in functions/source/KeyGen/pycparser/ply/yacc.py [0:0]
def lr_parse_table(self):
Productions = self.grammar.Productions
Precedence = self.grammar.Precedence
goto = self.lr_goto # Goto array
action = self.lr_action # Action array
log = self.log # Logger for output
actionp = {} # Action production array (temporary)
log.info('Parsing method: %s', self.lr_method)
# Step 1: Construct C = { I0, I1, ... IN}, collection of LR(0) items
# This determines the number of states
C = self.lr0_items()
if self.lr_method == 'LALR':
self.add_lalr_lookaheads(C)
# Build the parser table, state by state
st = 0
for I in C:
# Loop over each production in I
actlist = [] # List of actions
st_action = {}
st_actionp = {}
st_goto = {}
log.info('')
log.info('state %d', st)
log.info('')
for p in I:
log.info(' (%d) %s', p.number, p)
log.info('')
for p in I:
if p.len == p.lr_index + 1:
if p.name == "S'":
# Start symbol. Accept!
st_action['$end'] = 0
st_actionp['$end'] = p
else:
# We are at the end of a production. Reduce!
if self.lr_method == 'LALR':
laheads = p.lookaheads[st]
else:
laheads = self.grammar.Follow[p.name]
for a in laheads:
actlist.append((a, p, 'reduce using rule %d (%s)' % (p.number, p)))
r = st_action.get(a)
if r is not None:
# Whoa. Have a shift/reduce or reduce/reduce conflict
if r > 0:
# Need to decide on shift or reduce here
# By default we favor shifting. Need to add
# some precedence rules here.
# Shift precedence comes from the token
sprec, slevel = Precedence.get(a, ('right', 0))
# Reduce precedence comes from rule being reduced (p)
rprec, rlevel = Productions[p.number].prec
if (slevel < rlevel) or ((slevel == rlevel) and (rprec == 'left')):
# We really need to reduce here.
st_action[a] = -p.number
st_actionp[a] = p
if not slevel and not rlevel:
log.info(' ! shift/reduce conflict for %s resolved as reduce', a)
self.sr_conflicts.append((st, a, 'reduce'))
Productions[p.number].reduced += 1
elif (slevel == rlevel) and (rprec == 'nonassoc'):
st_action[a] = None
else:
# Hmmm. Guess we'll keep the shift
if not rlevel:
log.info(' ! shift/reduce conflict for %s resolved as shift', a)
self.sr_conflicts.append((st, a, 'shift'))
elif r < 0:
# Reduce/reduce conflict. In this case, we favor the rule
# that was defined first in the grammar file
oldp = Productions[-r]
pp = Productions[p.number]
if oldp.line > pp.line:
st_action[a] = -p.number
st_actionp[a] = p
chosenp, rejectp = pp, oldp
Productions[p.number].reduced += 1
Productions[oldp.number].reduced -= 1
else:
chosenp, rejectp = oldp, pp
self.rr_conflicts.append((st, chosenp, rejectp))
log.info(' ! reduce/reduce conflict for %s resolved using rule %d (%s)',
a, st_actionp[a].number, st_actionp[a])
else:
raise LALRError('Unknown conflict in state %d' % st)
else:
st_action[a] = -p.number
st_actionp[a] = p
Productions[p.number].reduced += 1
else:
i = p.lr_index
a = p.prod[i+1] # Get symbol right after the "."
if a in self.grammar.Terminals:
g = self.lr0_goto(I, a)
j = self.lr0_cidhash.get(id(g), -1)
if j >= 0:
# We are in a shift state
actlist.append((a, p, 'shift and go to state %d' % j))
r = st_action.get(a)
if r is not None:
# Whoa have a shift/reduce or shift/shift conflict
if r > 0:
if r != j:
raise LALRError('Shift/shift conflict in state %d' % st)
elif r < 0:
# Do a precedence check.
# - if precedence of reduce rule is higher, we reduce.
# - if precedence of reduce is same and left assoc, we reduce.
# - otherwise we shift
# Shift precedence comes from the token
sprec, slevel = Precedence.get(a, ('right', 0))
# Reduce precedence comes from the rule that could have been reduced
rprec, rlevel = Productions[st_actionp[a].number].prec
if (slevel > rlevel) or ((slevel == rlevel) and (rprec == 'right')):
# We decide to shift here... highest precedence to shift
Productions[st_actionp[a].number].reduced -= 1
st_action[a] = j
st_actionp[a] = p
if not rlevel:
log.info(' ! shift/reduce conflict for %s resolved as shift', a)
self.sr_conflicts.append((st, a, 'shift'))
elif (slevel == rlevel) and (rprec == 'nonassoc'):
st_action[a] = None
else:
# Hmmm. Guess we'll keep the reduce
if not slevel and not rlevel:
log.info(' ! shift/reduce conflict for %s resolved as reduce', a)
self.sr_conflicts.append((st, a, 'reduce'))
else:
raise LALRError('Unknown conflict in state %d' % st)
else:
st_action[a] = j
st_actionp[a] = p
# Print the actions associated with each terminal
_actprint = {}
for a, p, m in actlist:
if a in st_action:
if p is st_actionp[a]:
log.info(' %-15s %s', a, m)
_actprint[(a, m)] = 1
log.info('')
# Print the actions that were not used. (debugging)
not_used = 0
for a, p, m in actlist:
if a in st_action:
if p is not st_actionp[a]:
if not (a, m) in _actprint:
log.debug(' ! %-15s [ %s ]', a, m)
not_used = 1
_actprint[(a, m)] = 1
if not_used:
log.debug('')
# Construct the goto table for this state
nkeys = {}
for ii in I:
for s in ii.usyms:
if s in self.grammar.Nonterminals:
nkeys[s] = None
for n in nkeys:
g = self.lr0_goto(I, n)
j = self.lr0_cidhash.get(id(g), -1)
if j >= 0:
st_goto[n] = j
log.info(' %-30s shift and go to state %d', n, j)
action[st] = st_action
actionp[st] = st_actionp
goto[st] = st_goto
st += 1