public/rc/README.md

## rc (restrictions checker)

This program analyses a go source file and displays in standard output the imports, functions, array types and loops used without authorization.

### By default:

- NO imports and NO built-in functions are allowed.
- NO casting is allowed either.
- Only functions declared inside the source file are allowed.
- All array types are allowed
- Loops are allowed

### Flags

- Two flags are defined:
  - `--cast` allows casting to every built-in type.
  - `--no-for` prohibits the use of `for` loops in the program or function.
  - `--no-array`:
    - Prohibits all array types if no types are specified after the flag.
      Ex.
      ```console
	_$ ./rc main.go fmt.* github.com/01-edu/z01.PrintRune len --no-array
      ```
      All array type in main.go will cause an error message.
    - Prohibits only the types specified after the flag
      Ex.
      ```console
	_$ ./rc main.go fmt.* github.com/01-edu/z01.PrintRune len --no-array rune string
      ```
      Only array from the type rune and string are prohibit. All other array from built-in types are allowed

### Arguments:

- First Argument:

The program must be executed passing the go source file to be analyze as the first argument

- The remaining argument (from 2 to ...):

   Can be (without any particular order):

   - Allowed imports and functions from a package
     - `<package>.*` for full imports (all functions from that package are allowed)
     - `<package>`.`<function>` for partial imports (only the function is allowed)
     - `<package>`.`<function>#amout` for certain amounts (only certain amount os a function is allowed)
     - Ex: `fmt.*` (all functions from `fmt` are allowed), `github.com/01-edu/z01.PrintRune` (only `z01.PrintRune` is allowed), `append#2` (the only amount of `append`'s allowed is 2)
   - Allowed built-in functions
     - Use the name of the built-in function
     - Ex: `make`, `append`, `len`.
      - Allowed casting
      - by using the type of casting, ex: for allowing `string` casting, use `string`
      - Or use the flag `--cast`, to allow every type of casting

   - Import relative packages
     - Use the relative path
     - Ex: `../piscine`, `..`, `.`

   - Unallow for loops
     - Use the flags `--no-for`.
     - Note: remember to use it before the `--no-array` flag.
       - ex:
       ```console
       _$ ./rc main.go fmt.* github.com/01-edu/z01.PrintRune len --no-array <...> --no-for
       ```
       the last line produces undesired behaviors.
   - Unallow literals
     - Use the flag `--no-lit="{PATTERN}"`
     - Note: `"{PATTERN}"` must be a valid RegExp.
       - ex:
       ```console
       _$ ./rc main.go fmt.* github.com/01-edu/z01.PrintRune len --no-array --no-lit=[b-yB-Y]
       ```
- Optional lasts arguments
  - The flag `--no-array` must be given as the last argument or to signal that all the arguments after are unallowed array types 
### Usage:

- To allow the import of the whole `fmt` package, `z01.PrintRune` and the built-in functions len in the file `main.go`

   The imports must be writen exactly the way are writen inside the source code, example:

```console
   _$ ./rc main.go fmt.* github.com/01-edu/z01.PrintRune len
```
- More examples:

- import "fmt" is allowed by executing
   ```console
   _$ ./rc sourcefile.go fmt.*
   ```

   - import "go/parser" is allowed by executing
   ```console
   _$ ./rc sourcefile.go go/parser.*
   ```

   - import "github.com/01-edu/z01" is allowed by executing
   ```console
   ./rc sourcefile.go github.com/01-edu/z01.*
   ```

   - import "../../../all/tests/go/solutions" is allowed by executing
   ```console
   _$ ./rc sourcefile.go ../../../all/tests/go/solutions
   ```
   (no `.*` is needed, all the functions from this relative package are allowed)

- allow all type of casting

   ```console
   _$ ./rc sourcefile.go ../../../all/tests/go/solutions/ztail/ztail.go fmt.* github.com/01-edu/z01 os.* strconv.* make len append --cast
   ```
   - this will allow all type of casting in the file ztail.go

- to allow just one type of casting

   ```console
   _$ ./rc sourcefile.go ../../../all/tests/go/solutions/ztail/ztail.go fmt.* github.com/01-edu/z01 os.* strconv.* make len append rune
   ```
   - this will allow `rune`, but not `int8`, ..., `string`, `float32`, ...