org.apache.camel.language.simple
Class BaseSimpleParser

java.lang.Object
  org.apache.camel.language.simple.BaseSimpleParser

Direct Known Subclasses:

SimpleExpressionParser, SimplePredicateParser

public abstract class BaseSimpleParser
extends Object

Base class for Simple language parser.

This parser is based on the principles of a recursive descent parser.

Field Summary

protected boolean	allowEscape
protected String	expression
protected int	index
protected List<SimpleNode>	nodes
protected int	previousIndex
protected SimpleToken	token
protected List<SimpleToken>	tokens

Constructor Summary

protected

BaseSimpleParser(String expression, boolean allowEscape)

Method Summary

protected boolean	accept(TokenType accept) Accept the given token.
protected void	clear() Clears the parser state, which means it can be used for parsing a new input.
protected void	expect(TokenType expect) Expect a given token
protected void	expectAndAcceptMore(TokenType expect) Expect and accept a given number of tokens in sequence.
protected void	nextToken() Advances the parser position to the next known SimpleToken in the input.
protected void	nextToken(TokenType... filter) Advances the parser position to the next known SimpleToken in the input.
protected void	prepareBlocks() Prepares blocks, such as functions, single or double quoted texts.
protected void	prepareUnaryExpressions() Prepares unary expressions.

Methods inherited from class java.lang.Object

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

Field Detail

expression

protected final String expression

tokens

protected final List<SimpleToken> tokens

nodes

protected final List<SimpleNode> nodes

token

protected SimpleToken token

previousIndex

protected int previousIndex

index

protected int index

allowEscape

protected boolean allowEscape

Constructor Detail

BaseSimpleParser

protected BaseSimpleParser(String expression,
                           boolean allowEscape)

Method Detail

nextToken

protected void nextToken()

Advances the parser position to the next known SimpleToken in the input.

nextToken

protected void nextToken(TokenType... filter)

Advances the parser position to the next known SimpleToken in the input.

Parameters:

filter - filter for accepted token types

clear

protected void clear()

Clears the parser state, which means it can be used for parsing a new input.

prepareBlocks

protected void prepareBlocks()

Prepares blocks, such as functions, single or double quoted texts.

This process prepares the Blocks in the AST. This is done by linking child nodes which are within the start and end of the blocks, as child to the given block. This is done to have the AST graph updated and prepared properly.

So when the AST node is later used to create the Predicates or Expressions to be used by Camel then the AST graph has a linked and prepared graph of nodes which represent the input expression.

prepareUnaryExpressions

protected void prepareUnaryExpressions()

Prepares unary expressions.

This process prepares the unary expressions in the AST. This is done by linking the unary operator with the left hand side node, to have the AST graph updated and prepared properly.

So when the AST node is later used to create the Predicates or Expressions to be used by Camel then the AST graph has a linked and prepared graph of nodes which represent the input expression.

accept

protected boolean accept(TokenType accept)

Accept the given token.

This is to be used by the grammar to accept tokens and then continue parsing using the grammar, such as a function grammar.

Parameters:

accept - the token

Returns:

true if accepted, false otherwise.

expect

protected void expect(TokenType expect)
               throws SimpleParserException

Expect a given token

Parameters:

expect - the token to expect

Throws:

SimpleParserException - is thrown if the token is not as expected

expectAndAcceptMore

protected void expectAndAcceptMore(TokenType expect)

Expect and accept a given number of tokens in sequence.

This is used to accept whitespace or string literals.

Parameters:

expect - the token to accept