ostrich.preop.ExtractPreOp.scala Maven / Gradle / Ivy

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/**
 * This file is part of Ostrich, an SMT solver for strings.
 * Copyright (c) 2020 Zhilei Han. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 * 
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * 
 * * Neither the name of the authors nor the names of their
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package ostrich.preop

import ostrich.automata.{Regex2PFA, PrioStreamingTransducer, PrioAutomaton,
                         TLabelOps, AnchoredLabels, StreamingTransducer}
import StreamingTransducer._
import AnchoredLabels._

import scala.collection.mutable.{HashSet => MHashSet,
                                 LinkedHashSet => MLinkedHashSet,
                                 HashMap => MHashMap,
                                 Stack => MStack,
                                 MultiMap => MMultiMap,
                                 Set => MSet}

import dk.brics.automaton.{Automaton => BAutomaton,
                           State => BState,
                           Transition => BTransition}

object ExtractPreOp {

  import Regex2PFA.completeInfo

  def apply(index : Int, pat : completeInfo) : PreOp = 
    StreamingTransducerPreOp(buildPSST(index, pat))

  def buildPSST(index: Int, pat : completeInfo) : PrioStreamingTransducer = {
    val (aut, numCap, state2Caps, cap2Init) = pat

    // we just need one capture group
    val builder = PrioStreamingTransducer.getBuilder(1)

    type tranState = PrioStreamingTransducer#State
    type autState = PrioAutomaton.State
    type TLabel = PrioAutomaton.TLabel
    val LabelOps : TLabelOps[TLabel] = AnchoredLabelOps

    // some common update operations
    def nochange : Seq[Seq[UpdateOp]] = List(List(RefVariable(0)))
    def append_after : Seq[Seq[UpdateOp]] = List(List(RefVariable(0), Offset(0)))
    def clear : Seq[Seq[UpdateOp]] = List(List())
    def single : Seq[Seq[UpdateOp]] = List(List(Offset(0)))

    val output = List(RefVariable(0))

    val sMap = new MHashMap[tranState, autState]
    val sMapRev = new MHashMap[autState, tranState]

    // states of new transducer to be constructed
    val worklist = new MStack[tranState]

    def mapState(s : tranState, q : autState) = {
      sMap += (s -> q)
      sMapRev += (q -> s)
    }

    // creates and adds to worklist any new states if needed
    def getState(as : autState) : tranState = {
      sMapRev.getOrElse(as, {
        val s = builder.getNewState
        mapState(s, as)
        builder.setAccept(s, false, output)
        worklist.push(s)
        s
      })
    }

    val tranInit = builder.initialState
    builder.setInitialState(tranInit)

    val autInit = getState(aut.initial)
    //val initial_activated = state2Caps.getOrElse(aut.initial, Set()) contains index
    //if (initial_activated) {
      //builder.addPreETransition(tranInit, List(List()), autInit) // initialize to epsilon
    //} else {
      //builder.addPreETransition(tranInit, List(List(Constant('\u0000'))), autInit) // initialize to null
    //}
    builder.addPreETransition(tranInit, List(List(Constant('\u0000'))), autInit) // initialize to null

    def getOps(current : autState, next: autState) = {
      val caps_activated_old = state2Caps.getOrElse(current, Set())
      val is_activated_old = caps_activated_old contains index

      val caps_activated = state2Caps.getOrElse(next, Set())
      val is_activated = caps_activated contains index

      if (is_activated && is_activated_old) {
        // so the transition current -> next is in the
        // subgraph which is the counterpart of capture group `index`..

        // now let's check if `current` is in the initial states:
        val initials_of_index = cap2Init.getOrElse(index, Set())
        val is_current_initial = initials_of_index contains current
        if (is_current_initial) {
          // the subgraph is 're-entered', clear the content
          clear
        } else {
          // normal case
          append_after
        }
      } else {
        // the transition is not relevant to capture group `index`
        nochange
      }
    }

    // dfs
    while (!worklist.isEmpty) {
      val ts = worklist.pop()
      val as = sMap(ts)

      var priority = Int.MaxValue
      for (trans <- aut.preTran.get(as).iterator; next <- trans) {
        builder.addPreETransition(ts, getOps(as, next), priority, getState(next))
        priority -= 1
      }

      priority = Int.MaxValue
      for (trans <- aut.postTran.get(as).iterator; next <- trans) {
        builder.addPostETransition(ts, getOps(as, next), priority, getState(next))
        priority -= 1
      }

      priority = Int.MaxValue
      for (trans <- aut.sTran.get(as).iterator; (lbl, next) <- trans) {
        builder.addTransition(ts, lbl, getOps(as, next), priority, getState(next))
        priority -= 1
      }
    }

    val (f1, f2) = aut.accepting

    for (s <- f1) {
      val tranEnd = getState(s)
      builder.setAccept(tranEnd, true, output)
    }
    for (s <- f2) {
      val tranEnd = getState(s)
      builder.setAccept(tranEnd, true, output)
    }

    val tran = builder.getTransducer
    tran
  }
}