Expression Tree¶

This page documents the structure of the Expression object as returned by roll(...).expr. If you’re looking for the Expression object returned by parse(...), check out Abstract Syntax Tree.

class d20.Number(kept=True, annotation=None)[source]¶

Bases: abc.ABC, d20.diceast.ChildMixin

The base class for all expression objects.

Note that Numbers implement all the methods of a ChildMixin.

kept: bool¶: Whether this Number was kept or dropped in the final calculation.

annotation: Optional[str]¶: The annotation on this Number, if any.

property children¶

(read-only) The children of this Number, usually used for traversing the expression tree.

Return type: list[Number]

property left¶

The leftmost child of this Number, usually used for traversing the expression tree.

Return type: Number

property right¶

The rightmost child of this Number, usually used for traversing the expression tree.

Return type: Number

set_child(index, value)[source]¶

Sets the ith child of this Number.

Parameters

index (int) – Which child to set.
value (Number) – The Number to set it to.

drop()[source]¶: Makes the value of this Number node not count towards a total.

property keptset¶

Returns the set representation of this object, but only including children whose values were not dropped.

Return type: list[Number]

property number¶

Returns the numerical value of this object.

Return type: int or float

property set¶

Returns the set representation of this object.

Return type: list[Number]

property total¶

Returns the numerical value of this object with respect to whether it’s kept. Generally, this is preferred to use over number, as this will return 0 if the number node was dropped.

Return type: int or float

class d20.Expression(roll, comment, **kwargs)[source]¶

Bases: d20.expression.Number

Expressions are usually the root of all Number trees.

roll: d20.Number¶: The roll of this expression.

comment: Optional[str]¶: The comment of this expression.

class d20.Literal(value, **kwargs)[source]¶

Bases: d20.expression.Number

A literal integer or float.

values: list[Union[int, float]]¶: The history of numbers that this literal has been.

exploded: bool¶: Whether this literal was a value in a Die object that caused it to explode.

explode()[source]¶: Marks that this literal was a value in a Die object that caused it to explode.

update(value)[source]¶

Changes the literal value this literal represents.

Parameters: value (Union[int, float]) – The new value.

class d20.UnOp(op, value, **kwargs)[source]¶

Bases: d20.expression.Number

Represents a unary operation.

op: str¶: The unary operation.

value: d20.Number¶: The subtree that the operation operates on.

class d20.BinOp(left, op, right, **kwargs)[source]¶

Bases: d20.expression.Number

Represents a binary operation.

op: str¶: The binary operation.

left: d20.Number¶: The left subtree that the operation operates on.

right: d20.Number¶: The right subtree that the operation operates on.

class d20.Parenthetical(value, operations=None, **kwargs)[source]¶

Bases: d20.expression.Number

Represents a value inside parentheses.

value: d20.Number¶: The subtree inside the parentheses.

operations: list[d20.SetOperation]¶: If the value inside the parentheses is a Set, the operations to run on it.

class d20.Set(values, operations=None, **kwargs)[source]¶

Bases: d20.expression.Number

Represents a set of values.

values: list[d20.Number]¶: The elements of the set.

operations: list[d20.SetOperation]¶: The operations to run on the set.

class d20.Dice(num, size, values, operations=None, context=None, **kwargs)[source]¶

Bases: d20.expression.Set

A set of Die.

num: int¶: How many Die in this set of dice.

size: int¶: The size of each Die in this set of dice.

values: list[d20.Die]¶: The elements of the set.

operations: list[d20.SetOperation]¶: The operations to run on the set.

roll_another()[source]¶: Rolls another Die of the appropriate size and adds it to this set.

class d20.Die(size, values, context=None)[source]¶

Bases: d20.expression.Number

Represents a single die.

size: int¶: How many sides this Die has.

values: list[d20.Literal]¶: The history of values this die has rolled.

class d20.SetOperator(op, sels)[source]¶

Represents an operation on a set.

op: str¶: The operation to run on the selected elements of the set.

sels: list[d20.SetSelector]¶: The selectors that describe how to select operands.

select(target, max_targets=None)[source]¶

Selects the operands in a target set.

Parameters

target (Number) – The source of the operands.
max_targets (Optional[int]) – The maximum number of targets to select.

operate(target)[source]¶

Operates in place on the values in a target set.

Parameters: target (Number) – The source of the operands.

class d20.SetSelector(cat, num)[source]¶

Represents a selection on a set.

cat: Optional[str]¶: The type of selection (lowest, highest, literal, etc).

num: int¶: The number to select (the N in lowest/highest/etc N, or literally N).

select(target, max_targets=None)[source]¶

Selects operands from a target set.

Parameters

target (Number) – The source of the operands.
max_targets (int) – The maximum number of targets to select.

Returns

The targets in the set.

Return type

set of Number