root/trunk/ddl/DDLWriter.d

/+
    Copyright (c) 2006 Eric Anderton
        
    Permission is hereby granted, free of charge, to any person
    obtaining a copy of this software and associated documentation
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    sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following
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    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
    OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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+/
/**
    Provides Tango binary Writer support, with a few enhancements
    
    Authors: Eric Anderton
    License: BSD Derivative (see source for details)
    Copyright: 2006 Eric Anderton
*/
module ddl.DDLWriter;

private import ddl.Utils;
private import ddl.FileBuffer;

enum Anchor{
    None,
    Begin,
    End,
    Current
}

/**
    Tango IO Writer subclass.
    
    DDLWriter, apart from adding symmetry to DDLReader, provides seeking capability for 
    random-access <i>output</i>.
*/
public class DDLWriter{
    ubyte[] data;
    uint position;
    
    /**
        IBuffer style constructor.
        
        Params:
            buffer = buffer to read
    */
    public this (){
        position = 0;
    }
    
    public this (ubyte[] data){
        this.data = data;
        position = data.length;
    }   
    
    public this(FileBuffer buffer){
        this.data = buffer.data;
        position = 0;
    }   
    
    DDLWriter putAll(void[] x){
        ubyte[] newData = cast(ubyte[])x;
        if(position == data.length){
            data ~= newData;
            position = data.length;
        }
        else{
            data[position..position+newData.length] = newData;
        }
        return this;
    }
    
    DDLWriter put(T)(T x){
        ubyte[] newData = (cast(ubyte*)(cast(void*)&x))[0..T.sizeof];
        if(position == data.length){
            data ~= newData;
            position = data.length;
        }
        else{
            data[position..position+newData.length] = newData;
            position += newData.length;
        }
        return this;
    }
        
    /**
        Perform a seek relative to the current buffer position and status using the conduit.
        
        Some Tango conduits are seekable directly.  For all others, this method seeks by
        manipulating the buffer and the current read position instead.
        
        <b>NOTE:</b> this will clear out the current buffer, which may have some performance 
        implications.
        
        Params:
            offset = the number of bytes to seek from the specified anchor
            anchor = (default: Begin) specifies the point in the conduit from where seeks are
            calculated (see: ISeekable.SeekAnchor for more info).
    */
    DDLWriter seek(ulong offset, Anchor anchor = Anchor.Begin){
        switch(anchor){
        case Anchor.Begin:
            assert(offset < data.length);
            position = offset;
            break;
        case Anchor.End:
            assert(data.length + offset < data.length);
            position = data.length + offset;
            break;
        default:
        case Anchor.None:
        case Anchor.Current:
            assert(position + offset < data.length);
            position += offset;
            break;
        }
        return this;
    }
    
    /**
        Returns: The position relative to the current buffer position.
    */
    size_t getPosition(){
        return position;
    }
    
    ubyte[] getData(){
        return data;
    }
}