Interface ICallStackFrame

Namespace

RDCore.SDK.Runtime.Abstract.Execution

Assembly

RDCore.SDK.dll

Represents a single call stack frame: the activation record of one procedure call, owning the storage for every locally-scoped Symbol it declares — its parameters and its Dim/procedure-local declarations alike (RD-VBAL §2.3.1.2, the local stack frame heap tier). A Static local is the one exception: it lives in the module-level statics heap instead, so it keeps its value between calls.

public interface ICallStackFrame : IStackFrame

Inherited Members

IStackFrame.NodeId

IStackFrame.Inputs

Remarks

⚠️ A CallStackFrame frame is not immutable: the value retrieved for a given symbol may be different at a subsequent retrieval, and a frame is torn down (its storage freed) when it is popped from the ICallStack that owns it.

Properties

Directives

The ModuleDirectives of the module declaring the procedure: what the code of this activation is executed under — its comparison mode, chiefly (MS-VBAL §5.2.1.1).

ModuleDirectives Directives { get; }

Property Value

ModuleDirectives

Remarks

👉 A StaticSymbol identifies a procedure by its name and type alone; it does not say which module it is in.

ErrorHandler

This activation's current ErrorHandlerState (MS-VBAL §5.4.4) — a single mutable value, like Pc, not per-offset hidden state like TryGetBlockState(int, out VBTypedValue?)/TryGetForLoopState(int, out ForLoopState)/TryGetForEachState(int, out ForEachState): an On Error statement changes the activation's policy going forward, it isn't scoped to one block-opening instruction. Read-only here: only the interpreter's executor (RDCore.Runtime) updates it, through the concrete frame type it constructs.

ErrorHandlerState ErrorHandler { get; }

Property Value

ErrorHandlerState

GoSubDepth

The current depth of this activation's own GoSub Resumption List (MS-VBAL §5.4.2.14) — how many GoSub/On…GoSub calls are still awaiting their Return. Read-only here: only the interpreter's executor (RDCore.Runtime) pushes and pops it, through the concrete frame type it constructs. A Return (MS-VBAL §5.4.2.15) when this is zero is error 3, "Return without GoSub".

int GoSubDepth { get; }

Property Value

int

Pc

The offset, into this activation's own InstructionList, of the next instruction to fetch (RD-VBAL §3.5.1). Read-only here: only the interpreter's executor (RDCore.Runtime) advances it, through the concrete frame type it constructs.

int Pc { get; }

Property Value

int

ReturnValue

The current value of this activation's function result variable (MS-VBAL §5.3.1) — null for an activation of a Sub, a Property Let, or a Property Set, none of which have one. A bare reference to a Function/Property Get's own name, from within its own body, reads and writes this rather than the general symbol table (RD-VBAL §3.5.4). Read-only here: only RDCore.Runtime ever writes it, through the concrete frame type it constructs.

VBTypedValue? ReturnValue { get; }

Property Value

VBTypedValue

StaticSymbol

The StaticSymbol identifying the procedure this frame is an activation of.

StaticSymbol StaticSymbol { get; }

Property Value

StaticSymbol

Target

The object this activation is a call on - the Me of a member of a class module - or null for a procedure of a standard module. What an Instance symbol, a field of a class, is resolved against: it is the object's own storage, not the session's.

VBRuntimeObjectId? Target { get; }

Property Value

VBRuntimeObjectId?

Methods

GetValue(Symbol)

Gets the IBindingHandle currently held in this frame for the specified locally-scoped Symbol.

IBindingHandle GetValue(Symbol symbol)

Parameters

symbol Symbol

Returns

IBindingHandle

Exceptions

KeyNotFoundException

No binding exists yet for symbol on this frame.

IsByRefParameter(Symbol)

Whether symbol is a ByRef parameter of this activation: a second name for a variable of the caller's, and not a variable of its own (MS-VBAL §5.3.1.11).

bool IsByRefParameter(Symbol symbol)

Parameters

symbol Symbol

Returns

bool

LocksAddress(MemoryAddress)

Whether a ByRef parameter of this activation is the variable at address - whether this activation locks it (MS-VBAL §5.4.3.3: a variable "currently locked by a ByRef formal parameter" cannot be re-dimensioned by another name).

bool LocksAddress(MemoryAddress address)

Parameters

address MemoryAddress

Returns

bool

Push(Symbol, VBTypedValue)

Declares symbol on this frame and reserves storage sized for value, its initial value — the caller's argument for a parameter, the declared type's default value for a fresh Dim. MS-VBAL draws no distinction between a parameter and a Dim local for name-resolution purposes, so both are declared this way.

void Push(Symbol symbol, VBTypedValue value)

Parameters

symbol Symbol

value VBTypedValue

Exceptions

InvalidOperationException

symbol is already declared on this frame — a compile-time DuplicateDeclaration that should never reach runtime.

TryGetAddress(Symbol, out MemoryAddress)

Gets the MemoryAddress currently reserved for the specified locally-scoped Symbol on this frame, if any — a ByRef parameter (Push(Symbol, VBTypedValue)ed by aliasing an existing address rather than allocating one of its own) resolves to the SAME address its argument does, exactly like an ordinary declared local.

bool TryGetAddress(Symbol symbol, out MemoryAddress address)

Parameters

symbol Symbol

address MemoryAddress

Returns

bool

TryGetBlockState(int, out VBTypedValue?)

Gets the hidden value a block-opening instruction (a With's target, a Select Case's selector) stashed on this activation, keyed by that instruction's own offset (RD-VBAL §3.5.4) — however control reached the instruction reading it, a GoTo included, since the stash lives on the activation rather than on any call stack a structured walk would otherwise need to unwind.

bool TryGetBlockState(int openerOffset, out VBTypedValue? value)

Parameters

openerOffset int

The offset of the block-opening instruction that stashed the value.

value VBTypedValue

The stashed value, if one exists for openerOffset.

Returns

bool

Remarks

Read-only here: only the interpreter's executor (RDCore.Runtime) stashes a value, through the concrete frame type it constructs.

TryGetForEachState(int, out ForEachState)

Gets the ForEachState a For Each loop's own opener stashed on this activation, keyed by that instruction's own offset — mirrors TryGetForLoopState(int, out ForLoopState) for the different per-activation shape a For Each loop's own enumeration cursor needs.

bool TryGetForEachState(int openerOffset, out ForEachState state)

Parameters

openerOffset int

The offset of the ForEachOpener instruction that stashed the state.

state ForEachState

The stashed state, if one exists for openerOffset — its absence when a ForEachNext instruction looks it up is MS-VBAL §5.4.2.4 error 92, "For loop not initialized" (a GoTo landed directly on the closer this activation).

Returns

bool

Remarks

Read-only here: only the interpreter's executor (RDCore.Runtime) stashes a value, through the concrete frame type it constructs.

TryGetForLoopState(int, out ForLoopState)

Gets the ForLoopState a For loop's own opener stashed on this activation, keyed by that instruction's own offset — mirrors TryGetBlockState(int, out VBTypedValue?), but a For loop's per-activation hidden state is more than the single value that mechanism holds.

bool TryGetForLoopState(int openerOffset, out ForLoopState state)

Parameters

openerOffset int

The offset of the ForOpener instruction that stashed the state.

state ForLoopState

The stashed state, if one exists for openerOffset — its absence when a ForNext instruction looks it up is MS-VBAL §5.4.2.3 error 92, "For loop not initialized" (a GoTo landed directly on the closer this activation).

Returns

bool

Remarks

Read-only here: only the interpreter's executor (RDCore.Runtime) stashes a value, through the concrete frame type it constructs.

TryResolve(Symbol, out IBindingHandle?)

Gets the IBindingHandle currently held in this frame for the specified locally-scoped Symbol, if any.

bool TryResolve(Symbol symbol, out IBindingHandle? value)

Parameters

symbol Symbol

value IBindingHandle

Returns

bool