com.goldencode.p2j.convert

Class UnreachableCodeWorker.Helper

java.lang.Object

com.goldencode.p2j.convert.UnreachableCodeWorker.Helper

Enclosing class:

UnreachableCodeWorker

public class UnreachableCodeWorker.Helper
extends java.lang.Object

Provides user-level APIs necessary for unreachable code processing.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) java.util.HashMap	varPool Information about known variables

Constructor Summary

Constructors

Constructor and Description
Helper()

Method Summary

Modifier and Type	Method and Description
boolean	addKnownVarValue(java.lang.String variable, java.lang.String value) Add a variable to the pool of known variables.
private java.util.List	getKnownValues(java.lang.String var) Get list of known values of the variable for the expression evaluator.
long	tryEval(Aast node) Try to evaluate the expression defined by the passed AST node.
boolean	tryEvalCase(java.lang.String var, java.lang.String value) Try to evaluate CASE-WHEN-THEN statement expression which compares a VAR_CHAR to a STRING.
private long	tryEvalNode(AnnotatedAst node) Expression evaluation worker.

Methods inherited from class java.lang.Object

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

Field Detail

varPool

java.util.HashMap varPool

Information about known variables

Constructor Detail

Helper

public Helper()

Method Detail

addKnownVarValue

public boolean addKnownVarValue(java.lang.String variable,
                                java.lang.String value)

Add a variable to the pool of known variables. A variable consists of a name and a list of values. If the variable is already known in the pool, then a new value is added to the array of known values.

At this time, all variables must be of type VAR_CHAR and the values must be the Java version of the Progress STRING.

Parameters:

variable - Variable name. Must not be null.

value - New variable value. Must not be null.

Returns:

true if operation was successful.

tryEval

public long tryEval(Aast node)

Try to evaluate the expression defined by the passed AST node. If this can be done then return result of evaluation.

At present only the following expressions are recognized:

1. TRUE
2. FALSE
3. VAR_CHAR = STRING
4. STRING = VAR_CHAR
5. VAR_CHAR <> STRING
6. STRING <> VAR_CHAR

Parameters:

node - Expression root node.

Returns:

RES_UNKNOWN if the expression cannot be evaluated, RES_TRUE if the result is true and RES_FALSE if the result is false.

tryEvalCase

public boolean tryEvalCase(java.lang.String var,
                           java.lang.String value)

Try to evaluate CASE-WHEN-THEN statement expression which compares a VAR_CHAR to a STRING.

Parameters:

var - CASE statement variable name of type VAR_CHAR.

value - THEN statement value of type STRING.

Returns:

true if variable contains specified value.

getKnownValues

private java.util.List getKnownValues(java.lang.String var)

Get list of known values of the variable for the expression evaluator.

Parameters:

var - Variable name (will be automatically translated to lower case).

Returns:

Array with the variable values or null if no such variable defined.

tryEvalNode

private long tryEvalNode(AnnotatedAst node)

Expression evaluation worker.

Parameters:

node - Expression root node.

Returns:

RES_UNKNOWN if the expression cannot be evaluated, RES_TRUE if the result is true and RES_FALSE if the result is false.