public static void Bind(BindingContext context, Function function)
{
if (function.Type.Return == null) throw new InvalidOperationException("Can only bind functions whose type is already bound.");
var scope = new Scope();
// create a local slot for the arg if there is one
if (function.Type.Parameter.Unbound != Decl.Unit)
{
scope.Define(context.NameGenerator.Generate(), Decl.Unit /* ignored */, false);
}
var binder = new FunctionBinder(function, context, scope);
// bind the function
function.Bind(context, binder);
// make sure declared return type matches actual return type
if (!DeclComparer.TypesMatch(function.Type.Return.Bound, function.Body.Bound.Type))
{
if (function.Body.Bound.Type == Decl.EarlyReturn)
{
//### bob: should find the return expr
throw new CompileException(function.Position, "Unneeded explicit \"return\".");
}
else
{
throw new CompileException(function.Position, String.Format("{0} is declared to return {1} but is returning {2}.",
function.Name, function.Type.Return.Bound, function.Body.Bound.Type));
}
}
}
public ICallable Instantiate(BindingContext context, IEnumerable <IBoundDecl> typeArgs,
IBoundDecl argType)
{
// should have three args: an int, an array, and a value
var argTuple = argType as BoundTupleType;
if (argTuple == null)
{
return(null);
}
// index
if (argTuple.Fields[0] != Decl.Int)
{
return(null);
}
// array
var arrayType = argTuple.Fields[1] as BoundArrayType;
if (arrayType == null)
{
return(null);
}
// value
if (!DeclComparer.TypesMatch(argTuple.Fields[2], arrayType.ElementType))
{
return(null);
}
// make the intrinsic
return(new Intrinsic("__Call<-", OpCode.StoreArray, FuncType.Create(argTuple, Decl.Unit)));
}
IBoundExpr IUnboundExprVisitor<IBoundExpr>.Visit(ArrayExpr expr)
{
var elementType = (IBoundDecl)null;
if (expr.ElementType != null)
{
elementType = TypeBinder.Bind(mContext, expr.ElementType);
}
var elements = expr.Elements.Accept(this);
// infer the type from the elements
if (elementType == null)
{
var index = 0;
foreach (var element in elements)
{
if (elementType == null)
{
// take the type of the first
elementType = element.Type;
}
else
{
// make sure the others match
if (!DeclComparer.TypesMatch(elementType, element.Type))
throw new CompileException(expr.Position, String.Format("Array elements must all be the same type. Array is type {0}, but element {1} is type {2}.",
elementType, index, element.Type));
}
index++;
}
}
// build a structure for the array
var fields = new List<IBoundExpr>();
fields.Add(new IntExpr(expr.Elements.Count));
fields.AddRange(elements);
return new BoundTupleExpr(fields,
new BoundArrayType(elementType));
}
public ICallable Instantiate(BindingContext context, IEnumerable <IBoundDecl> typeArgs,
IBoundDecl argType)
{
bool canInfer;
var genericContext = BuildContext(context,
BaseType.Type.Parameter.Unbound,
argType, ref typeArgs, out canInfer);
// bail if we couldn't get the right number of type arguments
if ((typeArgs == null) || (TypeParameters.Count != typeArgs.Count()))
{
return(null);
}
// create a new bound function type with the type arguments applied
FuncType funcType = BaseType.Type.CloneFunc();
TypeBinder.Bind(genericContext, funcType);
// make sure the concrete argument types of this instance match what we're actually given
if (!DeclComparer.TypesMatch(funcType.Parameter.Bound, argType))
{
return(null);
}
// create a new unbound function with the proper type
Function instance = new Function(BaseType.Position, BaseType.BaseName,
funcType, BaseType.ParamNames, BaseType.Body.Unbound, typeArgs, canInfer);
instance.BindSearchSpace(BaseType.SearchSpace);
// don't instantiate it multiple times
// note that this must happen *before* the function is bound, in case the
// newly instantiated generic function is recursive.
context.Compiler.Functions.Add(instance);
// bind it with the type arguments in context
FunctionBinder.Bind(genericContext, instance);
return(instance);
}
private bool TryInferParam(IBoundDecl argType)
{
// see if the parameter type on top of the stack is a generic type
NamedType named = ParamType as NamedType;
if (named == null)
{
return(false);
}
// see if the named type is a generic type (instead of an actual concrete named type)
int typeParamIndex = mTypeParamNames.IndexOf(named.Name);
if (typeParamIndex == -1)
{
return(false);
}
// it is, so infer it from the arg
if (mTypeArguments[typeParamIndex] == null)
{
// first time inferring the arg
mTypeArguments[typeParamIndex] = argType;
}
else
{
// already inferred, make sure it matches
if (!DeclComparer.TypesMatch(mTypeArguments[typeParamIndex], argType))
{
// can't infer the same type parameter to multiple different types
// example: Foo'A (a A, b A)
// Foo (123, "string")
mFailed = true;
}
}
return(true);
}
IBoundExpr IUnboundExprVisitor<IBoundExpr>.Visit(IfExpr expr)
{
var bound = new BoundIfExpr(
expr.Condition.Accept(this),
expr.ThenBody.Accept(this),
(expr.ElseBody == null) ? null : expr.ElseBody.Accept(this));
if (bound.Condition.Type != Decl.Bool)
{
throw new CompileException(expr.Position, String.Format(
"Condition of if/then/else is returning type {0} but should be Bool.",
bound.Condition.Type));
}
if (bound.ElseBody != null)
{
// has an else, so make sure both arms match
if (!DeclComparer.TypesMatch(bound.ThenBody.Type, bound.ElseBody.Type))
{
throw new CompileException(expr.Position, String.Format(
"Branches of if/then/else do not return the same type. Then arm returns {0} while else arm returns {1}.",
bound.ThenBody.Type, bound.ElseBody.Type));
}
}
else
{
// no else, so make the then body doesn't return a value
if ((bound.ThenBody.Type != Decl.Unit) && (bound.ThenBody.Type != Decl.EarlyReturn))
{
throw new CompileException(expr.Position, String.Format(
"Body of if/then is returning type {0} but must be Unit (or a return) if there is no else branch.",
bound.ThenBody.Type));
}
}
return bound;
}
IBoundExpr IUnboundExprVisitor<IBoundExpr>.Visit(CallExpr expr)
{
var namedTarget = expr.Target as NameExpr;
// see if it's a macro call before binding the arg
if ((namedTarget != null) && (mContext.Compiler.MacroProcessor != null))
{
IUnboundExpr macroResult = mContext.Compiler.MacroProcessor.Process(namedTarget.Name, expr.Arg);
// if it was a macro call, bind the result of it
if (macroResult != null) return macroResult.Accept(this);
}
//### bob: handle array constructors. hack! should be intrinsic
if ((namedTarget != null) && (namedTarget.Name == "ArrayOf"))
{
// handle ArrayOf[Int]
if ((expr.Arg is UnitExpr) && (namedTarget.TypeArgs.Count == 1))
{
return new ArrayExpr(namedTarget.Position, namedTarget.TypeArgs[0]).Accept(this);
}
// handle ArrayOf (1, 2, 3)
var elements = (IEnumerable<IUnboundExpr>)(new IUnboundExpr[] { expr.Arg });
if (expr.Arg is TupleExpr)
{
elements = ((TupleExpr)expr.Arg).Fields;
}
return new ArrayExpr(namedTarget.Position, elements).Accept(this);
}
var boundArg = expr.Arg.Accept(this);
// see if we're accessing a record field
BoundRecordType recordType = boundArg.Type as BoundRecordType;
if ((namedTarget != null) &&
(recordType != null) &&
recordType.Fields.ContainsKey(namedTarget.Name))
{
// find the index of the field
//### bob: ToList() here is a gross hack.
var index = recordType.Fields.Keys.ToList().IndexOf(namedTarget.Name);
// bind it
return new LoadExpr(boundArg, recordType.Fields[namedTarget.Name], index);
}
if (namedTarget != null)
{
return mContext.ResolveName(mFunction, Scope, namedTarget.Position,
namedTarget.Name, namedTarget.TypeArgs, boundArg);
}
IBoundExpr target = expr.Target.Accept(this);
// see if we're calling a function
FuncType funcType = target.Type as FuncType;
if (funcType != null)
{
// check that args match
if (!DeclComparer.TypesMatch(funcType.Parameter.Bound, boundArg.Type))
{
throw new CompileException(expr.Position, "Argument types passed to evaluated function reference do not match function's parameter types.");
}
// simply apply the arg to the bound expression
return new BoundCallExpr(target, boundArg);
}
// see if we're accessing a tuple field
var tupleType = boundArg.Type as BoundTupleType;
if ((tupleType != null) && (target.Type == Decl.Int))
{
var index = target as IntExpr;
if (index == null) throw new CompileException(expr.Position, "Tuple fields can only be accessed using a literal index, not an int expression.");
// make sure the field is in range
if ((index.Value < 0) || (index.Value >= tupleType.Fields.Count))
throw new CompileException(expr.Position, String.Format("Cannot access field {0} because the tuple only has {1} fields.", index.Value, tupleType.Fields.Count));
// bind it
return new LoadExpr(boundArg, tupleType.Fields[index.Value], index.Value);
}
// not calling a function, so try to desugar to a __Call
var callArg = new BoundTupleExpr(new IBoundExpr[] { target, boundArg });
var call = mContext.ResolveFunction(mFunction, expr.Target.Position,
"__Call", new IUnboundDecl[0], callArg);
if (call != null) return call;
throw new CompileException(expr.Position, "Target of call is not a function.");
}
/// <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));
}