/// <summary>
/// 初始化 <see cref="SQLiteUpdateExpressionVisitor"/> 类的新实例
/// </summary>
/// <param name="ag">表别名解析器</param>
/// <param name="builder">SQL 语句生成器</param>
/// <param name="tree">更新语义</param>
/// <param name="alias">指定的表达式别名</param>
internal SQLiteUpdateExpressionVisitor(AliasGenerator ag, ISqlBuilder builder, DbQueryUpdateTree tree, string alias)
: base(ag, builder)
{
_tree = tree;
_alias = alias;
_builder = builder;
_visitedStack = base.VisitedStack;
}
// 解析查询语义
private static IDbQueryTree Parse(IDbQueryable source, Type elmentType, int startIndex)
{
// 目的：将query 转换成增/删/改/查
// 1、from a in context.GetTable<T>() select a 此时query里面可能没有SELECT 表达式
// 2、Take 视为一个查询的结束位，如有更多查询，应使用嵌套查询
// 3、uion 分页查询也使嵌套语义
// 4、uion 后面跟着 WHERE,GROUP BY,SELECT,JOIN语句时需要使用嵌套查询
Type fromType = null;
DbRawSql rawSql = null;
bool isDistinct = false;
bool isAny = false;
bool isSubquery = false;
int? skip = null;
int? take = null;
int? outerIndex = null;
List <DbExpression> wheres = null; // WHERE
List <DbExpression> havings = null; // HAVING
List <DbExpression> joins = null; // JOIN
List <DbExpression> orderBys = null; // ORDER BY
List <DbExpression> includes = null; // ORDER BY
List <DbQuerySelectTree> unions = null; // UNION ALL
Expression pickExpression = null;
DbExpression insert = null; // INSERT #
DbExpression update = null; // UPDATE #
DbExpression delete = null; // DELETE #
DbExpression group = null; // GROUP BY #
DbExpression aggregate = null; // SUM&MAX #
for (int index = startIndex; index < source.DbExpressions.Count; index++)
{
DbExpression item = source.DbExpressions[index];
// Take(n)
if (take != null || (skip != null && item.DbExpressionType != DbExpressionType.Take) || isDistinct || isSubquery)
{
outerIndex = index;
break;
}
#region 解析片断
switch (item.DbExpressionType)
{
case DbExpressionType.None:
case DbExpressionType.All:
continue;
case DbExpressionType.Any:
isAny = true;
if (item.Expressions != null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
break;
case DbExpressionType.AsSubquery:
isSubquery = true;
continue;
case DbExpressionType.Union:
var constExpression = item.Expressions[0] as ConstantExpression;
var uQuery = constExpression.Value as IDbQueryable;
var u = DbQueryableParser.Parse(uQuery, constExpression.Type.GetGenericArguments()[0], 0);
if (unions == null)
{
unions = new List <DbQuerySelectTree>();
}
unions.Add((DbQuerySelectTree)u);
// 如果下一个不是 union，就使用嵌套
if (index + 1 <= source.DbExpressions.Count - 1 && source.DbExpressions[index + 1].DbExpressionType != DbExpressionType.Union)
{
isSubquery = true;
}
continue;
case DbExpressionType.Include:
if (includes == null)
{
includes = new List <DbExpression>();
}
includes.Add(item);
continue;
case DbExpressionType.GroupBy:
group = item;
continue;
case DbExpressionType.GetTable:
fromType = (item.Expressions[0] as ConstantExpression).Value as Type;
if (fromType == null)
{
string text = (item.Expressions[0] as ConstantExpression).Value as string;
if (text != null)
{
rawSql = new DbRawSql(null, text, (object[])(item.Expressions[1] as ConstantExpression).Value);
}
}
continue;
case DbExpressionType.Average:
case DbExpressionType.Min:
case DbExpressionType.Sum:
case DbExpressionType.Max:
aggregate = item;
continue;
case DbExpressionType.Count:
aggregate = item;
if (item.Expressions != null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
continue;
case DbExpressionType.Distinct:
isDistinct = true;
continue;
case DbExpressionType.First:
case DbExpressionType.FirstOrDefault:
take = 1;
if (item.Expressions != null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
continue;
case DbExpressionType.Join:
case DbExpressionType.LeftOuterJoin:
case DbExpressionType.RightOuterJoin:
pickExpression = item.Expressions[3];
var j = item;
// GetTable 的参数
var inner = (j.Expressions[0] as ConstantExpression).Value as IDbQueryable;
if (inner.DbExpressions.Count == 1 && inner.DbExpressions[0].DbExpressionType == DbExpressionType.GetTable)
{
// 区别 GetTable 有三个重载，这里处理指定外键路径的重载
if (inner.DbExpressions[0].Expressions.Length == 2 && (inner.DbExpressions[0].Expressions[0] as ConstantExpression).Value is Type)
{
var expressions = new Expression[item.Expressions.Length + 1];
Array.Copy(item.Expressions, expressions, item.Expressions.Length);
expressions[expressions.Length - 1] = inner.DbExpressions[0].Expressions[1];
j = new DbExpression(item.DbExpressionType, expressions);
}
}
if (joins == null)
{
joins = new List <DbExpression>();
}
joins.Add(j);
continue;
case DbExpressionType.OrderBy:
case DbExpressionType.OrderByDescending:
if (orderBys == null)
{
orderBys = new List <DbExpression>();
}
orderBys.Add(item);
continue;
case DbExpressionType.Select:
pickExpression = item.Expressions != null ? item.Expressions[0] : null;
continue;
case DbExpressionType.SelectMany:
pickExpression = item.Expressions[1];
if (IsCrossJoinExression(source.DbExpressions, item, startIndex))
{
if (joins == null)
{
joins = new List <DbExpression>();
}
joins.Add(item);
}
continue;
case DbExpressionType.Single:
case DbExpressionType.SingleOrDefault:
take = 1;
if (item.Expressions != null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
continue;
case DbExpressionType.Skip:
skip = (int)(item.Expressions[0] as ConstantExpression).Value;
continue;
case DbExpressionType.Take:
take = (int)(item.Expressions[0] as ConstantExpression).Value;
continue;
case DbExpressionType.ThenBy:
case DbExpressionType.ThenByDescending:
if (orderBys == null)
{
orderBys = new List <DbExpression>();
}
orderBys.Add(item);
continue;
case DbExpressionType.Where:
if (item.Expressions != null)
{
if (group == null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
else
{
if (havings == null)
{
havings = new List <DbExpression>();
}
havings.Add(item);
}
}
continue;
case DbExpressionType.Insert:
insert = item;
continue;
case DbExpressionType.Update:
update = item;
continue;
case DbExpressionType.Delete:
delete = item;
continue;
default:
throw new NotSupportedException(string.Format("{0} is not support.", item.DbExpressionType));
}
#endregion
}
// 没有解析到INSERT/DELETE/UPDATE/SELECT表达式，并且没有相关聚合函数，则默认选择 FromEntityType 的所有字段
if (insert == null && delete == null && update == null && pickExpression == null && aggregate == null)
{
pickExpression = Expression.Constant(fromType ?? elmentType);
}
DbExpression select = new DbExpression(DbExpressionType.Select, pickExpression);
if (fromType == null)
{
fromType = elmentType;
}
var result_Query = new DbQuerySelectTree();
result_Query.From = fromType;
result_Query.FromSql = rawSql;
result_Query.HasDistinct = isDistinct;
result_Query.HasAny = isAny;
result_Query.Joins = joins;
result_Query.OrderBys = orderBys;
result_Query.GroupBy = group;
result_Query.Aggregate = aggregate;
result_Query.Unions = unions;
result_Query.Includes = includes;
result_Query.Skip = skip != null ? skip.Value : 0;
result_Query.Take = take != null ? take.Value : 0;
result_Query.Select = select;
result_Query.Wheres = wheres;
result_Query.Havings = havings;
#region 更新语义
if (update != null)
{
var result_Update = new DbQueryUpdateTree();
var constantExpression = update.Expressions != null ? update.Expressions[0] as ConstantExpression : null;
if (constantExpression != null)
{
result_Update.Entity = constantExpression.Value;
}
else
{
result_Update.Expression = update.Expressions[0];
}
result_Update.Select = result_Query;
return(result_Update);
}
#endregion
#region 除语义
else if (delete != null)
{
var result_Delete = new DbQueryDeleteTree();
var constantExpression = delete.Expressions != null ? delete.Expressions[0] as ConstantExpression : null;
if (constantExpression != null)
{
result_Delete.Entity = constantExpression.Value;
}
result_Delete.Select = result_Query;
return(result_Delete);
}
#endregion
#region 插入语义
else if (insert != null)
{
var result_Insert = new DbQueryInsertTree();
if (insert.Expressions != null)
{
result_Insert.Entity = (insert.Expressions[0] as ConstantExpression).Value;
if (insert.Expressions.Length > 1)
{
result_Insert.EntityColumns = (insert.Expressions[1] as ConstantExpression).Value as IList <Expression>;
}
}
result_Insert.Select = result_Query;
result_Insert.Bulk = ((DbQueryable)source).Bulk;
return(result_Insert);
}
#endregion
#region 择语义
else if (pickExpression != null)
{
// 检查嵌套查询语义
result_Query = DbQueryableParser.TryParseOutQuery(result_Query);
}
#endregion
#region 嵌套语义
// 解析嵌套查询
if (outerIndex != null)
{
// todo => elementType ???
var outQueryTree = DbQueryableParser.Parse(source, elmentType, outerIndex.Value);
var result_Insert = outQueryTree as DbQueryInsertTree;
var result_Update = outQueryTree as DbQueryUpdateTree;
var result_Delete = outQueryTree as DbQueryDeleteTree;
if (result_Insert != null)
{
if (result_Insert.Select != null)
{
result_Insert.Select.Subquery = result_Query;
}
else
{
result_Insert.Select = result_Query;
}
return(result_Insert);
}
else if (result_Update != null)
{
if (result_Update.Select != null)
{
result_Update.Select.Subquery = result_Query;
}
else
{
result_Update.Select = result_Query;
}
return(result_Update);
}
else if (result_Delete != null)
{
if (result_Delete.Select != null)
{
result_Delete.Select.Subquery = result_Query;
}
else
{
result_Delete.Select = result_Query;
}
return(result_Delete);
}
else
{
// 指定子查询
var iterator = (DbQuerySelectTree)outQueryTree;
while (iterator.Subquery != null)
{
iterator = iterator.Subquery;
}
iterator.Subquery = result_Query;
//// ?? AsSubquery(a=>a)，那么它所有的外层字段都要基于里层的字段
//if (isSubquery && startIndex == 0)
// LimitSelector((DbQuerySelectTree)outQueryTree);
// 如果外层是统计，内层没有分页，则不需要排序
iterator = (DbQuerySelectTree)outQueryTree;
while (iterator.Subquery != null)
{
// 没有分页的嵌套统计，不需要排序
if (iterator.Aggregate != null && !(iterator.Subquery.Take > 0 || iterator.Subquery.Skip > 0) && iterator.Subquery.OrderBys != null && iterator.Subquery.OrderBys.Count > 0)
{
iterator.Subquery.OrderBys = new List <DbExpression>(0);
}
// 继续下一轮迭代
iterator = iterator.Subquery;
}
return(outQueryTree);
}
}
#endregion
// 查询表达式
return(result_Query);
}
/// <summary> /// 创建 UPDATE 命令 /// </summary> /// <param name="tree">查询语义</param> /// <param name="context">解析上下文</param> /// <returns></returns> protected abstract DbRawCommand TranslateUpdateCommand <T>(DbQueryUpdateTree tree, ITranslateContext context);