designspace.BoolExpr

class designspace.BoolExpr

Bases: Expr

An expression node that evaluates to a (Kleene) truth value.

implies(other: BoolExpr) → BoolExpr

Material implication: if this holds, other must too.

The natural shape for a conditional rule such as “if we are on GPU, the batch must be at least 32”, and much clearer than the equivalent ~a | b, which it is exactly (down to the fingerprint).

Parameters:

other (BoolExpr) – The consequent.

Returns:

A condition, false only when this holds and other does not.

Return type:

BoolExpr

Raises:

TypeError – If other is not a boolean expression.

Examples

>>> s = ds.space(
...     ds.param("gpu").bool(),
...     ds.param("batch").integer(1, 64),
... ).require(ds.param("gpu").implies(ds.param("batch") >= 32))
>>> s.is_feasible({"gpu": True, "batch": 64})
True
>>> s.is_feasible({"gpu": True, "batch": 8})
False

The rule says nothing when the antecedent is false:

>>> s.is_feasible({"gpu": False, "batch": 8})
True

property children: tuple[Expr, ...]

The node’s operands, in order.

Together with .kind this is enough to walk or rebuild any expression tree. A leaf has none.

Examples

>>> [c.kind for c in (ds.param("x") < 3).children]
['ref', 'literal']

is_active() → BoolExpr

Whether the referenced parameter is active, as a condition.

Lets a constraint ask about presence rather than value: “if the cache is switched on at all, then …”. Distinct from reading the value, which would be unknown for an inactive parameter.

Returns:

A condition, true when the parameter is present.

Return type:

BoolExpr

Examples

>>> s = ds.space(
...     ds.param("use_cache").bool(),
...     ds.param("cache_mb").integer(64, 512).when(ds.param("use_cache")),
...     ds.param("workers").integer(1, 8),
... )
>>> s = s.require(
...     ds.param("cache_mb").is_active().implies(ds.param("workers") <= 4)
... )
>>> s.is_feasible({"use_cache": True, "cache_mb": 128, "workers": 2})
True
>>> s.is_feasible({"use_cache": True, "cache_mb": 128, "workers": 8})
False
>>> s.is_feasible({"use_cache": False, "workers": 8})
True

property kind: str

A short string naming the node type.

Examples

>>> ds.param("x").kind
'ref'
>>> (ds.param("x") < 3).kind
'lt'

property params: frozenset[str]

Every parameter path this expression references.

What the dependency graph is built from, and how a constraint knows which parameters it belongs to.

Examples

>>> sorted((ds.param("x") + ds.param("y") < 3).params)
['x', 'y']