public ConstantProvider(QueryContext context, MemberExpression expr)
{
var constant = (ConstantExpression)expr.Expression;
Value = constant.Type.GetField(expr.Member.Name).GetValue(constant.Value);
ParamName = context.NextParam(this);
}
public WhereConverter(Select select, QueryContext context)
{
if (select == null)
throw new ArgumentNullException("select");
if (context == null)
throw new ArgumentNullException("context");
_select = select;
_context = context;
}
public QueryConverter(QueryContext context)
{
_context = context;
}
public bool VisitPath(QueryContext context, PropertyInfo[] path, out BracketedName alias, out PropertyMap map)
{
var entity = EntityMap;
alias = Alias;
map = null;
for (var i = 0; i < path.Length - 1; i++)
{
var prop = path[i];
var item = JoinGroup.FindJoin(prop);
if (item == null)
{
var reference = entity.FindReferenceMap(prop);
if (reference == null)
return false;
item = JoinGroup.AddJoin(alias, context.NextAlias(), reference);
}
alias = item.ToAlias;
entity = item.ReferenceMap.To;
}
var last = path[path.Length - 1];
map = entity.FindPropertyMap(last) ?? entity.FindReferenceMap(last);
return true;
}
public Select(QueryContext context)
: this(context.GetEntityMap(context.EntityType), context.NextAlias())
{
}
public ParameterProvider(QueryContext context, ParameterExpression expr)
{
ExpressionName = expr.Name;
ParamName = context.NextParam(this);
}
public ConstantProvider(QueryContext context, object value)
{
Value = value;
ParamName = context.NextParam(this);
}
public ConstantProvider(QueryContext context, ConstantExpression expr)
{
Value = expr.Value;
ParamName = context.NextParam(this);
}
static string GetWhere(Expression<Func<Student, bool>> expr)
{
var convention = new DefaultConvention();
var builder = new EntityMapBuilder<Student>(convention);
var map = ((EntityMapBuilder<Student>)builder
.Key(_ => _.ID, "Student_id"))
.Build();
var context = new QueryContext(new[]{map}, "");
var selectEntity = new Select(map, "t0");
var whereParser = new WhereConverter(selectEntity, context);
var node = whereParser.Visit(expr);
node.Render(context.Writer);
var result = context.Writer.GetResult();
return result;
}
