Package net.sf.saxon.str

Class EmptyUnicodeString

java.lang.Object

net.sf.saxon.str.UnicodeString

net.sf.saxon.str.EmptyUnicodeString

All Implemented Interfaces:

java.lang.Comparable<UnicodeString>, AtomicMatchKey

public final class EmptyUnicodeString
extends UnicodeString

A zero-length Unicode string

Method Summary

Modifier and Type	Method	Description
int	codePointAt(long index)	Get the code point at a given position in the string
IntIterator	codePoints()	Get an iterator over the Unicode codepoints in the value.
int	compareTo(UnicodeString other)	Compare this string to another using codepoint comparison
UnicodeString	concat(UnicodeString other)	Concatenate another string
java.lang.String	details()
boolean	equals(java.lang.Object o)	Test whether this UnicodeString is equal to another under the rules of the codepoint collation.
static EmptyUnicodeString	getInstance()
int	getWidth()	Get the number of bits needed to hold all the characters in this string
int	hashCode()	Compute a hashCode.
long	indexOf(int code, long from)	Get the position of the first occurrence of the specified codepoint, starting the search at a given position in the string
long	indexOf(UnicodeString other, long from)	Get the first position, at or beyond start, where another string appears as a substring of this string, comparing codepoints.
long	indexWhere(java.util.function.IntPredicate predicate, long from)	Get the position of the first occurrence of the specified codepoint, starting the search at a given position in the string
boolean	isEmpty()	Determine whether the string is a zero-length string.
long	length()	Get the length of this string, in codepoints
int	length32()	Get the length of the string, provided it is less than 2^31 characters
UnicodeString	substring(long start, long end)	Get a substring of this string (following the rules of String.substring(int), but measuring Unicode codepoints rather than 16-bit code units)
java.lang.String	toString()	Display as a string.

Methods inherited from class net.sf.saxon.str.UnicodeString

asAtomic, checkSubstringBounds, economize, estimatedLength, hasSubstring, indexOf, prefix, requireInt, requireNonNegativeInt, substring, tidy, verifyCharacters

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

getInstance

public static EmptyUnicodeString getInstance()

length

public long length()

Get the length of this string, in codepoints

Specified by:

length in class UnicodeString

Returns:

the length of the string in Unicode code points

length32

public int length32()

Description copied from class: UnicodeString

Get the length of the string, provided it is less than 2^31 characters

Overrides:

length32 in class UnicodeString

Returns:

the length of the string if it fits within a Java int

concat

public UnicodeString concat(UnicodeString other)

Concatenate another string

Overrides:

concat in class UnicodeString

Parameters:

other - the string to be appended to this one

Returns:

the result of the concatenation (neither input string is altered)

substring

public UnicodeString substring(long start,
                               long end)

Get a substring of this string (following the rules of String.substring(int), but measuring Unicode codepoints rather than 16-bit code units)

Specified by:

substring in class UnicodeString

Parameters:

start - the offset of the first character to be included in the result, counting Unicode codepoints

end - the offset of the first character to be excluded from the result, counting Unicode codepoints

Returns:

the substring

codePointAt

public int codePointAt(long index)
                throws java.lang.IndexOutOfBoundsException

Description copied from class: UnicodeString

Get the code point at a given position in the string

Specified by:

codePointAt in class UnicodeString

Parameters:

index - the given position (0-based)

Returns:

the code point at the given position

Throws:

java.lang.IndexOutOfBoundsException - if the index is out of range

indexOf

public long indexOf(int code,
                    long from)

Description copied from class: UnicodeString

Get the position of the first occurrence of the specified codepoint, starting the search at a given position in the string

Specified by:

indexOf in class UnicodeString

Parameters:

code - the sought codePoint

from - the position from which the search should start (0-based). A negative value is treated as zero. A position beyond the end of the string results in a return value of -1 (meaning not found).

Returns:

the position (0-based) of the first occurrence found, or -1 if not found

indexOf

public long indexOf(UnicodeString other,
                    long from)

Get the first position, at or beyond start, where another string appears as a substring of this string, comparing codepoints.

Overrides:

indexOf in class UnicodeString

Parameters:

other - the other (sought) string

from - the position (0-based) where searching is to start (counting in codepoints)

Returns:

the first position where the substring is found, or -1 if it is not found. Also returns -1 if from is negative, or beyond the length of the string.

isEmpty

public boolean isEmpty()

Determine whether the string is a zero-length string. This may be more efficient than testing whether the length is equal to zero

Overrides:

isEmpty in class UnicodeString

Returns:

true if the string is zero length

getWidth

public int getWidth()

Description copied from class: UnicodeString

Get the number of bits needed to hold all the characters in this string

Specified by:

getWidth in class UnicodeString

Returns:

7 for ascii characters (not used??), 8 for latin-1, 16 for BMP, 24 for general Unicode.

codePoints

public IntIterator codePoints()

Get an iterator over the Unicode codepoints in the value. These will always be full codepoints, never surrogates (surrogate pairs are combined where necessary).

Specified by:

codePoints in class UnicodeString

Returns:

a sequence of Unicode codepoints

hashCode

public int hashCode()

Compute a hashCode. All implementations of UnicodeString use compatible hash codes and the hashing algorithm is therefore identical to that for java.lang.String. This means that for strings containing Astral characters, the hash code needs to be computed by decomposing an Astral character into a surrogate pair.

Overrides:

hashCode in class UnicodeString

Returns:

the hash code

equals

public boolean equals(java.lang.Object o)

Test whether this UnicodeString is equal to another under the rules of the codepoint collation.

Overrides:

equals in class UnicodeString

Parameters:

o - the value to be compared with this value

Returns:

true if the strings are equal on a codepoint-by-codepoint basis

compareTo

public int compareTo(UnicodeString other)

Description copied from class: UnicodeString

Compare this string to another using codepoint comparison

Specified by:

compareTo in interface java.lang.Comparable<UnicodeString>

Overrides:

compareTo in class UnicodeString

Parameters:

other - the other string

Returns:

-1 if this string comes first, 0 if they are equal, +1 if the other string comes first

toString

public java.lang.String toString()

Display as a string.

Overrides:

toString in class java.lang.Object

indexWhere

public long indexWhere(java.util.function.IntPredicate predicate,
                       long from)

Get the position of the first occurrence of the specified codepoint, starting the search at a given position in the string

Specified by:

indexWhere in class UnicodeString

Parameters:

predicate - condition that the codepoint must satisfy

from - the position from which the search should start (0-based)

Returns:

the position (0-based) of the first codepoint to match the predicate, or -1 if not found

Throws:

java.lang.UnsupportedOperationException - if the UnicodeString has not been prepared for codePoint access

details

public java.lang.String details()