// also now need to ensure that all arguments in regular expression
// get their values looked up if they are symbols
// implementation
// Note : sometimes env1 will not conform, or be pertinent to what is written relation to c# loops and scheme code
public override Node eval(Node node1, Environment env1)
{
if (node1 == null || node1.getCar() == null)
{
Console.WriteLine("Error: the expression is not initialized to values: null list and car");
return(Nil.getInstance());
}
// for any regular defined function enclosed in parentheses,
// the first element is supposed to be a function to be evaluated.
// this variable will hold the final function head term we get.
Node firstElem_car = node1.getCar();
// step one : if Car is a pair, evaluate it and store resulting ident, ... which ought to be
// another function once evaluated...
if (node1.getCar().isPair())
{
// build new environment for this to be computed for.
Environment envExtend = new Environment(env1);
firstElem_car = node1.getCar().eval(envExtend);
//report error if not a builtin/ or /closure
if (firstElem_car == null || !firstElem_car.isProcedure())
{
Console.WriteLine("Error: regular expression needs a function builtin/closure for first term!, __ + returning null instead.");
return(Nil.getInstance());
}
}
else if (node1.getCar().isSymbol())
{
// start loop to get closure from obstructing intermediate symbolic expression.
bool first_element_is_not_closure = true;
firstElem_car = node1.getCar();
while (first_element_is_not_closure)
{
firstElem_car = env1.lookup(firstElem_car);
//report error if not a builtin/ or /closure
if (firstElem_car == null)
{
Console.WriteLine("Error: regular expression needs a function builtin/closure for first term!, __ + returning null instead.");
return(Nil.getInstance());
}
else if (firstElem_car.isProcedure())
{
first_element_is_not_closure = false;
}
}
}
// this would be improper end for cons regular expression.
if (node1.getCdr() == null)
{
Console.WriteLine("error: one of regular expressions elements is null.");
return(Nil.getInstance());
}
// special builtIn eval case.
BuiltIn givenId = null;
if (firstElem_car.isBuiltIn())
{
givenId = (BuiltIn)firstElem_car;
// check if built in is eval
// note carefully: if symbol == null, null pointer will happen.
if (givenId.getSymbol().getName().Equals("eval"))
{
// build new environment for this to be computed for.
Environment envExtend = new Environment(env1);
// check for null values now so null pointer doesnt get encountered
if (node1.getCdr().getCar() == null || node1.getCdr().getCdr() == null ||
node1.getCdr().getCdr().getCar() == null)
{
Console.WriteLine("Error: lacking one of the following for eval : expression or environment.");
return(Nil.getInstance());
}
// side maneuver. _ work out the environment first...
bool environment_taken = false;
Node env_symbol_to_lookup = node1.getCdr().getCdr().getCar();
Node environment_found = null;
// check if symbol needs to be evaluated
if (env_symbol_to_lookup.isSymbol())
{
if (env1.lookup(env_symbol_to_lookup) != null)
{
environment_found = env1.lookup(env_symbol_to_lookup);
}
else
{
Console.WriteLine("Error: environment symbol was not found.");
return(Nil.getInstance());
}
} // check if expression needs to be evaluated
else if (env_symbol_to_lookup.isPair())
{
environment_found = env_symbol_to_lookup.eval(envExtend);
}
if (environment_found != null && environment_found.isEnvironment())
{
environment_taken = true;
}
else
{
Console.WriteLine("Error: evaluation op_ did not find a fitting environment.");
return(Nil.getInstance());
}
// working on expression now
Node args_to_eval = null;
Node localTerms_data = node1.getCdr().getCar();
// check if second argument is code
// and then evaluate if it needs more processing
// for eval to implement as code
if (localTerms_data.isPair() && environment_taken)
{
if (localTerms_data.getCar() != null && localTerms_data.getCar().isSymbol() &&
localTerms_data.getCar().getName().Equals("quote"))
{
Node args_of_Quote = localTerms_data.eval(envExtend);
if (args_of_Quote != null)
{
// copy evaluated quote expression
args_to_eval = args_of_Quote;
}
}
else if (localTerms_data.getCar() != null && localTerms_data.getCar().isSymbol() &&
localTerms_data.getCar().getName().Equals("lambda"))
{
Node args_of_Lambda = localTerms_data.eval(envExtend);
if (args_of_Lambda != null)
{
// copy evaluated lambda expression
args_to_eval = args_of_Lambda;
}
}
else
{
// this needs fine tuning for more special cases..\\
//("may have more cases... ")
//??
args_to_eval = localTerms_data;
}
}
else if (localTerms_data.isSymbol() && environment_taken)
{
Node node_symbol_expression = env1.lookup(localTerms_data);
if (node_symbol_expression != null)
{
// copy evaluated symbol and then the environment
args_to_eval = node_symbol_expression;
}
else
{
Console.WriteLine("Error: first expression argument symbol not found.");
return(Nil.getInstance());
}
}
// return the built in eval of args and environment given
if (args_to_eval != null)
{
Environment environment_copy_found = (Environment)environment_found;
if (args_to_eval.isPair())
{
return(args_to_eval.eval(environment_copy_found));
}
else
{
return(args_to_eval.eval(environment_copy_found));
}
}
else
{
Console.WriteLine("Error: expression arg was null.");
return(Nil.getInstance());
}
}
// note: looking at special eq? case
// check if built in is eq? only look at case of (eq? 'exp 'exp)
// note carefully: if symbol == null, null pointer will happen.
if (givenId.getSymbol().getName().Equals("eq?") &&
node1.getCdr().getCar() != null &&
node1.getCdr().getCdr() != null &&
node1.getCdr().getCdr().getCar() != null &&
node1.getCdr().getCdr().getCdr() != null &&
node1.getCdr().getCdr().getCdr().isNull() &&
node1.getCdr().getCar().isPair() &&
node1.getCdr().getCdr().getCar().isPair()
)
{
// first we must check if the arguments to (eq? ... )are in fact quote arguments.
Cons argument1 = (Cons)node1.getCdr().getCar();
Cons argument2 = (Cons)node1.getCdr().getCdr().getCar();
if (argument1.getForm_ofCons() is Tree.Quote && argument2.getForm_ofCons() is Tree.Quote)
{
String first_argument_printed = "";
String second_argument_printed = "";
// redirect output to evaulate if print of Pair nodes is same
var originalConsoleOut = Console.Out; // preserve the original stream
using (var writer = new StringWriter())
{
Console.SetOut(writer);
argument1.print(0);
writer.Flush();
var myString = writer.ToString();
first_argument_printed = myString.TrimEnd('\n');
}
using (var writer1 = new StringWriter())
{
Console.SetOut(writer1);
argument2.print(0);
writer1.Flush();
var myString_2 = writer1.ToString();
second_argument_printed = myString_2.TrimEnd('\n');
}
Console.SetOut(originalConsoleOut); // restore Console.Out
if (first_argument_printed.Equals(second_argument_printed))
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
}
// security check for eof-object? builtIn test...
if (givenId != null && givenId.getSymbol().getName().Equals("eof-object?"))
{
if (node1.getCdr().isNull() || !node1.getCdr().isPair())
{
Console.WriteLine("Error: no argument for eof-object? test. the BuiltIn function eof-object? requires one argument to test.");
return(Nil.getInstance());
}
}
}
// other cases builtin or closure...
Node args_given = node1.getCdr();
bool hasArguments = true;
// test if there are arguments to this form function
if (args_given.isNull())
{
hasArguments = false;
}
if (hasArguments)
{
if (args_given.getCdr() == null || args_given.getCar() == null)
{
Console.WriteLine("Error: one of passed arguments in function expression is null.");
return(Nil.getInstance());
}
// need to evaluate args (each car separately)... and then return what is resulting list of elements...
// build new environment on hand _ for each car to be computed at times.
Environment envExtend1 = new Environment(env1);
// this will hold the list of evaluated arguments cumulatively.
Cons evaluated_argsList__in_progress;
// this will hold a latest fringe of for extending fringe items.
Cons fringe_cons = null;
bool hasMoreDescendents = !args_given.getCdr().isNull();
if (hasMoreDescendents)
{
// start this off as unassigned.
Cons added_fringe_con = null;
// this will hold the list of evaluated arguments cumulatively.
// Cons evaluated_argsList__in_progress;
// check if eval is not null
Node evalItem1 = args_given.getCar().eval(envExtend1);
if (evalItem1 != null)
{
evaluated_argsList__in_progress = new Cons(evalItem1, added_fringe_con);
}
else
{
// first a detour...
//
// check for special case of eof-object? builtIn test
if (givenId != null && givenId.getSymbol().getName().Equals("eof-object?"))
{
Console.WriteLine("Error: too many args for function eof-object? test. ");
return(Nil.getInstance());
} // normal case where regular expression argument evaluated to null is to throw an error
else
{
Console.WriteLine("Error: one of the args items in regular function was null. ");
return(Nil.getInstance());
}
}
// under the alias of fringe_cons...
// we will continue this reference down to assess the next fringe branch
fringe_cons = evaluated_argsList__in_progress;
}
// dealt with the sole generation here.
// no more fringes left.
else
{
// check if eval is not null
Node evalItem1 = args_given.getCar().eval(envExtend1);
if (evalItem1 != null)
{
// first a detour...
//
// check for special case of eof-object? builtIn test is false
if (givenId != null && givenId.getSymbol().getName().Equals("eof-object?"))
{
return(BoolLit.getInstance(false));
} // normal case where regular expression argument evaluated to null is to throw an error
else
{
evaluated_argsList__in_progress = new Cons(evalItem1, Nil.getInstance());
}
}
else
{
// first a detour...
//
// check for special case of eof-object? builtIn test is true
if (givenId != null && givenId.getSymbol().getName().Equals("eof-object?"))
{
return(BoolLit.getInstance(true));
} // normal case where regular expression argument evaluated to null is to throw an error
else
{
Console.WriteLine("Error: the sole additional argument item in regular function was null. ");
return(Nil.getInstance());
}
}
}
// done with first step in two levels descendents
// get rest of fringes
while (hasMoreDescendents)
{
if (args_given.getCdr() == null)
{
Console.WriteLine("Error: one of the later argument items in regular function was null. ");
return(Nil.getInstance());
}
// precaution for null pointer so it is legal to use the cdr after this test
if (args_given.getCdr().isPair())
{
// build new environment for this to be computed for.
Environment envExtend2 = new Environment(env1);
// get next fringe descendent.
args_given = args_given.getCdr();
// start this off as unassigned.
Cons added_fringe_con = null;
// check if additional eval items are not null
Node evalItem_more = args_given.getCar().eval(envExtend2);
if (evalItem_more != null)
{
fringe_cons.setCdr(new Cons(evalItem_more, added_fringe_con));
}
else
{
Console.WriteLine("Error: one of the later argument items in regular function was null. ");
return(Nil.getInstance());
}
fringe_cons = (Cons)fringe_cons.getCdr();
}
else if (args_given.getCdr().isNull())
{
fringe_cons.setCdr(Nil.getInstance());
hasMoreDescendents = false;
}
else
{
// build new environment for this to be computed for.
Environment envExtend2 = new Environment(env1);
// get one remaining fringe descendent.
args_given = args_given.getCdr();
// check if additional eval items are not null
Node evalItem_more = args_given.getCar().eval(envExtend2);
if (evalItem_more != null)
{
fringe_cons.setCdr(new Cons(evalItem_more, Nil.getInstance()));
}
else
{
Console.WriteLine("Error: one of the later argument items in regular function was null. ");
return(Nil.getInstance());
}
hasMoreDescendents = false;
}
}
return(firstElem_car.apply(evaluated_argsList__in_progress));
}
return(firstElem_car.apply(Nil.getInstance()));
}
// TODO: The method apply() should be defined in class Node
// to report an error. It should be overridden only in classes
// BuiltIn and Closure.
public override Node apply(Node args)
{
// note for all built in functions that need arguments...
//
// the function will never do a test to check whether args is a pair, because
// args is always made a pair in special Regular for launching builtin_function apply.
if (this.symbol.getName().Equals("read"))
{
if (args == null || !args.isNull())
{
Console.WriteLine("Error: Read only needs no arguments for use.");
return(Nil.getInstance());
}
return((Node)Scheme4101.parser.parseExp());
}
else if (this.symbol.getName().Equals("write"))
{
if (args == null || args.isNull())
{
Console.WriteLine("Error: incorrect arguments. Nil passed, which cannot be used.");
return(Nil.getInstance());
}
args.getCar().print(0);
return(Nil.getInstance());
}
else if (this.symbol.getName().equals("set-car!"))
{
arg1.setCar(arg2);
return(arg1);
}
else if (this.symbol.getName().equals("set-cdr!"))
{
arg1.setCdr(arg2);
return(arg1);
}
else if (this.symbol.getName().Equals("display"))
{
if (args == null || args.isNull())
{
Console.WriteLine("Error: incorrect arguments. Nil passed, which cannot be used.");
return(Nil.getInstance());
}
Tree.BuiltIn.builtIn_display__do_not_print_double_quotes = true;
args.getCar().print(0);
Tree.BuiltIn.builtIn_display__do_not_print_double_quotes = false;
return(Nil.getInstance());
}
else if (this.symbol.getName().Equals("b+"))
{
// if there are no arguments, report error
if (args == null)
{
Console.WriteLine("Error: no arguments given for binary addition operation.");
return(Nil.getInstance());
}
// return zero if there are no arguments
if (args.isNull())
{
return(new IntLit(0));
}
// extend for all argument vars
// and
//check if first args have null
if (args.getCar() != null &&
args.getCdr() != null)
{
bool twoArguments_or_more;
// check if second argument is is nil.
if (args.getCdr().isNull())
{
twoArguments_or_more = false;
}
// see if there is a second item , ... and check that last tail of args is nil.
else if (args.getCdr().getCar() != null && args.getCdr().getCdr().isNull())
{
twoArguments_or_more = true;
}
else if (args.getCdr().getCar() != null && !args.getCdr().getCdr().isNull())
{
Console.WriteLine("Error: cannot process more than two args for binary addition.");
return(Nil.getInstance());
}
else
{
Console.WriteLine("Error: in b+ , one of arguments for expression has null node.");
return(Nil.getInstance());
}
if (twoArguments_or_more == false)
{
// check if argument is an intLit
if (args.getCar().isNumber())
{
// return the sole int lit node.
return(args.getCar());
}
else
{
Console.WriteLine("Error: in b+ , one of arguments for expression has null node.");
return(Nil.getInstance());
}
}
else
{
if (!args.getCar().isNumber() || !args.getCdr().getCar().isNumber())
{
Console.WriteLine("Error: arguments must be IntLit for binary addition.");
return(Nil.getInstance());
}
else
{
IntLit int1 = (IntLit)args.getCar();
IntLit int2 = (IntLit)args.getCdr().getCar();
return(new IntLit(int1.getInt() + int2.getInt()));
}
}
}
else
{
Console.WriteLine("Error: in b+ , there is a null external node");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("b-"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for binary subtraction operation.");
return(Nil.getInstance());
}
// extend for all argument vars
// and
//check if any args have null or nil.
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().getCar() != null &&
args.getCdr().getCdr().isNull())
{
if (!args.getCar().isNumber() || !args.getCdr().getCar().isNumber())
{
Console.WriteLine("Error: arguments must be IntLit for binary subtraction.");
return(Nil.getInstance());
}
else
{
IntLit int1 = (IntLit)args.getCar();
IntLit int2 = (IntLit)args.getCdr().getCar();
return(new IntLit(int1.getInt() - int2.getInt()));
}
}
else
{
Console.WriteLine("Error: more than two arguments for binary subtraction is not permissable.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("b*"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for binary multiplication operation.");
return(Nil.getInstance());
}
// extend for all argument vars
// and
//check if any args have null or nil.
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().getCar() != null &&
args.getCdr().getCdr().isNull())
{
if (!args.getCar().isNumber() || !args.getCdr().getCar().isNumber())
{
Console.WriteLine("Error: arguments must be IntLit for binary multiplication.");
return(Nil.getInstance());
}
else
{
IntLit int1 = (IntLit)args.getCar();
IntLit int2 = (IntLit)args.getCdr().getCar();
return(new IntLit(int1.getInt() * int2.getInt()));
}
}
else
{
Console.WriteLine("Error: more than two arguments for binary multiplication is not permissable.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("b/"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for binary division operation.");
return(Nil.getInstance());
}
// extend for all argument vars
// and
//check if any args have null or nil.
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().getCar() != null &&
args.getCdr().getCdr().isNull())
{
if (!args.getCar().isNumber() || !args.getCdr().getCar().isNumber())
{
Console.WriteLine("Error: arguments must be IntLit for binary division.");
return(Nil.getInstance());
}
else
{
IntLit int1 = (IntLit)args.getCar();
IntLit int2 = (IntLit)args.getCdr().getCar();
if (int2.getInt() == 0)
{
Console.WriteLine("Error: input not acceptable. cannot divide by zero.");
return(Nil.getInstance());
}
else
{
return(new IntLit(int1.getInt() / int2.getInt()));
}
}
}
else
{
Console.WriteLine("Error: more than two arguments for binary division is not permissable.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("b="))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for binary equality test operation.");
return(Nil.getInstance());
}
// extend for all argument vars
// and
//check if any args have null or nil.
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().getCar() != null &&
args.getCdr().getCdr().isNull())
{
if (!args.getCar().isNumber() || !args.getCdr().getCar().isNumber())
{
Console.WriteLine("Error: arguments must be IntLit for binary equality test.");
return(Nil.getInstance());
}
else
{
IntLit int1 = (IntLit)args.getCar();
IntLit int2 = (IntLit)args.getCdr().getCar();
bool resultOfTest = (int1.getInt() == int2.getInt());
if (resultOfTest)
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
}
else
{
Console.WriteLine("Error: more than two arguments for binary equality test is not permissable.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("b<"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for binary less than test operation.");
return(Nil.getInstance());
}
// extend for all argument vars
// and
//check if any args have null or nil.
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().getCar() != null &&
args.getCdr().getCdr().isNull())
{
if (!args.getCar().isNumber() || !args.getCdr().getCar().isNumber())
{
Console.WriteLine("Error: arguments must be IntLit for binary less than test.");
return(Nil.getInstance());
}
else
{
IntLit int1 = (IntLit)args.getCar();
IntLit int2 = (IntLit)args.getCdr().getCar();
bool resultOfTest = (int1.getInt() < int2.getInt());
if (resultOfTest)
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
}
else
{
Console.WriteLine("Error: more than two arguments for binary less than test is not permissable.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("b>"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for binary greater than test operation.");
return(Nil.getInstance());
}
// extend for all argument vars
// and
//check if any args have null or nil.
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().getCar() != null &&
args.getCdr().getCdr().isNull())
{
if (!args.getCar().isNumber() || !args.getCdr().getCar().isNumber())
{
Console.WriteLine("Error: arguments must be IntLit for binary greater than test.");
return(Nil.getInstance());
}
else
{
IntLit int1 = (IntLit)args.getCar();
IntLit int2 = (IntLit)args.getCdr().getCar();
bool resultOfTest = (int1.getInt() > int2.getInt());
if (resultOfTest)
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
}
else
{
Console.WriteLine("Error: more than two arguments for binary greater than test is not permissable.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("b<="))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for binary less than equal than test operation.");
return(Nil.getInstance());
}
// extend for all argument vars
// and
//check if any args have null or nil.
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().getCar() != null &&
args.getCdr().getCdr().isNull())
{
if (!args.getCar().isNumber() || !args.getCdr().getCar().isNumber())
{
Console.WriteLine("Error: arguments must be IntLit for binary less than equal than test.");
return(Nil.getInstance());
}
else
{
IntLit int1 = (IntLit)args.getCar();
IntLit int2 = (IntLit)args.getCdr().getCar();
bool resultOfTest = (int1.getInt() <= int2.getInt());
if (resultOfTest)
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
}
else
{
Console.WriteLine("Error: more than two arguments for binary less than equal than test is not permissable.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("b>="))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for binary greater than equal than test operation.");
return(Nil.getInstance());
}
// extend for all argument vars
// and
//check if any args have null or nil.
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().getCar() != null &&
args.getCdr().getCdr().isNull())
{
if (!args.getCar().isNumber() || !args.getCdr().getCar().isNumber())
{
Console.WriteLine("Error: arguments must be IntLit for binary greater than equal than test.");
return(Nil.getInstance());
}
else
{
IntLit int1 = (IntLit)args.getCar();
IntLit int2 = (IntLit)args.getCdr().getCar();
bool resultOfTest = (int1.getInt() >= int2.getInt());
if (resultOfTest)
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
}
else
{
Console.WriteLine("Error: more than two arguments for binary greater than equal than test is not permissable.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("null?"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for testing null evaluation.");
return(Nil.getInstance());
}
// extend for all argument vars
// check if number of args is correct
bool argument_number_good = false;
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().isNull())
{
argument_number_good = true;
}
if (argument_number_good)
{
if (args.getCar().isNull())
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
else
{
Console.WriteLine("Error: wrong number of arguments for test. only need 1 cons node with nil tail for argument.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("symbol?"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for testing symbol evaluation.");
return(Nil.getInstance());
}
// extend for all argument vars
// check if number of args is correct
bool argument_number_good = false;
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().isNull())
{
argument_number_good = true;
}
if (argument_number_good)
{
if (args.getCar().isSymbol())
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
else
{
Console.WriteLine("Error: wrong number of arguments for test. only need 1 cons node with nil tail for argument.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("number?"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for testing number evaluation.");
return(Nil.getInstance());
}
// extend for all argument vars
// check if number of args is correct
bool argument_number_good = false;
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().isNull())
{
argument_number_good = true;
}
if (argument_number_good)
{
if (args.getCar().isNumber())
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
else
{
Console.WriteLine("Error: wrong number of arguments for test. only need 1 cons node with nil tail for argument.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("boolean?"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for testing boolean evaluation.");
return(Nil.getInstance());
}
// extend for all argument vars
// check if number of args is correct
bool argument_number_good = false;
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().isNull())
{
argument_number_good = true;
}
if (argument_number_good)
{
if (args.getCar().isBool())
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
else
{
Console.WriteLine("Error: wrong number of arguments for test. only need 1 cons node with nil tail for argument.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("procedure?"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for testing procedure evaluation.");
return(Nil.getInstance());
}
// extend for all argument vars
// check if number of args is correct
bool argument_number_good = false;
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().isNull())
{
argument_number_good = true;
}
if (argument_number_good)
{
if (args.getCar().isProcedure())
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
else
{
Console.WriteLine("Error: wrong number of arguments for test. only need 1 cons node with nil tail for argument.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("pair?"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for testing pair evaluation.");
return(Nil.getInstance());
}
// extend for all argument vars
// check if number of args is correct
bool argument_number_good = false;
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().isNull())
{
argument_number_good = true;
}
if (argument_number_good)
{
if (args.getCar().isPair())
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
else
{
Console.WriteLine("Error: wrong number of arguments for test. only need 1 cons node with nil tail for argument.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("environment?"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for testing environment evaluation.");
return(Nil.getInstance());
}
// extend for all argument vars
// check if number of args is correct
bool argument_number_good = false;
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().isNull())
{
argument_number_good = true;
}
if (argument_number_good)
{
if (args.getCar().isEnvironment())
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
else
{
Console.WriteLine("Error: wrong number of arguments for test. only need 1 cons node with nil tail for argument.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("string?"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for testing string evaluation.");
return(Nil.getInstance());
}
// extend for all argument vars
// check if number of args is correct
bool argument_number_good = false;
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().isNull())
{
argument_number_good = true;
}
if (argument_number_good)
{
if (args.getCar().isString())
{
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
else
{
Console.WriteLine("Error: wrong number of arguments for test. only need 1 cons node with nil tail for argument.");
return(Nil.getInstance());
}
}
// working on predicate built in : eq?
else if (this.symbol.getName().Equals("eq?"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for eq? test operation.");
return(Nil.getInstance());
}
// extend for all argument vars
// and
//check if any args have null or nil.
if (args != null && args.getCar() != null &&
args.getCdr() != null && args.getCdr().getCar() != null &&
args.getCdr().getCdr().isNull())
{
//if (!args.getCar () || !args.getCdr ().getCar () )
// check nil/null? first
// first car is nil but second item is not nil...
// or the other way around (vice versa)
if ((args.getCar().isNull() && !args.getCdr().getCar().isNull()) ||
(!args.getCar().isNull() && args.getCdr().getCar().isNull()))
{
return(BoolLit.getInstance(false));
}
// success: both nil
else if (args.getCar().isNull() && args.getCdr().getCar().isNull())
{
return(BoolLit.getInstance(true));
}
// first car is type symbol but second item is not symbol...
// or the other way around (vice versa)
else if ((args.getCar().isSymbol() && !args.getCdr().getCar().isSymbol()) ||
(!args.getCar().isSymbol() && args.getCdr().getCar().isSymbol()))
{
return(BoolLit.getInstance(false));
}
// check if both symbol now...
else if (args.getCar().isSymbol() && args.getCdr().getCar().isSymbol())
{
// check if the symbol's are identical
if (args.getCar().getName().Equals(args.getCdr().getCar().getName()))
{
// success: both same symbol!
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
// first car is type number but second item is not number...
// or the other way around (vice versa)
else if ((args.getCar().isNumber() && !args.getCdr().getCar().isNumber()) ||
(!args.getCar().isNumber() && args.getCdr().getCar().isNumber()))
{
return(BoolLit.getInstance(false));
}
// check if both number now...
else if (args.getCar().isNumber() && args.getCdr().getCar().isNumber())
{
// cast to new IntLits
IntLit intLit_1 = (IntLit)args.getCar();
IntLit intLit_2 = (IntLit)args.getCdr().getCar();
// check if the int values's are equal
if (intLit_1.getInt() == intLit_2.getInt())
{
// success: both same integer!
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
// first car is type boolean but second item is not boolean...
// or the other way around (vice versa)
else if ((args.getCar().isBool() && !args.getCdr().getCar().isBool()) ||
(!args.getCar().isBool() && args.getCdr().getCar().isBool()))
{
return(BoolLit.getInstance(false));
}
// check if both boolean now...
else if (args.getCar().isBool() && args.getCdr().getCar().isBool())
{
// cast nodes as new booleanNodes
BoolLit boolVal1 = (BoolLit)args.getCar();
BoolLit boolVal2 = (BoolLit)args.getCdr().getCar();
// check if the bool's equal
if (boolVal1.Equals(boolVal2))
{
// success: both same bool!
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
// first car is type builtIn but second item is not builtIn...
// or the other way around (vice versa)
else if ((args.getCar().isBuiltIn() && !args.getCdr().getCar().isBuiltIn()) ||
(!args.getCar().isBuiltIn() && args.getCdr().getCar().isBuiltIn()))
{
return(BoolLit.getInstance(false));
}
// check if both builtIn now...
else if (args.getCar().isBuiltIn() && args.getCdr().getCar().isBuiltIn())
{
// cast nodes as new builtIn
BuiltIn builtIn_val_1 = (BuiltIn)args.getCar();
BuiltIn builtIn_val_2 = (BuiltIn)args.getCdr().getCar();
// check if the builtIn's are identical
if (builtIn_val_1.getSymbol().Equals(builtIn_val_2.getSymbol()))
{
// success: both same builtIn!
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
// by process of elimination
//now
// a object that ends up tested here would be surely a closure...
// first car is type closure but second item is not closure...
// or the other way around (vice versa)
else if ((args.getCar().isProcedure() && !args.getCdr().getCar().isProcedure()) ||
(!args.getCar().isProcedure() && args.getCdr().getCar().isProcedure()))
{
return(BoolLit.getInstance(false));
}
// check if both closure now...
else if (args.getCar().isProcedure() && args.getCdr().getCar().isProcedure())
{
// cast nodes as new builtIn
Closure closure_val_1 = (Closure)args.getCar();
Closure closure_val_2 = (Closure)args.getCdr().getCar();
// check if the closure's are identical
if (closure_val_1.Equals(closure_val_2))
{
// success: both same closure!
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
// first car is type environment but second item is not environment...
// or the other way around (vice versa)
else if ((args.getCar().isEnvironment() && !args.getCdr().getCar().isEnvironment()) ||
(!args.getCar().isEnvironment() && args.getCdr().getCar().isEnvironment()))
{
return(BoolLit.getInstance(false));
}
// check if both environment now...
else if (args.getCar().isEnvironment() && args.getCdr().getCar().isEnvironment())
{
// cast nodes as new Environment
Environment environ_1 = (Environment)args.getCar();
Environment environ_2 = (Environment)args.getCdr().getCar();
// check if the environment's are identical
if (environ_1.Equals(environ_2))
{
// success: both same environment!
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
// first car is type String but second item is not String...
// or the other way around (vice versa)
else if ((args.getCar().isString() && !args.getCdr().getCar().isString()) ||
(!args.getCar().isString() && args.getCdr().getCar().isString()))
{
return(BoolLit.getInstance(false));
}
// check if both String now...
else if (args.getCar().isString() && args.getCdr().getCar().isString())
{
// cast nodes as new StringLits
StringLit String_1 = (StringLit)args.getCar();
StringLit String_2 = (StringLit)args.getCdr().getCar();
// check if the StringLit's are identical
if (String_1.getString().Equals(String_2.getString()))
{
// success: both same StringLit!
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
}
// eq? test note: there is one caveat. If the items are both quote terms... this will be handled directly in regular eval
// first car is type Pair but second item is not Pair...
// or the other way around (vice versa)
else if ((args.getCar().isPair() && !args.getCdr().getCar().isPair()) ||
(!args.getCar().isPair() && args.getCdr().getCar().isPair()))
{
return(BoolLit.getInstance(false));
}
// check if both are type Pair now...
else if (args.getCar().isPair() && args.getCdr().getCar().isPair())
{
// cast nodes as new cons Pair
Cons cons_1 = (Cons)args.getCar();
Cons cons_2 = (Cons)args.getCdr().getCar();
// check if the Cons's are identical
if (cons_1.Equals(cons_2))
{
// success: both same pair reference!
return(BoolLit.getInstance(true));
}
else
{
return(BoolLit.getInstance(false));
}
// illegal function for argument
}
else
{
Console.WriteLine("Error: Argument types for eq? cannot be recognized in context.");
return(Nil.getInstance());
}
}
else
{
Console.WriteLine("Error: null parameter _ or _ more than two arguments for eq? test is not permissable.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("car"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for car operation.");
return(Nil.getInstance());
}
// check if args first item given is a pair and check if the number of arguments given is correctly 1
if (args.getCar() != null && args.getCdr() != null && args.getCdr().isNull())
{
if (args.getCar().isPair())
{
if (args.getCar().getCar() != null)
{
return(args.getCar().getCar());
}
else
{
Console.WriteLine("Error: for car function_ , one of arguments to return is null.");
return(Nil.getInstance());
}
}
else
{
Console.WriteLine("Error: for car function_ , item given is not a pair.");
return(Nil.getInstance());
}
}
else
{
Console.WriteLine("Error: wrong number of arguments for car, tail is not nil. or element in arguments is null.");
return(Nil.getInstance());
}
}
else if (this.symbol.getName().Equals("cdr"))
{
// if there are no arguments, report error
if (args == null || args.isNull())
{
Console.WriteLine("Error: no arguments given for cdr operation.");
return(Nil.getInstance());
}
// check if args first item given is a pair and check if the number of arguments given is correctly 1
if (args.getCar() != null && args.getCar().isPair() && args.getCdr() != null && args.getCdr().isNull())
{
// check if argument's cdr is not null
if (args.getCar().getCdr() != null)
{
return(args.getCar().getCdr());
}
else
{
Console.WriteLine("Error: for cdr function_ , one of arguments to return is null.");
return(Nil.getInstance());
}
}
else
{
Console.WriteLine("Error: for cdr, item is not pair or wrong number of arguments for cdr: tail is not nil. or element in arguments is null.");
return(Nil.getInstance());
}
}
else
{
Console.WriteLine("Error: builtin is not identifiable.");
return(Nil.getInstance());
}
}