com.tibbo.aggregate.common.expression

Class ParsedExpressionCache

java.lang.Object

com.tibbo.aggregate.common.expression.ParsedExpressionCache

public class ParsedExpressionCache
extends java.lang.Object

A wrapper around Guava's LoadingCache that stores parsed versions of AggreGate expressions, i.e. instances of abstract syntax trees. The caching is based on the fact that for every expression text there is only one parsed abstract syntax tree, so the text can be used as a key of the cache and the root of the tree can be a value.

Since:

AGG-16346

See Also:

Guava Caches Explained

Constructor Summary

Constructors

Constructor and Description
ParsedExpressionCache()

Method Summary

Modifier and Type	Method and Description
static ASTStart	getCachedAstRoot(java.lang.String expressionText) Tries to find corresponding parsed tree in the underlying cache and, if not found, transparently parses the expression, enters the tree into the cache and returns the tree as it was stored in the cache before.

Methods inherited from class java.lang.Object

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

Constructor Detail

ParsedExpressionCache

public ParsedExpressionCache()

Method Detail

getCachedAstRoot

public static ASTStart getCachedAstRoot(java.lang.String expressionText)
                                 throws SyntaxErrorException

Tries to find corresponding parsed tree in the underlying cache and, if not found, transparently parses the expression, enters the tree into the cache and returns the tree as it was stored in the cache before.

Parameters:

expressionText - the text of the expression to find corresponding AST for

Returns:

the root of the parsed tree, either cached previously or freshly built

Throws:

SyntaxErrorException - if the expression cannot be parsed due to a syntax error