src/expr/node_algorithm.h

   1 /*********************                                                        */
   2 /*! \file node_algorithm.h
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Andrew Reynolds, Andres Noetzli, Haniel Barbosa
   6  ** This file is part of the CVC4 project.
   7  ** Copyright (c) 2009-2019 by the authors listed in the file AUTHORS
   8  ** in the top-level source directory) and their institutional affiliations.
   9  ** All rights reserved.  See the file COPYING in the top-level source
  10  ** directory for licensing information.\endverbatim
  11  **
  12  ** \brief Common algorithms on nodes
  13  **
  14  ** This file implements common algorithms applied to nodes, such as checking if
  15  ** a node contains a free or a bound variable. This file should generally only
  16  ** be included in source files.
  17  **/
  18
  19 #include "cvc4_private.h"
  20
  21 #ifndef CVC4__EXPR__NODE_ALGORITHM_H
  22 #define CVC4__EXPR__NODE_ALGORITHM_H
  23
  24 #include <unordered_map>
  25 #include <vector>
  26
  27 #include "expr/node.h"
  28 #include "expr/type_node.h"
  29
  30 namespace CVC4 {
  31 namespace expr {
  32
  33 /**
  34  * Check if the node n has a subterm t.
  35  * @param n The node to search in
  36  * @param t The subterm to search for
  37  * @param strict If true, a term is not considered to be a subterm of itself
  38  * @return true iff t is a subterm in n
  39  */
  40 bool hasSubterm(TNode n, TNode t, bool strict = false);
  41
  42 /**
  43  * Check if the node n has >1 occurrences of a subterm t.
  44  */
  45 bool hasSubtermMulti(TNode n, TNode t);
  46
  47 /**
  48  * @param k The kind of node to check
  49  * @param n The node to search in.
  50  * @return true iff there is a term in n that has kind k
  51  */
  52 bool hasSubtermKind(Kind k, Node n);
  53
  54 /**
  55  * Check if the node n has a subterm that occurs in t.
  56  * @param n The node to search in
  57  * @param t The set of subterms to search for
  58  * @param strict If true, a term is not considered to be a subterm of itself
  59  * @return true iff there is a term in t that is a subterm in n
  60  */
  61 bool hasSubterm(TNode n, const std::vector<Node>& t, bool strict = false);
  62
  63 /**
  64  * Returns true iff the node n contains a bound variable, that is a node of
  65  * kind BOUND_VARIABLE. This bound variable may or may not be free.
  66  * @param n The node under investigation
  67  * @return true iff this node contains a bound variable
  68  */
  69 bool hasBoundVar(TNode n);
  70
  71 /**
  72  * Returns true iff the node n contains a free variable, that is, a node
  73  * of kind BOUND_VARIABLE that is not bound in n.
  74  * @param n The node under investigation
  75  * @return true iff this node contains a free variable.
  76  */
  77 bool hasFreeVar(TNode n);
  78
  79 /**
  80  * Returns true iff the node n contains a closure, that is, a node
  81  * whose kind is FORALL, EXISTS, WITNESS, LAMBDA, or any other closure currently
  82  * supported.
  83  * @param n The node under investigation
  84  * @return true iff this node contains a closure.
  85  */
  86 bool hasClosure(Node n);
  87
  88 /**
  89  * Get the free variables in n, that is, the subterms of n of kind
  90  * BOUND_VARIABLE that are not bound in n, adds these to fvs.
  91  * @param n The node under investigation
  92  * @param fvs The set which free variables are added to
  93  * @param computeFv If this flag is false, then we only return true/false and
  94  * do not add to fvs.
  95  * @return true iff this node contains a free variable.
  96  */
  97 bool getFreeVariables(TNode n,
  98                       std::unordered_set<Node, NodeHashFunction>& fvs,
  99                       bool computeFv = true);
 100
 101 /**
 102  * Get all variables in n.
 103  * @param n The node under investigation
 104  * @param vs The set which free variables are added to
 105  * @return true iff this node contains a free variable.
 106  */
 107 bool getVariables(TNode n, std::unordered_set<TNode, TNodeHashFunction>& vs);
 108
 109 /**
 110  * For term n, this function collects the symbols that occur as a subterms
 111  * of n. A symbol is a variable that does not have kind BOUND_VARIABLE.
 112  * @param n The node under investigation
 113  * @param syms The set which the symbols of n are added to
 114  */
 115 void getSymbols(TNode n, std::unordered_set<Node, NodeHashFunction>& syms);
 116
 117 /**
 118  * For term n, this function collects the symbols that occur as a subterms
 119  * of n. A symbol is a variable that does not have kind BOUND_VARIABLE.
 120  * @param n The node under investigation
 121  * @param syms The set which the symbols of n are added to
 122  * @param visited A cache to be used for visited nodes.
 123  */
 124 void getSymbols(TNode n,
 125                 std::unordered_set<Node, NodeHashFunction>& syms,
 126                 std::unordered_set<TNode, TNodeHashFunction>& visited);
 127
 128 /**
 129  * For term n, this function collects the operators that occur in n.
 130  * @param n The node under investigation
 131  * @param ops The map (from each type to operators of that type) which the
 132  * operators of n are added to
 133  */
 134 void getOperatorsMap(
 135     TNode n,
 136     std::map<TypeNode, std::unordered_set<Node, NodeHashFunction>>& ops);
 137
 138 /**
 139  * For term n, this function collects the operators that occur in n.
 140  * @param n The node under investigation
 141  * @param ops The map (from each type to operators of that type) which the
 142  * operators of n are added to
 143  * @param visited A cache to be used for visited nodes.
 144  */
 145 void getOperatorsMap(
 146     TNode n,
 147     std::map<TypeNode, std::unordered_set<Node, NodeHashFunction>>& ops,
 148     std::unordered_set<TNode, TNodeHashFunction>& visited);
 149
 150 /*
 151  * Substitution of Nodes in a capture avoiding way.
 152  * If x occurs free in n and it is substituted by a term t
 153  * and t includes some variable y that is bound in n,
 154  * then using alpha conversion y is replaced with a fresh bound variable
 155  * before the substitution.
 156  *
 157  */
 158 Node substituteCaptureAvoiding(TNode n, Node src, Node dest);
 159
 160 /**
 161  * Same as substituteCaptureAvoiding above, but with a
 162  * simultaneous substitution of a vector of variables.
 163  * Elements in source will be replaced by their corresponding element in dest.
 164  * Both vectors should have the same size.
 165  */
 166 Node substituteCaptureAvoiding(TNode n,
 167                                std::vector<Node>& src,
 168                                std::vector<Node>& dest);
 169
 170 /**
 171  * Get component types in type t. This adds all types that are subterms of t
 172  * when viewed as a term. For example, if t is (Array T1 T2), then
 173  * (Array T1 T2), T1 and T2 are component types of t.
 174  * @param t The type node under investigation
 175  * @param types The set which component types are added to.
 176  */
 177 void getComponentTypes(
 178     TypeNode t, std::unordered_set<TypeNode, TypeNodeHashFunction>& types);
 179
 180 }  // namespace expr
 181 }  // namespace CVC4
 182
 183 #endif