Crate autoperm

Autoperm is a tool for generating programs to apply stack effect diagrams.

It is backend agnostic and could be used to generate programs for any language as long as the language implements the Model trait.

A brainfuck backend is provided and accessible with autoperm_bf.

Binary

Installing the crate as a binary gives access to the autoperm command which uses this brainfuck backend as REPL.

cargo install autoperm

Usage:

$ autoperm a b -- b a
[->+<]<[->+<]>>[-<<+>>]<

$ autoperm
a b c -- c a b
[->+<]<[->+<]<[->+<]>>>[-<<<+>>>]<

a -- a a a a
[->>>>+<<<<]>>>>[-<+<+<+<+>>>>]<

a b c d -- d c a b
[->+<]<<[->>+<<]>[-<+>]<<[->>+<<]>>>>[-<<<<+>>>>]<

a b c -- c
<<[-]>[-]>[-<<+>>]<<

a b c d e f -- c d d f e e b
<<<<<[-]>[->>>>>+<<<<<]>[-<<+>>]>[-<+<+>>]>>[-<<+>>]<[->>>+<<<]>>>[-<<+<+>>>]<

The program assumes the memory pointer starts by pointing at the top of the stack. Any “new” cells (cells that are not defined in the input) should start empty. There must also be 1 free cell at the top of the stack for temporary storage.

For example:

(a b c -- c)
start must be:
  a  b *c  0 // a and b are cleared
<<[-]>[-]>[-<<+>>]<<
end:
 *c  0  0  0

(a -- a a a a)
start must be:
  a  0  0  0  0 // note: no 0s are initialized before usage
[->>>>+<<<<]>>>>[-<+<+<+<+>>>>]<
end:
  a  a  a *a  0

A walk through for (a b – a b a b)

a b -- a b a b
<[->>>>+<<<<]>>>>[-<<+<<+>>>>]<<<[->>>+<<<]>>>[-<+<<+>>>]<

# the tape
 0 *1  2  3  T
 a  b  0  0  0

<[->>>>+<<<<]      0 → {T}
*0  1  2  3  T
 0  b  0  0  a

>>>>[-<<+<<+>>>>]  T → {2 0}
 0  1  2  3 *T
 a  b  a  0  0

<<<[->>>+<<<]      1 → {T}
 0 *1  2  3  T
 a  0  a  0  b

>>>[-<+<<+>>>]     T → {1 3}
 0  1  2  3 *T
 a  b  a  b  0

<
 0  1  2 *3  T
 a  b  a  b  0

Modules

models

Predefined models for certain programming languages

Structs

StackEffectDiagram

Represents a stack effect diagram.

Enums

Instruction

Represents an instruction within the computation model

ParseError

Returned when parse fails

Traits

Model

The assumed model of computation

Functions

autoperm

Generate a program to apply a given StackEffectDiagram.

autoperm_bf

Generate a brainfuck program that applies a given StackEffectDiagram

generate

Generate a program from a list of Instructions using a given Model.

parse

A very simple parser for parsing StackEffectDiagrams.

solve

Given a StackEffectDiagram generate a list of instructions to apply that diagram.