Struct InternedString

Wraps around a string to allow for faster case-insensitive string comparisons while preserving original casing.

Namespace: UnityEngine.InputSystem.Utilities

Syntax

public struct InternedString : IEquatable<InternedString>, IComparable<InternedString>

Remarks

Unlike string, InternedStrings can be compared with a quick Object.ReferenceEquals comparison and without actually comparing string contents.

Also, unlike string, the representation of an empty and a null string is identical.

Note that all string comparisons using InternedStrings are both case-insensitive and culture-insensitive.

There is a non-zero cost to creating an InternedString. The first time a new unique InternedString is encountered, there may also be a GC heap allocation.

Constructors

InternedString(String)

Initialize the InternedString with the given string. Except if the string is null or empty, this requires an internal lookup (this is the reason the conversion from string to InternedString is not implicit).

Declaration

public InternedString(string text)

Parameters

Type	Name	Description
String	text	A string. Can be null.

Remarks

The InternedString preserves the original casing. Meaning that ToString() will return the string as it was supplied through text. However, comparison between two InternedStrings is still always just a reference comparisons regardless of case and culture.

var lowerCase = new InternedString("text");
var upperCase = new InternedString("TEXT");

// This is still just a quick reference comparison:
if (lowerCase == upperCase)
    Debug.Log("True");

// But this prints the strings in their original casing.
Debug.Log(lowerCase);
Debug.Log(upperCase);

Properties

length

Length of the string in characters. Equivalent to string.Length.

Declaration

public readonly int length { get; }

Property Value

Type	Description
Int32	Length of the string.

Methods

CompareTo(InternedString)

Declaration

public int CompareTo(InternedString other)

Parameters

Type	Name	Description
InternedString	other

Returns

Type	Description
Int32

Equals(Object)

Compare the InternedString to given object.

Declaration

public override bool Equals(object obj)

Parameters

Type	Name	Description
Object	obj	An object. If it is a string, performs a string comparison. If it is an InternedString, performs an InternedString-comparison. Otherwise returns false.

Returns

Type	Description
Boolean	True if the InternedString is equal to obj.

Equals(InternedString)

Compare two InternedStrings for equality. They are equal if, ignoring case and culture, their text is equal.

Declaration

public bool Equals(InternedString other)

Parameters

Type	Name	Description
InternedString	other	Another InternedString.

Returns

Type	Description
Boolean	True if the two InternedStrings are equal.

Remarks

This operation is cheap and does not involve an actual string comparison. Instead, a simple Object.ReferenceEquals comparison is performed.

GetHashCode()

Compute a hash code for the string. Equivalent to string.GetHashCode.

Declaration

public override int GetHashCode()

Returns

Type	Description
Int32	A hash code.

IsEmpty()

Whether the string is empty, i.e. has a length of zero. If so, the InternedString corresponds to default(InternedString).

Declaration

public bool IsEmpty()

Returns

Type	Description
Boolean	True if the string is empty.

ToLower()

Return a lower-case version of the string.

Declaration

public string ToLower()

Returns

Type	Description
String	A lower-case version of the string.

Remarks

InternedStrings internally always store a lower-case version which means that this method does not incur a GC heap allocation cost.

ToString()

Declaration

public override string ToString()

Returns

Type	Description
String

Operators

Equality(String, InternedString)

Declaration

public static bool operator ==(string a, InternedString b)

Parameters

Type	Name	Description
String	a
InternedString	b

Returns

Type	Description
Boolean

Equality(InternedString, String)

Declaration

public static bool operator ==(InternedString a, string b)

Parameters

Type	Name	Description
InternedString	a
String	b

Returns

Type	Description
Boolean

Equality(InternedString, InternedString)

Declaration

public static bool operator ==(InternedString a, InternedString b)

Parameters

Type	Name	Description
InternedString	a
InternedString	b

Returns

Type	Description
Boolean

GreaterThan(InternedString, InternedString)

Declaration

public static bool operator>(InternedString left, InternedString right)

Parameters

Type	Name	Description
InternedString	left
InternedString	right

Returns

Type	Description
Boolean

Implicit(InternedString to String)

Convert the given InternedString back to a string. Equivalent to ToString().

Declaration

public static implicit operator string (InternedString str)

Parameters

Type	Name	Description
InternedString	str	An InternedString.

Returns

Type	Description
String	A string.

Inequality(String, InternedString)

Declaration

public static bool operator !=(string a, InternedString b)

Parameters

Type	Name	Description
String	a
InternedString	b

Returns

Type	Description
Boolean

Inequality(InternedString, String)

Declaration

public static bool operator !=(InternedString a, string b)

Parameters

Type	Name	Description
InternedString	a
String	b

Returns

Type	Description
Boolean

Inequality(InternedString, InternedString)

Declaration

public static bool operator !=(InternedString a, InternedString b)

Parameters

Type	Name	Description
InternedString	a
InternedString	b

Returns

Type	Description
Boolean

LessThan(InternedString, InternedString)

Declaration

public static bool operator <(InternedString left, InternedString right)

Parameters

Type	Name	Description
InternedString	left
InternedString	right

Returns

Type	Description
Boolean