Function BeginConditional

Source/SpireCore/Preprocessor.cpp:937–970

Start a preprocessor conditional, with an initial enable/disable state.

// Start a preprocessor conditional, with an initial enable/disable state.
static void BeginConditional(PreprocessorDirectiveContext* context, bool enable)
{
    Preprocessor* preprocessor = context->preprocessor;
    PreprocessorInputStream* inputStream = preprocessor->inputStream;
    assert(inputStream);

    PreprocessorConditional* conditional = CreateConditional(preprocessor);

    conditional->ifToken = context->directiveToken;

    // Set state of this condition appropriately.
    //
    // Default to the "haven't yet seen a `true` branch" state.
    PreprocessorConditionalState state = PreprocessorConditionalState::Before;
    //
    // If we are nested inside a `false` branch of another condition, then
    // we never want to enable, so we act as if we already *saw* the `true` branch.
    //
    if (IsSkipping(preprocessor)) state = PreprocessorConditionalState::After;
    //
    // Similarly, if we ran into any parse errors when dealing with the
    // opening directive, then things are probably screwy and we should just
    // skip all the branches.
    if (IsSkipping(preprocessor)) state = PreprocessorConditionalState::After;
    //
    // Otherwise, if our condition was true, then set us to be inside the `true` branch
    else if (enable) state = PreprocessorConditionalState::During;

    conditional->state = state;

    // Push conditional onto the stack
    conditional->parent = inputStream->conditional;
    inputStream->conditional = conditional;
}

//
// Preprocessor Conditional Expressions