Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/Compilation/AppSettingsExpressionBuilder.cs

@@ -0,0 +1,85 @@
+//------------------------------------------------------------------------------
+// <copyright file="AppSettingsExpressionBuilder.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.Web.Compilation {
+    using System;
+    using System.Security.Permissions;
+    using System.CodeDom;
+    using System.ComponentModel;
+    using System.Configuration;
+    using System.Diagnostics;
+    using System.Web.UI;
+
+
+    [ExpressionPrefix("AppSettings")]
+    [ExpressionEditor("System.Web.UI.Design.AppSettingsExpressionEditor, " + AssemblyRef.SystemDesign)]
+    public class AppSettingsExpressionBuilder : ExpressionBuilder {
+        public override bool SupportsEvaluate {
+            get {
+                return true;
+            }
+        }
+
+
+        public override CodeExpression GetCodeExpression(BoundPropertyEntry entry,
+            object parsedData, ExpressionBuilderContext context) {
+
+            if (entry.DeclaringType == null || entry.PropertyInfo == null) {
+                return new CodeMethodInvokeExpression(
+                    new CodeTypeReferenceExpression(this.GetType()),
+                    "GetAppSetting",
+                    new CodePrimitiveExpression(entry.Expression.Trim()));
+            }
+            else {
+                return new CodeMethodInvokeExpression(
+                    new CodeTypeReferenceExpression(this.GetType()),
+                    "GetAppSetting",
+                    new CodePrimitiveExpression(entry.Expression.Trim()),
+                    new CodeTypeOfExpression(entry.DeclaringType),
+                    new CodePrimitiveExpression(entry.PropertyInfo.Name));
+            }
+        }
+
+        public override object EvaluateExpression(object target, BoundPropertyEntry entry,
+            object parsedData, ExpressionBuilderContext context) {
+
+            return GetAppSetting(entry.Expression, target.GetType(), entry.PropertyInfo.Name);
+        }
+
+        public static object GetAppSetting(string key) {
+            string value = ConfigurationManager.AppSettings[key];
+
+            if (value == null) {
+                throw new InvalidOperationException(SR.GetString(SR.AppSetting_not_found, key));
+            }
+            return value;
+        }
+
+        public static object GetAppSetting(string key, Type targetType, string propertyName) {
+            string value = ConfigurationManager.AppSettings[key];
+
+            if (targetType != null) {
+                PropertyDescriptor propDesc = TypeDescriptor.GetProperties(targetType)[propertyName];
+                if (propDesc != null) {
+                    if (propDesc.PropertyType != typeof(string)) {
+                        TypeConverter converter = propDesc.Converter;
+                        if (converter.CanConvertFrom(typeof(string))) {
+                            return converter.ConvertFrom(value);
+                        }
+                        else {
+                            throw new InvalidOperationException(SR.GetString(SR.AppSetting_not_convertible, value, propDesc.PropertyType.Name, propDesc.Name));
+                        }
+                    }
+                }
+            }
+
+            if (value == null) {
+                throw new InvalidOperationException(SR.GetString(SR.AppSetting_not_found, key));
+            }
+            return value;
+        }
+    }
+}