Flow PHP

ScalarFunction extends FunctionTree, Describable

Methods

children() : array<int, FunctionTree>: Every operand of this node that is an expression, in constructor order.
describe() : null|Description
deterministic() : bool: True when this node and every node in children() produce the same value for the same input row.
eval() : Column: One column of $rows->count() values, of returns()'s type (nullable), same row order.
fromDescription() : static
resolved() : bool: True when this node and every node in children() can answer returns().
returns() : Type<string|int, mixed>: The type of the column this function produces, before any row is read.
withChildren() : static: A copy of this node with $children in place of children(): same count, same order, same per-element narrowing. Never mutates $this.

children()

Every operand of this node that is an expression, in constructor order.


    public
                    children() : array<int, FunctionTree>

Raw scalars, enums, Types and scope-introducing bodies are fields, not children.

Return values

array<int, FunctionTree>

describe()


    public
                    describe() : null|Description

Return values

null|Description —

null when this instance cannot cross a process boundary (a live client, a custom collaborator)

deterministic()

True when this node and every node in children() produce the same value for the same input row.


    public
                    deterministic() : bool

False for a generator (now(), uuid, a random string): a caller that evaluates the tree once per FILE or per partition instead of once per row must refuse a non-deterministic one.

Return values

bool

eval()

One column of $rows->count() values, of returns()'s type (nullable), same row order.


    public
                    eval(Rows $rows, Backend $backend) : Column

Parameters

$rows : Rows
$backend : Backend

Return values

Column

fromDescription()


    public
            static        fromDescription(array<string|int, mixed> $data, Rebuild $rebuild) : static

Parameters

$data : array<string|int, mixed>
$rebuild : Rebuild

Return values

static

resolved()

True when this node and every node in children() can answer returns().


    public
                    resolved() : bool

Return values

bool

returns()

The type of the column this function produces, before any row is read.


    public
                    returns() : Type<string|int, mixed>

Column-representable only: MixedType and a multi-member UnionType are refused; NullType is permitted. A top-level OptionalType is permitted and is what "this column is nullable" means - it is the only legal OptionalType position for a declaration, because OptionalType never nests and type_bare() strips exactly one level.

Return values

Type<string|int, mixed>

withChildren()

A copy of this node with $children in place of children(): same count, same order, same per-element narrowing. Never mutates $this.


    public
                    withChildren(array<int, FunctionTree> $children) : static

Parameters

$children : array<int, FunctionTree>

Return values

static