001package Torello.Java;
002
003import java.util.function.Consumer;
004import java.util.function.Supplier;
005
006/**
007 * Provides any method the ability to provide its users the ability to choose what kind of data
008 * structure should be used for returning the method's results.  Currently, this class is used as 
009 * a helper class for class {@link FileNode}
010 * 
011 * @param <INSERT_TYPE> Currently, the only class using {@code VarType} is class {@link FileNode}.
012 * Within class {@link FileNode}, this Type-Parameter, {@code 'INSERT_TYPE'}, is always assigned
013 * the value of class {@code 'FileNode'}
014 * 
015 * @param <RET_DATA_STRUCTURE> This Generic Type-Parameter provides a user the ability to specify
016 * any Method Return-Type needed / desired.  In class {@link FileNode}, for instance, this
017 * Type-Parameter is often assigned to things such as: {@code Stream<FileNode>},
018 * {@code Iterator<FileNode>} or even {@code String[]} - where each of the {@code String's} are
019 * actual File-Names as a {@code String}.
020 * 
021 * <BR /><BR />If this class {@code VarType} where used elsewhere, outside of {@code FileNode},
022 * then the Generic Type-Parameter {@code 'RET_DATA_STRUCTURE'} would allow a user to provide a
023 * means for his / her users to specify, exactly, any method's Return Type/Class.
024 * 
025 * @see FileNode
026 */
027public class VarType<RET_DATA_STRUCTURE, INSERT_TYPE>
028{
029    /** Accepts and inserts data into the data-structure. */
030    public final Consumer<INSERT_TYPE> inserter;
031
032    /** Performs any finalizations on the data-structure, and then returns it */
033    public final Supplier<RET_DATA_STRUCTURE> finisher;
034
035    // Identifies whether this instance has already been run to completion
036    private boolean finished = false;
037
038    /** Identifies whether this is a "Reusable" instance */
039    public final boolean isReusable;
040
041    /**
042     * Constructs an instance of this class
043     * @param inserter This is assigned to the field {@link #inserter}.
044     * @param finisher Assigned to field {@link #finisher}.
045     */
046    public VarType(
047            final Consumer<INSERT_TYPE>         inserter,
048            final Supplier<RET_DATA_STRUCTURE>  finisher,
049            final boolean                       isReusable
050        )
051    {
052        if (isReusable)
053        {
054            this.isReusable = true;
055            this.inserter   = inserter;
056            this.finisher   = finisher;
057        }
058
059        else
060        {
061            this.isReusable = false;
062
063            this.inserter = (INSERT_TYPE data) ->
064            {
065                if (this.finished) throw new VarTypeAlreadyUsedException();
066                inserter.accept(data);
067            };
068
069            this.finisher = () ->
070            {
071                if (this.finished) throw new VarTypeAlreadyUsedException();
072                this.finished = true;
073                return finisher.get();
074            };
075        }
076    }
077}