mathexpr.hh revision 11545:17b2ccafd139 
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
48class 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
129