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// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
namespace System.Web.WebPages
{
public static class StringExtensions
{
public static bool IsEmpty(this string value)
{
return String.IsNullOrEmpty(value);
}
[SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "int", Justification = "We specificaly want type names")]
public static int AsInt(this string value)
{
return AsInt(value, 0);
}
[SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "int", Justification = "We specificaly want type names")]
public static int AsInt(this string value, int defaultValue)
{
int result;
return Int32.TryParse(value, out result) ? result : defaultValue;
}
public static decimal AsDecimal(this string value)
{
// Decimal.TryParse does not work consistently for some locales. For instance for lt-LT, it accepts but ignores decimal values so "12.12" is parsed as 1212.
return As<Decimal>(value);
}
public static decimal AsDecimal(this string value, decimal defaultValue)
{
return As<Decimal>(value, defaultValue);
}
[SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "float", Justification = "We specificaly want type names")]
public static float AsFloat(this string value)
{
return AsFloat(value, default(float));
}
[SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "float", Justification = "We specificaly want type names")]
public static float AsFloat(this string value, float defaultValue)
{
float result;
return Single.TryParse(value, out result) ? result : defaultValue;
}
public static DateTime AsDateTime(this string value)
{
return AsDateTime(value, default(DateTime));
}
public static DateTime AsDateTime(this string value, DateTime defaultValue)
{
DateTime result;
return DateTime.TryParse(value, out result) ? result : defaultValue;
}
public static TValue As<TValue>(this string value)
{
return As<TValue>(value, default(TValue));
}
[SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "bool", Justification = "We specificaly want type names")]
public static bool AsBool(this string value)
{
return AsBool(value, default(bool));
}
[SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "bool", Justification = "We specificaly want type names")]
public static bool AsBool(this string value, bool defaultValue)
{
bool result;
return Boolean.TryParse(value, out result) ? result : defaultValue;
}
[SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes", Justification = "We want to make this user friendly and return the default value on all failures")]
public static TValue As<TValue>(this string value, TValue defaultValue)
{
try
{
TypeConverter converter = TypeDescriptor.GetConverter(typeof(TValue));
if (converter.CanConvertFrom(typeof(string)))
{
return (TValue)converter.ConvertFrom(value);
}
// try the other direction
converter = TypeDescriptor.GetConverter(typeof(string));
if (converter.CanConvertTo(typeof(TValue)))
{
return (TValue)converter.ConvertTo(value, typeof(TValue));
}
}
catch
{
// eat all exceptions and return the defaultValue, assumption is that its always a parse/format exception
}
return defaultValue;
}
[SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "bool", Justification = "We specificaly want type names")]
public static bool IsBool(this string value)
{
bool result;
return Boolean.TryParse(value, out result);
}
[SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "int", Justification = "We specificaly want type names")]
public static bool IsInt(this string value)
{
int result;
return Int32.TryParse(value, out result);
}
public static bool IsDecimal(this string value)
{
// For some reason, Decimal.TryParse incorrectly parses floating point values as decimal value for some cultures.
// For example, 12.5 is parsed as 125 in lt-LT.
return Is<Decimal>(value);
}
[SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "float", Justification = "We specificaly want type names")]
public static bool IsFloat(this string value)
{
float result;
return Single.TryParse(value, out result);
}
public static bool IsDateTime(this string value)
{
DateTime result;
return DateTime.TryParse(value, out result);
}
[SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes", Justification = "This is the identical to the way it is done in TypeConverter.IsValid"),
SuppressMessage("Microsoft.Design", "CA1004:GenericMethodsShouldProvideTypeParameter", Justification = "This is the signature we want")]
public static bool Is<TValue>(this string value)
{
TypeConverter converter = TypeDescriptor.GetConverter(typeof(TValue));
if (converter != null)
{
try
{
if ((value == null) || converter.CanConvertFrom(null, value.GetType()))
{
// TypeConverter.IsValid essentially does this - a try catch - but uses InvariantCulture to convert.
converter.ConvertFrom(null, CultureInfo.CurrentCulture, value);
return true;
}
}
catch
{
}
}
return false;
}
}
}
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