#!/usr/bin/env python

# -*- coding: utf-8 -*-

""" java2python.mod.transform -> input AST transformer functions and constants. """

##

#

# This module provides several transformation functions which are

# simple callables that modify AST nodes. These functions are not

# responsible for selecting nodes, only changing the node content.

# Thus, we have AST generation decoupled from AST traversal and

# modification.

#

# See the `java2python.config.default` and

# `java2python.lang.selector` modules to understand how and when

# selectors are associated with these callables.

import keyword

import types

def invalidPythonNames():

""" Creates a list of valid Java identifiers that are invalid in Python. """

ts = [getattr(types, n) for n in dir(types) if not n.startswith('_')]

ns = [t.__name__ for t in ts if isinstance(t, type)]

return ['None', 'True', 'False', ] + ns + keyword.kwlist

def keywordSafeIdent(node, config, invalid=invalidPythonNames()):

""" Validates and possibly renames a Java identifier. """

ident = node.token.text

if ident in invalid:

node.token.text = '%s_' % ident

def makeConst(v):

""" Returns a closure that indiscriminately changes node text to a value. """

def xform(node, config):

node.token.text = v

return xform

# create transformers for mapping well-known Java idents into their

# Python counterparts.

null2None = makeConst('None')

false2False = makeConst('False')

true2True = makeConst('True')

def syntaxSafeFloatLiteral(node, config):

""" Ensures a Java float literal is a valid Python float literal. """

value = node.token.text

if value.startswith('.'):

value = '0' + value

if value.endswith(('f', 'd')):

value = value[:-1]

elif value.endswith(('l', 'L')):

value = value[:-1] + 'L'

node.token.text = value

def typeSub(node, config):

""" Maps specific, well-known Java types to their Python counterparts.

See the `java2python.config.default` module for the default type

mapping and further discussion.

"""

ident = node.token.text

subs = config.last('typeSubs')

if ident in subs:

node.token.text = subs[ident]