Michael Schimmel
499 lines
18 KiB
ObjectPascal
499 lines
18 KiB
ObjectPascal
unit Myc.Ast.Evaluator;
|
|
|
|
interface
|
|
|
|
uses
|
|
System.SysUtils,
|
|
System.Classes,
|
|
System.Generics.Collections,
|
|
Myc.Data.Scalar,
|
|
Myc.Data.Value,
|
|
Myc.Ast.Nodes,
|
|
Myc.Ast.Visitor,
|
|
Myc.Ast.Binding,
|
|
Myc.Ast.Scope;
|
|
|
|
type
|
|
// A factory for creating visitors, primarily used by the debugger subsystem.
|
|
TVisitorFactory = reference to function(const Scope: IExecutionScope): IAstVisitor;
|
|
|
|
IEvaluatorVisitor = interface(IAstVisitor)
|
|
function Execute(const RootNode: IAstNode): TDataValue;
|
|
end;
|
|
|
|
// The standard AST evaluator for production use.
|
|
TEvaluatorVisitor = class(TAstVisitor, IEvaluatorVisitor)
|
|
private
|
|
FScope: IExecutionScope;
|
|
procedure HandleTCO(var ResultValue: TDataValue);
|
|
|
|
protected
|
|
function VisitConstant(const Node: IConstantNode): TDataValue; override;
|
|
function VisitIdentifier(const Node: IIdentifierNode): TDataValue; override;
|
|
function VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue; override;
|
|
function VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue; override;
|
|
function VisitIfExpression(const Node: IIfExpressionNode): TDataValue; override;
|
|
function VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue; override;
|
|
function VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue; override;
|
|
function VisitFunctionCall(const Node: IFunctionCallNode): TDataValue; override;
|
|
function VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue; override;
|
|
function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue; override;
|
|
function VisitAssignment(const Node: IAssignmentNode): TDataValue; override;
|
|
function VisitIndexer(const Node: IIndexerNode): TDataValue; override;
|
|
function VisitMemberAccess(const Node: IMemberAccessNode): TDataValue; override;
|
|
function VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue; override;
|
|
function VisitAddSeriesItem(const Node: IAddSeriesItemNode): TDataValue; override;
|
|
function VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue; override;
|
|
function VisitRecurNode(const Node: IRecurNode): TDataValue; override;
|
|
|
|
function IsTruthy(const AValue: TDataValue): Boolean; inline;
|
|
|
|
// Returns a closure that can create the correct type of visitor for a lambda's body.
|
|
function CreateVisitorFactory: TVisitorFactory; virtual;
|
|
|
|
property Scope: IExecutionScope read FScope;
|
|
public
|
|
constructor Create(const AScope: IExecutionScope);
|
|
|
|
// Executes an AST with proper TCO handling. This is the main entry point.
|
|
function Execute(const RootNode: IAstNode): TDataValue;
|
|
end;
|
|
|
|
// Registers native Delphi functions into a scope.
|
|
procedure RegisterNativeFunctions(const AScope: IExecutionScope);
|
|
|
|
implementation
|
|
|
|
uses
|
|
System.TypInfo,
|
|
System.Generics.Defaults,
|
|
Myc.Data.Decimal,
|
|
Myc.Data.Series,
|
|
Myc.Data.Scalar.JSON;
|
|
|
|
// Helper type for TCO via trampolining.
|
|
type
|
|
TThunk = record
|
|
Callee: TDataValue;
|
|
Args: TArray<TDataValue>;
|
|
constructor Create(const ACallee: TDataValue; const AArgs: TArray<TDataValue>);
|
|
end;
|
|
|
|
constructor TThunk.Create(const ACallee: TDataValue; const AArgs: TArray<TDataValue>);
|
|
begin
|
|
Callee := ACallee;
|
|
Args := AArgs;
|
|
end;
|
|
|
|
// --- Native Functions Implementation ---
|
|
|
|
function NativeCreateRecordSeries(const Args: TArray<TDataValue>): TDataValue;
|
|
var
|
|
jsonDef: string;
|
|
recordDef: TScalarRecordDefinition;
|
|
series: IRecordSeries;
|
|
begin
|
|
if (Length(Args) <> 1) or (Args[0].Kind <> vkText) then
|
|
raise EArgumentException.Create('CreateRecordSeries requires one string argument.');
|
|
|
|
jsonDef := Args[0].AsText;
|
|
recordDef := TRttiAstHelper.JsonToRecordDefinition(jsonDef);
|
|
|
|
if Length(recordDef.Fields) = 0 then
|
|
raise EArgumentException.Create('Failed to parse record definition from JSON.');
|
|
|
|
series := TScalarRecordSeries.Create(recordDef);
|
|
Result := TDataValue.FromRecordSeries(series);
|
|
end;
|
|
|
|
// --- Registration Procedure ---
|
|
|
|
procedure RegisterNativeFunctions(const AScope: IExecutionScope);
|
|
begin
|
|
AScope.Define('CreateRecordSeries', TDataValue(NativeCreateRecordSeries));
|
|
end;
|
|
|
|
{ TEvaluatorVisitor }
|
|
|
|
constructor TEvaluatorVisitor.Create(const AScope: IExecutionScope);
|
|
begin
|
|
inherited Create;
|
|
Assert(Assigned(AScope));
|
|
FScope := AScope;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.Execute(const RootNode: IAstNode): TDataValue;
|
|
begin
|
|
if not Assigned(RootNode) then
|
|
exit(TDataValue.Void);
|
|
|
|
Result := RootNode.Accept(Self);
|
|
HandleTCO(Result);
|
|
end;
|
|
|
|
function TEvaluatorVisitor.CreateVisitorFactory: TVisitorFactory;
|
|
begin
|
|
// The production visitor returns a factory that creates another production visitor.
|
|
Result := function(const AScope: IExecutionScope): IAstVisitor begin Result := TEvaluatorVisitor.Create(AScope); end;
|
|
end;
|
|
|
|
procedure TEvaluatorVisitor.HandleTCO(var ResultValue: TDataValue);
|
|
begin
|
|
// This is the central trampoline loop for Tail Call Optimization.
|
|
// It runs as long as the evaluation returns a thunk.
|
|
while ResultValue.Kind = vkGeneric do
|
|
begin
|
|
var thunk := ResultValue.AsGeneric<TThunk>;
|
|
var callee := thunk.Callee.AsMethod();
|
|
ResultValue := callee(thunk.Args);
|
|
end;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.IsTruthy(const AValue: TDataValue): Boolean;
|
|
begin
|
|
if (AValue.Kind <> vkScalar) then
|
|
begin
|
|
Result := False;
|
|
exit;
|
|
end;
|
|
|
|
case AValue.AsScalar.Kind of
|
|
TScalar.TKind.Ordinal: Result := (AValue.AsScalar.Value.AsInt64 <> 0);
|
|
TScalar.TKind.Float: Result := (AValue.AsScalar.Value.AsDouble <> 0.0);
|
|
else
|
|
Result := False;
|
|
end;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue;
|
|
var
|
|
boundNode: TBoundLambdaExpressionNode;
|
|
capturedCells: TArray<IValueCell>;
|
|
i: Integer;
|
|
sourceAddresses: TArray<TResolvedAddress>;
|
|
closureScope: IExecutionScope;
|
|
visitorFactory: TVisitorFactory;
|
|
begin
|
|
// Cast to the bound node to access binder-specific information.
|
|
boundNode := Node as TBoundLambdaExpressionNode;
|
|
|
|
sourceAddresses := boundNode.Upvalues;
|
|
SetLength(capturedCells, Length(sourceAddresses));
|
|
for i := 0 to High(sourceAddresses) do
|
|
capturedCells[i] := FScope.Capture(sourceAddresses[i]);
|
|
|
|
if boundNode.HasNestedLambdas then
|
|
closureScope := FScope
|
|
else
|
|
closureScope := nil;
|
|
|
|
visitorFactory := CreateVisitorFactory();
|
|
|
|
var scopeDescriptor := boundNode.ScopeDescriptor;
|
|
var params := boundNode.Parameters;
|
|
|
|
var [weak] closure: TDataValue.TFunc;
|
|
var cNode: ILambdaExpressionNode := Node;
|
|
|
|
closure :=
|
|
TDataValue.TFunc(
|
|
function(const ArgValues: TArray<TDataValue>): TDataValue
|
|
var
|
|
lambdaScope: IExecutionScope;
|
|
bodyVisitor: IAstVisitor;
|
|
i: Integer;
|
|
adr: TResolvedAddress;
|
|
begin
|
|
if (Length(ArgValues) <> Length(params)) then
|
|
raise EArgumentException.CreateFmt('Argument count mismatch: expected %d, got %d', [Length(params), Length(ArgValues)]);
|
|
|
|
lambdaScope := TScope.CreateScope(closureScope, scopeDescriptor, capturedCells);
|
|
|
|
adr.Kind := akLocalOrParent;
|
|
adr.ScopeDepth := 0;
|
|
|
|
// Capture the closure itself in slot 0 for 'recur' to find it.
|
|
adr.SlotIndex := 0;
|
|
lambdaScope[adr] := TDataValue(closure);
|
|
|
|
// Populate the actual parameters.
|
|
for i := 0 to High(ArgValues) do
|
|
begin
|
|
// Parameters in a bound lambda must be bound identifiers.
|
|
adr.SlotIndex := (params[i] as TBoundIdentifierNode).Address.SlotIndex;
|
|
lambdaScope[adr] := ArgValues[i];
|
|
end;
|
|
|
|
bodyVisitor := visitorFactory(lambdaScope);
|
|
Result := cNode.Body.Accept(bodyVisitor);
|
|
end
|
|
);
|
|
|
|
Result := closure;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitFunctionCall(const Node: IFunctionCallNode): TDataValue;
|
|
var
|
|
calleeValue: TDataValue;
|
|
argValues: TArray<TDataValue>;
|
|
boundNode: TBoundFunctionCallNode;
|
|
begin
|
|
calleeValue := Node.Callee.Accept(Self);
|
|
if calleeValue.Kind <> vkMethod then
|
|
raise EArgumentException.Create('Expression is not invokable in this context.');
|
|
|
|
var argNodes := Node.Arguments;
|
|
SetLength(argValues, Length(argNodes));
|
|
for var i := 0 to High(argNodes) do
|
|
argValues[i] := argNodes[i].Accept(Self);
|
|
|
|
boundNode := Node as TBoundFunctionCallNode;
|
|
if boundNode.IsTailCall then
|
|
begin
|
|
// This is a tail call. Return a thunk to be processed by the trampoline.
|
|
Result := TDataValue.FromGeneric<TThunk>(TThunk.Create(calleeValue, argValues));
|
|
end
|
|
else
|
|
begin
|
|
// This is a non-tail call. It must execute the call and act as the trampoline.
|
|
Result := (calleeValue.AsMethod)(argValues);
|
|
HandleTCO(Result);
|
|
end;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitRecurNode(const Node: IRecurNode): TDataValue;
|
|
var
|
|
argValues: TArray<TDataValue>;
|
|
calleeAddress: TResolvedAddress;
|
|
calleeValue: TDataValue;
|
|
i: Integer;
|
|
begin
|
|
// The binder ensures this is only in a tail position.
|
|
SetLength(argValues, Length(Node.Arguments));
|
|
for i := 0 to High(Node.Arguments) do
|
|
argValues[i] := Node.Arguments[i].Accept(Self);
|
|
|
|
// The callee is the current function, stored in slot 0 of the current scope.
|
|
calleeAddress.Kind := akLocalOrParent;
|
|
calleeAddress.ScopeDepth := 0;
|
|
calleeAddress.SlotIndex := 0;
|
|
calleeValue := FScope[calleeAddress];
|
|
|
|
// Recur always returns a thunk for the trampoline.
|
|
Result := TDataValue.FromGeneric<TThunk>(TThunk.Create(calleeValue, argValues));
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitAddSeriesItem(const Node: IAddSeriesItemNode): TDataValue;
|
|
var
|
|
itemValue, lookbackValue, seriesVar: TDataValue;
|
|
lookback: Int64;
|
|
begin
|
|
seriesVar := FScope[(Node.Series as TBoundIdentifierNode).Address];
|
|
itemValue := Node.Value.Accept(Self);
|
|
lookback := -1;
|
|
|
|
if Assigned(Node.Lookback) then
|
|
begin
|
|
lookbackValue := Node.Lookback.Accept(Self);
|
|
if (lookbackValue.Kind <> vkScalar) or (lookbackValue.AsScalar.Kind <> TScalar.TKind.Ordinal) then
|
|
raise EArgumentException.Create('Lookback parameter must be an integer.');
|
|
lookback := lookbackValue.AsScalar.Value.AsInt64;
|
|
end;
|
|
|
|
case seriesVar.Kind of
|
|
vkRecordSeries:
|
|
begin
|
|
if (itemValue.Kind <> vkRecord) then
|
|
raise EArgumentException.Create('Can only add record values to a TScalarRecordSeries.');
|
|
|
|
with seriesVar.AsRecordSeries do
|
|
begin
|
|
Add(itemValue.AsRecord, lookback);
|
|
end;
|
|
end;
|
|
else
|
|
raise EArgumentException.Create('"add" operation is only supported for series types.');
|
|
end;
|
|
Result := TDataValue.Void;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitAssignment(const Node: IAssignmentNode): TDataValue;
|
|
begin
|
|
Result := Node.Value.Accept(Self);
|
|
FScope[(Node.Identifier as TBoundIdentifierNode).Address] := Result;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitConstant(const Node: IConstantNode): TDataValue;
|
|
begin
|
|
Result := Node.Value;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue;
|
|
var
|
|
def: string;
|
|
begin
|
|
def := Node.Definition.Trim;
|
|
if def.StartsWith('[') then
|
|
begin
|
|
var recordDef := TRttiAstHelper.JsonToRecordDefinition(def);
|
|
if Length(recordDef.Fields) = 0 then
|
|
raise EArgumentException.Create('Failed to parse record definition from JSON array.');
|
|
var recordSeries := TScalarRecordSeries.Create(recordDef);
|
|
Result := TDataValue.FromRecordSeries(recordSeries);
|
|
end
|
|
else
|
|
begin
|
|
var scalarKind := TScalar.StringToKind(def);
|
|
Result := TDataValue.FromSeries(TScalarSeries.Create(scalarKind));
|
|
end;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitIdentifier(const Node: IIdentifierNode): TDataValue;
|
|
begin
|
|
Result := FScope[(Node as TBoundIdentifierNode).Address];
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitIndexer(const Node: IIndexerNode): TDataValue;
|
|
var
|
|
baseValue, indexValue: TDataValue;
|
|
index: Int64;
|
|
begin
|
|
baseValue := Node.Base.Accept(Self);
|
|
indexValue := Node.Index.Accept(Self);
|
|
|
|
if (indexValue.Kind <> vkScalar) or (indexValue.AsScalar.Kind <> TScalar.TKind.Ordinal) then
|
|
raise EArgumentException.Create('Indexer `[]` requires an integer argument.');
|
|
|
|
index := indexValue.AsScalar.Value.AsInt64;
|
|
|
|
case baseValue.Kind of
|
|
vkSeries:
|
|
begin
|
|
with baseValue.AsSeries do
|
|
begin
|
|
if (index < 0) or (index >= TotalCount) then
|
|
raise EArgumentException.CreateFmt('Index %d is out of bounds for series with %d elements.', [index, TotalCount]);
|
|
Result := Items[Integer(index)];
|
|
end;
|
|
end;
|
|
vkRecordSeries:
|
|
begin
|
|
var series := baseValue.AsRecordSeries;
|
|
if (index < 0) or (index >= series.TotalCount) then
|
|
raise EArgumentException.CreateFmt('Index %d is out of bounds for series with %d elements.', [index, series.TotalCount]);
|
|
var recordValue := series.Items[Integer(index)];
|
|
Result := TDataValue.FromRecord(recordValue);
|
|
end;
|
|
else
|
|
raise EArgumentException.Create('Indexer `[]` is not supported for this value type.');
|
|
end;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitMemberAccess(const Node: IMemberAccessNode): TDataValue;
|
|
var
|
|
baseValue: TDataValue;
|
|
memberName: string;
|
|
begin
|
|
baseValue := Node.Base.Accept(Self);
|
|
memberName := Node.Member.Name;
|
|
|
|
case baseValue.Kind of
|
|
vkRecordSeries: Result := TDataValue.FromSeries(baseValue.AsRecordSeries.CreateMemberSeries(memberName));
|
|
vkRecord: Result := baseValue.AsRecord.Items[memberName];
|
|
else
|
|
raise EArgumentException.Create('Member access operator `.` is not supported for this value type.');
|
|
end;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue;
|
|
begin
|
|
if Assigned(Node.Initializer) then
|
|
Result := Node.Initializer.Accept(Self)
|
|
else
|
|
Result := TDataValue.Void;
|
|
|
|
FScope[(Node.Identifier as TBoundIdentifierNode).Address] := Result;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue;
|
|
var
|
|
leftValue, rightValue: TDataValue;
|
|
begin
|
|
leftValue := Node.Left.Accept(Self);
|
|
rightValue := Node.Right.Accept(Self);
|
|
|
|
if (leftValue.Kind <> vkScalar) or (rightValue.Kind <> vkScalar) then
|
|
raise ENotSupportedException.Create('Binary operations are only supported for scalar types.');
|
|
|
|
var res: TScalar;
|
|
if not TScalar.TryBinaryOperation(Node.Operator, leftValue.AsScalar, rightValue.AsScalar, res) then
|
|
raise ENotSupportedException.Create(
|
|
'Binary operation not supported for scalar types '
|
|
+ leftValue.AsScalar.Kind.ToString
|
|
+ ' and '
|
|
+ rightValue.AsScalar.Kind.ToString
|
|
+ ' .');
|
|
Result := res;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue;
|
|
var
|
|
rightValue: TDataValue;
|
|
begin
|
|
rightValue := Node.Right.Accept(Self);
|
|
|
|
if rightValue.Kind <> vkScalar then
|
|
raise ENotSupportedException.Create('Unary operations are only supported for scalar types.');
|
|
|
|
var res: TScalar;
|
|
if not TScalar.TryUnaryOperation(Node.Operator, rightValue.AsScalar, res) then
|
|
raise ENotSupportedException.Create('Unary operation not supported for scalar type' + rightValue.AsScalar.Kind.ToString + '.');
|
|
Result := res;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitIfExpression(const Node: IIfExpressionNode): TDataValue;
|
|
begin
|
|
if IsTruthy(Node.Condition.Accept(Self)) then
|
|
Result := Node.ThenBranch.Accept(Self)
|
|
else if Assigned(Node.ElseBranch) then
|
|
Result := Node.ElseBranch.Accept(Self)
|
|
else
|
|
Result := TDataValue.Void;
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue;
|
|
begin
|
|
if IsTruthy(Node.Condition.Accept(Self)) then
|
|
Result := Node.ThenBranch.Accept(Self)
|
|
else
|
|
Result := Node.ElseBranch.Accept(Self);
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue;
|
|
var
|
|
expression: IAstNode;
|
|
begin
|
|
Result := TDataValue.Void;
|
|
for expression in Node.Expressions do
|
|
Result := expression.Accept(Self);
|
|
end;
|
|
|
|
function TEvaluatorVisitor.VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue;
|
|
var
|
|
seriesValue: TDataValue;
|
|
len: Int64;
|
|
begin
|
|
seriesValue := FScope[(Node.Series as TBoundIdentifierNode).Address];
|
|
|
|
case seriesValue.Kind of
|
|
vkSeries: len := seriesValue.AsSeries.Count;
|
|
vkRecordSeries: len := seriesValue.AsRecordSeries.Count;
|
|
else
|
|
raise EArgumentException.CreateFmt('Cannot get length of type %s.', [GetEnumName(TypeInfo(TDataValueKind), Ord(seriesValue.Kind))]);
|
|
end;
|
|
|
|
Result := TScalar.FromInt64(len);
|
|
end;
|
|
|
|
end.
|