public override async IAsyncEnumerable <Path> ComputeSelect(EvaluationContext ctx)
{
_listCandidate ??= TemplexBase.Parse(ListExpression);
if (_listCandidate != null)
{
// Expression select
var select = _listCandidate.ComputeSelect(ctx);
await foreach (var atom in select)
{
yield return(atom);
}
// Expression paths
var paths = _listCandidate.ComputePaths(ctx);
await foreach (var path in paths)
{
yield return(path.Append("Id"));
}
// Inner template select
var scopedCtx = ctx.Clone();
scopedCtx.SetLocalVariable(IteratorVariableName, new EvaluationVariable(
eval: TemplateUtil.VariableThatThrows(IteratorVariableName),
selectResolver: () => select,
pathsResolver: () => paths
));
await foreach (var atom in Inner.ComputeSelect(scopedCtx))
{
yield return(atom);
}
}
}
/// <summary>
/// Creates a new <see cref="TemplexBinaryOperator"/> based on the operator.
/// </summary>
public static TemplexBinaryOperator Make(string op, TemplexBase left, TemplexBase right)
{
TemplexBinaryOperator result = op switch
{
// Arithmetic
"+" => new Addition(),
"-" => new Subtraction(),
"*" => new Multiplication(),
"/" => new Division(),
"%" => new Modulo(),
// Logical
"&&" => new Conjunction(),
"||" => new Disjunction(),
// Comparison
"!=" => new NotEqual(),
"<>" => new NotEqual(),
"<=" => new LessThanOrEqual(),
">=" => new GreaterThanOrEqual(),
"<" => new LessThan(),
">" => new GreaterThan(),
"=" => new AreEqual(),
// Error
_ => throw new TemplateException($"Unkown binary operator {op}.")
};
result.Left = left;
result.Right = right;
result._op = op;
return(result);
}
public override async Task GenerateOutputs(EvaluationContext ctx)
{
_listCandidate ??= TemplexBase.Parse(ListExpression);
if (_listCandidate != null)
{
var listObj = (await _listCandidate.Evaluate(ctx)) ?? new List <object>();
if (listObj is IList list)
{
foreach (var listItem in list)
{
// Initialize new evaluation context with the new variable in it
var scopedCtx = ctx.Clone();
scopedCtx.SetLocalVariable(IteratorVariableName, new EvaluationVariable(
evalAsync: () => Task.FromResult(listItem),
selectResolver: () => AsyncUtil.Empty <Path>(), // It doesn't matter when generating output
pathsResolver: () => AsyncUtil.Empty <Path>() // It doesn't matter when generating output
));
// Run the template again on that context
await Inner.GenerateOutputs(scopedCtx);
}
}
else
{
throw new TemplateException($"Expression does not evaluate to a list ({_listCandidate}).");
}
}
}
/// <summary>
/// Creates a new <see cref="TemplexIndexer"/>.
/// </summary>
public static TemplexIndexer Make(TemplexBase listCandidate, int index)
{
return(new TemplexIndexer
{
ListCandidate = listCandidate,
Index = index
});
}
/// <summary>
/// Creates a new <see cref="TemplexPropertyAccess"/>.
/// </summary>
public static TemplexPropertyAccess Make(TemplexBase entityCandidate, string propName)
{
return(new TemplexPropertyAccess
{
EntityCandidate = entityCandidate,
PropertyName = propName
});
}
/// <summary>
/// Clones the <see cref="EvaluationContext"/> and returns a new one that contains the new variable.
/// </summary>
private EvaluationContext GetScopeLocalContext(EvaluationContext ctx)
{
_varExpression ??= TemplexBase.Parse(VariableExpression);
var variable = new EvaluationVariable(
evalAsync: () => _varExpression.Evaluate(ctx),
selectResolver: () => _varExpression.ComputeSelect(ctx),
pathsResolver: () => _varExpression.ComputePaths(ctx));
var ctxClone = ctx.Clone();
ctxClone.SetLocalVariable(VariableName, variable);
return(ctxClone);
}
public override async IAsyncEnumerable <Path> ComputeSelect(EvaluationContext ctx)
{
_conditionCandidate ??= TemplexBase.Parse(ConditionExpression);
if (_conditionCandidate != null && Inner != null)
{
await foreach (var select in _conditionCandidate.ComputeSelect(ctx))
{
yield return(select);
}
await foreach (var select in Inner.ComputeSelect(ctx))
{
yield return(select);
}
}
}
/// <summary>
/// Creates a new <see cref="TemplexUnaryOperator"/> based on the operator.
/// </summary>
public static TemplexUnaryOperator Make(string op, TemplexBase operand)
{
if (operand is null)
{
throw new ArgumentNullException(nameof(operand));
}
TemplexUnaryOperator result = op switch
{
"!" => new Negation(),
"-" => new Negative(),
"+" => new Positive(),
_ => throw new TemplateException($"Unkown unary operator {op}.")
};
result.Operand = operand;
result._op = op;
return(result);
}
public override async Task GenerateOutputs(EvaluationContext ctx)
{
_conditionCandidate ??= TemplexBase.Parse(ConditionExpression);
if (_conditionCandidate != null && Inner != null)
{
var conditionObj = (await _conditionCandidate.Evaluate(ctx)) ?? false;
if (conditionObj is bool condition)
{
if (condition)
{
await Inner.GenerateOutputs(ctx);
}
}
else
{
throw new TemplateException($"If expression could not be applied. Expression ({_conditionCandidate}) does not evaluate to a true or false.");
}
}
}
/// <summary>
/// Divides left by right after converting both to their common numeric type.
/// Throws a meaningful exception if right is equal to 0.
/// </summary>
/// <exception cref="TemplateException">If <paramref name="right"/> is equal to zero.</exception>
public static object Divide(object left, object right, Type commonType, TemplexBase rightExp)
{
try
{
return(commonType.Name switch
{
_sbyte => Convert.ToSByte(left) / Convert.ToSByte(right),
_byte => Convert.ToByte(left) / Convert.ToByte(right),
_short => Convert.ToInt16(left) / Convert.ToInt16(right),
_ushort => Convert.ToUInt16(left) / Convert.ToUInt16(right),
_int => Convert.ToInt32(left) / Convert.ToInt32(right),
_uint => Convert.ToUInt32(left) / Convert.ToUInt32(right),
_long => Convert.ToInt64(left) / Convert.ToInt64(right),
_ulong => Convert.ToUInt64(left) / Convert.ToUInt64(right),
_float => Convert.ToSingle(left) / Convert.ToSingle(right),
_double => Convert.ToDouble(left) / Convert.ToDouble(right),
_decimal => Convert.ToDecimal(left) / Convert.ToDecimal(right),
_ => throw new InvalidOperationException($"Unknown numeric type {commonType.Name}"), // Developer mistake
});
}