org.datanucleus.query.compiler

Class Lexer

java.lang.Object

org.datanucleus.query.compiler.Lexer

public class Lexer
extends Object

Lexer for a Query. Allows a class to work its way through the parsed string, obtaining relevant components with each call, or peeking ahead before deciding what component to parse next. Would work with JDOQL or JPQL. The only difference is the input of parameter prefixes. With JDOQL all parameters are prefixed ":", whereas in JPQL you can have numbered parameters "?" and named parameters ":".

Field Summary

Fields

Modifier and Type	Field and Description
protected CharacterIterator	ci

Constructor Summary

Constructors

Constructor and Description
Lexer(String input, String paramPrefixes, boolean parseEscapedChars) Constructor

Method Summary

Modifier and Type	Method and Description
int	getIndex() Accessor for the current index in the input string.
String	getInput() Accessor for the input string.
boolean	nextIsDot() Utility to return if the next character is a dot.
boolean	nextIsSingleQuote() Utility to return if the next non-whitespace character is a single quote.
Boolean	parseBooleanLiteral() Parse a boolean from the current position.
Boolean	parseBooleanLiteralIgnoreCase() Parse a boolean from the current position (case insensitive).
String	parseCast() Parse a cast in the query from the current position, returning the name of the class that is being cast to.
boolean	parseChar(char c) Check if char c is found
boolean	parseChar(char c, char unlessFollowedBy) Check if char c is found
Character	parseCharacterLiteral() Parse a Character literal
boolean	parseEOS() Check if END OF TEXT is reached.
BigDecimal	parseFloatingPointLiteral() Parse a floating point number from the current position.
String	parseIdentifier() Parse a java identifier from the current position.
BigInteger	parseIntegerLiteral() Parse an integer number from the current position.
String	parseMethod() Checks if a java Method is found
String	parseName() Parses the text string (up to the next space) and returns it.
boolean	parseNullLiteral() Checks if null literal is parsed
boolean	parseNullLiteralIgnoreCase() Checks if null literal is parsed (case insensitive).
boolean	parseString(String s) Check if String s is found
boolean	parseStringIgnoreCase(String s) Check if String s is found ignoring the case
String	parseStringLiteral() Parse a String literal
boolean	peekString(String s) Check if String "s" is found and not moving the cursor position.
boolean	peekStringIgnoreCase(String s) Check if String "s" is found ignoring the case, and not moving the cursor position.
String	remaining() Method to return the remaining part of the string not yet processed.
int	skipWS() Skip over any whitespace from the current position.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

ci

protected final CharacterIterator ci

Constructor Detail

Lexer

public Lexer(String input,
             String paramPrefixes,
             boolean parseEscapedChars)

Constructor

Parameters:

input - The input string

paramPrefixes - String containing all possible prefixes for parameters

parseEscapedChars - Whether to prase escaped characters

Method Detail

getInput

public String getInput()

Accessor for the input string.

Returns:

The input string.

getIndex

public int getIndex()

Accessor for the current index in the input string.

Returns:

The current index.

skipWS

public int skipWS()

Skip over any whitespace from the current position.

Returns:

The new position

parseEOS

public boolean parseEOS()

Check if END OF TEXT is reached.

Returns:

true if END OF TEXT is reached

parseChar

public boolean parseChar(char c)

Check if char c is found

Parameters:

c - the Character to find

Returns:

true if c is found

parseChar

public boolean parseChar(char c,
                         char unlessFollowedBy)

Check if char c is found

Parameters:

c - the Character to find

unlessFollowedBy - the character to validate it does not follow c

Returns:

true if c is found and not followed by unlessFollowedBy

parseString

public boolean parseString(String s)

Check if String s is found

Parameters:

s - the String to find

Returns:

true if s is found

parseStringIgnoreCase

public boolean parseStringIgnoreCase(String s)

Check if String s is found ignoring the case

Parameters:

s - the String to find

Returns:

true if s is found

peekString

public boolean peekString(String s)

Check if String "s" is found and not moving the cursor position.

Parameters:

s - the String to find

Returns:

true if string is found

peekStringIgnoreCase

public boolean peekStringIgnoreCase(String s)

Check if String "s" is found ignoring the case, and not moving the cursor position.

Parameters:

s - the String to find

Returns:

true if string is found

parseIdentifier

public String parseIdentifier()

Parse a java identifier from the current position.

Returns:

The identifier

parseMethod

public String parseMethod()

Checks if a java Method is found

Returns:

true if a Method is found

parseName

public String parseName()

Parses the text string (up to the next space) and returns it. The name includes '.' characters. This can be used, for example, when parsing a class name wanting to read in the full name (including package) so that it can then be checked for existence in the CLASSPATH.

Returns:

The name

parseCast

public String parseCast()

Parse a cast in the query from the current position, returning the name of the class that is being cast to. Returns null if the current position doesn't have a cast. Does no checking as to whether the name is a valid class name, just whether there is "({name})" from the current position.

Returns:

The name of the class to cast to

parseIntegerLiteral

public BigInteger parseIntegerLiteral()

Parse an integer number from the current position.

Returns:

The integer number parsed (null if not valid).

parseFloatingPointLiteral

public BigDecimal parseFloatingPointLiteral()

Parse a floating point number from the current position.

Returns:

The floating point number parsed (null if not valid).

parseBooleanLiteral

public Boolean parseBooleanLiteral()

Parse a boolean from the current position.

Returns:

The boolean parsed (null if not valid).

parseBooleanLiteralIgnoreCase

public Boolean parseBooleanLiteralIgnoreCase()

Parse a boolean from the current position (case insensitive).

Returns:

The boolean parsed (null if not valid).

nextIsSingleQuote

public boolean nextIsSingleQuote()

Utility to return if the next non-whitespace character is a single quote.

Returns:

Whether it is a single quote at the current point (ignoring whitespace)

nextIsDot

public boolean nextIsDot()

Utility to return if the next character is a dot.

Returns:

Whether it is a dot at the current point

parseCharacterLiteral

public Character parseCharacterLiteral()

Parse a Character literal

Returns:

the Character parsed. null if single quotes is found

Throws:

NucleusUserException - if an invalid character is found or the CharacterIterator is finished

parseStringLiteral

public String parseStringLiteral()

Parse a String literal

Returns:

the String parsed. null if single quotes or double quotes is found

Throws:

NucleusUserException - if an invalid character is found or the CharacterIterator is finished

parseNullLiteral

public boolean parseNullLiteral()

Checks if null literal is parsed

Returns:

true if null literal is found

parseNullLiteralIgnoreCase

public boolean parseNullLiteralIgnoreCase()

Checks if null literal is parsed (case insensitive).

Returns:

true if null literal is found

remaining

public String remaining()

Method to return the remaining part of the string not yet processed. Doesn't move the current position.

Returns:

The remaining part of the string

toString

public String toString()

Overrides:

toString in class Object