void ReduceQuery(QueryTranslationState state, DiagnosticBag diagnostics)
{
var topClause = state.clauses.Pop();
if (topClause.Kind == SyntaxKind.WhereClause)
{
// A query expression with a where clause
// from x in e
// where f
// …
// is translated into
// from x in ( e ) . Where ( x => f )
var where = topClause as WhereClauseSyntax;
var lambda = MakeQueryUnboundLambda(state.QueryVariableMap(), state.queryVariable, where.Condition);
var invocation = MakeInvocation(where, state.fromExpression, "Where", lambda, diagnostics);
state.fromExpression = new BoundQueryClause(
syntax: where,
syntaxTree: SyntaxTree,
value: invocation,
definedSymbol: null,
queryMethod: invocation.Method,
castMethod: null,
type: invocation.Type);
}
else if (topClause.Kind == SyntaxKind.JoinClause && state.clauses.IsEmpty() && state.selectOrGroup.Kind == SyntaxKind.SelectClause)
{
var join = topClause as JoinClauseSyntax;
var select = state.selectOrGroup as SelectClauseSyntax;
var joinArgs = ArrayBuilder <BoundExpression> .GetInstance();
var e2 = BindValue(join.InExpression, BindValueKind.RValue, diagnostics);
MethodSymbol castMethod = null;
if (join.TypeOpt != null)
{
// A join clause that explicitly specifies a range variable type
// join T x in e on k1 equals k2
// is translated into
// join x in ( e ) . Cast < T > ( ) on k1 equals k2
var castType = BindType(join.TypeOpt, diagnostics);
var invocation = MakeInvocation(join, e2, "Cast", join.TypeOpt, castType, diagnostics);
castMethod = invocation.Method;
e2 = invocation;
}
joinArgs.Add(e2);
var lambda1 = MakeQueryUnboundLambda(state.QueryVariableMap(), state.queryVariable, join.LeftExpression);
joinArgs.Add(lambda1);
var x2 = state.AddQueryVariable(this, join.Identifier);
var lambda2 = MakeQueryUnboundLambda(state.QueryVariableMap(x2), x2, join.RightExpression); // TODO: ensure no other query variables in scope but x2.
joinArgs.Add(lambda2);
BoundExpression result;
if (join.IntoOpt == null)
{
// A query expression with a join clause without an into followed by a select clause
// from x1 in e1
// join x2 in e2 on k1 equals k2
// select v
// is translated into
// ( e1 ) . Join( e2 , x1 => k1 , x2 => k2 , ( x1 , x2 ) => v )
var lambda3 = MakeQueryUnboundLambda(state.QueryVariableMap(), Args(state.queryVariable, x2), select.Expression);
// TODO: lambda3's body should be surrounded by a BoundQueryClause for the select clause.
joinArgs.Add(lambda3);
var invocation = MakeInvocation(join, state.fromExpression, "Join", joinArgs.ToReadOnlyAndFree(), diagnostics);
result = new BoundQueryClause(
syntax: join,
syntaxTree: SyntaxTree,
value: invocation,
definedSymbol: x2,
queryMethod: invocation.Method,
castMethod: castMethod,
type: invocation.Type);
}
else
{
// A query expression with a join clause with an into followed by a select clause
// from x1 in e1
// join x2 in e2 on k1 equals k2 into g
// select v
// is translated into
// ( e1 ) . GroupJoin( e2 , x1 => k1 , x2 => k2 , ( x1 , g ) => v )
var g = state.AddQueryVariable(this, join.IntoOpt.Identifier);
// binder.queryVariable = g; // TODO: where to record the info symbol?
var lambda3 = MakeQueryUnboundLambda(state.QueryVariableMap(), Args(state.queryVariable, g), select.Expression);
// TODO: lambda3's body should be surrounded by a BoundQueryClause for the select clause.
joinArgs.Add(lambda3);
var invocation = MakeInvocation(join, state.fromExpression, "GroupJoin", joinArgs.ToReadOnlyAndFree(), diagnostics);
var newArguments = Args(invocation.Arguments[0], invocation.Arguments[1], invocation.Arguments[2],
new BoundQueryClause( // record the into clause's symbol in the bound tree
syntax: join.IntoOpt,
syntaxTree: SyntaxTree,
value: invocation.Arguments[3],
definedSymbol: g,
queryMethod: null,
castMethod: null,
type: invocation.Arguments[3].Type));
invocation = invocation.Update(
receiverOpt: invocation.ReceiverOpt,
method: invocation.Method,
arguments: newArguments);
result = new BoundQueryClause(
syntax: join,
syntaxTree: SyntaxTree,
value: invocation,
definedSymbol: x2,
queryMethod: invocation.Method,
castMethod: castMethod,
type: invocation.Type);
}
state.Clear(); // this completes the whole query
state.fromExpression = result;
}
else if (topClause.Kind == SyntaxKind.OrderByClause)
{
// A query expression with an orderby clause
// from x in e
// orderby k1 , k2 , … , kn
// …
// is translated into
// from x in ( e ) .
// OrderBy ( x => k1 ) .
// ThenBy ( x => k2 ) .
// … .
// ThenBy ( x => kn )
// …
// If an ordering clause specifies a descending direction indicator,
// an invocation of OrderByDescending or ThenByDescending is produced instead.
var orderby = topClause as OrderByClauseSyntax;
bool first = true;
Symbol lastMethod = null;
foreach (var ordering in orderby.Orderings)
{
string methodName = (first ? "OrderBy" : "ThenBy") + (ordering.Kind == SyntaxKind.DescendingOrdering ? "Descending" : "");
var lambda = MakeQueryUnboundLambda(state.QueryVariableMap(), state.queryVariable, ordering.Expression);
var invocation = MakeInvocation(ordering, state.fromExpression, methodName, lambda, diagnostics);
lastMethod = invocation.Method;
state.fromExpression = new BoundQueryClause(
syntax: ordering, syntaxTree: SyntaxTree, value: invocation,
definedSymbol: null, queryMethod: invocation.Method, castMethod: null, type: invocation.Type);
first = false;
}
state.fromExpression = new BoundQueryClause(
syntax: orderby, syntaxTree: SyntaxTree, value: state.fromExpression,
definedSymbol: null, queryMethod: lastMethod, castMethod: null, type: state.fromExpression.Type);
}
else if (topClause.Kind == SyntaxKind.FromClause && state.clauses.IsEmpty() && state.selectOrGroup.Kind == SyntaxKind.SelectClause)
{
// A query expression with a second from clause followed by a select clause
// from x1 in e1
// from x2 in e2
// select v
// is translated into
// ( e1 ) . SelectMany( x1 => e2 , ( x1 , x2 ) => v )
var fromClause = topClause as FromClauseSyntax;
var select = state.selectOrGroup as SelectClauseSyntax;
var x1 = state.queryVariable;
TypeSymbol castType = fromClause.TypeOpt == null ? null : BindType(fromClause.TypeOpt, diagnostics);
BoundExpression lambda1 = MakeQueryUnboundLambda(state.QueryVariableMap(), x1, fromClause.Expression, fromClause.TypeOpt, castType);
// TODO: wrap the bound version of lambda1 in a BoundQueryClause for the from clause defining x2.
var x2 = state.AddQueryVariable(this, fromClause.Identifier);
BoundExpression lambda2 = MakeQueryUnboundLambda(state.QueryVariableMap(), Args(x1, x2), select.Expression);
var result = MakeInvocation(fromClause, state.fromExpression, "SelectMany", Args(lambda1, lambda2), diagnostics);
// TODO: extract the Cast<T>() operation from the bound version of lambda1 (this invocation's first argument) and store it in e2Binder.castMethod
state.Clear();
state.fromExpression = new BoundQueryClause(
syntax: select, syntaxTree: SyntaxTree, value: result,
definedSymbol: null, queryMethod: result.Method, castMethod: null, type: result.Type);
}
else if (topClause.Kind == SyntaxKind.LetClause)
{
var let = topClause as LetClauseSyntax;
var x = state.queryVariable;
// A query expression with a let clause
// from x in e
// let y = f
// …
// is translated into
// from * in ( e ) . Select ( x => new { x , y = f } )
// …
// We use a slightly different translation strategy. We produce
// from * in ( e ) . Select ( x => new Pair<X,Y>(x, f) )
// Where X is the type of x, and Y is the type of the expression f.
// Subsequently, x (or members of x, if it is a transparent identifier)
// are accessed as TRID.Item1 (or members of that), and y is accessed
// as TRID.Item2, where TRID is the compiler-generated identifier used
// to represent the transparent identifier in the result. We place
// this mapping into the state and then, subsequently, into the binder
// for any further clauses.
LambdaBodyResolver resolver = (LambdaSymbol lambdaSymbol, ExecutableCodeBinder lambdaBodyBinder, DiagnosticBag d) =>
{
var xExpression = new BoundParameter(let, lambdaBodyBinder.SyntaxTree, lambdaSymbol.Parameters[0]);
var yExpression = lambdaBodyBinder.BindValue(let.Expression, BindValueKind.RValue, d);
var construction = MakePair(let, xExpression, yExpression, d);
return(lambdaBodyBinder.WrapExpressionLambdaBody(construction, let, d));
};
var lambda = MakeQueryUnboundLambda(state.QueryVariableMap(), x, let.Expression, resolver);
state.queryVariable = state.TransparentQueryVariable(this);
var invocation = MakeInvocation(let, state.fromExpression, "Select", lambda, diagnostics);
state.AddTransparentIdentifier("Item1");
var y = state.AddQueryVariable(this, let.Identifier);
state.allQueryVariables[y].Add("Item2");
state.fromExpression = new BoundQueryClause(
syntax: let, syntaxTree: SyntaxTree, value: invocation,
definedSymbol: y, queryMethod: invocation.Method, castMethod: null, type: invocation.Type);
}
else
{
diagnostics.Add(ErrorCode.ERR_NotYetImplementedInRoslyn, Location(topClause), "query expression");
var result = state.fromExpression; // short circuit any remaining reductions
state.Clear();
state.fromExpression = result;
}
}
internal BoundExpression BindQueryInternal1(QueryExpressionSyntax node, DiagnosticBag diagnostics)
{
var fromClause = (FromClauseSyntax)node.Clauses[0];
QueryTranslationState state = new QueryTranslationState();
state.fromSyntax = fromClause;
state.fromExpression = BindValue(fromClause.Expression, BindValueKind.RValue, diagnostics);
state.queryVariable = state.AddQueryVariable(this, fromClause.Identifier);
for (int i = node.Clauses.Count - 1; i > 0; i--)
{
state.clauses.Push(node.Clauses[i]);
}
state.selectOrGroup = node.SelectOrGroup;
// A from clause that explicitly specifies a range variable type
// from T x in e
// is translated into
// from x in ( e ) . Cast < T > ( )
MethodSymbol castMethod = null;
if (fromClause.TypeOpt != null)
{
var typeRestriction = BindType(fromClause.TypeOpt, diagnostics);
var cast = MakeInvocation(state.fromSyntax, state.fromExpression, "Cast", fromClause.TypeOpt, typeRestriction, diagnostics);
castMethod = cast.Method;
state.fromExpression = cast;
}
state.fromExpression = new BoundQueryClause(
syntax: fromClause,
syntaxTree: this.SyntaxTree,
value: state.fromExpression,
definedSymbol: state.queryVariable,
queryMethod: null,
castMethod: castMethod,
type: state.fromExpression.Type);
// If the query is a degenerate one the form "from x in e select x", but in source,
// then we go ahead and generate the select anyway. We do this by skipping BindQueryInternal2,
// whose job it is to (reduce away the whole query and) optimize away degenerate queries.
BoundExpression result = (fromClause.TypeOpt == null && IsDegenerateQuery(state))
? FinalTranslation(state, diagnostics)
: BindQueryInternal2(state, diagnostics);
QueryContinuationSyntax continuation = node.ContinuationOpt;
while (continuation != null)
{
// A query expression with a continuation
// from … into x …
// is translated into
// from x in ( from … ) …
state.Clear();
state.fromExpression = result;
var x = state.AddQueryVariable(this, continuation.Identifier);
state.fromExpression = new BoundQueryClause(
syntax: continuation,
syntaxTree: SyntaxTree,
value: state.fromExpression,
definedSymbol: x,
queryMethod: null,
castMethod: null,
type: state.fromExpression.Type);
state.queryVariable = x;
Debug.Assert(state.clauses.IsEmpty());
var clauses = continuation.Query.Clauses;
for (int i = clauses.Count - 1; i >= 0; i--)
{
state.clauses.Push(clauses[i]);
}
state.selectOrGroup = continuation.Query.SelectOrGroup;
result = BindQueryInternal2(state, diagnostics);
continuation = continuation.Query.ContinuationOpt;
}
state.Free();
return(result);
}
