public static JsBlockStatement RewriteAsyncMethod(JsBlockStatement block, Func<JsExpression, bool> isExpressionComplexEnoughForATemporaryVariable, Func<string> allocateTempVariable, Func<string> allocateStateVariable, Func<string> allocateLoopLabel, string stateMachineVariableName, string doFinallyBlocksVariableName, JsVariableDeclaration taskCompletionSource, Func<JsExpression, JsExpression> makeSetResult, Func<JsExpression, JsExpression> makeSetException, Func<JsExpression> getTask, Func<JsExpression, JsExpression, JsExpression> bindToContext) {
var obj = new StateMachineRewriter(isExpressionComplexEnoughForATemporaryVariable, allocateTempVariable, allocateStateVariable, allocateLoopLabel);
return obj.ProcessAsyncMethod(block, stateMachineVariableName, doFinallyBlocksVariableName, taskCompletionSource, makeSetResult, makeSetException, getTask, bindToContext);
}
private JsBlockStatement ProcessAsyncMethod(JsBlockStatement statement, string stateMachineMethodName, string doFinallyBlocksVariableName, JsVariableDeclaration taskCompletionSource, Func<JsExpression, JsExpression> makeSetResult, Func<JsExpression, JsExpression> makeSetException, Func<JsExpression> getTask, Func<JsExpression, JsExpression, JsExpression> bindToContext) {
_stateMachineMethodName = stateMachineMethodName;
_doFinallyBlocksVariableName = doFinallyBlocksVariableName;
_makeSetResult = taskCompletionSource != null ? makeSetResult : null;
_needDoFinallyBlocksVariable = new HasAwaitInsideTryWithFinallyVisitor().Analyze(statement);
var result = Process(statement, isIteratorBlock: false, isAsync: true);
var hoistResult = VariableHoistingVisitor.Process(result);
string catchVariable = _allocateTempVariable();
JsStatement body;
if (taskCompletionSource != null && (statement.Statements.Count == 0 || IsNextStatementReachable(statement.Statements[statement.Statements.Count - 1]))) { // If we return the task, and if we risk falling out of the original method, we need to add a setResult call.
body = JsStatement.Block(hoistResult.Item1.Statements.Concat(new JsStatement[] { makeSetResult(null) }));
}
else {
body = hoistResult.Item1;
}
if (taskCompletionSource != null)
body = JsStatement.Try(body, JsStatement.Catch(catchVariable, JsStatement.Block(makeSetException(JsExpression.Identifier(catchVariable)))), null);
IEnumerable<JsVariableDeclaration> declarations = new[] { JsStatement.Declaration(_stateVariableName, JsExpression.Number(0)) };
if (taskCompletionSource != null)
declarations = declarations.Concat(new[] { taskCompletionSource });
declarations = declarations.Concat(hoistResult.Item2.Select(v => JsStatement.Declaration(v, null)));
if (_needDoFinallyBlocksVariable)
body = JsStatement.Block(new[] { JsStatement.Var(_doFinallyBlocksVariableName, JsExpression.True) }.Concat(body is JsBlockStatement ? ((JsBlockStatement)body).Statements : (IEnumerable<JsStatement>)new[] { body }));
var stateMachine = JsExpression.FunctionDefinition(new string[0], body);
var boundStateMachine = UsesThisVisitor.Analyze(stateMachine.Body) ? bindToContext(stateMachine, JsExpression.This) : stateMachine;
IEnumerable<JsStatement> stmts = new JsStatement[] { JsStatement.Var(declarations),
JsStatement.Var(stateMachineMethodName, boundStateMachine),
JsExpression.Invocation(JsExpression.Identifier(stateMachineMethodName))
};
if (taskCompletionSource != null)
stmts = stmts.Concat(new[] { JsStatement.Return(getTask()) });
return JsStatement.Block(stmts);
}