Package scriptella.expression

Class PropertiesSubstitutor

java.lang.Object

scriptella.expression.PropertiesSubstitutor

public class PropertiesSubstitutor
extends Object

Substitutes properties(or expressions) in strings.

$ symbol indicate property or expression to evaluate and substitute.

The following properties/expression syntax is used:

Property reference

References named property.
Examples:

 $foo
 

Expression

. Expression is wrapped by braces and evaluated by Expression engine. Examples:

 ${name+' '+surname} etc.
 

This class is not thread safe

Version:

1.0

Author:

Fyodor Kupolov

Field Summary

Fields

Modifier and Type	Field	Description
static final Pattern	EXPR_PTR	Expression pattern, e.g.
static final Pattern	PROP_PTR	Simple property patterns, e.g.

Constructor Summary

Constructors

Constructor	Description
PropertiesSubstitutor()	Creates a properties substitutor.
PropertiesSubstitutor(Map<String,?> map)	Creates a properties substitutor based on specified properties map.
PropertiesSubstitutor(ParametersCallback parameters)	Creates a properties substitutor.

Method Summary

Modifier and Type	Method	Description
String	getNullString()	Returns string literal representing null value.
ParametersCallback	getParameters()
static boolean	hasProperties(String string)	Tests if the given string contains properties/expressions.
void	setNullString(String nullString)	Sets string literal representing null.
void	setParameters(ParametersCallback parameters)	Sets parameters callback used for substitution.
String	substitute(Reader reader)	Reads content from reader and expands properties.
void	substitute(Reader reader, Writer writer)	Copies content from reader to writer and expands properties.
String	substitute(String s)	Substitutes properties/expressions in s and returns the result string.
protected String	toString(Object o)	Converts specified object to string.

Methods inherited from class java.lang.Object

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

Field Details

PROP_PTR

public static final Pattern PROP_PTR

Simple property patterns, e.g. $property

EXPR_PTR

public static final Pattern EXPR_PTR

Expression pattern, e.g. ${property} etc.

Constructor Details

PropertiesSubstitutor

public PropertiesSubstitutor()

Creates a properties substitutor.

This constructor is used for performance critical places where multiple instantiation via PropertiesSubstitutor(scriptella.spi.ParametersCallback) is expensive.

Note: setParameters(scriptella.spi.ParametersCallback) must be called before substitute(String).

PropertiesSubstitutor

public PropertiesSubstitutor(ParametersCallback parameters)

Creates a properties substitutor.

Parameters:

parameters - parameters callback to use for substitution.

PropertiesSubstitutor

public PropertiesSubstitutor(Map<String,?> map)

Creates a properties substitutor based on specified properties map.

Parameters:

map - parameters to substitute.

Method Details

substitute

public String substitute(String s)

Substitutes properties/expressions in s and returns the result string.

If result of evaluation is null or the property being substitued doesn't have value in callback - the whole expressions is copied into result string as is.

Parameters:

s - string to substitute. Null strings allowed.

Returns:

substituted string.

substitute

public void substitute(Reader reader,
 Writer writer)
                throws IOException

Copies content from reader to writer and expands properties.

Parameters:

reader - reader to process.

writer - writer to output substituted content to.

Throws:

IOException - if I/O error occurs.

substitute

public String substitute(Reader reader)
                  throws IOException

Reads content from reader and expands properties.

Note: For performance reasons use substitute(java.io.Reader,java.io.Writer) if possible.

Parameters:

reader - reader to process.

Returns:

reader's content with properties expanded.

Throws:

IOException - if I/O error occurs.

See Also:

• substitute(java.io.Reader,java.io.Writer)

getParameters

public ParametersCallback getParameters()

Returns:

parameter callback used for substitution.

setParameters

public void setParameters(ParametersCallback parameters)

Sets parameters callback used for substitution.

Parameters:

parameters - not null parameters callback.

getNullString

public String getNullString()

Returns string literal representing null value.

Used when converting objects toString(Object).

Returns:

string representing null value.

setNullString

public void setNullString(String nullString)

Sets string literal representing null.

Used when converting objects toString(Object).

Parameters:

nullString - string literal representing null

toString

protected String toString(Object o)

Converts specified object to string.

getNullString() represents null values.

Subclasses may provide custom conversion strategy here.

Parameters:

o - object to convert to String.

Returns:

string representation of object.

hasProperties

public static boolean hasProperties(String string)

Tests if the given string contains properties/expressions.

Parameters:

string - string to check.

Returns:

true if a given string contains properties/expressions.