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package org.jruby.runtime.ivars;

A lazy mechanism for accessing VariableAccessors for a given variable name.
/**
 * A lazy mechanism for accessing VariableAccessors for a given variable name.
 */
public final class VariableAccessorField {
    
the name of the variable /** the name of the variable */
    private final String name;
    
    
the accessor cached after it has been allocated /** the accessor cached after it has been allocated */
    private volatile VariableAccessor variableAccessor = VariableAccessor.DUMMY_ACCESSOR;

    
Construct a new VariableAccessorField for the given named variable.
Params:
name – the name of the variable/**
     * Construct a new VariableAccessorField for the given named variable.
     * 
     * @param name the name of the variable
     */
    public VariableAccessorField(String name) {
        this.name = name;
    }

    
Retrieve the variable accessor for read.
Returns:
the variable accessor appropriate for reads/**
     * Retrieve the variable accessor for read.
     * 
     * @return the variable accessor appropriate for reads
     */
    public VariableAccessor getVariableAccessorForRead() {
        return variableAccessor;
    }

    
Retrieve the variable access for write.
Params:
tableMgr – the VariableTableManager for which to allocate an
accessor, if it has not already been allocated.
Returns:
the variable accessor appropriate for writes./**
     * Retrieve the variable access for write.
     * 
     * @param tableMgr the VariableTableManager for which to allocate an
     * accessor, if it has not already been allocated.
     * @return the variable accessor appropriate for writes.
     */
    public VariableAccessor getVariableAccessorForWrite(VariableTableManager tableMgr) {
        return variableAccessor != VariableAccessor.DUMMY_ACCESSOR ? variableAccessor : allocateVariableAccessor(tableMgr);
    }

    
Retrieve or allocate the variable accessor for this variable. This
version differs from getVariableAccessorForWrite only in its visibility
and the fact that it is synchronized against this field to ensure
volatile behavior of the variableAccessor field.
Params:
tableMgr – the VariableTableManager for which to allocate an
accessor, if it has not already been allocated.
Returns:
the variable accessor appropriate for writes/**
     * Retrieve or allocate the variable accessor for this variable. This
     * version differs from getVariableAccessorForWrite only in its visibility
     * and the fact that it is synchronized against this field to ensure
     * volatile behavior of the variableAccessor field.
     * 
     * @param tableMgr the VariableTableManager for which to allocate an
     * accessor, if it has not already been allocated.
     * @return the variable accessor appropriate for writes
     */
    private synchronized VariableAccessor allocateVariableAccessor(VariableTableManager tableMgr) {
        if (variableAccessor == VariableAccessor.DUMMY_ACCESSOR) {
            variableAccessor = tableMgr.allocateVariableAccessor(name);
        }
        return variableAccessor;
    }
    
}