java.lang.Object
- net.sf.saxon.str.UnicodeString
- - net.sf.saxon.str.ZenoString

All Implemented Interfaces:

java.lang.Comparable<UnicodeString>, AtomicMatchKey
```
public class ZenoString
extends UnicodeString
```
A ZenoString is an implementation of UnicodeString that comprises a list of segments representing substrings of the total string. By convention the segments are not themselves ZenoStrings, so the structure is a shallow tree. An index holds pointers to the segments and their offsets within the string as a whole; this is used to locate the codepoint at any particular location in the string.
The segments will always be non-empty. An empty string contains no segments.

The key to the performance of the data structure (and its name) is the algorithm for consolidating segments when strings are concatenated, so as to keep the number of segments increasing logarithmically with the string size, with short segments at the extremities to allow efficient further concatenation at the ends.

For further details see the paper by Michael Kay at Balisage 2021.

Field Summary

Fields
Modifier and Type Field Description

static ZenoString EMPTY
An empty ZenoString

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
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 code points present in the string.
`ZenoString`	`concat(UnicodeString other)`	Concatenate another string
`static UnicodeString`	`concatSegments(UnicodeString left, UnicodeString right)`
`java.util.List<java.lang.Long>`	`debugSegmentLengths()`	This method is for diagnostics and unit testing only: it exposes the lengths of the internal segments.
`UnicodeString`	`economize()`	Get an equivalent UnicodeString that uses the most economical representation available
`int`	`getWidth()`	Get the number of bits needed to hold all the characters in this string
`boolean`	`hasSubstring(UnicodeString other, long offset)`	Ask whether this string has another string as its content starting at a given offset
`long`	`indexOf(int codePoint, long from)`	Get the position of the first occurrence of the specified codepoint, starting the search at a given position in the string
`long`	`indexWhere(java.util.function.IntPredicate predicate, long from)`	Get the position of the first occurrence of a codepoint that matches a supplied predicate, starting the search at a given position in the string
`boolean`	`isEmpty()`	Ask whether the string is empty
`long`	`length()`	Get the length of the string
`static ZenoString`	`of(UnicodeString content)`	Construct a ZenoString from a supplied UnicodeString
`UnicodeString`	`substring(long start, long end)`	Get a substring of this codepoint sequence, with a given start and end position
`java.lang.String`	`toString()`
`void`	`writeSegments(UnicodeWriter writer)`	Write each of the segments in turn to a UnicodeWriter

Methods inherited from class net.sf.saxon.str.UnicodeString
asAtomic, checkSubstringBounds, compareTo, equals, estimatedLength, hashCode, indexOf, indexOf, length32, prefix, requireInt, requireNonNegativeInt, substring, tidy, verifyCharacters

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - EMPTY
```
public static final ZenoString EMPTY
```
    An empty ZenoString
- Method Detail
  - of
```
public static ZenoString of(UnicodeString content)
```
    Construct a ZenoString from a supplied UnicodeString
    
    Parameters:
    
    content - the supplied UnicodeString
    
    Returns:
    
    the resulting ZenoString
  - codePoints
```
public IntIterator codePoints()
```
    Get an iterator over the code points present in the string.
    
    Specified by:
    
    codePoints in class UnicodeString
    
    Returns:
    
    an iterator that delivers the individual code points
  - length
```
public long length()
```
    Get the length of the string
    
    Specified by:
    
    length in class UnicodeString
    
    Returns:
    
    the number of code points in the string
  - isEmpty
```
public boolean isEmpty()
```
    Ask whether the string is empty
    
    Overrides:
    
    isEmpty in class UnicodeString
    
    Returns:
    
    true if the length of the string is zero
  - getWidth
```
public int getWidth()
```
    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, 8 for latin-1, 16 for BMP, 24 for general Unicode.
  - indexOf
```
public long indexOf(int codePoint,
                    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:
    
    indexOf in class UnicodeString
    
    Parameters:
    
    codePoint - 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
    
    Throws:
    
    java.lang.IndexOutOfBoundsException - if the from value is out of range
  - indexWhere
```
public long indexWhere(java.util.function.IntPredicate predicate,
                       long from)
```
    Description copied from class: UnicodeString
    
    Get the position of the first occurrence of a codepoint that matches a supplied predicate, 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). 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 codepoint to match the predicate, or -1 if not found
  - codePointAt
```
public int codePointAt(long index)
```
    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
  - substring
```
public UnicodeString substring(long start,
                               long end)
```
    Get a substring of this codepoint sequence, with a given start and end position
    
    Specified by:
    
    substring in class UnicodeString
    
    Parameters:
    
    start - the start position (0-based): that is, the position of the first code point to be included
    
    end - the end position (0-based): specifically, the position of the first code point not to be included
    
    Returns:
    
    the requested substring
  - hasSubstring
```
public boolean hasSubstring(UnicodeString other,
                            long offset)
```
    Ask whether this string has another string as its content starting at a given offset
    
    Overrides:
    
    hasSubstring in class UnicodeString
    
    Parameters:
    
    other - the other string
    
    offset - the starting position in this string (counting in codepoints)
    
    Returns:
    
    true if the other string appears as a substring of this string starting at the given position.
    
    Throws:
    
    java.lang.IndexOutOfBoundsException - if offset is less than zero or greater than the length of this string. Note that there is no exception if offset + other.length() exceeds this.length() - instead this results in a return value of false.
  - concat
```
public ZenoString 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)
  - writeSegments
```
public void writeSegments(UnicodeWriter writer)
                   throws java.io.IOException
```
    Write each of the segments in turn to a UnicodeWriter
    
    Parameters:
    
    writer - the writer to which the string is to be written
    
    Throws:
    
    java.io.IOException
  - concatSegments
```
public static UnicodeString concatSegments(UnicodeString left,
                                           UnicodeString right)
```
  - economize
```
public UnicodeString economize()
```
    Get an equivalent UnicodeString that uses the most economical representation available
    
    Overrides:
    
    economize in class UnicodeString
    
    Returns:
    
    an equivalent UnicodeString
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - debugSegmentLengths
```
public java.util.List<java.lang.Long> debugSegmentLengths()
```
    This method is for diagnostics and unit testing only: it exposes the lengths of the internal segments. This is an implementation detail that is subject to change and does not affect the exposed functionality.
    
    Returns:
    
    the lengths of the segments

Class ZenoString

Field Summary

Method Summary

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

Methods inherited from class java.lang.Object

Field Detail

EMPTY

Method Detail

of

codePoints

length

isEmpty

getWidth

indexOf

indexWhere

codePointAt

substring

hasSubstring

concat

writeSegments

concatSegments

economize

toString

debugSegmentLengths