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/********************************************************
* ADO.NET 2.0 Data Provider for SQLite Version 3.X
* Written by Robert Simpson (robert@blackcastlesoft.com)
*
* Released to the public domain, use at your own risk!
********************************************************/
using System.Collections.Generic;
using System.Globalization;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Security.Permissions;
namespace System.Data.SQLite
{
/// <summary>
/// This abstract class is designed to handle user-defined functions easily. An instance of the derived class is made for each
/// connection to the database.
/// </summary>
/// <remarks>
/// Although there is one instance of a class derived from SQLiteFunction per database connection, the derived class has no access
/// to the underlying connection. This is necessary to deter implementers from thinking it would be a good idea to make database
/// calls during processing.
///
/// It is important to distinguish between a per-connection instance, and a per-SQL statement context. One instance of this class
/// services all SQL statements being stepped through on that connection, and there can be many. One should never store per-statement
/// information in member variables of user-defined function classes.
///
/// For aggregate functions, always create and store your per-statement data in the contextData object on the 1st step. This data will
/// be automatically freed for you (and Dispose() called if the item supports IDisposable) when the statement completes.
/// </remarks>
public abstract class SQLiteFunction : IDisposable
{
private class AggregateData
{
internal int _count = 1;
internal object _data;
}
/// <summary>
/// The base connection this function is attached to
/// </summary>
internal SQLiteBase _base;
/// <summary>
/// Internal array used to keep track of aggregate function context data
/// </summary>
private Dictionary<long, AggregateData> _contextDataList;
/// <summary>
/// Holds a reference to the callback function for user functions
/// </summary>
private SQLiteCallback _InvokeFunc;
/// <summary>
/// Holds a reference to the callbakc function for stepping in an aggregate function
/// </summary>
private SQLiteCallback _StepFunc;
/// <summary>
/// Holds a reference to the callback function for finalizing an aggregate function
/// </summary>
private SQLiteFinalCallback _FinalFunc;
/// <summary>
/// Holds a reference to the callback function for collation sequences
/// </summary>
private SQLiteCollation _CompareFunc;
private SQLiteCollation _CompareFunc16;
/// <summary>
/// Current context of the current callback. Only valid during a callback
/// </summary>
internal IntPtr _context;
/// <summary>
/// This static list contains all the user-defined functions declared using the proper attributes.
/// </summary>
private static readonly List<SQLiteFunctionAttribute> _registeredFunctions;
/// <summary>
/// Internal constructor, initializes the function's internal variables.
/// </summary>
protected SQLiteFunction()
{
_contextDataList = new Dictionary<long, AggregateData>();
}
/// <summary>
/// Returns a reference to the underlying connection's SQLiteConvert class, which can be used to convert
/// strings and DateTime's into the current connection's encoding schema.
/// </summary>
public SQLiteConvert SQLiteConvert
{
get { return _base; }
}
/// <summary>
/// Scalar functions override this method to do their magic.
/// </summary>
/// <remarks>
/// Parameters passed to functions have only an affinity for a certain data type, there is no underlying schema available
/// to force them into a certain type. Therefore the only types you will ever see as parameters are
/// DBNull.Value, Int64, Double, String or byte[] array.
/// </remarks>
/// <param name="args">The arguments for the command to process</param>
/// <returns>You may return most simple types as a return value, null or DBNull.Value to return null, DateTime, or
/// you may return an Exception-derived class if you wish to return an error to SQLite. Do not actually throw the error,
/// just return it!</returns>
public virtual object Invoke(object[] args)
{
return null;
}
/// <summary>
/// Aggregate functions override this method to do their magic.
/// </summary>
/// <remarks>
/// Typically you'll be updating whatever you've placed in the contextData field and returning as quickly as possible.
/// </remarks>
/// <param name="args">The arguments for the command to process</param>
/// <param name="stepNumber">The 1-based step number. This is incrememted each time the step method is called.</param>
/// <param name="contextData">A placeholder for implementers to store contextual data pertaining to the current context.</param>
public virtual void Step(object[] args, int stepNumber, ref object contextData)
{
}
/// <summary>
/// Aggregate functions override this method to finish their aggregate processing.
/// </summary>
/// <remarks>
/// If you implemented your aggregate function properly,
/// you've been recording and keeping track of your data in the contextData object provided, and now at this stage you should have
/// all the information you need in there to figure out what to return.
/// NOTE: It is possible to arrive here without receiving a previous call to Step(), in which case the contextData will
/// be null. This can happen when no rows were returned. You can either return null, or 0 or some other custom return value
/// if that is the case.
/// </remarks>
/// <param name="contextData">Your own assigned contextData, provided for you so you can return your final results.</param>
/// <returns>You may return most simple types as a return value, null or DBNull.Value to return null, DateTime, or
/// you may return an Exception-derived class if you wish to return an error to SQLite. Do not actually throw the error,
/// just return it!
/// </returns>
public virtual object Final(object contextData)
{
return null;
}
/// <summary>
/// User-defined collation sequences override this method to provide a custom string sorting algorithm.
/// </summary>
/// <param name="param1">The first string to compare</param>
/// <param name="param2">The second strnig to compare</param>
/// <returns>1 if param1 is greater than param2, 0 if they are equal, or -1 if param1 is less than param2</returns>
public virtual int Compare(string param1, string param2)
{
return 0;
}
/// <summary>
/// Converts an IntPtr array of context arguments to an object array containing the resolved parameters the pointers point to.
/// </summary>
/// <remarks>
/// Parameters passed to functions have only an affinity for a certain data type, there is no underlying schema available
/// to force them into a certain type. Therefore the only types you will ever see as parameters are
/// DBNull.Value, Int64, Double, String or byte[] array.
/// </remarks>
/// <param name="nArgs">The number of arguments</param>
/// <param name="argsptr">A pointer to the array of arguments</param>
/// <returns>An object array of the arguments once they've been converted to .NET values</returns>
internal object[] ConvertParams(int nArgs, IntPtr argsptr)
{
var parms = new object[nArgs];
#if !PLATFORM_COMPACTFRAMEWORK
var argint = new IntPtr[nArgs];
#else
int[] argint = new int[nArgs];
#endif
Marshal.Copy(argsptr, argint, 0, nArgs);
for (int n = 0; n < nArgs; n++)
{
switch (_base.GetParamValueType(argint[n]))
{
case TypeAffinity.Null:
parms[n] = DBNull.Value;
break;
case TypeAffinity.Int64:
parms[n] = _base.GetParamValueInt64(argint[n]);
break;
case TypeAffinity.Double:
parms[n] = _base.GetParamValueDouble(argint[n]);
break;
case TypeAffinity.Text:
parms[n] = _base.GetParamValueText(argint[n]);
break;
case TypeAffinity.Blob:
{
int x;
byte[] blob;
x = (int) _base.GetParamValueBytes(argint[n], 0, null, 0, 0);
blob = new byte[x];
_base.GetParamValueBytes(argint[n], 0, blob, 0, x);
parms[n] = blob;
}
break;
case TypeAffinity.DateTime: // Never happens here but what the heck, maybe it will one day.
parms[n] = _base.ToDateTime(_base.GetParamValueText(argint[n]));
break;
}
}
return parms;
}
/// <summary>
/// Takes the return value from Invoke() and Final() and figures out how to return it to SQLite's context.
/// </summary>
/// <param name="context">The context the return value applies to</param>
/// <param name="returnValue">The parameter to return to SQLite</param>
private void SetReturnValue(IntPtr context, object returnValue)
{
if (returnValue == null || returnValue == DBNull.Value)
{
_base.ReturnNull(context);
return;
}
Type t = returnValue.GetType();
if (t == typeof (DateTime))
{
_base.ReturnText(context, _base.ToString((DateTime) returnValue));
return;
}
else
{
var r = returnValue as Exception;
if (r != null)
{
_base.ReturnError(context, r.Message);
return;
}
}
switch (SQLiteConvert.TypeToAffinity(t))
{
case TypeAffinity.Null:
_base.ReturnNull(context);
return;
case TypeAffinity.Int64:
_base.ReturnInt64(context, Convert.ToInt64(returnValue, CultureInfo.CurrentCulture));
return;
case TypeAffinity.Double:
_base.ReturnDouble(context, Convert.ToDouble(returnValue, CultureInfo.CurrentCulture));
return;
case TypeAffinity.Text:
_base.ReturnText(context, returnValue.ToString());
return;
case TypeAffinity.Blob:
_base.ReturnBlob(context, (byte[]) returnValue);
return;
}
}
/// <summary>
/// Internal scalar callback function, which wraps the raw context pointer and calls the virtual Invoke() method.
/// </summary>
/// <param name="context">A raw context pointer</param>
/// <param name="nArgs">Number of arguments passed in</param>
/// <param name="argsptr">A pointer to the array of arguments</param>
internal void ScalarCallback(IntPtr context, int nArgs, IntPtr argsptr)
{
_context = context;
SetReturnValue(context, Invoke(ConvertParams(nArgs, argsptr)));
}
/// <summary>
/// Internal collation sequence function, which wraps up the raw string pointers and executes the Compare() virtual function.
/// </summary>
/// <param name="ptr">Not used</param>
/// <param name="len1">Length of the string pv1</param>
/// <param name="ptr1">Pointer to the first string to compare</param>
/// <param name="len2">Length of the string pv2</param>
/// <param name="ptr2">Pointer to the second string to compare</param>
/// <returns>Returns -1 if the first string is less than the second. 0 if they are equal, or 1 if the first string is greater
/// than the second.</returns>
internal int CompareCallback(IntPtr ptr, int len1, IntPtr ptr1, int len2, IntPtr ptr2)
{
return Compare(SQLiteConvert.UTF8ToString(ptr1, len1), SQLiteConvert.UTF8ToString(ptr2, len2));
}
internal int CompareCallback16(IntPtr ptr, int len1, IntPtr ptr1, int len2, IntPtr ptr2)
{
return Compare(SQLite3_UTF16.UTF16ToString(ptr1, len1), SQLite3_UTF16.UTF16ToString(ptr2, len2));
}
/// <summary>
/// The internal aggregate Step function callback, which wraps the raw context pointer and calls the virtual Step() method.
/// </summary>
/// <remarks>
/// This function takes care of doing the lookups and getting the important information put together to call the Step() function.
/// That includes pulling out the user's contextData and updating it after the call is made. We use a sorted list for this so
/// binary searches can be done to find the data.
/// </remarks>
/// <param name="context">A raw context pointer</param>
/// <param name="nArgs">Number of arguments passed in</param>
/// <param name="argsptr">A pointer to the array of arguments</param>
internal void StepCallback(IntPtr context, int nArgs, IntPtr argsptr)
{
long nAux;
AggregateData data;
nAux = (long) _base.AggregateContext(context);
if (_contextDataList.TryGetValue(nAux, out data) == false)
{
data = new AggregateData();
_contextDataList[nAux] = data;
}
try
{
_context = context;
Step(ConvertParams(nArgs, argsptr), data._count, ref data._data);
}
finally
{
data._count++;
}
}
/// <summary>
/// An internal aggregate Final function callback, which wraps the context pointer and calls the virtual Final() method.
/// </summary>
/// <param name="context">A raw context pointer</param>
internal void FinalCallback(IntPtr context)
{
var n = (long) _base.AggregateContext(context);
object obj = null;
if (_contextDataList.ContainsKey(n))
{
obj = _contextDataList[n]._data;
_contextDataList.Remove(n);
}
_context = context;
SetReturnValue(context, Final(obj));
var disp = obj as IDisposable;
if (disp != null) disp.Dispose();
}
/// <summary>
/// Placeholder for a user-defined disposal routine
/// </summary>
/// <param name="disposing">True if the object is being disposed explicitly</param>
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
IDisposable disp;
foreach (var kv in _contextDataList)
{
disp = kv.Value._data as IDisposable;
if (disp != null)
disp.Dispose();
}
_contextDataList.Clear();
_InvokeFunc = null;
_StepFunc = null;
_FinalFunc = null;
_CompareFunc = null;
_base = null;
_contextDataList = null;
}
}
/// <summary>
/// Disposes of any active contextData variables that were not automatically cleaned up. Sometimes this can happen if
/// someone closes the connection while a DataReader is open.
/// </summary>
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Using reflection, enumerate all assemblies in the current appdomain looking for classes that
/// have a SQLiteFunctionAttribute attribute, and registering them accordingly.
/// </summary>
#if !PLATFORM_COMPACTFRAMEWORK
[FileIOPermission(SecurityAction.Assert, AllFiles = FileIOPermissionAccess.PathDiscovery)]
#endif
static SQLiteFunction()
{
_registeredFunctions = new List<SQLiteFunctionAttribute>();
try
{
#if !PLATFORM_COMPACTFRAMEWORK
SQLiteFunctionAttribute at;
Assembly[] arAssemblies = AppDomain.CurrentDomain.GetAssemblies();
int w = arAssemblies.Length;
AssemblyName sqlite = Assembly.GetCallingAssembly().GetName();
for (int n = 0; n < w; n++)
{
Type[] arTypes;
bool found = false;
AssemblyName[] references;
try
{
// Inspect only assemblies that reference SQLite
references = arAssemblies[n].GetReferencedAssemblies();
int t = references.Length;
for (int z = 0; z < t; z++)
{
if (references[z].Name == sqlite.Name)
{
found = true;
break;
}
}
if (found == false)
continue;
arTypes = arAssemblies[n].GetTypes();
}
catch (ReflectionTypeLoadException e)
{
arTypes = e.Types;
}
int v = arTypes.Length;
for (int x = 0; x < v; x++)
{
if (arTypes[x] == null) continue;
object[] arAtt = arTypes[x].GetCustomAttributes(typeof (SQLiteFunctionAttribute), false);
int u = arAtt.Length;
for (int y = 0; y < u; y++)
{
at = arAtt[y] as SQLiteFunctionAttribute;
if (at != null)
{
at._instanceType = arTypes[x];
_registeredFunctions.Add(at);
}
}
}
}
#endif
}
catch // SQLite provider can continue without being able to find built-in functions
{
}
}
/// <summary>
/// Manual method of registering a function. The type must still have the SQLiteFunctionAttributes in order to work
/// properly, but this is a workaround for the Compact Framework where enumerating assemblies is not currently supported.
/// </summary>
/// <param name="typ">The type of the function to register</param>
public static void RegisterFunction(Type typ)
{
object[] arAtt = typ.GetCustomAttributes(typeof (SQLiteFunctionAttribute), false);
int u = arAtt.Length;
SQLiteFunctionAttribute at;
for (int y = 0; y < u; y++)
{
at = arAtt[y] as SQLiteFunctionAttribute;
if (at != null)
{
at._instanceType = typ;
_registeredFunctions.Add(at);
}
}
}
/// <summary>
/// Called by SQLiteBase derived classes, this function binds all user-defined functions to a connection.
/// It is done this way so that all user-defined functions will access the database using the same encoding scheme
/// as the connection (UTF-8 or UTF-16).
/// </summary>
/// <remarks>
/// The wrapper functions that interop with SQLite will create a unique cookie value, which internally is a pointer to
/// all the wrapped callback functions. The interop function uses it to map CDecl callbacks to StdCall callbacks.
/// </remarks>
/// <param name="sqlbase">The base object on which the functions are to bind</param>
/// <returns>Returns an array of functions which the connection object should retain until the connection is closed.</returns>
internal static SQLiteFunction[] BindFunctions(SQLiteBase sqlbase)
{
SQLiteFunction f;
var lFunctions = new List<SQLiteFunction>();
foreach (SQLiteFunctionAttribute pr in _registeredFunctions)
{
f = (SQLiteFunction) Activator.CreateInstance(pr._instanceType);
f._base = sqlbase;
f._InvokeFunc = (pr.FuncType == FunctionType.Scalar) ? new SQLiteCallback(f.ScalarCallback) : null;
f._StepFunc = (pr.FuncType == FunctionType.Aggregate) ? new SQLiteCallback(f.StepCallback) : null;
f._FinalFunc = (pr.FuncType == FunctionType.Aggregate) ? new SQLiteFinalCallback(f.FinalCallback) : null;
f._CompareFunc = (pr.FuncType == FunctionType.Collation) ? new SQLiteCollation(f.CompareCallback) : null;
f._CompareFunc16 = (pr.FuncType == FunctionType.Collation)
? new SQLiteCollation(f.CompareCallback16)
: null;
if (pr.FuncType != FunctionType.Collation)
sqlbase.CreateFunction(pr.Name, pr.Arguments, (f is SQLiteFunctionEx), f._InvokeFunc, f._StepFunc,
f._FinalFunc);
else
sqlbase.CreateCollation(pr.Name, f._CompareFunc, f._CompareFunc16);
lFunctions.Add(f);
}
var arFunctions = new SQLiteFunction[lFunctions.Count];
lFunctions.CopyTo(arFunctions, 0);
return arFunctions;
}
}
/// <summary>
/// Extends SQLiteFunction and allows an inherited class to obtain the collating sequence associated with a function call.
/// </summary>
/// <remarks>
/// User-defined functions can call the GetCollationSequence() method in this class and use it to compare strings and char arrays.
/// </remarks>
public class SQLiteFunctionEx : SQLiteFunction
{
/// <summary>
/// Obtains the collating sequence in effect for the given function.
/// </summary>
/// <returns></returns>
protected CollationSequence GetCollationSequence()
{
return _base.GetCollationSequence(this, _context);
}
}
/// <summary>
/// The type of user-defined function to declare
/// </summary>
public enum FunctionType
{
/// <summary>
/// Scalar functions are designed to be called and return a result immediately. Examples include ABS(), Upper(), Lower(), etc.
/// </summary>
Scalar = 0,
/// <summary>
/// Aggregate functions are designed to accumulate data until the end of a call and then return a result gleaned from the accumulated data.
/// Examples include SUM(), COUNT(), AVG(), etc.
/// </summary>
Aggregate = 1,
/// <summary>
/// Collation sequences are used to sort textual data in a custom manner, and appear in an ORDER BY clause. Typically text in an ORDER BY is
/// sorted using a straight case-insensitive comparison function. Custom collating sequences can be used to alter the behavior of text sorting
/// in a user-defined manner.
/// </summary>
Collation = 2,
}
/// <summary>
/// An internal callback delegate declaration.
/// </summary>
/// <param name="context">Raw context pointer for the user function</param>
/// <param name="nArgs">Count of arguments to the function</param>
/// <param name="argsptr">A pointer to the array of argument pointers</param>
#if !PLATFORM_COMPACTFRAMEWORK
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
#endif
internal delegate void SQLiteCallback(IntPtr context, int nArgs, IntPtr argsptr);
/// <summary>
/// An internal final callback delegate declaration.
/// </summary>
/// <param name="context">Raw context pointer for the user function</param>
#if !PLATFORM_COMPACTFRAMEWORK
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
#endif
internal delegate void SQLiteFinalCallback(IntPtr context);
/// <summary>
/// Internal callback delegate for implementing collation sequences
/// </summary>
/// <param name="puser">Not used</param>
/// <param name="len1">Length of the string pv1</param>
/// <param name="pv1">Pointer to the first string to compare</param>
/// <param name="len2">Length of the string pv2</param>
/// <param name="pv2">Pointer to the second string to compare</param>
/// <returns>Returns -1 if the first string is less than the second. 0 if they are equal, or 1 if the first string is greater
/// than the second.</returns>
#if !PLATFORM_COMPACTFRAMEWORK
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
#endif
internal delegate int SQLiteCollation(IntPtr puser, int len1, IntPtr pv1, int len2, IntPtr pv2);
/// <summary>
/// The type of collating sequence
/// </summary>
public enum CollationTypeEnum
{
/// <summary>
/// The built-in BINARY collating sequence
/// </summary>
Binary = 1,
/// <summary>
/// The built-in NOCASE collating sequence
/// </summary>
NoCase = 2,
/// <summary>
/// The built-in REVERSE collating sequence
/// </summary>
Reverse = 3,
/// <summary>
/// A custom user-defined collating sequence
/// </summary>
Custom = 0,
}
/// <summary>
/// The encoding type the collation sequence uses
/// </summary>
public enum CollationEncodingEnum
{
/// <summary>
/// The collation sequence is UTF8
/// </summary>
UTF8 = 1,
/// <summary>
/// The collation sequence is UTF16 little-endian
/// </summary>
UTF16LE = 2,
/// <summary>
/// The collation sequence is UTF16 big-endian
/// </summary>
UTF16BE = 3,
}
/// <summary>
/// A struct describing the collating sequence a function is executing in
/// </summary>
public struct CollationSequence
{
/// <summary>
/// The text encoding of the collation sequence
/// </summary>
public CollationEncodingEnum Encoding;
/// <summary>
/// The name of the collating sequence
/// </summary>
public string Name;
/// <summary>
/// The type of collating sequence
/// </summary>
public CollationTypeEnum Type;
/// <summary>
/// Context of the function that requested the collating sequence
/// </summary>
internal SQLiteFunction _func;
/// <summary>
/// Calls the base collating sequence to compare two strings
/// </summary>
/// <param name="s1">The first string to compare</param>
/// <param name="s2">The second string to compare</param>
/// <returns>-1 if s1 is less than s2, 0 if s1 is equal to s2, and 1 if s1 is greater than s2</returns>
public int Compare(string s1, string s2)
{
return _func._base.ContextCollateCompare(Encoding, _func._context, s1, s2);
}
/// <summary>
/// Calls the base collating sequence to compare two character arrays
/// </summary>
/// <param name="c1">The first array to compare</param>
/// <param name="c2">The second array to compare</param>
/// <returns>-1 if c1 is less than c2, 0 if c1 is equal to c2, and 1 if c1 is greater than c2</returns>
public int Compare(char[] c1, char[] c2)
{
return _func._base.ContextCollateCompare(Encoding, _func._context, c1, c2);
}
}
}