Note: Deprecated!

An introduction

In short, a flow is a template definition of recognizable data. It is used to transform a stream of neurons into another stream of neurons (doesn’t sound very useful, but trust me, it is).  To get a visual image on how a flow works, you can perhaps think of those toddler toys where the child needs to fit different types of blocks into different types of wholes (see image).

Well, a Flow is the yellow filter at the top of the box. As the blocks pass along, a flow tries to find a set that fits it’s filter. When it finds one, it collects this set, tags it, and stores it for further use. This process is done by the flow recognition algorithm.

A flow is a template definition, used to recognize sequences of data in a stream.

flow items

So, what is this filter that’s supposed to recognize the data, actually constructed of? Well, flow definitions are very (mmm, perhaps not so very) similar to Coco/R definitions. In short, you use constants, other (nested) flows, loops and options to build up a definition. Here’s a short example:
This flow can recognize the sequence: Agent verb possibly followed by a not. It’s actually the definition for the simple past tense (there’s an extra hidden filter on ‘verb’ which I’m not showing yet for this example). ‘Agent’ is underscored, indicating that it is another flow, verb is not, so it’s a static, like not. Which is surrounded by strait brackets, indicating that it’s optional. So basically, this flow can recognize statements like: I swam, you dug, the brown men found not,… Without the filter (like here), sentences like: I fish, they eat not,… would also be recognized.

Statics and nested flows

Most of the items in a flow definition tend to be statics and other, nested flows. This forms the meat, the data that can be found in the input stream itself. When 2 statics are declared in sequence, the same sequence needs to be found in the input, without anything in between.

Nested flows can easily be recognized. They are underlined. If you double-click on them, you will jump automatically to the flow (you can navigate back and forward between the selected flows using the navigation commands). Behavior-wise, nested flows are the same as statics. If you declare 2 nested flows in sequence, the input stream should contain the data for the 2 flows in the same sequence.

Floating flows

A floating flow is a special type of flow that can be recognized anywhere in the stream without having to be specifically declared in any other flows. They are mostly used for things like spaces and newlines. You usually don’t integrate them into other flows, as nested.

Floating flows can be destructive or not. When a destructive flow is found, it will break up the recognition of other data in the stream. So this type of flow can not be found between 2 statics, but can be between 2 nested flows or between options, loops or conditional parts (see further). If you need to have a floating flow between 2 statics, it needs to be non destructive. The type of flow can be assigned from a context menu on the flows: you can select for normal flows (not floating), floating (visualized by a green bar in front of the flow) and non destructive floating (displayed using a blue bar).

You can also specify if the data that a floating flow finds is discarded or not. Discarding the data can be useful in cases where you are really not interested in it, like for empty space. This is also selected from the context menu on the flows and is visualized by using an extra bar at the end of the flow.

Options

With an option you can define a number of different paths, from which 1 can or has to be selected. The following example of options defines the ‘can’ verb:A blue block (also called ‘conditional part’) represents a single path. If the frontal bracket of the options contains a vertical line, 1 path has to be selected, if there is no line, no path has to be selected but 1 can be. The content of a conditional has to be recognized in the same sequence as the way that it is defined and can consist of statics, flows, loops and other options, but no conditional parts. The option itself can only contain conditional parts.

Just like statics and nested flows, you can also reuse the same option in different places. In fact, the more you can do this, the more processing power can be saved. The same goes for the conditional parts (the blue blocks). These can also be shared by different options (and loops). This can be done by drag and drop from within the editor.

Loops

Loops are very similar to options, they also consist of conditional parts and they can also be defined with a vertical line in front, indicating that 1 path has to be selected or not. The main difference with options is that a loop can recognize 0, 1 or more of it’s conditional parts in sequence. They are declared using curly brackets, like in the following example: This loop simply declares a sequence of digits, with at least 1 required digit. In other words, it’s the definition for an integer.

Loops can have some more lines in the front to declare extra info. If there is a green line present, to the right of the black one, it means there can’t be a floating flow in between 2 conditional parts, otherwise this is allowed (see floating flows). A red line to the left of the black one, indicates exactly the opposite: 2 conditionals need to have a floating flow in between them for a valid parse (not often used).

As a final example, here’s the entire scanner definition which is used to recognize words, numbers (integer and doubles), signs and spaces: