/// <summary>
/// Binds this function to an instance of a class,
/// allowing it to access the instance's 'this' variable.
/// </summary>
/// <param name="instance">Instance to bind to.</param>
/// <returns>The bound function.</returns>
public Function Bind(Instance instance)
{
var environment = new EnvironmentState(outerEnvironment: _closure);
environment.Define("this", instance);
return(new Function(_declaration, environment, _name, _isInit));
}
/// <summary>
/// Calls the function.
/// </summary>
/// <param name="interpreter">Interpreter calling the function.</param>
/// <param name="arguments">Arguments to pass to the function.</param>
/// <returns>The result of the function call.</returns>
public object Call(Interpreter interpreter, IEnumerable <object> arguments)
{
// each call gets its own scope so that it can keep track of its individual state
var environment = new EnvironmentState(outerEnvironment: _closure);
// combine the params and the arguments into one collection
var paramArguments = _declaration.Params.Zip(arguments, (param, argument) => new
{
Name = param.WrappedSource,
Value = argument
});
// define scoped variables for each param/argument
foreach (var item in paramArguments)
{
environment.Define(item.Name, item.Value);
}
try
{
// execute the function body with the new scope we just created
interpreter.ExecuteBlock(_declaration.Body, environment);
}
catch (ReturnException ex)
{
return(_isInit
? _closure.GetValue("this", 0)
: ex.Value);
}
// constructors will always return 'this'
return(_isInit
? _closure.GetValue("this", 0)
: null);
}
/// <summary>
/// Initialize a <see cref="Function"/> with the
/// <see cref="FunctionStatement"/> declaration it originated from.
/// </summary>
/// <param name="declaration">Parsed source of the function.</param>
public Function(FunctionExpression declaration, EnvironmentState closure,
Token name = null, bool isInit = false)
{
_declaration = declaration;
_closure = closure;
_name = name;
_isInit = isInit;
ParamCount = _declaration.Params.Count();
}
/// <summary>
/// Interprets and executes the given statements.
/// </summary>
/// <param name="statements">Statements to execute.</param>
public void Interpret(IEnumerable <StatementBase> statements)
{
RuntimeExceptionThrown = false;
_environment = GlobalState;
PrepareGlobalScope();
try
{
foreach (var statement in statements)
{
Execute(statement);
}
}
catch (RuntimeException ex)
{
RuntimeExceptionThrown = true;
ErrorReporter.ReportRuntimeException(ex);
}
}
/// <summary>
/// <see cref="Execute(StatementBase)"/>s all statements in a block.
/// </summary>
/// <param name="statements">Statements to execute.</param>
/// <param name="environment">The block's environment.</param>
public void ExecuteBlock(IEnumerable <StatementBase> statements, EnvironmentState environment)
{
// hang on to the current scope
var outerEnvironment = _environment;
try
{
// our scope is now this block's scope
_environment = environment;
foreach (var statement in statements)
{
Execute(statement);
}
}
finally
{
// restore to the first scope
_environment = outerEnvironment;
}
}
/// <summary>
/// Initializes an <see cref="EnvironmentState"/>, optionally with an enclosing environment.
/// </summary>
/// <param name="outerEnvironment">The <see cref="EnvironmentState"/> enclosing this one.</param>
public EnvironmentState(EnvironmentState outerEnvironment = null)
{
OuterEnvironment = outerEnvironment;
}