public void Process(DbMethodCallExpression exp, SqlGenerator generator)
{
DbExpression arg = exp.Arguments[0];
DbExpression e = DbExpression.Convert(arg, exp.Method.ReturnType);
e.Accept(generator);
}
public override DbExpression Visit(DbConvertExpression exp)
{
exp = DbExpression.Convert(exp.Operand.Accept(this), exp.Type);
if (!IsConstantOrParameter(exp.Operand))
{
return(exp);
}
return(DbExpression.Parameter(exp.Evaluate(), exp.Type));
}
public void Process(DbMethodCallExpression exp, SqlGenerator generator)
{
if (exp.Object.Type == PublicConstants.TypeOfString)
{
exp.Object.Accept(generator);
return;
}
DbConvertExpression c = DbExpression.Convert(exp.Object, PublicConstants.TypeOfString);
c.Accept(generator);
}
public void Process(DbMethodCallExpression exp, SqlGenerator generator)
{
DbExpression arg = exp.Arguments[0];
DbExpression e = DbExpression.Convert(arg, exp.Method.ReturnType);
if (exp.Method.ReturnType == PublicConstants.TypeOfBoolean)
{
e.Accept(generator);
generator.SqlBuilder.Append(" = ");
DbConstantExpression.True.Accept(generator);
}
else
{
e.Accept(generator);
}
}
public void Process(DbMethodCallExpression exp, SqlGenerator generator)
{
MethodInfo method = exp.Method;
if (method.DeclaringType == UtilConstants.TypeOfSql)
{
Method_Sql_Equals(exp, generator);
return;
}
DbExpression right = exp.Arguments[0];
if (right.Type != exp.Object.Type)
{
right = DbExpression.Convert(right, exp.Object.Type);
}
DbExpression.Equal(exp.Object, right).Accept(generator);
}
public override object Visit(DbConvertExpression exp)
{
object operandValue = exp.Operand.Accept(this);
//(int)null
if (operandValue == null)
{
//(int)null
if (exp.Type.IsValueType && !exp.Type.IsNullable())
{
throw new NullReferenceException();
}
return(null);
}
Type operandValueType = operandValue.GetType();
if (exp.Type == operandValueType || exp.Type.IsAssignableFrom(operandValueType))
{
return(operandValue);
}
Type underlyingType;
if (exp.Type.IsNullable(out underlyingType))
{
//(int?)int
if (underlyingType == operandValueType)
{
var constructor = exp.Type.GetConstructor(new Type[] { operandValueType });
var val = constructor.Invoke(new object[] { operandValue });
return(val);
}
else
{
//如果不等，则诸如：(long?)int / (long?)int? --> (long?)((long)int) / (long?)((long)int?)
var c = DbExpression.Convert(DbExpression.Constant(operandValue), underlyingType);
var cc = DbExpression.Convert(c, exp.Type);
return(this.Visit(cc));
}
}
//(int)int?
if (operandValueType.IsNullable(out underlyingType))
{
if (underlyingType == exp.Type)
{
var pro = operandValueType.GetProperty("Value");
var val = pro.GetValue(operandValue, null);
return(val);
}
else
{
//如果不等，则诸如：(long)int? --> (long)((long)int)
var c = DbExpression.Convert(DbExpression.Constant(operandValue), underlyingType);
var cc = DbExpression.Convert(c, exp.Type);
return(this.Visit(cc));
}
}
if (exp.Type.IsEnum)
{
return(Enum.ToObject(exp.Type, operandValue));
}
//(long)int
if (operandValue is IConvertible)
{
return(Convert.ChangeType(operandValue, exp.Type));
}
throw new NotSupportedException(string.Format("Does not support the type '{0}' converted to type '{1}'.", operandValueType.FullName, exp.Type.FullName));
}
static void StringConcat(DbBinaryExpression exp, SqlGeneratorBase generator)
{
List <DbExpression> operands = new List <DbExpression>();
operands.Add(exp.Right);
DbExpression left = exp.Left;
DbAddExpression e = null;
while ((e = (left as DbAddExpression)) != null && (e.Method == PublicConstants.MethodInfo_String_Concat_String_String || e.Method == PublicConstants.MethodInfo_String_Concat_Object_Object))
{
operands.Add(e.Right);
left = e.Left;
}
operands.Add(left);
DbExpression whenExp = null;
List <DbExpression> operandExps = new List <DbExpression>(operands.Count);
for (int i = operands.Count - 1; i >= 0; i--)
{
DbExpression operand = operands[i];
DbExpression opBody = operand;
if (opBody.Type != PublicConstants.TypeOfString)
{
// 需要 cast type
opBody = DbExpression.Convert(opBody, PublicConstants.TypeOfString);
}
DbExpression equalNullExp = DbExpression.Equal(opBody, PublicConstants.DbConstant_Null_String);
if (whenExp == null)
{
whenExp = equalNullExp;
}
else
{
whenExp = DbExpression.And(whenExp, equalNullExp);
}
operandExps.Add(opBody);
}
generator.SqlBuilder.Append("CASE", " WHEN ");
whenExp.Accept(generator);
generator.SqlBuilder.Append(" THEN ");
DbConstantExpression.Null.Accept(generator);
generator.SqlBuilder.Append(" ELSE ");
generator.SqlBuilder.Append("(");
for (int i = 0; i < operandExps.Count; i++)
{
if (i > 0)
{
generator.SqlBuilder.Append(" + ");
}
generator.SqlBuilder.Append("ISNULL(");
operandExps[i].Accept(generator);
generator.SqlBuilder.Append(",");
DbConstantExpression.StringEmpty.Accept(generator);
generator.SqlBuilder.Append(")");
}
generator.SqlBuilder.Append(")");
generator.SqlBuilder.Append(" END");
}
public override DbExpression Visit(DbConvertExpression exp)
{
exp = DbExpression.Convert(exp.Operand.Accept(this), exp.Type);
return(exp);
}