public static BinaryFragment Equal(this GenerateContext context, IExpressionFragment left, IExpressionFragment right)
{
return(new BinaryFragment(context, EBinaryKind.Equal)
{
Left = left,
Right = right
});
}
/// <summary>
/// 合并多个<see cref="IExpressionFragment"/>片段为一个逻辑判断语句片段。
/// </summary>
/// <param name="fragments">合并的语句片段集合。</param>
/// <param name="kind">逻辑操作符种类。</param>
/// <returns>合并结果。</returns>
public static ILogicFragment Merge(this IEnumerable <IExpressionFragment> fragments, EBinaryKind kind = EBinaryKind.AndAlso)
{
var array = fragments.ToArray();
if (array.Length == 1)
{
return(array[0] as ILogicFragment);
}
var other = new IExpressionFragment[array.Length - 1];
Array.Copy(array, 1, other, 0, other.Length);
return(Merge(array[0], kind, other));
}
/// <summary>
/// 向指定的表达式语句片段合并多个<see cref="IExpressionFragment"/>片段。
/// </summary>
/// <param name="target">目标语句片段</param>
/// <param name="kind">逻辑操作符种类。</param>
/// <param name="fragments">合并的语句片段集合。</param>
/// <returns>合并结果。</returns>
public static ILogicFragment Merge(this IExpressionFragment target, EBinaryKind kind, IEnumerable <IExpressionFragment> fragments)
{
var current = target as BinaryLogicalFragment;
if (!fragments.Any())
{
throw new ArgumentException(Res.ExceptionMergeFragmentIsNotEmpty, nameof(fragments));
}
foreach (var fragment in fragments)
{
if (current == null)
{
if (fragment is BinaryLogicalFragment binary && binary.Kind == kind)
{
current = binary;
current.Expressions.Insert(0, target);
}
else
{
current = new BinaryLogicalFragment(target.Context, kind);
current.Expressions.Add(target);
current.Expressions.Add(fragment);
}
}
/// <inheritdoc/>
protected override void WriteFragmentForUpdate(SqlWriter writer, ISqlFragment fragment)
{
var update = (UpdateFragment)fragment;
writer.Write("UPDATE ");
WriteFragmentForSource(writer, update.Target);
writer.WriteLine();
writer.Write("SET ");
var values = update.Values.ToArray();
for (int i = 0; i < update.Members.Count; i++)
{
var member = update.Members[i];
var value = values[i];
if (i > 0)
{
writer.Write(", ");
}
WriteDbName(writer, member.OutputName);
writer.Write(" = ");
value.WriteSql(writer);
}
var sources = update.Sources.Where(a => a != update.Target).ToArray();
IExpressionFragment joinfilter = null;
if (sources.Length > 0)
{
writer.WriteLine();
writer.Write("FROM ");
if (sources[0].Join.HasValue)
{
joinfilter = sources[0].Condition;
WriteFragmentForSourceContent(writer, sources[0]);
for (int i = 1; i < sources.Length; i++)
{
writer.WriteLine();
WriteFragmentForSource(writer, sources[i]);
}
}
else
{
sources.ForEach(() => writer.WriteLine(),
source => WriteFragmentForSource(writer, source));
}
}
if (joinfilter != null)
{
writer.WriteLine();
writer.Write("WHERE ");
if (update.Where != null)
{
joinfilter.Merge(update.Where).WriteSql(writer);
}
else
{
joinfilter.WriteSql(writer);
}
}
else
{
WriteFragmentForWhere(writer, update.Where);
}
OutputReturnMembers(writer, update.ReturnMembers, update.Target);
}
/// <summary>
/// 初始化排序。
/// </summary>
/// <param name="context">生成上下文。</param>
/// <param name="content">成员表达式。</param>
/// <param name="kind">排序种类。</param>
public SortFragment(GenerateContext context, IExpressionFragment content, EOrderKind kind = EOrderKind.Ascending)
: base(context)
{
Content = content;
Kind = kind;
}
/// <summary>
/// 创建WHILE循环。
/// </summary>
/// <param name="context">生成上下文。</param>
/// <param name="condition">循环条件语句。</param>
public WhileFragment(GenerateContext context, IExpressionFragment condition)
: base(context)
{
Block = new BlockFragment(context);
Condition = condition;
}
/// <summary>
/// 创建表达式成员。
/// </summary>
/// <param name="context">生成上下文。</param>
/// <param name="source">成员所有者。</param>
/// <param name="property">成员属性。</param>
/// <param name="expression">表达式语句。</param>
public ExpressionMemberFragment(GenerateContext context, ISourceFragment source, MemberInfo property, IExpressionFragment expression)
: base(context, source, property)
{
Expression = expression;
}
/// <summary>
/// 初始化字符串连接语句片段。
/// </summary>
/// <param name="context">生成上下文。</param>
/// <param name="left">左表达式。</param>
/// <param name="right">右表达式。</param>
public StringConcatFragment(GenerateContext context, IExpressionFragment left, IExpressionFragment right)
: base(context)
{
Left = left;
Right = right;
}
