mathexpr.hh revision 11531 
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 <functional>
45#include <string>
46
47class 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  private:
71    enum Operator {
72        bAdd, bSub, bMul, bDiv, bPow, uNeg, sValue, sVariable, nInvalid
73    };
74
75    // Match operators
76    const int MAX_PRIO = 4;
77    typedef double (*binOp)(double, double);
78    struct OpSearch {
79        bool binary;
80        Operator op;
81        int priority;
82        char c;
83        binOp fn;
84    };
85
86    /** Operator list */
87    std::array<OpSearch, uNeg + 1> ops;
88
89    class Node {
90      public:
91        Node() : op(nInvalid), l(0), r(0), value(0) {}
92        std::string toStr() const {
93            const char opStr[] = {'+', '-', '*', '/', '^', '-'};
94            switch (op) {
95              case nInvalid:
96                return "INVALID";
97              case sVariable:
98                return variable;
99              case sValue:
100                return std::to_string(value);
101              default:
102                return std::string(1, opStr[op]);
103            };
104        }
105
106        Operator op;
107        Node *l, *r;
108        double value;
109        std::string variable;
110    };
111
112    /** Root node */
113    Node * root;
114
115    /** Parse and create nodes from string */
116    Node *parse(std::string expr);
117
118    /** Print tree as string */
119    std::string toStr(Node *n, std::string prefix) const;
120
121    /** Eval a node */
122    double eval(const Node *n, EvalCallback fn) const;
123};
124
125#endif
126
127
128