private Expression BuildIdentifierRootExpression(ParseTreeNode root, CompilerState state)
{
AtomMetadata atom;
var name = root.ChildNodes[0].Token.ValueString;
// first, look for an argument with this name
var argument = state.TryGetArgumentByName(name);
if (argument != null)
{
return(argument);
}
var context = state.Context;
// next, see if we have a field or property on the context (if any context present)
var contextBoundExpression = TryGetFieldOrPropertyInfoFromContext(name, context);
if (contextBoundExpression != null)
{
return(contextBoundExpression);
}
// and only then look through available IDENTIFIER atoms
if (m_atoms.TryGetValue(name, out atom) && atom.AtomType == AtomType.Identifier)
{
if (atom.ExpressionGenerator != null)
{
return(atom.ExpressionGenerator(root, state));
}
if (atom.MethodInfo == null)
{
// internal error, somebody screwed up with configuration of runtime
throw new Exception("ExpressionGenerator and MethodInfo are both null on atom: " + atom.Name);
}
// no arguments? great
var paramInfo = atom.MethodInfo.GetParameters();
if (paramInfo.Length == 0)
{
return(BuildFunctorInvokeExpression(atom, (Expression[])null));
}
// any arguments? must have exactly one argument, context must be registered, and context type must be adjustable to this method's arg type
if (context == null)
{
throw new CompilationException("Atom's MethodInfo cannot be used for an Id expression, because context is not available: " + atom.Name, root);
}
Expression adjustedContext;
if (paramInfo.Length > 1 || !ExpressionTreeExtensions.TryAdjustReturnType(root, context, paramInfo[0].ParameterType, out adjustedContext))
{
throw new CompilationException("Atom's MethodInfo may only have either zero arguments or one argument of the same type as expression context: " + atom.Name, root);
}
return(BuildFunctorInvokeExpression(atom, adjustedContext));
}
// still nothing found? ask IDENTIFIER atom handlers
foreach (var handler in m_atomHandlers)
{
if (handler.AtomType != AtomType.Identifier)
{
continue;
}
if (handler.ExpressionGenerator == null)
{
// internal error, somebody screwed up with configuration of runtime
throw new Exception("ExpressionGenerator is null on atom handler: " + handler.Name);
}
// only pass the first portion of dot-notation identifier to handler
var result = handler.ExpressionGenerator(root.ChildNodes[0], state);
if (result != null)
{
return(result);
}
}
throw new CompilationException("Unknown atom: " + name, root);
}