5.4.2.21 With Statement

Note

This section describes the implementation of MS-VBAL §5.4.2.21 With Statement.

Syntax

AST node	Instruction kind	Notes
WithStatementNode	`With`	The opener's Instruction`.End` is right past the block.

With...End With is a block statement (RD-VBAL §3.4.1 Block Statements). Its opener lowers to the InstructionKind With (RD-VBAL §3.5.2 Instruction).

Static Semantics

Lowering records the enclosing With block on every instruction inside it (RD-VBAL §3.5.3 Lowering Block Statements):

Every instruction lexically inside a With block, however deeply nested (through an If or a loop), carries Instruction.EnclosingWith set to that With's opener offset.
When lowering leaves a With block, EnclosingWith is restored to its value before the block.
EnclosingWith is computed once, at lowering time. It is not tracked as a runtime stack the interpreter pushes and pops.

Because EnclosingWith is static, a GoTo into or out of a With block leaves no stale state to unwind (RD-VBAL §5.4.2.12 GoTo Statement).

Runtime Semantics

The executor runs the With instruction as follows:

The header expression (the target) is evaluated once.
The target is Set-coerced or Let-coerced:
- a class-valued target is Set-assigned through ISetCoercionRuntimeSemantics (RD-VBAL §5.5.2.2 Runtime semantics);
- a UDT-valued target is Let-assigned through ILetCoercionRuntimeSemanticsProvider.EvaluateLetCoercionSemantics directly.
The result is stored on the activation, keyed by the With instruction's own offset.
Execution falls through into the body.

The With block has no separate closer instruction to pop the stored target on exit.

Every Simple and ConditionalBranch instruction's RuntimeEvaluationContext is recomputed before each dispatch, from Instruction.EnclosingWith (RD-VBAL §3.5.4 Execution). A .Member or !member with-expression then resolves against the innermost enclosing With's stored target, however control reached the instruction, including via GoTo (RD-VBAL §5.6.15 With Expressions).

Implementation

RDCore.Runtime.Execution.ProcedureExecutor dispatches With instructions.
RDCore.Runtime.Semantics.Statements.WithStatementRuntimeSemantics performs the Set-coercion or Let-coercion of step 2.
The target is stored through CallStackFrame.SetBlockState and read back through ICallStackFrame.TryGetBlockState, keyed by the opener's offset. Select Case stores its selector the same way (RD-VBAL §5.4.2.10 Select Case Statement); a single block-state value is enough for either.
RuntimeExpressionEvaluator resolves the with-expression target through its EnclosingWithTarget resolution.