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(in progress)

Concepts

The execution of the program is divided into super-step(s) also called burst(s). Each super-step is divided into micro-step(s).

The program is executed using a Frame Tree (FT). The concept of Frame Tree is just an extension of the concept of Frame Stack (more commonly known as Call Stack). In place of a linear Frame stack, funcSug uses a Frame Stack (called Frame Tree) that has a tree structure.

Each frame contains:

  • a copy of a part of the AST, its code (FrameCode)
  • a local namespace (LN)
  • the multivalue to be returned to the parent frame
  • the multivalues returned by the child frames
  • the awake state of the Frame (Awake)
  • a step counter (independent of micro-steps and super-steps) (Step Counter: SCNT)
  • a description of the path in FT from the root node to this node (Path of Execution: POE)
  • other information relevant to the execution

The execution is done by "activating" some FT nodes and executing leaf nodes.

The execution of some nodes may cause the addition of child nodes. When a node has completely finished its execution, it is removed from FT and the multivalue to be returned is set in the parent frame.

The variables are distributed in the local namespaces during the execution of the program. A variable consists of an association between a label and a LiveBox.

Return multivalues don't use a LiveBox.

A LiveBox includes:

  • a multivalue called previous multivalue
  • a stamped multivalue called current multivalue
  • a boolean called previous bip state
  • a boolean called previous beep state
  • a boolean called current bip state
  • a boolean called current beep state

There are two types of LiveBox: simple (the most common type) and special.

A multivalue is a list of values. A stamped multivalue is a list of (value, stamp) pairs Each pair is called stamped value. The stamp is the POE of the Frame that caused this value to be added.

The content of a LiveBox can be modified by an assignment. An assignment has two parameters:

  • a LiveBox lb
  • a value v (TODO I have to specify the value types)

An assignment is performed by a Frame f as follows:

  • For each stamped value (v', e') of the current multivalue of lb:

    • If lb is simple or if the FrameCode of the last node of the intersection of the POE of the Frame f and the stamp e' is one of the instructions "seq", "while", "mix"
    • then the stamped value (v', e') is removed from the current multivalue of lb

  • The pair (v, POE of f) is added to the current multivalue of lb

Execution of a program

The program is executed as follows:

  • At the beginning of the execution, FT contains only one node: a Frame containing a copy of the root of the AST.
  • Then a burst is executed.
  • The following bursts will be executed thanks to the "ext" instructions.

A burst is executed as follows:

  • As long as there is a FT leaf in the Awake state:
    • execute a micro-step

A micro-step is executed as follows:

  • All "cancellableExec" frames are activated
  • All "dynamicPar" frames are activated
  • All leaf frame are executed
  • All non frozen LiveBoxes are updated

Updating a LiveBox is done as follows:

  • the previous multivalue becomes a copy of the current multivalue without the stamps
  • the previous bip state becomes a copy of the current bip state
  • the previous beep state becomes a copy of the current beep state
  • the current bip state is set to false (the current beep state is not modified)

An "execution" of a node f is executed differently depending on the instuction of the FrameCode of the node.

To be continued...