// <-- Name
// | FN Name TupleType
// | BOOL_LITERAL
// | INT_LITERAL
// | STRING_LITERAL
// | LPAREN (Expression)? RPAREN
private IUnboundExpr PrimaryExpr()
{
IUnboundExpr expression;
if (CurrentIs(TokenType.Name))
{
var name = Consume();
expression = new NameExpr(name.Position, name.StringValue, TypeArgs());
}
else if (CurrentIs(TokenType.Fn))
{
expression = FuncExpr();
}
else if (CurrentIs(TokenType.Bool))
{
expression = new BoolExpr(Consume(TokenType.Bool));
}
else if (CurrentIs(TokenType.Int))
{
expression = new IntExpr(Consume(TokenType.Int));
}
else if (CurrentIs(TokenType.String))
{
expression = new StringExpr(Consume(TokenType.String));
}
else if (CurrentIs(TokenType.LeftParen))
{
Token leftParen = Consume(TokenType.LeftParen);
if (CurrentIs(TokenType.RightParen))
{
// () -> unit
expression = new UnitExpr(leftParen.Position);
}
else if (CurrentIs(TokenType.Operator))
{
// ( OPERATOR ) -> an operator in prefix form
Token op = Consume(TokenType.Operator);
expression = new NameExpr(op.Position, op.StringValue);
}
else
{
// anything else is a regular parenthesized expression
expression = Expression();
}
Consume(TokenType.RightParen);
}
else
{
expression = null;
}
return(expression);
}
bool IBoundExprVisitor <bool> .Visit(UnitExpr expr)
{
return(true);
} // do nothing
public virtual IUnboundExpr Transform(UnitExpr expr)
{
return(expr);
}
IBoundExpr IUnboundExprVisitor<IBoundExpr>.Visit(UnitExpr expr)
{
return expr;
}
/// <summary>
/// Resolves and binds a reference to a name.
/// </summary>
/// <param name="function">The function being compiled.</param>
/// <param name="scope">The scope in which the name is being bound.</param>
/// <param name="name">The name being resolved. May or may not be fully-qualified.</param>
/// <param name="typeArgs">The type arguments being applied to the name. For
/// example, resolving "foo'(int, bool)" would pass in {int, bool} here.</param>
/// <param name="arg">The argument being applied to the name.</param>
/// <returns></returns>
public IBoundExpr ResolveName(Function function,
Scope scope, Position position, string name,
IList <IUnboundDecl> typeArgs, IBoundExpr arg)
{
IBoundDecl argType = null;
if (arg != null)
{
argType = arg.Type;
}
IBoundExpr resolved = null;
// see if it's an argument
if (function.ParamNames.Contains(name))
{
// load the argument
resolved = new LoadExpr(new LocalsExpr(), function.ParameterType, 0);
if (function.ParamNames.Count > 1)
{
// function takes multiple parameters, so load it from the tuple
var paramTuple = (BoundTupleType)function.ParameterType;
var argIndex = (byte)function.ParamNames.IndexOf(name);
resolved = new LoadExpr(resolved, paramTuple.Fields[argIndex], argIndex);
}
}
// see if it's a local
if (scope.Contains(name))
{
var local = scope[name];
// just load the value
resolved = new LoadExpr(new LocalsExpr(), scope[name]);
}
// if we resolved to a local name, handle it
if (resolved != null)
{
if (typeArgs.Count > 0)
{
throw new CompileException(position, "Cannot apply type arguments to a local variable or function argument.");
}
// if the local or argument is holding a function reference and we're passed args, call it
if (argType != null)
{
var funcType = resolved.Type as FuncType;
if (funcType != null)
{
// check that args match
if (!DeclComparer.TypesMatch(funcType.Parameter.Bound, argType))
{
throw new CompileException(position, "Argument types passed to local function reference do not match function's parameter types.");
}
// call it
resolved = new BoundCallExpr(resolved, arg);
}
else
{
// not calling a function, so try to desugar to a __Call
var callArg = new BoundTupleExpr(new IBoundExpr[] { resolved, arg });
resolved = ResolveFunction(function, position,
"__Call", new IUnboundDecl[0], callArg);
if (resolved == null)
{
throw new CompileException(position, "Cannot call a local variable or argument that is not a function reference, and could not find a matching __Call.");
}
}
}
return(resolved);
}
// implicitly apply () as the argument if no other argument was provided.
// note that we do this *after* checking for locals because locals aren't
// implicitly applied. since most locals aren't functions anyway, it won't
// matter in most cases, and in cases where a local holds a function, the
// user will mostly likely want to treat that function like a value: return
// it, pass it around, etc.
if (arg == null)
{
arg = new UnitExpr(Position.None);
argType = arg.Type;
}
return(ResolveFunction(function, position, name, typeArgs, arg));
}
IUnboundExpr IUnboundExprVisitor <IUnboundExpr> .Visit(UnitExpr expr)
{
return(Call("UnitExpr", Unit()));
}