public Expression <Action <StringBuilder, T, Y> > Generate <T, Y>(ExpressContext expressContext, ScriptBlockStatement scriptBlockStatement)
{
ParameterExpression StringBuilderParmeter = Expression.Parameter(typeof(StringBuilder));
ParameterExpression inputParameter = Expression.Parameter(typeof(T), "Model");
ParameterExpression libraryParameter = Expression.Parameter(typeof(Y), "Library");
ParameterFinder parameterFinder = new ParameterFinder();
parameterFinder.AddParameter(libraryParameter);
parameterFinder.AddParameter(inputParameter);
var blockExpression = GetStatementExpression(expressContext, StringBuilderParmeter, scriptBlockStatement, parameterFinder);
return(Expression.Lambda <Action <StringBuilder, T, Y> >(blockExpression, StringBuilderParmeter, inputParameter, libraryParameter));
}
public Expression GetStatementExpression(ExpressContext expressContext, ParameterExpression stringBuilderParameter, ScriptStatement scriptStatement, ParameterFinder parameterFinder)
{
var appendMethodInfo = typeof(StringBuilder).GetMethod("Append", new[] { typeof(string) });
switch (scriptStatement)
{
case ScriptRawStatement scriptRawStatement:
var constant = Expression.Constant(scriptRawStatement.ToString());
var methodCall = Expression.Call(stringBuilderParameter, appendMethodInfo, constant);
return(methodCall);
case ScriptExpressionStatement scriptExpressionStatement:
var expressionBody = expressionGenerator.GetExpressionBody(scriptExpressionStatement.Expression, parameterFinder, null);
expressionBody = AddToString(expressionBody);
var scriptmethodCall = Expression.Call(stringBuilderParameter, appendMethodInfo, expressionBody);
return(scriptmethodCall);
case ScriptIfStatement scriptIfStatement:
var predicateExpression = expressionGenerator.GetExpressionBody(scriptIfStatement.Condition, parameterFinder, null);
var trueStatementBlock = GetStatementExpression(expressContext, stringBuilderParameter, scriptIfStatement.Then, parameterFinder);
if (scriptIfStatement.Else != null)
{
var elseStatment = GetStatementExpression(expressContext, stringBuilderParameter, scriptIfStatement.Else, parameterFinder);
ConditionalExpression ifThenElseExpr = Expression.IfThenElse(predicateExpression, trueStatementBlock, elseStatment);
return(ifThenElseExpr);
}
else
{
ConditionalExpression ifThenExpr = Expression.IfThen(predicateExpression, trueStatementBlock);
return(ifThenExpr);
}
case ScriptElseStatement scriptElseStatement:
var elseStatmentExpression = GetStatementExpression(expressContext, stringBuilderParameter, scriptElseStatement.Body, parameterFinder);
return(elseStatmentExpression);
case ScriptBlockStatement scriptBlockStatement:
List <Expression> statements = new List <Expression>();
foreach (var statement in scriptBlockStatement.Statements)
{
try
{
statements.Add(GetStatementExpression(expressContext, stringBuilderParameter, statement, parameterFinder));
}
catch (SpanException ex)
{
logger.LogError(ex, "Failed to build: {statement}", statement);
expressContext.Messages.Add(new LogMessage(ParserMessageType.Error, ex.Span, ex.Message));
}
catch (Exception ex)
{
logger.LogError(ex, "Statement Failed to build: {statement}", statement);
expressContext.Messages.Add(new LogMessage(ParserMessageType.Error, scriptBlockStatement.Span, $"Statement Failed to build: {statement?.GetType()}"));
}
}
var blockExpression = Expression.Block(statements);
return(blockExpression);
case ScriptForStatement scriptForStatement:
// foreach(item in items)
var itemsExpression = expressionGenerator.GetExpressionBody(scriptForStatement.Iterator, parameterFinder, null);
var itemVariableName = (scriptForStatement.Variable as ScriptVariableGlobal).Name;
var itemType = itemsExpression.Type.GenericTypeArguments[0];
ParameterExpression itemVariable = Expression.Parameter(itemType, itemVariableName);
using (var scopedParameterFinder = parameterFinder.CreateScope())
{
scopedParameterFinder.AddLocalVariable(itemVariable);
var body = GetStatementExpression(expressContext, stringBuilderParameter, scriptForStatement.Body, scopedParameterFinder);
var foreachExpression = ExpressionHelpers.ForEach(itemsExpression, itemVariable, body);
return(foreachExpression);
}
default:
throw new NotImplementedException("Unknown ScriptStatement");
}
}
public Expression GetExpressionBody(ScriptExpression scriptExpression, ParameterFinder parameterFinder, List <Expression> arguments)
{
switch (scriptExpression)
{
case ScriptVariableGlobal scriptVariableGlobal:
var variable = parameterFinder.GetProperty(scriptVariableGlobal.Name);
if (variable == null)
{
throw new SpanException($"Variable Not Found: {scriptVariableGlobal.Name}", scriptVariableGlobal.Span);
}
return(variable);
case ScriptLiteral scriptLiteral:
return(Expression.Constant(scriptLiteral.Value, scriptLiteral.Value.GetType()));
case ScriptUnaryExpression scriptUnaryExpression:
switch (scriptUnaryExpression.Operator)
{
case ScriptUnaryOperator.Not:
var right = GetExpressionBody(scriptUnaryExpression.Right, parameterFinder, arguments);
return(Expression.Not(right));
default:
throw new SpanException($"Unknown ScriptUnaryOperator: {scriptUnaryExpression.Operator}", scriptUnaryExpression.Span);
}
case ScriptMemberExpression scriptMemberExpression:
// it's impossible to tell if we have a member or a method, so we check for both
var memberTarget = GetExpressionBody(scriptMemberExpression.Target, parameterFinder, null);
var memberName = scriptMemberExpression.Member.Name;
// TODO: we should remove the need to calculate a method with Args here, should not need to pass down info
// still need the argument list as ScriptPipeCall still needs to pass the args in
var argumentTypeList = arguments.ToNullSafe().Select(e => e.Type);
var methodInfo = memberFinder.FindMember(memberTarget.Type, memberName, argumentTypeList);
if (methodInfo != null)
{
var convertedArgs = ConvertArgs(methodInfo as MethodInfo, arguments);
return(ExpressionHelpers.CallMember(memberTarget, methodInfo, convertedArgs));
}
throw new SpanException($"Member Not Found: {memberName}", scriptMemberExpression.Span);
case ScriptPipeCall scriptPipeCall:
// I'm not a huge fan of this because it requires pushing args down to sub nodes, could cause issues with multi funtions tree
var fromExpression = GetExpressionBody(scriptPipeCall.From, parameterFinder, null);
// prepare args (input type + ScriptFunctionCall args )
var pipelineArgs = new List <Expression> {
fromExpression
};
switch (scriptPipeCall.To)
{
case ScriptFunctionCall scriptFunctionCall:
pipelineArgs.AddRange(scriptFunctionCall.Arguments.Select(arg => GetExpressionBody(arg, parameterFinder, null)));
return(GetExpressionBody(scriptFunctionCall.Target, parameterFinder, pipelineArgs));
case ScriptMemberExpression scriptMemberExpression:
return(GetExpressionBody(scriptMemberExpression, parameterFinder, pipelineArgs));
case ScriptPipeCall toScriptPipeCall:
var nestedfromExpression = GetExpressionBody(toScriptPipeCall.From, parameterFinder, pipelineArgs);
return(GetExpressionBody(toScriptPipeCall.To, parameterFinder, new List <Expression> {
nestedfromExpression
}));
default:
throw new NotSupportedException("Pipeline Expression Not Supported");
}
case ScriptFunctionCall scriptFunctionCall:
return(CalculateScriptFunctionCall(scriptFunctionCall, parameterFinder, arguments));
case ScriptNestedExpression scriptNestedExpression:
return(GetExpressionBody(scriptNestedExpression.Expression, parameterFinder, arguments));
case ScriptBinaryExpression scriptBinaryExpression:
var leftExpression = GetExpressionBody(scriptBinaryExpression.Left, parameterFinder, null);
var rightExpression = GetExpressionBody(scriptBinaryExpression.Right, parameterFinder, null);
switch (scriptBinaryExpression.Operator)
{
case ScriptBinaryOperator.Add:
leftExpression = ConvertIfNeeded(leftExpression, rightExpression.Type);
rightExpression = ConvertIfNeeded(rightExpression, leftExpression.Type);
return(Expression.Add(leftExpression, rightExpression));
case ScriptBinaryOperator.EmptyCoalescing:
return(Expression.Coalesce(leftExpression, rightExpression));
case ScriptBinaryOperator.CompareEqual:
return(Expression.Equal(leftExpression, rightExpression));
default:
throw new SpanException($"Unknown ScriptBinaryExpression Operator: {scriptBinaryExpression.Operator}", scriptBinaryExpression.Span);
}
case ScriptIndexerExpression scriptIndexerExpression:
//https://stackoverflow.com/questions/31924907/accessing-elements-of-types-with-indexers-using-expression-trees
// TODO: consider wrapping an enumerable to an array
var arrayTarget = GetExpressionBody(scriptIndexerExpression.Target, parameterFinder, null);
var arrayIndex = GetExpressionBody(scriptIndexerExpression.Index, parameterFinder, null);
var indexed = Expression.Property(arrayTarget, "Item", arrayIndex);
return(indexed);
default:
throw new SpanException($"Unknown Expression Type: {scriptExpression?.GetType()}", scriptExpression.Span);
}
}
private ParameterFinder(ParameterFinder parent) : this()
{
this.parentFinder = parent;
}
public Expression CalculateScriptFunctionCall(ScriptFunctionCall scriptFunctionCall, ParameterFinder parameterFinder, List <Expression> arguments)
{
var args = scriptFunctionCall.Arguments.Select(arg => GetExpressionBody(arg, parameterFinder, null));
//add first argument if it's being supplied (probably from ScriptPipeCall)
if (arguments != null)
{
args = arguments.Union(args);
}
// we are attempting to pull the bottom target member up, so we know the method Name
var toMember = scriptFunctionCall.Target as ScriptMemberExpression;
if (toMember == null)
{
throw new NotSupportedException();
}
else
{
var argumentTypes = args.ToNullSafe().Select(e => e.Type);
var targetType = GetExpressionBody(toMember.Target, parameterFinder, null);
ScriptVariable functionNameScript = toMember.Member;
var methodInfo = memberFinder.FindMember(targetType.Type, functionNameScript.Name, argumentTypes.ToArray());
var convertedArgs = ConvertArgs(methodInfo as MethodInfo, args);
return(ExpressionHelpers.CallMember(targetType, methodInfo, convertedArgs));
}
}
