net.sf.saxon.value
Class StringValue

java.lang.Object
  net.sf.saxon.value.Value
      net.sf.saxon.value.AtomicValue
          net.sf.saxon.value.StringValue

All Implemented Interfaces:

Serializable, PullEvent, SequenceIterable, GroundedValue, Item, ValueRepresentation, ConversionResult

Direct Known Subclasses:

AnyURIValue, UntypedAtomicValue

public class StringValue
extends AtomicValue

An atomic value of type xs:string. This class is also used for types derived from xs:string. Subclasses of StringValue are used for xs:untypedAtomic and xs:anyURI values.

See Also:

Serialized Form

Nested Class Summary

class

StringValue.CharacterIterator CharacterIterator is used to iterate over the characters in a string, returning them as integers representing the Unicode code-point.

Field Summary

static StringValue	EMPTY_STRING
static StringValue	FALSE
protected boolean	noSurrogates
static StringValue	SINGLE_SPACE
static StringValue	TRUE
protected CharSequence	value

Fields inherited from class net.sf.saxon.value.AtomicValue

typeLabel

Fields inherited from class net.sf.saxon.value.Value

INDETERMINATE_ORDERING

Fields inherited from interface net.sf.saxon.om.ValueRepresentation

EMPTY_VALUE_ARRAY

Constructor Summary

protected	StringValue() Protected constructor for use by subtypes
	StringValue(CharSequence value) Constructor.

Method Summary

boolean	codepointEquals(StringValue other) Test whether this StringValue is equal to another under the rules of the codepoint collation
boolean	containsSurrogatePairs() Determine whether the string contains surrogate pairs
static CharSequence	contract(int[] codes, int used) Contract an array of integers containing Unicode codepoints into a Java string
ConversionResult	convertPrimitive(BuiltInAtomicType requiredType, boolean validate, XPathContext context) Convert a value to another primitive data type, with control over how validation is handled.
static ConversionResult	convertStringToAtomicType(CharSequence value, AtomicType targetType, NameChecker checker) Convert the value to a given type.
static ConversionResult	convertStringToBuiltInType(CharSequence value, BuiltInAtomicType requiredType, NameChecker checker) Convert a string value to another built-in data type, with control over how validation is handled.
AtomicValue	copyAsSubType(AtomicType typeLabel) Create a copy of this atomic value, with a different type label
static String	diagnosticDisplay(String s) Produce a diagnostic representation of the contents of the string
boolean	effectiveBooleanValue() Get the effective boolean value of a string
boolean	equals(Object other) Determine if two AtomicValues are equal, according to XPath rules.
int[]	expand() Expand a string containing surrogate pairs into an array of 32-bit characters
static int[]	expand(CharSequence s) Expand a string containing surrogate pairs into an array of 32-bit characters
String	getPrimitiveStringValue() Get the string value as a String
BuiltInAtomicType	getPrimitiveType() Determine the primitive type of the value.
Comparable	getSchemaComparable() Get a Comparable value that implements the XML Schema comparison semantics for this value.
int	getStringLength() Get the length of this string, as defined in XPath.
static int	getStringLength(CharSequence s) Get the length of a string, as defined in XPath.
Object	getXPathComparable(boolean ordered, StringCollator collator, XPathContext context) Get an object value that implements the XPath equality and ordering comparison semantics for this value.
boolean	isIdentical(Value v) Determine whether two atomic values are identical, as determined by XML Schema rules.
boolean	isKnownToContainNoSurrogates() Ask whether the string is known to contain no surrogate pairs.
boolean	isZeroLength() Determine whether the string is a zero-length string.
UnfailingIterator	iterateCharacters() Iterate over a string, returning a sequence of integers representing the Unicode code-point values
static ConversionResult	makeRestrictedString(CharSequence value, BuiltInAtomicType typeLabel, NameChecker checker) Factory method to create a string value belonging to a built-in type derived from string
static StringValue	makeStringValue(CharSequence value) Factory method.
void	setContainsNoSurrogates() Assert that the string is known to contain no surrogate pairs
void	setStringValueCS(CharSequence value) Set the value of the item as a CharSequence.
String	toString() Get string value.
static ValidationFailure	validate(BuiltInAtomicType typeLabel, CharSequence val, NameChecker checker) Validate that the string conforms to the rules for a built-in subtype of xs:string

Methods inherited from class net.sf.saxon.value.AtomicValue

asAtomic, checkPermittedContents, convert, convert, getCardinality, getComponent, getItemType, getLength, getStringValue, getStringValueCS, getTypedValue, getTypeLabel, isNaN, itemAt, iterate, process, setTypeLabel, subsequence

Methods inherited from class net.sf.saxon.value.Value

asItem, asItem, asIterator, asValue, convertToJava, fromItem, getCanonicalLexicalRepresentation, getIterator, iterate, reduce, stringToNumber

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_STRING

public static final StringValue EMPTY_STRING

SINGLE_SPACE

public static final StringValue SINGLE_SPACE

TRUE

public static final StringValue TRUE

FALSE

public static final StringValue FALSE

value

protected CharSequence value

noSurrogates

protected boolean noSurrogates

Constructor Detail

StringValue

protected StringValue()

Protected constructor for use by subtypes

StringValue

public StringValue(CharSequence value)

Constructor. Note that although a StringValue may wrap any kind of CharSequence (usually a String, but it can also be, for example, a StringBuffer), the caller is responsible for ensuring that the value is immutable.

Parameters:

value - the String value. Null is taken as equivalent to "".

Method Detail

setContainsNoSurrogates

public void setContainsNoSurrogates()

Assert that the string is known to contain no surrogate pairs

copyAsSubType

public AtomicValue copyAsSubType(AtomicType typeLabel)

Create a copy of this atomic value, with a different type label

Specified by:

copyAsSubType in class AtomicValue

Parameters:

typeLabel - the type label of the new copy. The caller is responsible for checking that the value actually conforms to this type.

Returns:

the copied value

getPrimitiveType

public BuiltInAtomicType getPrimitiveType()

Determine the primitive type of the value. This delivers the same answer as getItemType().getPrimitiveItemType(). The primitive types are the 19 primitive types of XML Schema, plus xs:integer, xs:dayTimeDuration and xs:yearMonthDuration, and xs:untypedAtomic. For external objects, the result is AnyAtomicType.

Specified by:

getPrimitiveType in class AtomicValue

Returns:

the primitive type

makeStringValue

public static StringValue makeStringValue(CharSequence value)

Factory method. Unlike the constructor, this avoids creating a new StringValue in the case of a zero-length string (and potentially other strings, in future)

Parameters:

value - the String value. Null is taken as equivalent to "".

Returns:

the corresponding StringValue

getPrimitiveStringValue

public final String getPrimitiveStringValue()

Get the string value as a String

Specified by:

getPrimitiveStringValue in class AtomicValue

Returns:

the value converted to a string according to the rules for the primitive type

setStringValueCS

public final void setStringValueCS(CharSequence value)

Set the value of the item as a CharSequence.

For system use only. In principle, a StringValue is immutable. However, in special circumstances, if it is newly constructed, the content can be changed to reflect the effect of the whiteSpace facet.

Parameters:

value - the value of the string

convertPrimitive

public ConversionResult convertPrimitive(BuiltInAtomicType requiredType,
                                         boolean validate,
                                         XPathContext context)

Convert a value to another primitive data type, with control over how validation is handled.

Specified by:

convertPrimitive in class AtomicValue

Parameters:

requiredType - type code of the required atomic type. This must not be a namespace-sensitive type.

validate - true if validation is required. If set to false, the caller guarantees that the value is valid for the target data type, and that further validation is therefore not required. Note that a validation failure may be reported even if validation was not requested.

context - XPath dynamic context. Used only where the target type is one such as NCName whose definition is context-sensitive

Returns:

the result of the conversion, if successful. If unsuccessful, the value returned will be a ValidationErrorValue. The caller must check for this condition. No exception is thrown, instead the exception will be encapsulated within the ErrorValue.

convertStringToBuiltInType

public static ConversionResult convertStringToBuiltInType(CharSequence value,
                                                          BuiltInAtomicType requiredType,
                                                          NameChecker checker)

Convert a string value to another built-in data type, with control over how validation is handled.

Parameters:

value - the value to be converted

requiredType - the required atomic type. This must not be a namespace-sensitive type.

checker - if validation is required, a NameChecker. If set to null, the caller guarantees that the value is valid for the target data type, and that further validation is therefore not required. Note that a validation failure may be reported even if validation was not requested.

Returns:

the result of the conversion, if successful. If unsuccessful, the value returned will be a ValidationFailure. The caller must check for this condition. No exception is thrown, instead the exception will be encapsulated within the ValidationFailure.

convertStringToAtomicType

public static ConversionResult convertStringToAtomicType(CharSequence value,
                                                         AtomicType targetType,
                                                         NameChecker checker)

Convert the value to a given type. The result of the conversion will be an atomic value of the required type. This method works where the target type is a built-in atomic type and also where it is a user-defined atomic type. It does not handle namespace-sensitive types (QName, NOTATION, and derivatives).

Parameters:

value - the value to be converted

targetType - the type to which the value is to be converted. This must not be a namespace-sensitive type.

checker - a NameChecker if validation is required, null if the caller already knows that the value is valid. Note that a non-null NameChecker acts as a signal that validation is required, even when the value to be checked is not a name.

Returns:

the value after conversion if successful; or a ValidationFailure if conversion failed. The caller must check for this condition. Validation may fail even if validation was not requested.

getStringLength

public int getStringLength()

Get the length of this string, as defined in XPath. This is not the same as the Java length, as a Unicode surrogate pair counts as a single character

Returns:

the length of the string in Unicode code points

getStringLength

public static int getStringLength(CharSequence s)

Get the length of a string, as defined in XPath. This is not the same as the Java length, as a Unicode surrogate pair counts as a single character.

Parameters:

s - The string whose length is required

Returns:

the length of the string in Unicode code points

isZeroLength

public boolean isZeroLength()

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

Returns:

true if the string is zero length

containsSurrogatePairs

public boolean containsSurrogatePairs()

Determine whether the string contains surrogate pairs

Returns:

true if the string contains any non-BMP characters

isKnownToContainNoSurrogates

public boolean isKnownToContainNoSurrogates()

Ask whether the string is known to contain no surrogate pairs.

Returns:

true if it is known to contain no surrogates, false if the answer is not known

iterateCharacters

public UnfailingIterator iterateCharacters()

Iterate over a string, returning a sequence of integers representing the Unicode code-point values

Returns:

an iterator over the characters (Unicode code points) in the string

expand

public int[] expand()

Expand a string containing surrogate pairs into an array of 32-bit characters

Returns:

an array of integers representing the Unicode code points

expand

public static int[] expand(CharSequence s)

Expand a string containing surrogate pairs into an array of 32-bit characters

Parameters:

s - the string to be expanded

Returns:

an array of integers representing the Unicode code points

contract

public static CharSequence contract(int[] codes,
                                    int used)

Contract an array of integers containing Unicode codepoints into a Java string

Parameters:

codes - an array of integers representing the Unicode code points

used - the number of items in the array that are actually used

Returns:

the constructed string

getXPathComparable

public Object getXPathComparable(boolean ordered,
                                 StringCollator collator,
                                 XPathContext context)

Get an object value that implements the XPath equality and ordering comparison semantics for this value. If the ordered parameter is set to true, the result will be a Comparable and will support a compareTo() method with the semantics of the XPath lt/gt operator, provided that the other operand is also obtained using the getXPathComparable() method. In all cases the result will support equals() and hashCode() methods that support the semantics of the XPath eq operator, again provided that the other operand is also obtained using the getXPathComparable() method. A context argument is supplied for use in cases where the comparison semantics are context-sensitive, for example where they depend on the implicit timezone or the default collation.

Specified by:

getXPathComparable in class AtomicValue

Parameters:

ordered - true if an ordered comparison is required. In this case the result is null if the type is unordered; in other cases the returned value will be a Comparable.

collator - Collation to be used for comparing strings

context - the XPath dynamic evaluation context, used in cases where the comparison is context sensitive

Returns:

an Object whose equals() and hashCode() methods implement the XPath comparison semantics with respect to this atomic value. If ordered is specified, the result will either be null if no ordering is defined, or will be a Comparable

equals

public boolean equals(Object other)

Determine if two AtomicValues are equal, according to XPath rules. (This method is not used for string comparisons, which are always under the control of a collation. If we get here, it's because there's a type error in the comparison.)

Specified by:

equals in class AtomicValue

Parameters:

other - the other value

Returns:

true if the other operand is an atomic value and the two values are equal as defined by the XPath eq operator

Throws:

ClassCastException - always

codepointEquals

public boolean codepointEquals(StringValue other)

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

Parameters:

other - the value to be compared with this value

Returns:

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

effectiveBooleanValue

public boolean effectiveBooleanValue()

Get the effective boolean value of a string

Overrides:

effectiveBooleanValue in class AtomicValue

Returns:

true if the string has length greater than zero

toString

public String toString()

Description copied from class: AtomicValue

Get string value. In general toString() for an atomic value displays the value as it would be written in XPath: that is, as a literal if available, or as a call on a constructor function otherwise.

Overrides:

toString in class AtomicValue

makeRestrictedString

public static ConversionResult makeRestrictedString(CharSequence value,
                                                    BuiltInAtomicType typeLabel,
                                                    NameChecker checker)

Factory method to create a string value belonging to a built-in type derived from string

Parameters:

value - the String value. Null is taken as equivalent to "".

typeLabel - the required type, must be a built in type derived from xs:string

checker - a NameChecker if validation is required, null if the caller already knows that the value is valid

Returns:

either the required StringValue if the value is valid, or a ValidationFailure encapsulating the error message if not.

validate

public static ValidationFailure validate(BuiltInAtomicType typeLabel,
                                         CharSequence val,
                                         NameChecker checker)

Validate that the string conforms to the rules for a built-in subtype of xs:string

Parameters:

typeLabel - the built-in atomic type against which the string should be validated

val - the string to be validated

checker - object that checks names against the XML 1.0 or XML 1.1 rules as appropriate

Returns:

null if the value is OK, otherwise a ValidationException containing details of the failure

getSchemaComparable

public Comparable getSchemaComparable()

Get a Comparable value that implements the XML Schema comparison semantics for this value. Returns null if the value is not comparable according to XML Schema rules. This implementation returns the underlying Java string, which works because strings will only be compared for equality, not for ordering, and the equality rules for strings in XML schema are the same as in Java.

Specified by:

getSchemaComparable in class AtomicValue

Returns:

a Comparable that follows XML Schema comparison rules

isIdentical

public boolean isIdentical(Value v)

Determine whether two atomic values are identical, as determined by XML Schema rules. This is a stronger test than equality (even schema-equality); for example two dateTime values are not identical unless they are in the same timezone.

Note that even this check ignores the type annotation of the value. The integer 3 and the short 3 are considered identical, even though they are not fully interchangeable. "Identical" means the same point in the value space, regardless of type annotation.

NaN is identical to itself.

Overrides:

isIdentical in class AtomicValue

Parameters:

v - the other value to be compared with this one

Returns:

true if the two values are identical, false otherwise.

diagnosticDisplay

public static String diagnosticDisplay(String s)

Produce a diagnostic representation of the contents of the string

Parameters:

s - the string

Returns:

a string in which non-Ascii-printable characters are replaced by \ uXXXX escapes