/// <summary>
/// 获取表达式的执行计划。
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
public Expression GetExecutionPlan(Expression expression)
{
try
{
if (expression is LambdaExpression lambda)
{
expression = lambda.Body;
}
var section = ConfigurationUnity.GetSection <TranslatorConfigurationSection>();
var trans = service.InitializeContext.Provider.GetTranslateProvider();
var options = GetTranslateOptions();
using (var scope = new TranslateScope(service, trans, options))
{
var translation = trans.Translate(expression);
var translator = trans.CreateTranslator();
return(ExecutionBuilder.Build(translation, e => translator.Translate(e)));
}
}
catch (Exception ex)
{
throw new TranslateException(expression, ex);
}
}
public static Expression Build(Expression expression, Expression provider, TranslatorBase translator)
{
var executor = Expression.Constant(translator.InternalContext.Database);
var builder = new ExecutionBuilder()
{
executor = executor, translator = translator
};
return(builder.Bind(expression));
}
/// <summary>
/// 构造最终执行的表达式。
/// </summary>
/// <param name="expression"></param>
/// <param name="translator">翻译器。</param>
/// <returns></returns>
public static Expression Build(Expression expression, Func <Expression, TranslateResult> translator)
{
//定义 IDatabase 参数，最终交给IDatabase执行
var executor = Expression.Parameter(typeof(IDatabase), "db");
var builder = new ExecutionBuilder()
{
executor = executor, translator = translator
};
var newExpression = Expression.Convert(builder.Bind(expression), typeof(object));
return(Expression.Lambda(newExpression, executor));
}
private Expression BuildInner(Expression expression)
{
var eb = new ExecutionBuilder();
eb.executor = executor;
eb.scope = this.scope;
eb.receivingMember = receivingMember;
eb.nReaders = nReaders;
eb.nLookup = nLookup;
eb.translator = translator;
eb.variableMap = variableMap;
return(eb.Visit(expression));
}
/// <summary>
/// 构造最终执行的表达式。
/// </summary>
/// <param name="expression"></param>
/// <param name="translator">翻译器。</param>
/// <returns></returns>
public static Expression Build(Expression expression, Func <Expression, TranslateResult> translator, bool?isAsync = null)
{
var builder = new ExecutionBuilder()
{
executor = Expression.Parameter(typeof(IDatabase), "db"), translator = translator
};
if (isAsync != null)
{
builder.isAsync = (bool)isAsync;
}
var newExpression = builder.Bind(expression);
if (builder.isAsync)
{
var cancelToken = builder.cancelToken ?? Expression.Parameter(typeof(CancellationToken), "token");
return(Expression.Lambda(newExpression, builder.executor, cancelToken));
}
return(Expression.Lambda(newExpression, builder.executor));
}
