com.bea.content.expression
Class ExpressionHelper

java.lang.Object
  com.bea.content.expression.ExpressionHelper

public class ExpressionHelper
extends Object

Helper class to handle dealing with content Expressions.

For details on what content expressions should look like, see parse().

Nested Class Summary

static class

ExpressionHelper.ParseException Exception to report an error while parsing a query expression.

Field Summary

static String	AND Syntax textual and logical operator.
static String	CONTAINS Syntax textual contains operator.
static String	CONTAINS_ALL Syntax textual contains all operator.
static String	CONTAINS_ANY Syntax textual contains any operator.
static String	defDateFormatStr The default datetime format string in the content expression syntax ("MM/dd/yyyy HH:mm:ss z").
static String	EQUALS Syntax textual equals operator.
static String	GREATER_THAN Syntax textual greater than operator.
static String	GREATER_THAN_EQUALS Syntax textual greater than or equals operator.
static String	IN Syntax textual in operator.
static String	LESS_THAN Syntax textual less than operator.
static String	LESS_THAN_EQUALS Syntax textual less than or equals operator.
static String	LIKE Syntax textual like operator.
static String	LIKE_IGNORE_CASE Syntax textual like (case insensitive) operator.
static String	NOT_EQUALS Syntax textual not equals operator.
static String	OR Syntax textual or logical operator.

Constructor Summary

ExpressionHelper()

Method Summary

static Expression	convertContainsAnyOperators(Expression expr) Convert an expression tree to not contain any 'containsany' comparison operators.
static Expression	convertInOperators(Expression expr) Convert an expression tree to not contain any 'in' comparison operators.
static String	fromStringLiteral(String in) Convert a String literal (which may contain quoted characters) into a corresponding String value.
static String	getComparator(Expression expr) Get the syntax comparator textual operator for the given leaf node.
static String	getContentId(Expression expr) Return the content id from the expression, if it's an expression for a single content object based upon identifier.
static Search	getContentIdSearch(String contentId) Get a search object for a single content based upon the supplied id.
static Search	getContentPathSearch(ID uid, String version) Get a search object for a single version based upon the supplied UID and version.
static Search	getContentPathSearch(String contentPath) Get a search object for a single content based upon the supplied path.
static PropertyRef	getLeftHandSide(Expression expr) Get the left-hand-side of a valid leaf node, which should be a PropertyRef.
static String	getLogicalComparator(Expression expr) Get the syntax logical comparator textual operator for the given branch node.
static int	getOrdinalValue(char ch) Get the ordinal (Unicode) value of a character.
static Object	getRightHandSide(Expression expr) Get the right-hand-side of a valid leaf node.
static Expression	getSubExpression(Expression expr, int count) Get a child expression of the specified expression at the count index.
static boolean	isHexString(String str) Determine if a string contains only ASCII hexidecimal characters ([0-9a-fA-F]).
static Expression	isLogicalNot(Expression expr) Tell if an expression is really a logical not and, if so, returns the contained expression.
static boolean	isValidBranchNode(Expression expr) Tell if an expression is a valid content branch node type.
static boolean	isValidLeafNode(Expression expr) Tell if an expression is a valid content leaf node type.
static LogicalAnd	join(Expression expr1, Expression expr2) Join together two expression via an AND expression.
static Expression	normalize(Expression expr) Normalize an Expression.
static Expression	parse(String queryStr) Convert a query expression string into an Expression object.
static void	print(PrintWriter out, Expression expr) Print a string representation of the given expression.
static void	printBranchNode(PrintWriter out, Expression expr) Return a string representation of the given expression branch.
static void	printLeafNode(PrintWriter out, Expression expr) Return a string representation of the given leaf expression node.
static Expression	realize(Expression expr, PropertyProvider props) Realize an expression, which can contain property references, into an an expression which contains only literal values and can be sent to a ISearchManager.
static String	retrievePathFromVersionPath(String path)
static String	retrieveVersionFromVersionPath(String path)
static String	toString(Expression expr) Get a string representation of the given expression.
static String	toStringLiteral(String in) Get an ASCII String literal from a Java string.

Methods inherited from class java.lang.Object

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

Field Detail

defDateFormatStr

public static final String defDateFormatStr

The default datetime format string in the content expression syntax ("MM/dd/yyyy HH:mm:ss z").

See Also

Constants Summary

EQUALS

public static final String EQUALS

Syntax textual equals operator.

See Also

Constants Summary

NOT_EQUALS

public static final String NOT_EQUALS

Syntax textual not equals operator.

See Also

Constants Summary

GREATER_THAN

public static final String GREATER_THAN

Syntax textual greater than operator.

See Also

Constants Summary

LESS_THAN

public static final String LESS_THAN

Syntax textual less than operator.

See Also

Constants Summary

GREATER_THAN_EQUALS

public static final String GREATER_THAN_EQUALS

Syntax textual greater than or equals operator.

See Also

Constants Summary

LESS_THAN_EQUALS

public static final String LESS_THAN_EQUALS

Syntax textual less than or equals operator.

See Also

Constants Summary

LIKE

public static final String LIKE

Syntax textual like operator.

See Also

Constants Summary

LIKE_IGNORE_CASE

public static final String LIKE_IGNORE_CASE

Syntax textual like (case insensitive) operator.

See Also

Constants Summary

CONTAINS

public static final String CONTAINS

Syntax textual contains operator.

See Also

Constants Summary

CONTAINS_ALL

public static final String CONTAINS_ALL

Syntax textual contains all operator.

See Also

Constants Summary

CONTAINS_ANY

public static final String CONTAINS_ANY

Syntax textual contains any operator.

See Also

Constants Summary

IN

public static final String IN

Syntax textual in operator.

See Also

Constants Summary

AND

public static final String AND

Syntax textual and logical operator.

See Also

Constants Summary

OR

public static final String OR

Syntax textual or logical operator.

See Also

Constants Summary

Constructor Detail

ExpressionHelper

public ExpressionHelper()

Method Detail

parse

public static Expression parse(String queryStr)
                        throws ExpressionHelper.ParseException,
                               IllegalArgumentException

Convert a query expression string into an Expression object.

The string should follow the query syntax specified in the Personalization Server documentation. The expression syntax is tree-based, with each leaf in the tree beinging of the form "property comparator value" (e.g. "cm_BinarySize <= 1234").

Property (LHS)

This specifies the object property to match against. To specify a property name which contains non-identifier characters (e.g. whitespace, double quotes, dashes), you can use the "toProperty('property name')" form in the left-hand-side. To specify property set names as part of the property name, either use the "properyset.name" form or the "toProperty('propertyset', 'property')" form in the left-hand-side.

Comparators

The valid comparision operators are = (or ==), !=, <, >, <=, >=, "like", "likeignorecase", "contains", "containsall" "containsany", and "in".
The "like" and "likeignorecase" operators expect the pattern (which is the value of the leaf) to use * (match all) and ? (match any); "like" and "likeignorecase" also are only expected to work against String values, although they might work with other datatypes depending upon the search implementation. "like" does case sensitive matching; "likeignorecase" does case insensitive matching.
The "in" operator expects the value to be a list. Otherwise, it's equivalent to =.
The "contains" operator is only expected to work against multi-valued properties, although it might work with other datatypes depending upon the search implementation.
The "containsall" and "containsany" operators are only expected to work against multi-valued properties, although they might work with other datatypes depending upon the search implementation. They expect the value to be a list. Otherwise, they're equivalent to "contains".

Value (RHS)

• String literal values are enclosed in single quotes (back-slash is the quoting character, unicode characters not supported). Additionally, unicode (e.g. "\u6565"), octal (e.g. "\7", "\65", "\377"), and standard Java escape sequences (e.g. "\n", "\r", "\b") are allowed in the string literals.
• Boolean literals are either the "true" or "false" keyword (without quotes).
• Number literals are Java form (scientific notation is supported).
• Time literals are presented in "toDate(['formatStr'], 'dateStr')" format. formatStr must be a valid SimpleDateFormat format string; if omitted, 'MM/dd/yyyy HH:mm:ss z' is used. Also, the "now" keyword specifies the time at which the expression was created.
• Lists are a comma-separated list of the other value types inside parenthesis. Lists are 1-dimensional; they cannot contain other lists. Lists are only valid values with:
  • =, !=, "containsany" or "containsall" against multi-valued property
  • "in" against single-valued property
• References to user, request, or session properties are represented as such:

  
   <type>Property(<propertyset>, <propertyname>)
   
   where <type> is one of 'user', 'request',
   or 'session', <propertyset> is the property set name
   and follows the rules for string literals.
   <propertyname> is the property name and follows the
   rules for string literals.
  
   References to properties should not be passed into the
   ISearchManager class.  Expressions which
   contain references to properties should be realized into a
   searchable expression via the realize() method.
   

Each branch in the tree is comprised of 1 or more leafs or branches separated by either "&&" (boolean AND) or "||" (boolean OR). They can be enclosed in parenthesis for clearity and ordering (AND has precendance over OR). Additionally, "!" marks a branch as using negative logic (boolean NOT). The "!" operator can only be used preceding an open parenthesis.

Examples of valid expression strings:

• identifier == '00099abv48932ds'
• keys == ('00099abv48932ds', -1, 2.0, true, now, null)
• language == userProperty('MyProperties', 'userPreferredLang')
• ((UserAge <= 35 && colors contains 'red') || (UserAge > 35 && !(colors contains 'black')) && mimeType == 'text/html'
• toProperty('MyApp', 'Launch Date') < now && !(MyApp.expireDate > toDate('HH:mm:ss MM-dd-yyyy', '12:12:12 12/12/2002'))

In the resulting expression tree, the following caveats apply for it to be valid for the ISearchManager:

• Each branch node can only be a LogicalAnd, LogicalOr, LogicalMulitAnd, or LogicalMultiOr. Any other branch node type is invalid.
• Each leaf node can only be an Equals, GreaterOrEquals, GreaterThan, LessOrEquals, LessThan, NotEquals, StringLike, ContainedIn, CollectionContains, CollectionContainsAll, or CollectionContainsAny. Any other branch node type is invalid.
• Any valid branch or leaf node may be contained in a LogicalNot node.
• In each leaf node, the left-hand-side will always be a PropertyRef node, which must contain Strings for getPropertySet() and getPropertyName(). In non-realized expression, a leaf node can be a UserPropertyRef, RequestPropertyRef, or SessionPropertyRef to represent a reference to an external property. Repositories should not receive non-realized expression, and, therefore, should not handle these objects; they are free to raise an exception if one is found.
• The right-hand-side of Equals, NotEquals, GreaterOrEquals, GreaterThan, LessOrEquals, LessThan, or CollectionContains leaf nodes can be a Collection, Long, Double, String, or Timestamp.
• The right-hand-side of StringLike leaf nodes can be a String. Anything else is invalid (i.e. should not match). The isCaseInsensitiveMatch() flag of the StringLike will be set depending upon whether it should do case sensitive (false, i.e. like) or case insensitive (true, i.e. likeignorecase) matching.
• The right-hand-side of CollectionContainsAll, CollectionContainsAny, or ContainedIn leaf nodes can be a Collection. Anything else is invalid (i.e. should not match).

Parameters

queryStr - the query expression string

Returns

an Expression object representing (null if queryStr is a null expression).

Throws

ExpressionHelper.ParseException - thrown on a an invalid expression query or a parser error.

IllegalArgumentException - thrown on a general error.

See Also

normalize(com.bea.p13n.expression.Expression)

join

public static LogicalAnd join(Expression expr1,
                              Expression expr2)

Join together two expression via an AND expression.

Parameters

expr1 - the first expression.

expr2 - the second expression.

Returns

a LogicalAnd of the two expressions.

getContentIdSearch

public static Search getContentIdSearch(String contentId)

Get a search object for a single content based upon the supplied id.

getContentPathSearch

public static Search getContentPathSearch(String contentPath)

Get a search object for a single content based upon the supplied path.

getContentPathSearch

public static Search getContentPathSearch(ID uid,
                                          String version)

Get a search object for a single version based upon the supplied UID and version.

getContentId

public static String getContentId(Expression expr)

Return the content id from the expression, if it's an expression for a single content object based upon identifier.

Returns

the content id, or null if it's not a identifier equality expression.

normalize

public static Expression normalize(Expression expr)
                            throws IllegalArgumentException

Normalize an Expression.

This will recursively remove branches that contain only one Expression (which are boolean equivelant to the one child expression) or that contain no children (which are considered empty).

Parameters

expr - the incoming expression.

Returns

the normalized expression, null if normalized to nothing.

Throws

IllegalArgumentException - thrown if the expression is not a valid content expression.

convertInOperators

public static Expression convertInOperators(Expression expr)
                                     throws IllegalArgumentException

Convert an expression tree to not contain any 'in' comparison operators.

This will change all ContainedIn leafs into a MultiOr branch of Equals leafs for each element of the ContainedIn right-hand-side list. Or, in syntax terms, "prop in (1, 2, 3)" will become "(prop == 1 || prop == 2 || prop == 3)".

Parameters

expr - the incoming expression.

Returns

the updated expression, which might not be the same as what's passed in depending upon the structure (can be null if it normalizes down to "prop in null" or "prop in ()").

Throws

IllegalArgumentException - if the expression structure isn't valid.

convertContainsAnyOperators

public static Expression convertContainsAnyOperators(Expression expr)
                                              throws IllegalArgumentException

Convert an expression tree to not contain any 'containsany' comparison operators.

This will change all CollectionContainsAny leafs into a MultiOr branch of CollectionContains leafs for each element of the CollectionContainsAny right-hand-side list. Or, in syntax terms, "prop containsany (1, 2, 3)" will become "(prop contains 1 || prop contains== 2 || prop contains 3)".

Parameters

expr - the incoming expression.

Returns

the updated expression, which might not be the same as what's passed in depending upon the structure (can be null if it normalizes down to "prop containsany null" or "prop containsany ()").

Throws

IllegalArgumentException - if the expression structure isn't valid.

realize

public static Expression realize(Expression expr,
                                 PropertyProvider props)
                          throws IllegalArgumentException

Realize an expression, which can contain property references, into an an expression which contains only literal values and can be sent to a ISearchManager. Or, in syntax terms, if the user's "prop" property in the 'propset' Property Set is 'red', "prop == userProperty('propset', 'prop')" will become "prop == 'red'".

This will modify the passed in expression.

Parameters

expr - the expression to realize.

props - the object which provides values for property references.

Returns

the modified expression

Throws

IllegalArgumentException - thrown if the expr is not a valid content expression or contain a reference to an unknown property type.

isLogicalNot

public static Expression isLogicalNot(Expression expr)

Tell if an expression is really a logical not and, if so, returns the contained expression.

Parameters

expr - the expression.

Returns

the contained expressions if expr is a logical not, null otherwise.

isValidLeafNode

public static boolean isValidLeafNode(Expression expr)

Tell if an expression is a valid content leaf node type.

isValidBranchNode

public static boolean isValidBranchNode(Expression expr)

Tell if an expression is a valid content branch node type.

toString

public static String toString(Expression expr)
                       throws IllegalArgumentException

Get a string representation of the given expression.

Pretty much, a string generated from this method can be parse()'ed into the semantically equivalent (not neccessarily identical) expression tree.

Parameters

expr - the expression.

Returns

the query syntax representation of the expression.

Throws

IllegalArgumentException - thrown if the given expression is not a valid content expression.

print

public static void print(PrintWriter out,
                         Expression expr)
                  throws IllegalArgumentException

Print a string representation of the given expression.

Pretty much, a string generated from this method can be parse()'ed into the semantically equivalent (not neccessarily identical) expression tree.

Parameters

out - the output writer.

expr - the expression.

Throws

IllegalArgumentException - thrown if the given expression is not a valid content expression.

printLeafNode

public static void printLeafNode(PrintWriter out,
                                 Expression expr)
                          throws IllegalArgumentException

Return a string representation of the given leaf expression node.

Parameters

out - the output writer.

expr - the expression.

Throws

IllegalArgumentException - thrown if the given expression is not a valid leaf expression.

getLeftHandSide

public static PropertyRef getLeftHandSide(Expression expr)
                                   throws IllegalArgumentException

Get the left-hand-side of a valid leaf node, which should be a PropertyRef.

Parameters

expr - the leaf node expression.

Returns

the left-hand-side content property ref

Throws

IllegalArgumentException - if the the left-hand-side is null or not a PropertyRef.

getComparator

public static String getComparator(Expression expr)
                            throws IllegalArgumentException

Get the syntax comparator textual operator for the given leaf node.

Parameters

expr - the leaf node expression.

Returns

the syntax operator constant, one of EQUALS, NOT_EQUALS, GREATER_THAN, GREATER_THAN_EQUALS, LESS_THAN, LESS_THAN_EQUALS, LIKE, LIKE_IGNORE_CASE, IN, CONTAINS, CONTAINS_ALL, or CONTAINS_ANY or null if the expression is null.

Throws

IllegalArgumentException - if the expression is not a valid leaf node.

getRightHandSide

public static Object getRightHandSide(Expression expr)
                               throws IllegalArgumentException

Get the right-hand-side of a valid leaf node.

Parameters

expr - the leaf node expression.

Returns

the right-hand-side value, which should be an Object value, null, a RequestPropertyRef, a SessionPropertyRef, or a UserPropertyRef.

Throws

IllegalArgumentException - if the expression is not a valid leaf node.

printBranchNode

public static void printBranchNode(PrintWriter out,
                                   Expression expr)

Return a string representation of the given expression branch.

Parameters

out - the output writer.

expr - the expression.

Throws

IllegalArgumentException - thrown if the given expression is not a valid branch node expression or one it's children is invalid.

getLogicalComparator

public static String getLogicalComparator(Expression expr)
                                   throws IllegalArgumentException

Get the syntax logical comparator textual operator for the given branch node.

Parameters

expr - the expression.

Returns

the boolean logic syntax operator constant, either AND or OR, or null if the expression is null.

Throws

IllegalArgumentException - thrown if the given expression is not a valid branch node expression.

getSubExpression

public static Expression getSubExpression(Expression expr,
                                          int count)
                                   throws IllegalArgumentException

Get a child expression of the specified expression at the count index.

Parameters

expr - the parent expression.

count - the index.

Returns

the child expression or null if no such child.

Throws

IllegalArgumentException - if the child is not an Expression.

fromStringLiteral

public static String fromStringLiteral(String in)

Convert a String literal (which may contain quoted characters) into a corresponding String value.

This supports the standard Java Language Specification escape sequences.

In addition, this also supports escaping of wildcard characters '*' & '?' used by the expression helper

Parameters

in - the input string literal.

Returns

the string value.

isHexString

public static boolean isHexString(String str)

Determine if a string contains only ASCII hexidecimal characters ([0-9a-fA-F]).

Parameters

str - the input string.

Returns

true if the string contains only ASCII hex characters.

toStringLiteral

public static String toStringLiteral(String in)

Get an ASCII String literal from a Java string.

This will quote some special characters with back-slashes.

The output of this can be sent through fromStringLiteral(java.lang.String) to result in the original String.

getOrdinalValue

public static int getOrdinalValue(char ch)

Get the ordinal (Unicode) value of a character.

retrieveVersionFromVersionPath

public static String retrieveVersionFromVersionPath(String path)

retrievePathFromVersionPath

public static String retrievePathFromVersionPath(String path)