src/sim/mathexpr.hh

   1 /*
   2  * Copyright (c) 2016 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,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  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  * Authors: David Guillen Fandos
  38  */
  39
  40 #ifndef __SIM_MATHEXPR_HH__
  41 #define __SIM_MATHEXPR_HH__
  42
  43 #include <algorithm>
  44 #include <array>
  45 #include <functional>
  46 #include <string>
  47
  48 class MathExpr {
  49   public:
  50
  51     MathExpr(std::string expr);
  52
  53     typedef std::function<double(std::string)> EvalCallback;
  54
  55     /**
  56      * Prints an ASCII representation of the expression tree
  57      *
  58      * @return A string containing the ASCII representation of the expression
  59      */
  60     std::string toStr() const { return toStr(root, ""); }
  61
  62     /**
  63      * Evaluates the expression
  64      *
  65      * @param fn A callback funcion to evaluate variables
  66      *
  67      * @return The value for this expression
  68      */
  69     double eval(EvalCallback fn) const { return eval(root, fn); }
  70
  71   private:
  72     enum Operator {
  73         bAdd, bSub, bMul, bDiv, bPow, uNeg, sValue, sVariable, nInvalid
  74     };
  75
  76     // Match operators
  77     const int MAX_PRIO = 4;
  78     typedef double (*binOp)(double, double);
  79     struct OpSearch {
  80         bool binary;
  81         Operator op;
  82         int priority;
  83         char c;
  84         binOp fn;
  85     };
  86
  87     /** Operator list */
  88     std::array<OpSearch, uNeg + 1> ops;
  89
  90     class Node {
  91       public:
  92         Node() : op(nInvalid), l(0), r(0), value(0) {}
  93         std::string toStr() const {
  94             const char opStr[] = {'+', '-', '*', '/', '^', '-'};
  95             switch (op) {
  96               case nInvalid:
  97                 return "INVALID";
  98               case sVariable:
  99                 return variable;
 100               case sValue:
 101                 return std::to_string(value);
 102               default:
 103                 return std::string(1, opStr[op]);
 104             };
 105         }
 106
 107         Operator op;
 108         Node *l, *r;
 109         double value;
 110         std::string variable;
 111     };
 112
 113     /** Root node */
 114     Node * root;
 115
 116     /** Parse and create nodes from string */
 117     Node *parse(std::string expr);
 118
 119     /** Print tree as string */
 120     std::string toStr(Node *n, std::string prefix) const;
 121
 122     /** Eval a node */
 123     double eval(const Node *n, EvalCallback fn) const;
 124 };
 125
 126 #endif
 127
 128