nikololiahim/py2eo

Python to EOLANG transpiler

This is a translator of Python to EOLANG.

What is the traspiler?

A source-to-source translator, source-to-source compiler (S2S compiler), transcompiler, or transpiler is a type of translator that takes the source code of a program written in a programming language as its input and produces an equivalent source code in the same or a different programming language

What is it?

This is a translator of Python to EOLANG. It is needed for transpiling Python code to EOLANG programming language. After successful transpiling final EOLANG code will be available for analyzing via Polystat analyzer which will notify you about leak places in the code.

How does it work?

This transpiler receives as input data python code. Then received code is simplified with AST usage. After successfull simplyfying it is sent to the py2eo translator for getting EOLANG.

What do you need to use it?

• Ubuntu (20.04+) or Windows (7+)
• Java 14+ - check in command line java --version. Use sudo apt install openjdk-16-jdk-headless in Ubuntu 20 (there is no java 14 package there).
• For contributors: Maven 3.6.3 with Java 14 or Maven 3.8.4 with Java 17 (but there is no Maven 3.8 package in Ubuntu and no Java 14 package, so manual installation is needed anyway)

How to use it?

• Go to some directory on your PC
• Create directory Transpiler Test
• Download and save into this folder py2eo transpiler executable from this link
• Create in this folder test file with python code named sample_test.py and paste the code below into it:

  def conditionalCheck2():
      a = 4
      b = 2
  

• Open command line and move to the folder Transpiler Test
• Run command java -jar .\py2eo-${version_code}-SNAPSHOT-jar-with-dependencies.jar .\sample_test.py
• Check output .eo file in Transpiler Test/genCageEO/sample_test.eo or in path_to_output_folder/sample_test.eo in case of usage -o command line parameter

Command line arguments

Option	Action
-h,--help	Display help information
-o	path to output .eo file
-X,--debug	Produce execution debug output
-v,--version	Display version information

How to contribute?

• This instruction is for Ubuntu 20.04
• Check git version git -version or install it via sudo apt install git
• Install maven (sudo apt install maven)
• You need exactly Java version 14, so download it here, unpack it and manually setup the PATH and JAVA_HOME variables. For example, you may open command line and run these commands:

cd ~
wget https://download.java.net/java/GA/jdk14.0.1/664493ef4a6946b186ff29eb326336a2/7/GPL/openjdk-14.0.1_linux-x64_bin.tar.gz
tar x -z < openjdk-14.0.1_linux-x64_bin.tar.gz
PATH="$PWD/jdk-14.0.1/bin/:$PATH"
export JAVA_HOME="$PWD/jdk-14.0.1/"

• Check java version java -version
• Download project of Python to EOLANG transpiler with source code (via git clone or downloading of zip)
• Run command mvn clean package -DskipTests=true in the same command line runtime were you have set PATH and JAVA_HOME variables
• Open ./target folder (via cd target for example)
• Create test file named sample_test.py in this folder and paste the code below into it:

  def conditionalCheck2():
      a = 4
      b = 2
  

• Run command java -jar .\py2eo-${version_code}-SNAPSHOT-jar-with-dependencies.jar .\sample_test.py
• Check output .eo file in ./genCageEO/sample_test.eo

Checker

This repository's CI includes checker - a tool that reduces project testing time using input test mutations. Checkout more here.

Examples of translation projections

6.1 Arithmetic conversion

Complex and float numbers are not yet supported, so no implicit conversion is needed.

6.2.4 6.2.5 6.2.6 6.2.7 Displays for lists, sets and dictionaries

Will be supported via a python-to-python pass: a display will be converted to a for loop

6.2.8 Generator expressions

Same as displays

6.2.9 Yield expression

Is a part of coroutines. No plans to support the coroutines now.

6.3.4 Call

7.1 Expressions statements

Should be easy but not yet done.

7.2 Assignment statements

Note:

• x is prepended to each variable name in order to support capital first letter of a name
• local variable names are statically extracted and declared as cage in the beginning of a generated output

Python

x = 1

EO

This is added at the start of the generated function

cage > xx

This is put at the appropriate place according to the execution order

(xx).write (1)

Python

x = x + 1

EO

Seems overly complicated, but this is a generalized variant of this hack. Maybe the part with dddata can be simplified.

seq > @
  [] > tmp1
    memory > dddata
    dddata.write (((xx).add 1)) > @
  (e0).write (tmp1.dddata)
  ((e0).<)
  mkCopy (e0) > tmp2
  (xx).write (tmp2.copy)
  123

where mkCopy looks like this

[x] > mkCopy
  x' > copy
  copy.< > @

7.3 Assert

Will be done as a python-to-python pass, which basically substitutes assert to raise AssertionException

7.4 Pass

Does nothing

7.5 Del

Is an operator to delete attributes of objects dynamically. Not supported therefore.

7.6 Return

See the section on function definition

7.7 Yield

Is a part of coroutines. No plans to support the coroutines now.

7.8 Raise

See the section on exceptions

7.9 Break

See the section on while

7.10 Continue

See the section on while

7.11 Import

Not yet supported.

7.12 Global

Later. Needs closure for full support.

7.13 Nonlocal

Later. Needs closure for full support.

8.1 If-elif-else

Python

x = 1
if True:
  x = 2

EO

cage > tmp
cage > xx
seq > @
  (xx).write (1)
  TRUE.if
    seq
      (xx).write (2)
      TRUE
    seq
      TRUE
  123

Python

x = 1
if True:
  x = 2
elif False:
  x = 3
else:
  x = 4

EO

cage > tmp
cage > xx
seq > @
  (xx).write (1)
  TRUE.if
    seq
      (xx).write (2)
      TRUE
    seq
      FALSE.if
        seq
          (xx).write (3)
          TRUE
        seq
          (xx).write (4)
          TRUE
      TRUE
  123

Tests

https://github.com/polystat/py2eo/wiki/Tests-Structure#the-if-statement

8.2 While

Python

Imagine that the following code is a whole body of a function

x = 0
while True:
  x = x + 1

EO

Here, we have to support break with the help of goto, but also we should be able to pass other non-trivial returns like exceptions and return through the goto construct. This makes the code more complicated than just a direct use of while First, we declare x and some temporary variables

[stackUp]
  seq > @
    cage > tmp
    cage > xx
    cage > e0

    seq > @
      (xx).write (0)

Here, we wrap the while in a goto and store the result

      write.
        xcurrent-exception
        goto
          [stackUp]
            seq > @
              TRUE.while
                [unused]
                  seq > @

This part is just an overly generalized implementation of x = x + 1

                   [] > tmp1
                     memory > dddata
                     dddata.write (((xx).add 1)) > @
                   (e0).write (tmp1.dddata)
                   ((e0).<)
                   mkCopy (e0) > tmp2
                   (xx).write (tmp2.copy)
                   TRUE

Now, if we leave the while normally, we must still return something to be written to the current-exception variable, which is the raiseNothing object

             stackUp.forward raiseNothing

Next, if the goto result is not break, we basically rethrow it to the outer frame. Note, there are two stackUp objects here. The inner one is used to exit the while loop, while the outer one is used to exit the whole code block. It is only needed if the block is a body of another while or function or try block.

      if.
       xcurrent-exception.xclass.xid.neq (break.xclass.xid)
       stackUp.forward xcurrent-exception
       0

8.3 For

A for loop over an iterator is transformed into a while inside a try:

Python

x = 0
for i in r: x = x + i

Python after for elimination

x = 0
it0 = r.__iter__()
try:
    while (True):
        i = it0.__next__()
        x = (x + i)
except StopIteration:
    pass

The resulting code is then transformed to EO.

8.4 Try

try_2

Python

  def f(a, b):
    try:
      return a
    finally:
      return b

EO

[] > f
  [xaNotCopied xbNotCopied] > apply
    [stackUp] > @
      cage > tmp
      xaNotCopied' > xa
      xbNotCopied' > xb
      seq > @
        stdout "xf\n"
        xa.<
        xb.<
        write.
          xcurrent-exception
          goto
            [stackUp]
              seq > @
                stackUp.forward (return (xa))
                stackUp.forward raiseNothing
        seq
          if.
            xcurrent-exception.xclass.xid.eq (raiseNothing.xclass.xid)
            seq
            0
          stackUp.forward (return (xb))
          (xcurrent-exception.xclass.xid.neq (raiseNothing.xclass.xid)).if (stackUp.forward xcurrent-exception) 0
        123

Tests

https://github.com/polystat/py2eo/wiki/Tests-Structure#the-try-statement

8.5 With

Not yet implemented. The plan is to do it as a python-to-python pass according do the example here

8.6 Function definition

The non-trivial part here is to allow a function body to both do a return and to throw exceptions, which are not caught inside the function. This necessity forces us to wrap a function body in an object to be called with the help of goto.

Function definition example

Python

def f(): return 5

EO

Here, apply subobject is used to pass parameters (none in this example), the inner anonymous object with parameter stackUp should be called with the goto.

The stackUp is used both

• to throw exceptions
• to return values normally, in which case they are wrapped into a return object, so that they can be differentiated from exceptions

[] > f
  [] > apply
    [stackUp] > @
      cage > tmp
      seq > @
        stackUp.forward (return 5)
        123

Function call example

Python

x = f()

EO

Here, we first actually call f, then we must check if it returned normally or with exception. The exception is rethrown. The call

tmp.write (goto ((((xf)).apply).@))

Check for exception

(tmp.xclass.xid.neq (return.xclass.xid)).if (stackUp.forward tmp) 0

Extract a result from the return object

(e0).write (tmp.result)
((e0).<)

Assign its copy to x.

mkCopy (e0) > tmp1
(xx).write (tmp1.copy)
123

8.7 Class

A class is basically its constructor, i.e., a function, which returns an object.

Python

class c:
  field = 1
o = c()
o.field = 2

EO

Here c has the same calling convention as other functions (it has a field apply and must be called with goto). The inner result is the object to be returned. It is returned through a cage, otherwise this code just hangs.

[] > c
  newUID.apply 0 > xid
  [] > apply
    [stackUp] > @
      cage > pResult
      [] > result
        cage > xfield
        xc > xclass
        seq > initFields
          xfield.write 1
      seq (result.initFields) (pResult.write result) (stackUp.forward (return pResult)) > @

This is how object o is created:

tmp.write (goto ((((xc)).apply).@))
(tmp.xclass.xid.neq (return.xclass.xid)).if (stackUp.forward tmp) 0
(e0).write (tmp.result)
((e0).<)
mkCopy (e0) > tmp1
(xo).write (tmp1.copy)

Field assignment is then straightforward:

((xo).xfield).write (2)

8.8 Coroutines

No plans to support this.