protected override Expression OnBuild(ExpressionBuilderContext <ExpressionOptimizerState> context)
{
if (context.State.Hits <= 1)
{
return(context.Expression);
}
if (context.State.Index++ == 0)
{
ParameterExpression variable = context.State.Variable = Expression.Variable(context.Expression.Type);
context.Variables.Add(variable);
return(Expression.Assign(variable, context.Expression));
}
return(context.State.Variable);
}
private Expression ScanHandler(Expression expression)
{
if (this.idMap.TryGetValue(expression, out object key))
{
ExpressionBuilderContext <TState> context = new ExpressionBuilderContext <TState>()
{
Key = key,
Batch = this.exprMap[key],
Expression = expression,
State = this.stateMap[key],
Variables = new List <ParameterExpression>(),
};
this.OnScan(context);
}
return(expression);
}
private Expression BuildHandler(Expression expression)
{
if (this.idMap.TryGetValue(expression, out object key))
{
ExpressionBuilderContext <TState> context = new ExpressionBuilderContext <TState>()
{
Key = key,
Batch = this.exprMap[key],
Expression = expression,
State = this.stateMap[key],
Variables = new List <ParameterExpression>(),
};
Expression result = this.OnBuild(context);
this.variables.AddRange(context.Variables);
return(result);
}
return(expression);
}
protected abstract Expression OnBuild(ExpressionBuilderContext <TState> context);
protected abstract void OnScan(ExpressionBuilderContext <TState> context);
protected override void OnScan(ExpressionBuilderContext <ExpressionOptimizerState> context)
{
context.State.Hits++;
}