async Task <bool> OnEvaluateOnCallFrame(MessageId msg_id, int scope_id, string expression, CancellationToken token)
{
try
{
var context = GetContext(msg_id);
if (context.CallStack == null)
{
return(false);
}
var resolver = new MemberReferenceResolver(this, context, msg_id, scope_id, logger);
JObject retValue = await resolver.Resolve(expression, token);
if (retValue == null)
{
retValue = await EvaluateExpression.CompileAndRunTheExpression(expression, resolver, token);
}
if (retValue != null)
{
SendResponse(msg_id, Result.OkFromObject(new
{
result = retValue
}), token);
}
else
{
SendResponse(msg_id, Result.Err($"Unable to evaluate '{expression}'"), token);
}
}
catch (ReturnAsErrorException ree)
{
SendResponse(msg_id, ree.Error, token);
}
catch (Exception e)
{
logger.LogDebug($"Error in EvaluateOnCallFrame for expression '{expression}' with '{e}.");
SendResponse(msg_id, Result.Exception(e), token);
}
return(true);
}
private static async Task <IList <JObject> > ResolveMemberAccessExpressions(IEnumerable <MemberAccessExpressionSyntax> member_accesses,
MemberReferenceResolver resolver, CancellationToken token)
{
var memberAccessValues = new List <JObject>();
foreach (MemberAccessExpressionSyntax maes in member_accesses)
{
string memberAccessString = maes.ToString();
JObject value = await resolver.Resolve(memberAccessString, token);
if (value == null)
{
throw new ReturnAsErrorException($"Failed to resolve member access for {memberAccessString}", "ReferenceError");
}
memberAccessValues.Add(value);
}
return(memberAccessValues);
}
internal static async Task <JObject> CompileAndRunTheExpression(string expression, MemberReferenceResolver resolver, CancellationToken token)
{
expression = expression.Trim();
if (!expression.StartsWith('('))
{
expression = "(" + expression + ")";
}
SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(@"
using System;
public class CompileAndRunTheExpression
{
public static object Evaluate()
{
return " + expression + @";
}
}", cancellationToken: token);
SyntaxNode expressionTree = GetExpressionFromSyntaxTree(syntaxTree);
if (expressionTree == null)
{
throw new Exception($"BUG: Unable to evaluate {expression}, could not get expression from the syntax tree");
}
FindVariableNMethodCall findVarNMethodCall = new FindVariableNMethodCall();
findVarNMethodCall.VisitInternal(expressionTree);
// this fails with `"a)"`
// because the code becomes: return (a));
// and the returned expression from GetExpressionFromSyntaxTree is `a`!
if (expressionTree.Kind() == SyntaxKind.IdentifierName || expressionTree.Kind() == SyntaxKind.ThisExpression)
{
string varName = expressionTree.ToString();
JObject value = await resolver.Resolve(varName, token);
if (value == null)
{
throw new ReturnAsErrorException($"Cannot find member named '{varName}'.", "ReferenceError");
}
return(value);
}
IList <JObject> memberAccessValues = await ResolveMemberAccessExpressions(findVarNMethodCall.memberAccesses, resolver, token);
// eg. "this.dateTime", " dateTime.TimeOfDay"
if (expressionTree.Kind() == SyntaxKind.SimpleMemberAccessExpression && findVarNMethodCall.memberAccesses.Count == 1)
{
return(memberAccessValues[0]);
}
IList <JObject> identifierValues = await ResolveIdentifiers(findVarNMethodCall.identifiers, resolver, token);
syntaxTree = findVarNMethodCall.ReplaceVars(syntaxTree, memberAccessValues, identifierValues, null);
if (findVarNMethodCall.hasMethodCalls)
{
expressionTree = GetExpressionFromSyntaxTree(syntaxTree);
findVarNMethodCall.VisitInternal(expressionTree);
IList <JObject> methodValues = await ResolveMethodCalls(findVarNMethodCall.methodCall, findVarNMethodCall.memberAccessValues, resolver, token);
syntaxTree = findVarNMethodCall.ReplaceVars(syntaxTree, null, null, methodValues);
}
expressionTree = GetExpressionFromSyntaxTree(syntaxTree);
if (expressionTree == null)
{
throw new Exception($"BUG: Unable to evaluate {expression}, could not get expression from the syntax tree");
}
MetadataReference[] references = new MetadataReference[]
{
MetadataReference.CreateFromFile(typeof(object).Assembly.Location),
MetadataReference.CreateFromFile(typeof(Enumerable).Assembly.Location)
};
CSharpCompilation compilation = CSharpCompilation.Create(
"compileAndRunTheExpression",
syntaxTrees: new[] { syntaxTree },
references: references,
options: new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));
SemanticModel semanticModel = compilation.GetSemanticModel(syntaxTree);
CodeAnalysis.TypeInfo TypeInfo = semanticModel.GetTypeInfo(expressionTree, cancellationToken: token);
using (var ms = new MemoryStream())
{
EmitResult result = compilation.Emit(ms, cancellationToken: token);
if (!result.Success)
{
var sb = new StringBuilder();
foreach (Diagnostic d in result.Diagnostics)
{
sb.Append(d.ToString());
}
throw new ReturnAsErrorException(sb.ToString(), "CompilationError");
}
ms.Seek(0, SeekOrigin.Begin);
Assembly assembly = Assembly.Load(ms.ToArray());
Type type = assembly.GetType("CompileAndRunTheExpression");
object ret = type.InvokeMember("Evaluate",
BindingFlags.InvokeMethod | BindingFlags.Static | BindingFlags.Public,
null,
null,
findVarNMethodCall.argValues.ToArray());
return(JObject.FromObject(ConvertCSharpToJSType(ret, TypeInfo.Type)));
}
}
private static async Task <IList <JObject> > ResolveMethodCalls(IEnumerable <InvocationExpressionSyntax> methodCalls, Dictionary <string, JObject> memberAccessValues, MemberReferenceResolver resolver, CancellationToken token)
{
var values = new List <JObject>();
foreach (InvocationExpressionSyntax methodCall in methodCalls)
{
JObject value = await resolver.Resolve(methodCall, memberAccessValues, token);
if (value == null)
{
throw new ReturnAsErrorException($"Failed to resolve member access for {methodCall}", "ReferenceError");
}
values.Add(value);
}
return(values);
}
private static async Task <IList <JObject> > ResolveIdentifiers(IEnumerable <IdentifierNameSyntax> identifiers, MemberReferenceResolver resolver, CancellationToken token)
{
var values = new List <JObject>();
foreach (IdentifierNameSyntax var in identifiers)
{
JObject value = await resolver.Resolve(var.Identifier.Text, token);
if (value == null)
{
throw new ReturnAsErrorException($"The name {var.Identifier.Text} does not exist in the current context", "ReferenceError");
}
values.Add(value);
}
return(values);
}
internal static async Task <JObject> CompileAndRunTheExpression(string expression, MemberReferenceResolver resolver, CancellationToken token)
{
expression = expression.Trim();
if (!expression.StartsWith('('))
{
expression = "(" + expression + "\n)";
}
SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(expression + @";", cancellationToken: token);
SyntaxNode expressionTree = syntaxTree.GetCompilationUnitRoot(token);
if (expressionTree == null)
{
throw new Exception($"BUG: Unable to evaluate {expression}, could not get expression from the syntax tree");
}
FindVariableNMethodCall findVarNMethodCall = new FindVariableNMethodCall();
findVarNMethodCall.VisitInternal(expressionTree);
// this fails with `"a)"`
// because the code becomes: return (a));
// and the returned expression from GetExpressionFromSyntaxTree is `a`!
if (expressionTree.Kind() == SyntaxKind.IdentifierName || expressionTree.Kind() == SyntaxKind.ThisExpression)
{
string varName = expressionTree.ToString();
JObject value = await resolver.Resolve(varName, token);
if (value == null)
{
throw new ReturnAsErrorException($"Cannot find member named '{varName}'.", "ReferenceError");
}
return(value);
}
IList <JObject> memberAccessValues = await ResolveMemberAccessExpressions(findVarNMethodCall.memberAccesses, resolver, token);
// eg. "this.dateTime", " dateTime.TimeOfDay"
if (expressionTree.Kind() == SyntaxKind.SimpleMemberAccessExpression && findVarNMethodCall.memberAccesses.Count == 1)
{
return(memberAccessValues[0]);
}
IList <JObject> identifierValues = await ResolveIdentifiers(findVarNMethodCall.identifiers, resolver, token);
syntaxTree = findVarNMethodCall.ReplaceVars(syntaxTree, memberAccessValues, identifierValues, null, null);
if (findVarNMethodCall.hasMethodCalls)
{
expressionTree = syntaxTree.GetCompilationUnitRoot(token);
findVarNMethodCall.VisitInternal(expressionTree);
IList <JObject> methodValues = await ResolveMethodCalls(findVarNMethodCall.methodCall, findVarNMethodCall.memberAccessValues, resolver, token);
syntaxTree = findVarNMethodCall.ReplaceVars(syntaxTree, null, null, methodValues, null);
}
// eg. "elements[0]"
if (findVarNMethodCall.hasElementAccesses)
{
expressionTree = syntaxTree.GetCompilationUnitRoot(token);
findVarNMethodCall.VisitInternal(expressionTree);
IList <JObject> elementAccessValues = await ResolveElementAccess(findVarNMethodCall.elementAccess, findVarNMethodCall.memberAccessValues, resolver, token);
syntaxTree = findVarNMethodCall.ReplaceVars(syntaxTree, null, null, null, elementAccessValues);
}
expressionTree = syntaxTree.GetCompilationUnitRoot(token);
if (expressionTree == null)
{
throw new Exception($"BUG: Unable to evaluate {expression}, could not get expression from the syntax tree");
}
try
{
var newScript = script.ContinueWith(
string.Join("\n", findVarNMethodCall.variableDefinitions) + "\nreturn " + syntaxTree.ToString());
var state = await newScript.RunAsync(cancellationToken : token);
return(JObject.FromObject(ConvertCSharpToJSType(state.ReturnValue, state.ReturnValue?.GetType())));
}
catch (CompilationErrorException cee)
{
throw new ReturnAsErrorException($"Cannot evaluate '{expression}': {cee.Message}", "CompilationError");
}
catch (Exception ex)
{
throw new Exception($"Internal Error: Unable to run {expression}, error: {ex.Message}.", ex);
}
}
private static async Task <IList <JObject> > ResolveElementAccess(IEnumerable <ElementAccessExpressionSyntax> elementAccesses, Dictionary <string, JObject> memberAccessValues, MemberReferenceResolver resolver, CancellationToken token)
{
var values = new List <JObject>();
JObject index = null;
foreach (ElementAccessExpressionSyntax elementAccess in elementAccesses.Reverse())
{
index = await resolver.Resolve(elementAccess, memberAccessValues, index, token);
if (index == null)
{
throw new ReturnAsErrorException($"Failed to resolve element access for {elementAccess}", "ReferenceError");
}
}
values.Add(index);
return(values);
}