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Struct = require './Struct'
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class VersionedStruct extends Struct
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constructor: (@type, @versions = {}) ->
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if typeof @type is 'string'
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@versionGetter = new Function('parent', "return parent.#{@type}")
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@versionSetter = new Function('parent', 'version', "return parent.#{@type} = version")
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decode: (stream, parent, length = 0) ->
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res = @_setup stream, parent, length
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if typeof @type is 'string'
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res.version = @versionGetter parent
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else
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res.version = @type.decode(stream)
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if @versions.header
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@_parseFields stream, res, @versions.header
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fields = @versions[res.version]
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if not fields?
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throw new Error "Unknown version #{res.version}"
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if fields instanceof VersionedStruct
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return fields.decode(stream, parent)
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@_parseFields stream, res, fields
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@process?.call(res, stream)
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return res
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size: (val, parent, includePointers = true) ->
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unless val
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throw new Error 'Not a fixed size'
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ctx =
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parent: parent
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val: val
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pointerSize: 0
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size = 0
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if typeof @type isnt 'string'
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size += @type.size(val.version, ctx)
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if @versions.header
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for key, type of @versions.header when type.size?
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size += type.size(val[key], ctx)
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fields = @versions[val.version]
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if not fields?
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throw new Error "Unknown version #{val.version}"
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for key, type of fields when type.size?
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size += type.size(val[key], ctx)
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if includePointers
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size += ctx.pointerSize
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return size
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encode: (stream, val, parent) ->
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@preEncode?.call(val, stream)
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ctx =
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pointers: []
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startOffset: stream.pos
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parent: parent
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val: val
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pointerSize: 0
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ctx.pointerOffset = stream.pos + @size(val, ctx, false)
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if typeof @type isnt 'string'
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@type.encode(stream, val.version)
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if @versions.header
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for key, type of @versions.header when type.encode?
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type.encode(stream, val[key], ctx)
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fields = @versions[val.version]
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for key, type of fields when type.encode?
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type.encode(stream, val[key], ctx)
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i = 0
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while i < ctx.pointers.length
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ptr = ctx.pointers[i++]
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ptr.type.encode(stream, ptr.val, ptr.parent)
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return
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module.exports = VersionedStruct
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