public static (string Collection, (string Script, string[] Functions), bool Revisions) ParseSubscriptionQuery(string query)
{
var queryParser = new QueryParser();
queryParser.Init(query);
var q = queryParser.Parse();
if (q.IsDistinct)
{
throw new NotSupportedException("Subscription does not support distinct queries");
}
if (q.From.Index)
{
throw new NotSupportedException("Subscription must specify a collection to use");
}
if (q.GroupBy != null)
{
throw new NotSupportedException("Subscription cannot specify a group by clause");
}
if (q.OrderBy != null)
{
throw new NotSupportedException("Subscription cannot specify an order by clause");
}
if (q.Include != null)
{
throw new NotSupportedException("Subscription cannot specify an include clause");
}
if (q.UpdateBody != null)
{
throw new NotSupportedException("Subscription cannot specify an update clause");
}
bool revisions = false;
if (q.From.Filter is BinaryExpression filter)
{
switch (filter.Operator)
{
case OperatorType.Equal:
case OperatorType.NotEqual:
if (!(filter.Left is FieldExpression fe) || fe.Compound.Count != 1)
{
throw new NotSupportedException("Subscription collection filter can only specify 'Revisions = true'");
}
if (string.Equals(fe.Compound[0], "Revisions", StringComparison.OrdinalIgnoreCase) == false)
{
throw new NotSupportedException("Subscription collection filter can only specify 'Revisions = true'");
}
if (filter.Right is ValueExpression ve)
{
revisions = filter.Operator == OperatorType.Equal && ve.Value == ValueTokenType.True;
if (ve.Value != ValueTokenType.True && ve.Value != ValueTokenType.False)
{
throw new NotSupportedException("Subscription collection filter can only specify 'Revisions = true'");
}
}
else
{
throw new NotSupportedException("Subscription collection filter can only specify 'Revisions = true'");
}
break;
default:
throw new NotSupportedException("Subscription must not specify a collection filter (move it to the where clause)");
}
}
else if (q.From.Filter != null)
{
throw new NotSupportedException("Subscription must not specify a collection filter (move it to the where clause)");
}
var collectionName = q.From.From.FieldValue;
if (q.Where == null && q.Select == null && q.SelectFunctionBody == null)
{
return(collectionName, (null, null), revisions);
}
var writer = new StringWriter();
if (q.From.Alias != null)
{
writer.Write("var ");
writer.Write(q.From.Alias);
writer.WriteLine(" = this;");
}
else if (q.Select != null || q.SelectFunctionBody != null || q.Load != null)
{
throw new InvalidOperationException("Cannot specify a select or load clauses without an alias on the query");
}
if (q.Load != null)
{
Debug.Assert(q.From.Alias != null);
var fromAlias = q.From.Alias.Value;
foreach (var tuple in q.Load)
{
writer.Write("var ");
writer.Write(tuple.Alias);
writer.Write(" = loadPath(this,'");
var fieldExpression = ((FieldExpression)tuple.Expression);
if (fieldExpression.Compound[0] != fromAlias)
{
throw new InvalidOperationException("Load clause can only load paths starting from the from alias: " + fromAlias);
}
writer.Write(fieldExpression.FieldValueWithoutAlias);
writer.WriteLine("');");
}
}
if (q.Where != null)
{
writer.Write("if (");
new JavascriptCodeQueryVisitor(writer.GetStringBuilder(), q).VisitExpression(q.Where);
writer.WriteLine(" )");
writer.WriteLine("{");
}
if (q.SelectFunctionBody != null)
{
writer.Write(" return ");
writer.Write(q.SelectFunctionBody);
writer.WriteLine(";");
}
else if (q.Select != null)
{
if (q.Select.Count != 1 || q.Select[0].Expression is MethodExpression == false)
{
throw new NotSupportedException("Subscription select clause must specify an object literal");
}
writer.WriteLine();
writer.Write(" return ");
new JavascriptCodeQueryVisitor(writer.GetStringBuilder(), q).VisitExpression(q.Select[0].Expression);
writer.WriteLine(";");
}
else
{
writer.WriteLine(" return true;");
}
writer.WriteLine();
if (q.Where != null)
{
writer.WriteLine("}");
}
var script = writer.GetStringBuilder().ToString();
// verify that the JS code parses
new Esprima.JavaScriptParser(script).ParseProgram();
return(collectionName, (script, q.DeclaredFunctions?.Values?.ToArray() ?? Array.Empty <string>()), revisions);
}
public static (string Collection, (string Script, string[] Functions), bool Revisions) ParseSubscriptionQuery(string query)
{
var queryParser = new QueryParser();
queryParser.Init(query);
var q = queryParser.Parse();
if (q.IsDistinct)
{
throw new NotSupportedException("Subscription does not support distinct queries");
}
if (q.From.Index)
{
throw new NotSupportedException("Subscription must specify a collection to use");
}
if (q.GroupBy != null)
{
throw new NotSupportedException("Subscription cannot specify a group by clause");
}
if (q.OrderBy != null)
{
throw new NotSupportedException("Subscription cannot specify an order by clause");
}
if (q.Include != null)
{
throw new NotSupportedException("Subscription cannot specify an include clause");
}
if (q.UpdateBody != null)
{
throw new NotSupportedException("Subscription cannot specify an update clause");
}
bool revisions = false;
if (q.From.Filter != null)
{
switch (q.From.Filter.Type)
{
case OperatorType.Equal:
case OperatorType.NotEqual:
var field = QueryExpression.Extract(query, q.From.Filter.Field);
if (string.Equals(field, "Revisions", StringComparison.OrdinalIgnoreCase) == false)
{
throw new NotSupportedException("Subscription collection filter can only specify 'Revisions = true'");
}
if (q.From.Filter.Value.Type != ValueTokenType.True)
{
throw new NotSupportedException("Subscription collection filter can only specify 'Revisions = true'");
}
revisions = q.From.Filter.Type == OperatorType.Equal;
break;
default:
throw new NotSupportedException("Subscription must not specify a collection filter (move it to the where clause)");
}
}
var collectionName = QueryExpression.Extract(query, q.From.From);
if (q.Where == null && q.Select == null && q.SelectFunctionBody == null)
{
return(collectionName, (null, null), revisions);
}
var writer = new StringWriter();
if (q.From.Alias != null)
{
writer.Write("var ");
writer.Write(QueryExpression.Extract(query, q.From.Alias));
writer.WriteLine(" = this;");
}
else if (q.Select != null || q.SelectFunctionBody != null || q.Load != null)
{
throw new InvalidOperationException("Cannot specify a select or load clauses without an alias on the query");
}
if (q.Load != null)
{
var fromAlias = QueryExpression.Extract(query, q.From.Alias);
foreach (var tuple in q.Load)
{
writer.Write("var ");
writer.Write(QueryExpression.Extract(query, tuple.Alias));
writer.Write(" = loadPath(this,'");
var fullFieldPath = QueryExpression.Extract(query, tuple.Expression.Field);
if (fullFieldPath.StartsWith(fromAlias) == false)
{
throw new InvalidOperationException("Load clause can only load paths starting from the from alias: " + fromAlias);
}
var indexOfDot = fullFieldPath.IndexOf('.', fromAlias.Length);
fullFieldPath = fullFieldPath.Substring(indexOfDot + 1);
writer.Write(fullFieldPath.Trim());
writer.WriteLine("');");
}
}
if (q.Where != null)
{
writer.Write("if (");
q.Where.ToJavaScript(query, q.From.Alias != null ? null : "this", writer);
writer.WriteLine(" )");
writer.WriteLine("{");
}
if (q.SelectFunctionBody != null)
{
writer.Write(" return ");
writer.Write(QueryExpression.Extract(query, q.SelectFunctionBody));
writer.WriteLine(";");
}
else if (q.Select != null)
{
if (q.Select.Count != 1 || q.Select[0].Expression.Type != OperatorType.Method)
{
throw new NotSupportedException("Subscription select clause must specify an object literal");
}
writer.WriteLine();
writer.Write(" return ");
q.Select[0].Expression.ToJavaScript(query, q.From.Alias != null ? null : "this", writer);
writer.WriteLine(";");
}
else
{
writer.WriteLine(" return true;");
}
writer.WriteLine();
if (q.Where != null)
{
writer.WriteLine("}");
}
var script = writer.GetStringBuilder().ToString();
// verify that the JS code parses
new Esprima.JavaScriptParser(script).ParseProgram();
return(collectionName, (script, q.DeclaredFunctions?.Values?.ToArray() ?? Array.Empty <string>()), revisions);
}