"""
Optional fixer to transform set() calls to set literals.
"""

# Author: Benjamin Peterson

from lib2to3 import fixer_base, pytree
from lib2to3.fixer_util import token, syms



class FixSetLiteral(fixer_base.BaseFix):

BM_compatible = True
explicit = True

PATTERN = """power< 'set' trailer< '('
(atom=atom< '[' (items=listmaker< any ((',' any)* [',']) >
|
single=any) ']' >
|
atom< '(' items=testlist_gexp< any ((',' any)* [',']) > ')' >
)
')' > >
"""

def transform(self, node, results):
single = results.get("single")
if single:
# Make a fake listmaker
fake = pytree.Node(syms.listmaker, [single.clone()])
single.replace(fake)
items = fake
else:
items = results["items"]

# Build the contents of the literal
literal = [pytree.Leaf(token.LBRACE, "{")]
literal.extend(n.clone() for n in items.children)
literal.append(pytree.Leaf(token.RBRACE, "}"))
# Set the prefix of the right brace to that of the ')' or ']'
literal[-1].prefix = items.next_sibling.prefix
maker = pytree.Node(syms.dictsetmaker, literal)
maker.prefix = node.prefix

# If the original was a one tuple, we need to remove the extra comma.
if len(maker.children) == 4:
n = maker.children[2]
n.remove()
maker.children[-1].prefix = n.prefix

# Finally, replace the set call with our shiny new literal.
return maker