Class: Racc::StateTransitionTableGenerator

Inherits:
Object
  • Object
show all
Defined in:
lib/racc/statetransitiontable.rb

Instance Method Summary collapse

Constructor Details

#initialize(states) ⇒ StateTransitionTableGenerator

Returns a new instance of StateTransitionTableGenerator.


70
71
72
73
# File 'lib/racc/statetransitiontable.rb', line 70

def initialize(states)
  @states = states
  @grammar = states.grammar
end

Instance Method Details

#act2actid(act) ⇒ Object


252
253
254
255
256
257
258
259
260
261
# File 'lib/racc/statetransitiontable.rb', line 252

def act2actid(act)
  case act
  when Shift  then act.goto_id
  when Reduce then -act.ruleid
  when Accept then @states.shift_n
  when Error  then @states.reduce_n * -1
  else
    raise "racc: fatal: wrong act type #{act.class} in action table"
  end
end

#addent(all, arr, chkval, ptr) ⇒ Object


174
175
176
177
178
179
180
181
182
183
184
185
# File 'lib/racc/statetransitiontable.rb', line 174

def addent(all, arr, chkval, ptr)
  max = arr.size
  min = nil
  arr.each_with_index do |item, idx|
    if item
      min ||= idx
    end
  end
  ptr.push(-7777)    # mark
  arr = arr[min...max]
  all.push [arr, chkval, mkmapexp(arr), min, ptr.size - 1]
end

#gen_action_tables(t, states) ⇒ Object


110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
# File 'lib/racc/statetransitiontable.rb', line 110

def gen_action_tables(t, states)
  t.action_table = yytable  = []
  t.action_check = yycheck  = []
  t.action_default = yydefact = []
  t.action_pointer = yypact   = []
  e1 = []
  e2 = []
  states.each do |state|
    yydefact.push act2actid(state.defact)
    if state.action.empty?
      yypact.push nil
      next
    end
    vector = []
    state.action.each do |tok, act|
      vector[tok.ident] = act2actid(act)
    end
    addent e1, vector, state.ident, yypact
  end
  set_table e1, e2, yytable, yycheck, yypact
end

#gen_goto_tables(t, grammar) ⇒ Object


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
# File 'lib/racc/statetransitiontable.rb', line 132

def gen_goto_tables(t, grammar)
  t.goto_table   = yytable2  = []
  t.goto_check   = yycheck2  = []
  t.goto_pointer = yypgoto   = []
  t.goto_default = yydefgoto = []
  e1 = []
  e2 = []
  grammar.each_nonterminal do |tok|
    tmp = []

    # decide default
    freq = Array.new(@states.size, 0)
    @states.each do |state|
      st = state.goto_table[tok]
      if st
        st = st.ident
        freq[st] += 1
      end
      tmp[state.ident] = st
    end
    max = freq.max
    if max > 1
      default = freq.index(max)
      tmp.map! {|i| default == i ? nil : i }
    else
      default = nil
    end
    yydefgoto.push default

    # delete default value
    tmp.pop until tmp.last or tmp.empty?
    if tmp.compact.empty?
      # only default
      yypgoto.push nil
      next
    end

    addent e1, tmp, (tok.ident - grammar.nonterminal_base), yypgoto
  end
  set_table e1, e2, yytable2, yycheck2, yypgoto
end

#generateObject


75
76
77
78
79
80
81
82
83
84
85
86
# File 'lib/racc/statetransitiontable.rb', line 75

def generate
  t = StateTransitionTable.new(@states)
  gen_action_tables t, @states
  gen_goto_tables t, @grammar
  t.token_table = token_table(@grammar)
  t.reduce_table = reduce_table(@grammar)
  t.reduce_n = @states.reduce_n
  t.shift_n = @states.shift_n
  t.nt_base = @grammar.nonterminal_base
  t.token_to_s_table = @grammar.symbols.map {|sym| sym.to_s }
  t
end

#mkmapexp(arr) ⇒ Object


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
224
225
# File 'lib/racc/statetransitiontable.rb', line 196

def mkmapexp(arr)
  i = ii = 0
  as = arr.size
  map = ''
  maxdup = RE_DUP_MAX
  curr = nil
  while i < as
    ii = i + 1
    if arr[i]
      ii += 1 while ii < as and arr[ii]
      curr = '-'
    else
      ii += 1 while ii < as and not arr[ii]
      curr = '.'
    end

    offset = ii - i
    if offset == 1
      map << curr
    else
      while offset > maxdup
        map << "#{curr}{#{maxdup}}"
        offset -= maxdup
      end
      map << "#{curr}{#{offset}}" if offset > 1
    end
    i = ii
  end
  Regexp.compile(map, 'n')
end

#reduce_table(grammar) ⇒ Object


88
89
90
91
92
93
94
95
96
97
98
99
100
# File 'lib/racc/statetransitiontable.rb', line 88

def reduce_table(grammar)
  t = [0, 0, :racc_error]
  grammar.each_with_index do |rule, idx|
    next if idx == 0
    t.push rule.size
    t.push rule.target.ident
    t.push(if rule.action.empty?   # and @params.omit_action_call?
           then :_reduce_none
           else "_reduce_#{idx}".intern
           end)
  end
  t
end

#set_table(entries, dummy, tbl, chk, ptr) ⇒ Object


227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
# File 'lib/racc/statetransitiontable.rb', line 227

def set_table(entries, dummy, tbl, chk, ptr)
  upper = 0
  map = '-' * 10240

  # sort long to short
  entries.sort! {|a,b| b[0].size <=> a[0].size }

  entries.each do |arr, chkval, expr, min, ptri|
    if upper + arr.size > map.size
      map << '-' * (arr.size + 1024)
    end
    idx = map.index(expr)
    ptr[ptri] = idx - min
    arr.each_with_index do |item, i|
      if item
        i += idx
        tbl[i] = item
        chk[i] = chkval
        map[i] = ?o
      end
    end
    upper = idx + arr.size
  end
end

#token_table(grammar) ⇒ Object


102
103
104
105
106
107
108
# File 'lib/racc/statetransitiontable.rb', line 102

def token_table(grammar)
  h = {}
  grammar.symboltable.terminals.each do |t|
    h[t] = t.ident
  end
  h
end