src/sim/mathexpr.hh

   1 /*
   2  * Copyright (c) 2016, 2020 ARM Limited
   3  * All rights reserved
   4  *
   5  * The license below extends only to copyright in the software and shall
   6  * not be construed as granting a license to any other intellectual
   7  * property including but not limited to intellectual property relating
   8  * to a hardware implementation of the functionality of the software
   9  * licensed hereunder.  You may use the software subject to the license
  10  * terms below provided that you ensure that this notice is replicated
  11  * unmodified and in its entirety in all distributions of the software,
  12  * modified or unmodified, in source code or in binary form.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions are
  16  * met: redistributions of source code must retain the above copyright
  17  * notice, this list of conditions and the following disclaimer;
  18  * redistributions in binary form must reproduce the above copyright
  19  * notice, this list of conditions and the following disclaimer in the
  20  * documentation and/or other materials provided with the distribution;
  21  * neither the name of the copyright holders nor the names of its
  22  * contributors may be used to endorse or promote products derived from
  23  * this software without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  26  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  28  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  29  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  31  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  35  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 #ifndef __SIM_MATHEXPR_HH__
  39 #define __SIM_MATHEXPR_HH__
  40
  41 #include <algorithm>
  42 #include <array>
  43 #include <functional>
  44 #include <string>
  45 #include <vector>
  46
  47 class MathExpr {
  48   public:
  49
  50     MathExpr(std::string expr);
  51
  52     typedef std::function<double(std::string)> EvalCallback;
  53
  54     /**
  55      * Prints an ASCII representation of the expression tree
  56      *
  57      * @return A string containing the ASCII representation of the expression
  58      */
  59     std::string toStr() const { return toStr(root, ""); }
  60
  61     /**
  62      * Evaluates the expression
  63      *
  64      * @param fn A callback funcion to evaluate variables
  65      *
  66      * @return The value for this expression
  67      */
  68     double eval(EvalCallback fn) const { return eval(root, fn); }
  69
  70     /**
  71      * Return all variables in the this expression.
  72      *
  73      * This function starts from the root node and traverses all nodes
  74      * while adding the variables it finds to a vector. Returns the
  75      * found variables in a vector of strings
  76      *
  77      * @return A Vector with the names of all variables
  78     */
  79     std::vector<std::string> getVariables() const
  80     {
  81         std::vector<std::string> vars;
  82         getVariables(root, vars);
  83         return vars;
  84     }
  85
  86   private:
  87     enum Operator {
  88         bAdd, bSub, bMul, bDiv, bPow, uNeg, sValue, sVariable, nInvalid
  89     };
  90
  91     // Match operators
  92     const int MAX_PRIO = 4;
  93     typedef double (*binOp)(double, double);
  94     struct OpSearch {
  95         bool binary;
  96         Operator op;
  97         int priority;
  98         char c;
  99         binOp fn;
 100     };
 101
 102     /** Operator list */
 103     std::array<OpSearch, uNeg + 1> ops;
 104
 105     class Node {
 106       public:
 107         Node() : op(nInvalid), l(0), r(0), value(0) {}
 108         std::string toStr() const {
 109             const char opStr[] = {'+', '-', '*', '/', '^', '-'};
 110             switch (op) {
 111               case nInvalid:
 112                 return "INVALID";
 113               case sVariable:
 114                 return variable;
 115               case sValue:
 116                 return std::to_string(value);
 117               default:
 118                 return std::string(1, opStr[op]);
 119             };
 120         }
 121
 122         Operator op;
 123         Node *l, *r;
 124         double value;
 125         std::string variable;
 126     };
 127
 128     /** Root node */
 129     Node * root;
 130
 131     /** Parse and create nodes from string */
 132     Node *parse(std::string expr);
 133
 134     /** Print tree as string */
 135     std::string toStr(Node *n, std::string prefix) const;
 136
 137     /** Eval a node */
 138     double eval(const Node *n, EvalCallback fn) const;
 139
 140     /** Return all variable reachable from a node to a vector of
 141      * strings */
 142     void getVariables(const Node *n, std::vector<std::string> &vars) const;
 143 };
 144
 145 #endif