ConfigDict, Field, StrictFloat
+
+# A roll off exponent outside the -2.0 to -4.0 range is deemed unphysical
+ROLL_OFF_UPPER_BOUND: Final[float] = -2.0
+ROLL_OFF_LOWER_BOUND: Final[float] = -4.0
+
+
+class FittedAbsorptionCurveSpec(BaseModel):
+    """JSON built sub-dict of one absorption curve, used in specifying material absorption spectra.
+
+    Note:
+        One spectrum absorption curve covers a specific energy range where it is valid.
+        One or more such curves make up one absorption spectrum.
+
+    Attributes:
+        photon_absorption:
+            Material characteristic scaling constant which defines absorption curve.
+        roll_off:
+            Power-law exponent for variation with energy, usually something like -2.75 ∓ 0.24.
+        residuals_polynomial_coeffs:
+            Optional residuals correction, zeroth order parameter first.
+    """
+
+    photon_absorption: StrictFloat = Field(gt=0.0)
+    roll_off: StrictFloat = Field(gt=ROLL_OFF_LOWER_BOUND, lt=ROLL_OFF_UPPER_BOUND)
+    residuals_polynomial_coeffs: list[StrictFloat] = Field(default_factory=list)
+
+    # Base Model internal setting to make this class immutable
+    model_config = ConfigDict(frozen=True, extra="forbid")

src/dodal/devices/beamlines/i19/transmission/spec_from_config/foil_spec.py

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+from pydantic import (
+    BaseModel,
+    ConfigDict,
+    StrictFloat,
+)
+
+from dodal.common.general_maths.absorber_geometry import SupportedThicknessUnits
+
+
+class FoilThicknessSpec(BaseModel):
+    """The specification for a flat foil thickness (as specified by configuration, typically **JSON**).
+
+    Attributes:
+        units: The length unit used to specify the foil thickness.
+        value: The foil thickness in the specified unit.
+    """
+
+    units: SupportedThicknessUnits
+    value: StrictFloat
+
+    # Base Model internal setting to make this class immutable
+    model_config = ConfigDict(frozen=True, extra="forbid")
+
+
+class AbsorberSpec(BaseModel):
+    """The specification for a FixedDepth absorber (as specified by configuration, typically **JSON**).
+
+    Attributes:
+        material: The name of the absorber material, as present the in the materials section of the configuration.
+        thickness: ThicknessProvider geometry of the flat foil absorber.
+    """
+
+    material: str
+    thickness: FoilThicknessSpec
+
+    # Base Model internal setting to make this class immutable
+    model_config = ConfigDict(frozen=True, extra="forbid")
+
+
+class FoilSpec(BaseModel):
+    """The specification for a filter slot in a wheel.
+
+    Attributes:
+        absorber: Absorbing filter configuration for a given slot.
+    """
+
+    absorber: AbsorberSpec
+
+    # Base Model internal setting to make this class immutable
+    model_config = ConfigDict(frozen=True, extra="forbid")

src/dodal/devices/beamlines/i19/transmission/spec_from_config/lateral_motor_spec.py

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+from typing import Literal
+
+from pydantic import (
+    BaseModel,
+    ConfigDict,
+    Field,
+    StrictFloat,
+    model_validator,
+)
+
+from dodal.common.general_maths.interval import ClosedInterval
+from dodal.devices.beamlines.i19.transmission.spec_from_config.name_validation import (
+    AxisNameValidation,
+)
+from dodal.devices.beamlines.i19.transmission.spec_from_config.system_aspect_base_parser import (
+    SystemAspectBaseParser,
+)
+from dodal.devices.beamlines.i19.transmission.spec_from_config.system_configuration import (
+    SystemConfiguration,
+)
+
+
+class LateralMotorSpec(BaseModel):
+    """The positions scale for an axial wedge motor (as specified by configuration, typically **JSON**).
+
+    Notes:
+        - The (potentially counterintuitive) class' attribute names match beamline scientists' "domain jargon".
+
+        - Each lateral motor drives one absorber wedge sideways across the x-ray beam:
+            - typically the motion axis aligns with a beamline coordinate axis ( x or y )
+            - The wedge motor scale has
+                - an **out** position
+                - and a range of "active" positions, where the taper is smooth.
+            - The wedge "internal" coordinate system defines tip as position zero
+                - in general the motor position zero is offset,
+                - the wedge's tip parameter reflects that offset.
+
+        - Although the units here will default to **mm** when unspecified (i.e. when omitted),
+        the units setting is still likely to appear in the JSON, reminding humans.
+
+    Attributes:
+        units: At present only "mm" are supported.
+        out: Motor position consistent with having fully retracted the wedge from the x-ray beam.
+        threshold: Motor position for minimal absorption in the permitted active absorbing position range.
+        max: Motor position for maximum absorption in the permitted active range.
+        tolerance: Motor position accepted margin for readout error.
+    """
+
+    units: Literal["mm"]
+    out: StrictFloat
+    threshold: StrictFloat
+    max: StrictFloat
+    tolerance: StrictFloat = Field(default=5.0e-3)
+
+    # Base Model internal setting to make this class immutable
+    model_config = ConfigDict(frozen=True, extra="forbid")
+
+    @model_validator(mode="after")
+    def validate_attributes(self) -> "LateralMotorSpec":
+        # counter-intuitive naming, but depending on
+        # motor scale orientation relative to wedge orientation
+        # max (thickness) position could be greater or smaller than threshold
+        _lower = min(self.out, self.max)
+        _upper = max(self.out, self.max)
+        _interval = ClosedInterval(lower=_lower, upper=_upper)
+        if self.threshold in _interval:
+            return self
+        msg: str = r"Inconsistent wedge geometry: Threshold not between max and out."
+        raise ValueError(msg)
+
+
+class LateralMotorsConfig(SystemAspectBaseParser[LateralMotorSpec]):
+    """Maps from highest level configuration (JSON) dict to extract lateral motor specifications.
+
+    Uses base class method **extract_specifications** and some pythonic type handling magic.
+
+    See Also:
+        Base of this parser class, namely **SystemAspectBaseParser**
+    """
+
+    def validate_key_name(self, *, key_name: str) -> None:
+        AxisNameValidation.validate_axis_name(axis_name=key_name)
+
+    @classmethod
+    def extract_motors_specifications(
+        cls,
+        *,
+        system_configuration: SystemConfiguration,
+        motor_identifier: str,
+    ) -> LateralMotorSpec:
+        """Extracts lateral motor specification from configuration of the transmission system."""
+        _motors: dict[str, LateralMotorSpec] = cls.get_aspect_specifications(
+            system_configuration=system_configuration
+        )
+        return _motors[motor_identifier]

src/dodal/devices/beamlines/i19/transmission/spec_from_config/material_absorption_spectrum_spec.py

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+from typing import Any
+
+from pydantic import (
+    BaseModel,
+    ConfigDict,
+    Field,
+    field_validator,
+    model_validator,
+)
+
+from dodal.devices.beamlines.i19.transmission.spec_from_config.energy_interval_spec import (
+    EnergyIntervalSpec,
+)
+from dodal.devices.beamlines.i19.transmission.spec_from_config.fitted_absorption_curve_spec import (
+    FittedAbsorptionCurveSpec,
+)
+from dodal.devices.beamlines.i19.transmission.spec_from_config.name_validation import (
+    MaterialNameValidation,
+)
+from dodal.devices.beamlines.i19.transmission.spec_from_config.system_aspect_base_parser import (
+    SystemAspectBaseParser,
+)
+from dodal.devices.beamlines.i19.transmission.spec_from_config.system_configuration import (
+    SystemConfiguration,
+)
+
+
+class AbsorptionVsEnergyRelation(BaseModel):
+    """Configuration dict for one piece of an absorption spectrum, one energy range specific fit curve.
+
+    Note:
+        This relation class is a pairing.  The internal pair consists of :
+        - The x-ray energy interval over which this piece of the spectrum is valid (a.k.a. domain).
+        - The parameters of a fitted absorption curve.
+
+    Attributes:
+        valid_energies: Specifies x-ray energy *domain* valid for the fitted curve.
+        fit_parameters: Specifies parameters needed to calculate absorption values on the fitted curve.
+
+    *See also, these closely related classes:*
+        **FittedAbsorptionCurveSpec**: Fitted curve specification
+        **EnergyIntervalSpec**: Energy range (interval) specification
+        **ClosedInterval**: General maths class underpinning interval definition
+    """
+
+    valid_energies: EnergyIntervalSpec
+    fit_parameters: FittedAbsorptionCurveSpec
+
+    # Base Model internal setting to make this class immutable
+    model_config = ConfigDict(frozen=True, extra="forbid")
+
+
+class MaterialAbsorptionSpectrumSpec(BaseModel):
+    """Configuration dict for the absorption spectrum of a specific material.
+
+    Note:
+        One spectrum absorption curve covers a specific energy range where it is valid.
+        One or more such curves make up one absorption spectrum.
+
+    Attributes:
+        absorption_curves: List of absorption curves
+    """
+
+    absorption_curves: list[AbsorptionVsEnergyRelation] = Field(..., min_length=1)
+
+    # Base Model internal setting to make this class immutable and valid
+    model_config = ConfigDict(frozen=True, extra="forbid")
+
+    @model_validator(mode="before")
+    @classmethod
+    def _coerce_raw_list_to_absorption_curves_dict(cls, data: Any) -> Any:
+        """Wrap spectrum pieces listing internally as a dict."""
+        if isinstance(data, list):
+            return {"absorption_curves": data}
+        if isinstance(data, dict):
+            return data
+        raise ValueError(
+            "Absorption spectrum data should be a list or dict of fitted curves."
+        )
+
+
+class MaterialAbsorptionSpectralConfig(
+    SystemAspectBaseParser[MaterialAbsorptionSpectrumSpec]
+):
+    """Configuration dict for the absorption spectra of all specified absorber materials.
+
+    Maps each material name to its absorption spectrum specification, as extracted from configuration (JSON).
+
+    Note:
+        Base class does most of the work - except for material name validation.
+    """
+
+    def validate_key_name(self, *, key_name: str) -> None:
+        MaterialNameValidation.validate_material_name(material_name=key_name)
+
+    @field_validator("root")
+    @classmethod
+    def _ensure_at_least_one_absorber_material_has_been_specified(
+        cls,
+        all_absorber_materials_specifications: dict[
+            str, MaterialAbsorptionSpectrumSpec
+        ],
+    ) -> dict[str, MaterialAbsorptionSpectrumSpec]:
+        """Invalidates configuration if that features zero absorber materials.
+
+        Raises:
+            ValueError - if no absorbers are present.
+        """
+        _specified_absorber_materials = all_absorber_materials_specifications.keys()
+        if len(_specified_absorber_materials) < 1:
+            raise ValueError(
+                "Empty absorber materials configuration! This is not valid input."
+            )
+        return all_absorber_materials_specifications
+
+    @classmethod
+    def extract_absorber_material_specifications(
+        cls,
+        *,
+        system_configuration: SystemConfiguration,
+        material_name: str,
+    ) -> MaterialAbsorptionSpectrumSpec:
+        """Extracts the absorption spectrum specification for a specific material."""
+        _materials_spectra: dict[str, MaterialAbsorptionSpectrumSpec] = (
+            cls.get_aspect_specifications(system_configuration=system_configuration)
+        )
+        return _materials_spectra[material_name]