org.apache.phoenix.expression

Class LikeExpression

java.lang.Object

org.apache.phoenix.expression.BaseExpression

org.apache.phoenix.expression.BaseCompoundExpression

org.apache.phoenix.expression.LikeExpression

All Implemented Interfaces:

org.apache.hadoop.io.Writable, Expression, PDatum

Direct Known Subclasses:

ByteBasedLikeExpression, StringBasedLikeExpression

public abstract class LikeExpression
extends BaseCompoundExpression

Implementation for LIKE operation where the first child expression is the string and the second is the pattern. The pattern supports '_' character for single character wildcard match and '%' for zero or more character match. where these characters may be escaped by preceding them with a '\'. Example: foo LIKE 'ab%' will match a row in which foo starts with 'ab'

Since:

0.1

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.phoenix.expression.BaseExpression

BaseExpression.ExpressionComparabilityWrapper

Field Summary

Fields inherited from class org.apache.phoenix.expression.BaseCompoundExpression

children

Constructor Summary

Constructors

Constructor and Description
LikeExpression()
LikeExpression(List<Expression> children)

Method Summary

Modifier and Type	Method and Description
<T> T	accept(ExpressionVisitor<T> visitor) Means of traversing expression tree through visitor.
protected static List<Expression>	addLikeTypeChild(List<Expression> children, LikeParseNode.LikeType likeType)
abstract LikeExpression	clone(List<Expression> children)
protected AbstractBasePattern	compilePattern(String value)
protected abstract AbstractBasePattern	compilePatternSpec(String value)
boolean	endsWithOnlyWildcard()
boolean	evaluate(Tuple tuple, ImmutableBytesWritable ptr) Access the value by setting a pointer to it (as opposed to making a copy of it which can be expensive)
PDataType	getDataType()
LikeParseNode.LikeType	getLikeType()
String	getLiteralPrefix()
static String	getStartsWithPrefix(String s)
static boolean	hasWildcards(String s)
static int	indexOfWildcard(String s)
void	readFields(DataInput input)
boolean	startsWithWildcard()
String	toString()
static String	unescapeLike(String s)
static String	wildCardToLike(String s) Replace unescaped '*' and '?' in s with '%' and '_' respectively such that the returned string may be used in a LIKE expression.
void	write(DataOutput output)

Methods inherited from class org.apache.phoenix.expression.BaseCompoundExpression

equals, getChildren, getDeterminism, hashCode, isNullable, isStateless, requiresFinalEvaluation, reset

Methods inherited from class org.apache.phoenix.expression.BaseExpression

acceptChildren, coerce, coerce, getMaxLength, getScale, getSortOrder

Methods inherited from class java.lang.Object

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

Constructor Detail

LikeExpression

public LikeExpression()

LikeExpression

public LikeExpression(List<Expression> children)

Method Detail

unescapeLike

public static String unescapeLike(String s)

getStartsWithPrefix

public static String getStartsWithPrefix(String s)

Returns:

the substring of s for which we have a literal string that we can potentially use to set the start/end key, or null if there is none.

hasWildcards

public static boolean hasWildcards(String s)

wildCardToLike

public static String wildCardToLike(String s)

Replace unescaped '*' and '?' in s with '%' and '_' respectively such that the returned string may be used in a LIKE expression. Provides an alternate way of expressing a LIKE pattern which is more friendly for wildcard matching when the source string is likely to contain an '%' or '_' character.

Parameters:

s - wildcard pattern that may use '*' for multi character match and '?' for single character match, escaped by the backslash character

Returns:

replaced

indexOfWildcard

public static int indexOfWildcard(String s)

addLikeTypeChild

protected static List<Expression> addLikeTypeChild(List<Expression> children,
                                                   LikeParseNode.LikeType likeType)

getLikeType

public LikeParseNode.LikeType getLikeType()

startsWithWildcard

public boolean startsWithWildcard()

compilePatternSpec

protected abstract AbstractBasePattern compilePatternSpec(String value)

compilePattern

protected AbstractBasePattern compilePattern(String value)

evaluate

public boolean evaluate(Tuple tuple,
                        ImmutableBytesWritable ptr)

Description copied from interface: Expression

Access the value by setting a pointer to it (as opposed to making a copy of it which can be expensive)

Parameters:

tuple - Single row result during scan iteration

ptr - Pointer to byte value being accessed

Returns:

true if the expression could be evaluated (i.e. ptr was set) and false otherwise

readFields

public void readFields(DataInput input)
                throws IOException

Specified by:

readFields in interface org.apache.hadoop.io.Writable

Overrides:

readFields in class BaseCompoundExpression

Throws:

IOException

write

public void write(DataOutput output)
           throws IOException

Specified by:

write in interface org.apache.hadoop.io.Writable

Overrides:

write in class BaseCompoundExpression

Throws:

IOException

getDataType

public PDataType getDataType()

Returns:

data type of the column

accept

public final <T> T accept(ExpressionVisitor<T> visitor)

Description copied from interface: Expression

Means of traversing expression tree through visitor.

getLiteralPrefix

public String getLiteralPrefix()

endsWithOnlyWildcard

public boolean endsWithOnlyWildcard()

toString

public String toString()

Overrides:

toString in class BaseCompoundExpression

clone

public abstract LikeExpression clone(List<Expression> children)