/******************************************************************************

 * Top contributors (to current version):

 *   Andrew Reynolds, Andres Noetzli, Yoni Zohar

 *

 * This file is part of the cvc5 project.

 *

 * Copyright (c) 2009-2021 by the authors listed in the file AUTHORS

 * in the top-level source directory and their institutional affiliations.

 * All rights reserved.  See the file COPYING in the top-level source

 * directory for licensing information.

 * ****************************************************************************

 *

 * Rewriter for the theory of strings and sequences.

 */

#include "cvc5_private.h"

#ifndef CVC5__THEORY__STRINGS__SEQUENCES_REWRITER_H

#define CVC5__THEORY__STRINGS__SEQUENCES_REWRITER_H

#include <vector>

#include "expr/node.h"

#include "theory/strings/rewrites.h"

#include "theory/strings/sequences_stats.h"

#include "theory/strings/strings_entail.h"

#include "theory/theory_rewriter.h"

namespace cvc5 {

namespace theory {

namespace strings {

{

 public:

  SequencesRewriter(HistogramStat<Rewrite>* statistics);

 protected:

  /** rewrite regular expression concatenation

   *

   * This is the entry point for post-rewriting applications of re.++.

   * Returns the rewritten form of node.

   */

  Node rewriteConcatRegExp(TNode node);

  /** rewrite regular expression star

   *

   * This is the entry point for post-rewriting applications of re.*.

   * Returns the rewritten form of node.

   */

  Node rewriteStarRegExp(TNode node);

  /** rewrite regular expression intersection/union

   *

   * This is the entry point for post-rewriting applications of re.inter and

   * re.union. Returns the rewritten form of node.

   */

  Node rewriteAndOrRegExp(TNode node);

  /** rewrite regular expression loop

   *

   * This is the entry point for post-rewriting applications of re.loop.

   * Returns the rewritten form of node.

   */

  Node rewriteLoopRegExp(TNode node);

  /** rewrite regular expression repeat

   *

   * This is the entry point for post-rewriting applications of re.repeat.

   * Returns the rewritten form of node.

   */

  Node rewriteRepeatRegExp(TNode node);

  /** rewrite regular expression option

   *

   * This is the entry point for post-rewriting applications of re.opt.

   * Returns the rewritten form of node.

   */

  Node rewriteOptionRegExp(TNode node);

  /** rewrite regular expression plus

   *

   * This is the entry point for post-rewriting applications of re.+.

   * Returns the rewritten form of node.

   */

  Node rewritePlusRegExp(TNode node);

  /** rewrite regular expression difference

   *

   * This is the entry point for post-rewriting applications of re.diff.

   * Returns the rewritten form of node.

   */

  Node rewriteDifferenceRegExp(TNode node);

  /** rewrite regular expression range

   *

   * This is the entry point for post-rewriting applications of re.range.

   * Returns the rewritten form of node.

   */

  Node rewriteRangeRegExp(TNode node);

  /** rewrite regular expression membership

   *

   * This is the entry point for post-rewriting applications of str.in.re

   * Returns the rewritten form of node.

   */

  Node rewriteMembership(TNode node);

  /** rewrite string equality extended

   *

   * This method returns a formula that is equivalent to the equality between

   * two strings s = t, given by node. It is called by rewriteEqualityExt.

   */

  Node rewriteStrEqualityExt(Node node);

  /** rewrite arithmetic equality extended

   *

   * This method returns a formula that is equivalent to the equality between

   * two arithmetic string terms s = t, given by node. t is called by

   * rewriteEqualityExt.

   */

  Node rewriteArithEqualityExt(Node node);

  /**

   * Called when node rewrites to ret.

   *

   * The rewrite r indicates the justification for the rewrite, which is printed

   * by this function for debugging.

   */

  Node returnRewrite(Node node, Node ret, Rewrite r);

 public:

  RewriteResponse postRewrite(TNode node) override;

  RewriteResponse preRewrite(TNode node) override;

  /** Expand definition */

  TrustNode expandDefinition(Node n) override;

  /** rewrite equality

   *

   * This method returns a formula that is equivalent to the equality between

   * two strings s = t, given by node. The result of rewrite is one of

   * { s = t, t = s, true, false }.

   */

  Node rewriteEquality(Node node);

  /** rewrite equality extended

   *

   * This method returns a formula that is equivalent to the equality between

   * two terms s = t, given by node, where s and t are terms in the signature

   * of the theory of strings. Notice that s and t may be of string type or

   * of Int type.

   *

   * Specifically, this function performs rewrites whose conclusion is not

   * necessarily one of { s = t, t = s, true, false }.

   */

  Node rewriteEqualityExt(Node node) override;

  /** rewrite string length

   * This is the entry point for post-rewriting terms node of the form

   *   str.len( t )

   * Returns the rewritten form of node.

   */

  Node rewriteLength(Node node);

  /** rewrite concat

   * This is the entry point for post-rewriting terms node of the form

   *   str.++( t1, .., tn )

   * Returns the rewritten form of node.

   */

  Node rewriteConcat(Node node);

  /** rewrite character at

   * This is the entry point for post-rewriting terms node of the form

   *   str.charat( s, i1 )

   * Returns the rewritten form of node.

   */

  Node rewriteCharAt(Node node);

  /** rewrite substr

   * This is the entry point for post-rewriting terms node of the form

   *   str.substr( s, i1, i2 )

   * Returns the rewritten form of node.

   */

  Node rewriteSubstr(Node node);

  /** rewrite update

   * This is the entry point for post-rewriting terms node of the form

   *   str.update( s, i1, i2 )

   * Returns the rewritten form of node.

   */

  Node rewriteUpdate(Node node);

  /** rewrite contains

   * This is the entry point for post-rewriting terms node of the form

   *   str.contains( t, s )

   * Returns the rewritten form of node.

   *

   * For details on some of the basic rewrites done in this function, see Figure

   * 7 of Reynolds et al "Scaling Up DPLL(T) String Solvers Using

   * Context-Dependent Rewriting", CAV 2017.

   */

  Node rewriteContains(Node node);

  /** rewrite indexof

   * This is the entry point for post-rewriting terms n of the form

   *   str.indexof( s, t, n )

   * Returns the rewritten form of node.

   */

  Node rewriteIndexof(Node node);

  /** rewrite indexof regular expression match

   * This is the entry point for post-rewriting terms n of the form

   *   str.indexof_re( s, r, n )

   * Returns the rewritten form of node.

   */

  Node rewriteIndexofRe(Node node);

  /** rewrite replace

   * This is the entry point for post-rewriting terms n of the form

   *   str.replace( s, t, r )

   * Returns the rewritten form of node.

   */

  Node rewriteReplace(Node node);

  /** rewrite replace all

   * This is the entry point for post-rewriting terms n of the form

   *   str.replaceall( s, t, r )

   * Returns the rewritten form of node.

   */

  Node rewriteReplaceAll(Node node);

  /** rewrite replace internal

   *

   * This method implements rewrite rules that apply to both str.replace and

   * str.replaceall. If it returns a non-null ret, then node rewrites to ret.

   */

  Node rewriteReplaceInternal(Node node);

  /** rewrite regular expression replace

   *

   * This method implements rewrite rules that apply to terms of the form

   * str.replace_re(s, r, t).

   *

   * @param node The node to rewrite

   * @return The rewritten node

   */

  Node rewriteReplaceRe(Node node);

  /** rewrite regular expression replace

   *

   * This method implements rewrite rules that apply to terms of the form

   * str.replace_re_all(s, r, t).

   *

   * @param node The node to rewrite

   * @return The rewritten node

   */

  Node rewriteReplaceReAll(Node node);

  /**

   * Returns the first, shortest sequence in n that matches r.

   *

   * @param n The constant string or sequence to search in.

   * @param r The regular expression to search for.

   * @return A pair holding the start position and the end position of the

   *         match or a pair of string::npos if r does not appear in n.

   */

  std::pair<size_t, size_t> firstMatch(Node n, Node r);

  /** rewrite string reverse

   *

   * This is the entry point for post-rewriting terms n of the form

   *   str.rev( s )

   * Returns the rewritten form of node.

   */

  Node rewriteStrReverse(Node node);

  /** rewrite prefix/suffix

   * This is the entry point for post-rewriting terms n of the form

   *   str.prefixof( s, t ) / str.suffixof( s, t )

   * Returns the rewritten form of node.

   */

  Node rewritePrefixSuffix(Node node);

  /** rewrite str.to_code

   * This is the entry point for post-rewriting terms n of the form

   *   str.to_code( t )

   * Returns the rewritten form of node.

   */

  Node rewriteStringToCode(Node node);

  /** rewrite seq.unit

   * This is the entry point for post-rewriting terms n of the form

   *   seq.unit( t )

   * Returns the rewritten form of node.

   */

  Node rewriteSeqUnit(Node node);

  /** rewrite seq.nth

   * This is the entry point for post-rewriting terms n of the form

   *   seq.nth(s, i)

   * Returns the rewritten form of node.

   */

  Node rewriteSeqNth(Node node);

  /** length preserving rewrite

   *

   * Given input n, this returns a string n' whose length is equivalent to n.

   * We apply certain normalizations to n', such as replacing all constants

   * that are not relevant to length by "A".

   */

  static Node lengthPreserveRewrite(Node n);

  /**

   * Given a symbolic length n, returns the canonical string (of type stype)

   * for that length. For example if n is constant, this function returns a

   * string consisting of "A" repeated n times. Returns the null node if no such

   * string exists.

   */

  static Node canonicalStrForSymbolicLength(Node n, TypeNode stype);

  /**

   * post-process rewrite

   *

   * If node is not an equality and ret is an equality,

   * this method applies an additional rewrite step (rewriteEqualityExt) that

   * performs additional rewrites on ret, after which we return the result of

   * this call. Otherwise, this method simply returns ret.

   */

  Node postProcessRewrite(Node node, Node ret);

  /** Reference to the rewriter statistics. */

  HistogramStat<Rewrite>* d_statistics;

  /** Instance of the entailment checker for strings. */

  StringsEntail d_stringsEntail;

}; /* class SequencesRewriter */

}  // namespace strings

}  // namespace theory

}  // namespace cvc5

#endif /* CVC5__THEORY__STRINGS__SEQUENCES_REWRITER_H */