151 lines
5.4 KiB
C#
151 lines
5.4 KiB
C#
// ==========================================================================
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// This software is subject to the provisions of the Zope Public License,
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// Version 2.0 (ZPL). A copy of the ZPL should accompany this distribution.
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// THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
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// WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
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// FOR A PARTICULAR PURPOSE.
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// ==========================================================================
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using System;
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using System.Collections;
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using System.Reflection;
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using System.Runtime.InteropServices;
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namespace Python.Runtime {
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//========================================================================
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// Implements a Python descriptor type that provides access to CLR fields.
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//========================================================================
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internal class FieldObject : ExtensionType {
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FieldInfo info;
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public FieldObject(FieldInfo info) : base() {
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this.info = info;
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}
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//====================================================================
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// Descriptor __get__ implementation. This method returns the
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// value of the field on the given object. The returned value
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// is converted to an appropriately typed Python object.
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//====================================================================
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public static IntPtr tp_descr_get(IntPtr ds, IntPtr ob, IntPtr tp) {
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FieldObject self = (FieldObject)GetManagedObject(ds);
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Object result;
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if (self == null) {
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return IntPtr.Zero;
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}
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FieldInfo info = self.info;
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if ((ob == IntPtr.Zero) || (ob == Runtime.PyNone)) {
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if (!info.IsStatic) {
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Exceptions.SetError(Exceptions.TypeError,
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"instance attribute must be accessed " +
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"through a class instance"
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);
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return IntPtr.Zero;
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}
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try {
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result = info.GetValue(null);
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return Converter.ToPython(result, info.FieldType);
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}
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catch(Exception e) {
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Exceptions.SetError(Exceptions.TypeError, e.Message);
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return IntPtr.Zero;
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}
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}
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try {
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CLRObject co = (CLRObject)GetManagedObject(ob);
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result = info.GetValue(co.inst);
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return Converter.ToPython(result, info.FieldType);
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}
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catch(Exception e) {
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Exceptions.SetError(Exceptions.TypeError, e.Message);
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return IntPtr.Zero;
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}
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}
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//====================================================================
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// Descriptor __set__ implementation. This method sets the value of
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// a field based on the given Python value. The Python value must be
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// convertible to the type of the field.
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//====================================================================
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public static new int tp_descr_set(IntPtr ds, IntPtr ob, IntPtr val) {
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FieldObject self = (FieldObject)GetManagedObject(ds);
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Object newval;
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if (self == null) {
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return -1;
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}
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if (val == IntPtr.Zero) {
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Exceptions.SetError(Exceptions.TypeError,
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"cannot delete field"
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);
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return -1;
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}
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FieldInfo info = self.info;
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if (info.IsLiteral || info.IsInitOnly) {
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Exceptions.SetError(Exceptions.TypeError,
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"field is read-only"
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);
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return -1;
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}
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bool is_static = info.IsStatic;
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if ((ob == IntPtr.Zero) || (ob == Runtime.PyNone)) {
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if (!is_static) {
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Exceptions.SetError(Exceptions.TypeError,
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"instance attribute must be set " +
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"through a class instance"
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);
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return -1;
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}
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}
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if (!Converter.ToManaged(val, info.FieldType, out newval,
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true)) {
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return -1;
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}
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try {
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if (!is_static) {
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CLRObject co = (CLRObject)GetManagedObject(ob);
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info.SetValue(co.inst, newval);
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}
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else {
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info.SetValue(null, newval);
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}
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return 0;
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}
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catch(Exception e) {
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Exceptions.SetError(Exceptions.TypeError, e.Message);
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return -1;
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}
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}
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//====================================================================
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// Descriptor __repr__ implementation.
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//====================================================================
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public static IntPtr tp_repr(IntPtr ob) {
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FieldObject self = (FieldObject)GetManagedObject(ob);
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string s = String.Format("<field '{0}'>", self.info.Name);
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return Runtime.PyString_FromStringAndSize(s, s.Length);
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}
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}
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}
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