/// <summary>
/// Compile a custom function definition
/// </summary>
private static void CompileFunctionDefinition(int level, bool debug, Node node, NanCodeWriter wr, Scope parameterNames)
{
// 1) Compile the func to a temporary string
// 2) Inject a new 'def' op-code, that names the function and does an unconditional jump over it.
// 3) Inject the compiled func
// 4) Inject a new 'return' op-code
if (node.Children.Count != 2)
{
throw new Exception("Function definition must have 3 parts: the name, the parameter list, and the definition.\r\n" +
"Call like `def ( myFunc ( param1 param2 ) ( ... statements ... ) )`");
}
var bodyNode = node.Children.Last.Value;
var definitionNode = node.Children.First.Value;
if (definitionNode.Children.Any(c => c.IsLeaf == false))
{
throw new Exception("Function parameters must be simple names.\r\n" +
"`def ( myFunc ( param1 ) ( ... ) )` is OK,\r\n" +
"`def ( myFunc ( (param1) ) ( ... ) )` is not OK");
}
if (bodyNode.Text != "()")
{
throw new Exception("Bare functions not supported. Wrap your function body in (parenthesis)");
}
var functionName = definitionNode.Text;
var argCount = definitionNode.Children.Count;
ParameterPositions(parameterNames, definitionNode.Children.Select(c => c.Text), wr);
var subroutine = Compile(bodyNode, level, debug, parameterNames, null, Context.Default);
var tokenCount = subroutine.OpCodeCount();
if (debug)
{
wr.Comment("// Function definition : \"" + functionName
+ "\" with " + argCount + " parameter(s)");
}
wr.FunctionDefine(functionName, argCount, tokenCount);
wr.Merge(subroutine);
if (subroutine.ReturnsValues)
{
// Add an invalid return opcode. This will show an error message.
wr.InvalidReturn();
}
else
{
// Add the 'return' call
wr.Return(0);
}
// Then the runner will need to interpret both the new op-codes
// This would include a return-stack-push for calling functions,
// a jump-to-absolute-position by name
// a jump-to-absolute-position by return stack & pop
}