/usr/lib/pypy/dist-packages/rply/grammar.py is in pypy-rply 0.7.4-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 | from rply.errors import ParserGeneratorError
from rply.utils import iteritems
def rightmost_terminal(symbols, terminals):
for sym in reversed(symbols):
if sym in terminals:
return sym
return None
class Grammar(object):
def __init__(self, terminals):
# A list of all the productions
self.productions = [None]
# A dictionary mapping the names of non-terminals to a list of all
# productions of that nonterminal
self.prod_names = {}
# A dictionary mapping the names of terminals to a list of the rules
# where they are used
self.terminals = dict((t, []) for t in terminals)
self.terminals["error"] = []
# A dictionary mapping names of nonterminals to a list of rule numbers
# where they are used
self.nonterminals = {}
self.first = {}
self.follow = {}
self.precedence = {}
self.start = None
def add_production(self, prod_name, syms, func, precedence):
if prod_name in self.terminals:
raise ParserGeneratorError("Illegal rule name %r" % prod_name)
if precedence is None:
precname = rightmost_terminal(syms, self.terminals)
prod_prec = self.precedence.get(precname, ("right", 0))
else:
try:
prod_prec = self.precedence[precedence]
except KeyError:
raise ParserGeneratorError(
"Precedence %r doesn't exist" % precedence
)
pnumber = len(self.productions)
self.nonterminals.setdefault(prod_name, [])
for t in syms:
if t in self.terminals:
self.terminals[t].append(pnumber)
else:
self.nonterminals.setdefault(t, []).append(pnumber)
p = Production(pnumber, prod_name, syms, prod_prec, func)
self.productions.append(p)
self.prod_names.setdefault(prod_name, []).append(p)
def set_precedence(self, term, assoc, level):
if term in self.precedence:
raise ParserGeneratorError(
"Precedence already specified for %s" % term
)
if assoc not in ["left", "right", "nonassoc"]:
raise ParserGeneratorError(
"Precedence must be one of left, right, nonassoc; not %s" % (
assoc
)
)
self.precedence[term] = (assoc, level)
def set_start(self):
start = self.productions[1].name
self.productions[0] = Production(0, "S'", [start], ("right", 0), None)
self.nonterminals[start].append(0)
self.start = start
def unused_terminals(self):
return [
t
for t, prods in iteritems(self.terminals)
if not prods and t != "error"
]
def unused_productions(self):
return [p for p, prods in iteritems(self.nonterminals) if not prods]
def build_lritems(self):
"""
Walks the list of productions and builds a complete set of the LR
items.
"""
for p in self.productions:
lastlri = p
i = 0
lr_items = []
while True:
if i > p.getlength():
lri = None
else:
try:
before = p.prod[i - 1]
except IndexError:
before = None
try:
after = self.prod_names[p.prod[i]]
except (IndexError, KeyError):
after = []
lri = LRItem(p, i, before, after)
lastlri.lr_next = lri
if lri is None:
break
lr_items.append(lri)
lastlri = lri
i += 1
p.lr_items = lr_items
def _first(self, beta):
result = []
for x in beta:
x_produces_empty = False
for f in self.first[x]:
if f == "<empty>":
x_produces_empty = True
else:
if f not in result:
result.append(f)
if not x_produces_empty:
break
else:
result.append("<empty>")
return result
def compute_first(self):
for t in self.terminals:
self.first[t] = [t]
self.first["$end"] = ["$end"]
for n in self.nonterminals:
self.first[n] = []
changed = True
while changed:
changed = False
for n in self.nonterminals:
for p in self.prod_names[n]:
for f in self._first(p.prod):
if f not in self.first[n]:
self.first[n].append(f)
changed = True
def compute_follow(self):
for k in self.nonterminals:
self.follow[k] = []
start = self.start
self.follow[start] = ["$end"]
added = True
while added:
added = False
for p in self.productions[1:]:
for i, B in enumerate(p.prod):
if B in self.nonterminals:
fst = self._first(p.prod[i + 1:])
has_empty = False
for f in fst:
if f != "<empty>" and f not in self.follow[B]:
self.follow[B].append(f)
added = True
if f == "<empty>":
has_empty = True
if has_empty or i == (len(p.prod) - 1):
for f in self.follow[p.name]:
if f not in self.follow[B]:
self.follow[B].append(f)
added = True
class Production(object):
def __init__(self, num, name, prod, precedence, func):
self.name = name
self.prod = prod
self.number = num
self.func = func
self.prec = precedence
self.unique_syms = []
for s in self.prod:
if s not in self.unique_syms:
self.unique_syms.append(s)
self.lr_items = []
self.lr_next = None
self.lr0_added = 0
self.reduced = 0
def __repr__(self):
return "Production(%s -> %s)" % (self.name, " ".join(self.prod))
def getlength(self):
return len(self.prod)
class LRItem(object):
def __init__(self, p, n, before, after):
self.name = p.name
self.prod = p.prod[:]
self.prod.insert(n, ".")
self.number = p.number
self.lr_index = n
self.lookaheads = {}
self.unique_syms = p.unique_syms
self.lr_before = before
self.lr_after = after
def __repr__(self):
return "LRItem(%s -> %s)" % (self.name, " ".join(self.prod))
def getlength(self):
return len(self.prod)
|