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Expanding Macro and Function Calls

The Macro or Function contains EntityConstants pointing to ArgumentExpression placeholders for the argument names. The names inside the Body of the Macro or Expression of the Function refer to those.

The default arguments are wrapped in EntityConstants.

Before the expansion:

MacroBody owns the provided arguments, which are a vector of Expression.

After the expansion:

MacroBody is replaced with a ScopeBody. The provided arguments are ArgumentConstant in the ScopeBody. The default arguments are EntityConstant in the Macro.

During Expansion:

  1. The ScopeBody is created.

  2. The provided arguments are wrapped in ArgumentConstant and added as constants to the ScopeBody. The ArgumentExpression placeholders in the Macro are mapped to the corresponding ArgumentConstant (for provided arguments) or EntityConstant (for default arguments) in the CloneContext.

  3. The body of the Macro is cloned and set as the body of the ScopeBody, replacing the argument references with the corresponding ConstantExpression via the CloneContext mapping.

  4. The ScopeBody is returned as the result of the expansion.