Class OperationPlan

Namespace

RDCore.SDK.Semantics.Plans

Assembly

RDCore.SDK.dll

What an operation does, decided from the types of its operands alone - before, and apart from, any value it is evaluated on (IR lowering §3.2).

public sealed record OperationPlan : IEquatable<OperationPlan>

Inheritance

object

OperationPlan

Implements

IEquatable<OperationPlan>

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

A plan is the value-independent half of an operation: its effective type, and what follows from it - the type each operand is let-coerced to, and whether the operation is a type mismatch. The other half, evaluating the plan on values, is the runtime's.

The same planner answers for two kinds of types. Given the value types of the operands - what the interpreter has, a Variant operand being the type of what it holds - a plan is final. Given declared types, an operand declared Variant or Object says nothing about the value it will hold, and the plan is IsDeferred: it is made again, at run time, from the value types. The tables of the specification are keyed by value types, so for any other operand the value type is the declared type, and the two plans agree.

Constructors

OperationPlan(string, IReadOnlyList<VBType>, VBType?, bool)

What an operation does, decided from the types of its operands alone - before, and apart from, any value it is evaluated on (IR lowering §3.2).

public OperationPlan(string Operator, IReadOnlyList<VBType> Operands, VBType? EffectiveType, bool IsDeferred = false)

Parameters

Operator string

The operator: one of the Tokens operators.

Operands IReadOnlyList<VBType>

The types the plan was made for, one for each operand, in order.

EffectiveType VBType

The effective type of the operation, or null when there is none: a type mismatch, or a plan that is deferred.

IsDeferred bool

Whether the plan depends on the value an operand declared Variant or Object holds, and is made at run time.

Remarks

A plan is the value-independent half of an operation: its effective type, and what follows from it - the type each operand is let-coerced to, and whether the operation is a type mismatch. The other half, evaluating the plan on values, is the runtime's.

The same planner answers for two kinds of types. Given the value types of the operands - what the interpreter has, a Variant operand being the type of what it holds - a plan is final. Given declared types, an operand declared Variant or Object says nothing about the value it will hold, and the plan is IsDeferred: it is made again, at run time, from the value types. The tables of the specification are keyed by value types, so for any other operand the value type is the declared type, and the two plans agree.

Properties

EffectiveType

The effective type of the operation, or null when there is none: a type mismatch, or a plan that is deferred.

public VBType? EffectiveType { get; init; }

Property Value

VBType

IsDeferred

Whether the plan depends on the value an operand declared Variant or Object holds, and is made at run time.

public bool IsDeferred { get; init; }

Property Value

bool

IsTypeMismatch

Whether the operation has no effective type for these operands: run-time error 13, Type mismatch.

public bool IsTypeMismatch { get; }

Property Value

bool

OperandDestination

What a non-Null operand is let-coerced to before the operation is evaluated: the effective type, except that a Date operation is evaluated in Double (MS-VBAL §5.6.9.3). null when nothing is coerced - a Null effective type, whose result is Null whatever the other operand is, a plan with no effective type, and Is, which compares two object references as they are (§5.6.9.7). Worked out once, with the plan: it is asked for every time the plan is evaluated.

public VBType? OperandDestination { get; }

Property Value

VBType

Operands

The types the plan was made for, one for each operand, in order.

public IReadOnlyList<VBType> Operands { get; init; }

Property Value

IReadOnlyList<VBType>

Operator

The operator: one of the Tokens operators.

public string Operator { get; init; }

Property Value

string

Methods

Equals(OperationPlan?)

Whether two plans agree: the same operator, the same operand types, the same outcome. A record of an array compares the arrays by reference, which is not what makes two plans the same.

public bool Equals(OperationPlan? other)

Parameters

other OperationPlan

Returns

bool

GetHashCode()

Serves as the default hash function.

public override int GetHashCode()

Returns

int

A hash code for the current object.