Scala Function & Tuple generator for java

scala_funcgen.py

#!/usr/bin/env python3

'''
A script to generate the barebone implementation of scala’s
Function# and Tuple# types for use in java.

I made this to allow Java projects to specify function signatures
which play nice with scala, without depending on scala’s stdlib.
'''

from os.path import basename

#Maximum number of Tuple and Product items, as well as function arguments
MAX_ARGS = 22

INTRO = '''/** This class is generated automatically.
  * Run {} to regenerate it. */

package scala;

'''.format(basename(__file__))

FUNC_TEMPLATE = INTRO + '''public abstract class Function{i}<{typeparamsR}> {{
	public abstract R apply({args});{tupled}
}}'''

METHOD_TUPLED_TEPLATE = '''
	
	public R tupled(Tuple{i}<{typeparams}> t) {{
		return apply({telems});
	}}'''

TUPLE_TEMPLATE = INTRO + '''public class Tuple{i}<{typeparams}> {{
	{fields}
	
	public Tuple{i}({args}) {{
		{assigns}
	}}
	
	public boolean equals(Tuple{i}<{objects}> t) {{
		return {equal};
	}}
	
	public String toString() {{
		return "(" + {stradd} + ")";
	}}
}}'''

def jsep(fmt, i, sep=', ', extra=None):
	'''Returns a joined list of `format` with increasing numbers until i'''
	elems = [fmt.format(j) for j in range(1, i+1)]
	if extra is not None:
		elems.append(extra)
	return sep.join(elems)

def create_function(i, fdict):
	'''Creates Function<i>.java'''
	fdict['typeparamsR'] = jsep('T{}', i, extra='R')
	fdict['tupled'] = ''
	if i != 0:
		fdict['telems'] = jsep('t._{}', i)
		fdict['tupled'] = METHOD_TUPLED_TEPLATE.format_map(fdict)
	
	with open('Function{}.java'.format(i), 'w') as function_file:
		function_file.write(FUNC_TEMPLATE.format_map(fdict))

def create_tuple(i, fdict):
	'''Creates Tuple<i>.java'''
	fdict['fields'] = jsep('public T{0} _{0};', i, sep='\n\t')
	fdict['assigns'] = jsep('this._{0} = t{0};', i, sep='\n\t\t')
	fdict['equal'] = jsep('_{0}.equals(t._{0})', i, sep='\n\t\t\t&& ')
	fdict['stradd'] = jsep('_{}', i, sep=' + ", " +')
	fdict['objects'] = jsep('Object', i)
	with open('Tuple{}.java'.format(i), 'w') as tuple_file:
		tuple_file.write(TUPLE_TEMPLATE.format_map(fdict))

def main():
	'''Creates all functions and tuples scala provides'''
	fdict = {'i': 0, 'args': ''}
	
	create_function(0, fdict)
	for i in range(1, MAX_ARGS+1):
		fdict['i'] = i
		fdict['typeparams'] = jsep('T{}', i)
		fdict['args'] = jsep('T{0} t{0}', i)
		
		create_tuple(i, fdict)
		create_function(i, fdict)

if __name__ == '__main__':
	main()