#region Disclaimer / License
// Copyright (C) 2010, Jackie Ng
// http://trac.osgeo.org/mapguide/wiki/maestro, jumpinjackie@gmail.com
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//
#endregion
using System;
using System.Collections.Generic;
using System.Text;
using Ciloci.Flee;
using System.Reflection;
using System.Globalization;
using OSGeo.MapGuide.MaestroAPI.Feature;
namespace OSGeo.MapGuide.MaestroAPI.Expression
{
///
/// A FDO expression evaluation engine
///
internal class ExpressionEngine
{
private ReaderBase _reader;
private ExpressionContext _context;
public ExpressionEngine(ReaderBase reader, CultureInfo ci)
{
_reader = reader;
//_cls = cls;
_context = new ExpressionContext();
_context.Options.ParseCulture = ci;
//Register standard FDO functions
_context.Imports.AddType(typeof(FdoFunctionNamespace));
//Register standard MapGuide function
_context.Imports.AddType(typeof(MgFunctionNamespace));
}
public void RegisterFunction(MethodInfo method, string @namespace)
{
_context.Imports.AddMethod(method, @namespace);
}
public void RegisterFunctions(Type functionType)
{
_context.Imports.AddType(functionType);
}
/*
public ExpressionEngine(FeatureSetReader reader, object customFunctions)
: this(reader)
{
}*/
///
/// Updates the variables in the expression context. This is called by the reader
/// as part of advancing to the next feature.
///
internal void UpdateVariables()
{
if (_reader.Current == null)
throw new InvalidOperationException(Strings.ErrorCurrentRecordIsEmpty);
_context.Variables.Clear();
for (int i = 0; i < _reader.FieldCount; i++)
{
string name = _reader.GetName(i);
if (_reader.IsNull(i))
{
_context.Variables.Add(name, DBNull.Value);
}
else
{
object value = _reader[i];
_context.Variables.Add(name, value);
}
}
}
///
/// Evalutes the expression against the current row
///
///
///
internal object Evaluate(string expression)
{
//Under FDO expression syntax:
//
// Double-quoted string literals represent identifiers
// Single-quoted string literals represent string literals
//
// So convert this to FLEE-compatible format by:
//
// Stripping double quotes (variables are not quoted)
// Convert single to double quotes (string literals are just CLR strings)
var exprText = expression.Replace("\"", string.Empty) //NOXLATE
.Replace("'", "\""); //NOXLATE
if (_reader.Current == null)
throw new InvalidOperationException(Strings.ErrorExprCurrentRowIsEmpty);
try
{
var expr = _context.CompileDynamic(exprText);
return expr.Evaluate();
}
catch
{
return null;
}
}
///
///
///
///
///
///
internal T Evaluate(string expression)
{
//Under FDO expression syntax:
//
// Double-quoted string literals represent identifiers
// Single-quoted string literals represent string literals
//
// So convert this to FLEE-compatible format by:
//
// Stripping double quotes (variables are not quoted)
// Convert single to double quotes (string literals are just CLR strings)
var exprText = expression.Replace("\"", string.Empty) //NOXLATE
.Replace("'", "\""); //NOXLATE
if (_reader.Current == null)
throw new InvalidOperationException(Strings.ErrorExprCurrentRowIsEmpty);
var expr = _context.CompileGeneric(exprText);
return expr.Evaluate();
}
}
}