cirilisp/eval.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "util.h"
#include "symtable.h"

object apply(object function, object parameters);

object eval(object input)
{
	object result;

	if (TYPE(input) == nilObject || TYPE(input) == numberObject ||
			TYPE(input) == errorObject)
	{
		result = copyObject(input);
	}
	else if (TYPE(input) == symbolObject)
	{
		if (symbolExists(SYM(input)))
		{
			if (typeOf(SYM(input)) == variableSymbol)
			{
				result = referVariable(SYM(input));
			}
			else
			{
				result = copyObject(input);
			}
		}
		else
		{
			TYPE(result) = errorObject;
			ERR(result) = unrecognizedSymbolError;
		}
	}
	else if (TYPE(input) == consObject)
	{
		if (!properList(input))
		{
			TYPE(result) = errorObject;
			ERR(result) = improperListError;
		}
		else
		{
			object *currentCell = &input;
			int noErrors = 1;
			while (TYPE(*currentCell) != nilObject)
			{
				if (TYPE(CAR(input)) != symbolObject ||
					!isSpecialForm(SYM(CAR(input))))
				{
					CAR(*currentCell) =
						eval(CAR(*currentCell));
				}

				if (TYPE(CAR(*currentCell)) == errorObject)
				{
					noErrors = 0;
					TYPE(result) = errorObject;
					ERR(result) = ERR(CAR(*currentCell));
					break;
				}
				currentCell = &CDR(*currentCell);
			}

			if (noErrors)
			{
				result = apply(CAR(input), CDR(input));
			}
		}
	}

	deleteObject(input);
	return result;
}

object apply(object function, object parameters)
{
	object result;

	if (TYPE(function) != symbolObject)
	{
		deleteObject(function);
		TYPE(result) = errorObject;
		ERR(result) = notApplicableError;
	}
	else if (symbolExists(SYM(function)))
	{
		object(*f)();
		if ((f = internalFunction(SYM(function))) != NULL)
		{
			result = f(parameters);
		}
	}
	else
	{
		deleteObject(function);
		TYPE(result) = errorObject;
		ERR(result) = unrecognizedSymbolError;
	}

	return result;
}