def peglet_to_parson(text):
nonterminals = set()
def equ(name, space):
nonterminals.add(name)
return name, space, ': '
g = grammar(equ=alter(equ), mk_regex=mk_regex)
tokens = g.grammar(text)
return ''.join(':'+token if re.match(name+'$', token) and token not in nonterminals
else token
for token in tokens)
def peglet_to_parson(text):
nonterminals = set()
def equ(name, space):
nonterminals.add(name)
return name, space, ': '
g = grammar(equ=alter(equ), mk_regex=mk_regex)
tokens = g.grammar(text)
return ''.join(
':' +
token if re.match(name +
'$', token) and token not in nonterminals else token
for token in tokens)
def nullify(fn):
def nullified(*args):
fn(*args)
return ()
return alter(nullified)
"""
Tiny example of 'compiling'.
"""
from parson import Grammar, alter
g = Grammar(r""" stmt* :end.
stmt : ident '=' exp0 ';' :assign.
exp0 : exp1 ('+' exp1 :'add')*.
exp1 : exp2 ('*' exp2 :'mul')*.
exp2 : '(' exp0 ')'
| /(\d+)/
| ident :'fetch'.
ident : /([A-Za-z]+)/.
FNORD ~: /\s*/.
""")(assign=alter(lambda name, *rpn: rpn + (name, 'store')))
## print ' '.join(g('v = 42 * (5+3) + 2*2; v = v + 1;'))
#. 42 5 3 add mul 2 2 mul add v store v fetch 1 add v store
def nullify(fn):
return alter(lambda *args: (fn(*args), ())[1]) # XXX kinda ugh
def nullify(fn):
return alter(lambda *args: (fn(*args), ())[1]) # XXX kinda ugh
opid : /([~!@%&*\-+=|\\<>,?\\\/]+)/.
number : /(-?\d+)/ :int.
string : /'((?:''|[^'])*)'/.
FNORD ~: whitespace*.
whitespace ~: /\s+|-- .*/.
"""
# XXX string literals with '' need unescaping
def mk_block_method(params, body):
cue = ('of',) + ('and',)*(len(params)-1) if params else ('run',)
return Method(cue, params, body)
def mk_body(*exprs): return Nest(reduce(Then, exprs))
unzip = alter(lambda *parts: (parts[0::2], parts[1::2]))
parse = Grammar(parser_grammar)(**globals()).program
# Smoke test
## parse('adjoining of (k + 5) to empty')[0]
#. {adjoining of (k + 5) to empty}
## parse(': { 1 }')[0]
#. {:: {run: {1}}}
text1 = """
empty ::
{ is-empty: { yes }
; has k: { no }
