org.jpox.store.rdbms.query
Class JDOQLQueryCompiler

java.lang.Object
  org.jpox.store.query.QueryCompiler
      org.jpox.store.rdbms.query.JavaQueryCompiler
          org.jpox.store.rdbms.query.JDOQLQueryCompiler

All Implemented Interfaces:

org.jpox.store.mapped.expression.UnboundVariable.VariableBinder

public class JDOQLQueryCompiler
extends JavaQueryCompiler

Compiler of JDOQL queries for RDBMS datastores. Takes the input query and provides two forms of compilation :-

• preCompile - where all is compiled except that parameter values arent known
• executionCompile - like preCompile except also using the parameter values, just before execution

During either compilation step other parts of the query are resolved and are available for update by accessors.

Version:

$Revision$

Field Summary

protected boolean	explicitParameters Flag for whether we have explicit parameters.
protected boolean	explicitVariables Flag for whether we have explicit variables.
protected int	implicitParamNo State variable for the current implicit parameter number.
protected boolean	subqueryAliasSet Flag for whether we have set the alias of the subquery.
protected java.util.Map	subqueryParameters Parameter map when treating as a subquery.

Fields inherited from class org.jpox.store.rdbms.query.JavaQueryCompiler

candidateCmd, candidates, distinct, expressionsByVariableName, parentExpr, qs, rangeFromIncl, rangeToExcl, resultClass, resultMetaData, subqueryCandidateExpr, subqueryCandidateExprRootAliasInfo

Fields inherited from class org.jpox.store.query.QueryCompiler

candidateAlias, candidateClass, COMPILE_EXECUTION, COMPILE_EXPLICIT_PARAMETERS, COMPILE_EXPLICIT_VARIABLES, COMPILE_SYNTAX, executionCompile, imports, language, LOCALISER, p, parameterNames, parameters, parameterTypesByName, query, variableNames, variableTypesByName

Constructor Summary

JDOQLQueryCompiler(org.jpox.store.query.AbstractJDOQLQuery query, org.jpox.util.Imports imports, java.util.Map parameters)
Constructor.

Method Summary

java.lang.Object	compile(int type) Method to compile the query.
protected void	compileCandidates() Convenience method to process the candidates for this query.
protected org.jpox.store.mapped.expression.ScalarExpression	compileExpression() Principal method for compiling an expression.
protected org.jpox.store.mapped.expression.ScalarExpression	compileExpressionFromString(java.lang.String str) Convenience method to parse an expression string into its query expression.
protected org.jpox.store.mapped.expression.ScalarExpression	compileNamedImplicitParameter(java.lang.String id) Method to compile a named implicit parameter into an expression.
protected org.jpox.store.mapped.expression.ScalarExpression	compilePrimary() this compiles a primary.
protected org.jpox.store.mapped.expression.ScalarExpression	compileSubqueryVariable(java.lang.String id) Method to compile a subquery, replacing the specified variable with a SubqueryExpression.
protected java.lang.Class	getClassForSubqueryCandidateExpression() Convenience method to process the subquery "" to return the class to use.
protected org.jpox.store.mapped.expression.ScalarExpression	getExpressionForSubqueryParentParameter(java.lang.String val) Convenience method to obtain an expression for the value of a parameter in a subquery where it relates back to the parent query.
protected void	performCompile(org.jpox.store.mapped.expression.QueryExpression qs) Perform the actual compilation of the query.
void	processAsSubquery(org.jpox.store.mapped.expression.QueryExpression parentExpr, java.lang.String candidateExpression, java.util.Map paramMap) Method to set the parent expression that this is a subquery of.

Methods inherited from class org.jpox.store.rdbms.query.JavaQueryCompiler

bindVariable, callUserDefinedScalarExpression, checkExpressionsAgainstGrouping, checkVariableBinding, close, compileAdditiveExpression, compileCastExpression, compileExplicitVariable, compileExpressionsFromString, compileFilter, compileGrouping, compileHaving, compileLiteral, compileMultiplicativeExpression, compileNewObject, compileRange, compileResult, compileSubqueryCandidateExpression, compileUnaryExpression, compileUnaryExpressionNotPlusMinus, executionCompile, getCandidates, getDistinct, getRangeFromIncl, getRangeToExcl, getResultClass, getResultMetaData, preCompile

Methods inherited from class org.jpox.store.query.QueryCompiler

compileExplicitParameters, compileExplicitVariables, getCandidateAlias, getCandidateClass, getParameterNames, getParameterTypesByName

Methods inherited from class java.lang.Object

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

Field Detail

explicitParameters

protected boolean explicitParameters

Flag for whether we have explicit parameters. JDO allows both types but either all explicit or all implicit.

explicitVariables

protected boolean explicitVariables

Flag for whether we have explicit variables. JDO allows both types but either all explicit or all implicit.

implicitParamNo

protected int implicitParamNo

State variable for the current implicit parameter number.

subqueryParameters

protected java.util.Map subqueryParameters

Parameter map when treating as a subquery.

subqueryAliasSet

protected boolean subqueryAliasSet

Flag for whether we have set the alias of the subquery. If this is true then the subquery would have had use of "this" implying the subquery candidate. Otherwise "this" would refer to the parent query.

Constructor Detail

JDOQLQueryCompiler

public JDOQLQueryCompiler(org.jpox.store.query.AbstractJDOQLQuery query,
                          org.jpox.util.Imports imports,
                          java.util.Map parameters)

Constructor.

Parameters:

query - JDOQL query to compile

imports - Imports handler to use for class resolution

parameters - map of declared parameters in the query

Method Detail

processAsSubquery

public void processAsSubquery(org.jpox.store.mapped.expression.QueryExpression parentExpr,
                              java.lang.String candidateExpression,
                              java.util.Map paramMap)

Method to set the parent expression that this is a subquery of. Should be set before calling preCompile/executionCompile.

Parameters:

parentExpr - The parent expression

compile

public java.lang.Object compile(int type)

Method to compile the query.

Overrides:

compile in class JavaQueryCompiler

Parameters:

type - Type of compilation

Returns:

the compilation artifact (if any)

performCompile

protected void performCompile(org.jpox.store.mapped.expression.QueryExpression qs)

Perform the actual compilation of the query.

Specified by:

performCompile in class JavaQueryCompiler

Parameters:

qs - The QueryExpression to use during compilation (if required)

compileCandidates

protected void compileCandidates()

Convenience method to process the candidates for this query. Processes the "candidateClassName" and "candidateClass" and sets up "candidates".

Specified by:

compileCandidates in class JavaQueryCompiler

getClassForSubqueryCandidateExpression

protected java.lang.Class getClassForSubqueryCandidateExpression()

Convenience method to process the subquery "" to return the class to use.

Returns:

Class for candidate expression

compileExpressionFromString

protected org.jpox.store.mapped.expression.ScalarExpression compileExpressionFromString(java.lang.String str)

Convenience method to parse an expression string into its query expression.

Specified by:

compileExpressionFromString in class JavaQueryCompiler

Parameters:

str - The string

Returns:

The query expression for the passed string

compileExpression

protected org.jpox.store.mapped.expression.ScalarExpression compileExpression()

Principal method for compiling an expression. An expression could be the filter, the range, the result, etc.

Specified by:

compileExpression in class JavaQueryCompiler

Returns:

The compiled expression

compilePrimary

protected org.jpox.store.mapped.expression.ScalarExpression compilePrimary()

this compiles a primary. First look for a literal (e.g. "text"), then an identifier(e.g. variable) In the next step, call a function, if executing a function, on the literal or the identifier found.

Specified by:

compilePrimary in class JavaQueryCompiler

Returns:

Scalar Expression for the primary compiled expression

compileSubqueryVariable

protected org.jpox.store.mapped.expression.ScalarExpression compileSubqueryVariable(java.lang.String id)

Method to compile a subquery, replacing the specified variable with a SubqueryExpression.

Parameters:

id - Variable name that the subquery replaces.

Returns:

Expression for the subquery

compileNamedImplicitParameter

protected org.jpox.store.mapped.expression.ScalarExpression compileNamedImplicitParameter(java.lang.String id)

Method to compile a named implicit parameter into an expression.

Parameters:

id - Identifier of the named parameter, starts with ":"

Returns:

Expression representing the named param

getExpressionForSubqueryParentParameter

protected org.jpox.store.mapped.expression.ScalarExpression getExpressionForSubqueryParentParameter(java.lang.String val)

Convenience method to obtain an expression for the value of a parameter in a subquery where it relates back to the parent query.

Parameters:

val - The value

Returns:

The expression for this field in the parent query