summaryrefslogtreecommitdiff
path: root/src/sim/mathexpr.cc
blob: d94639823faab1c4ce8c8d947155871f5c7a348f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
/*
 * Copyright (c) 2016 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: David Guillen Fandos
 */

#include "sim/mathexpr.hh"

#include <algorithm>
#include <regex>
#include <string>

#include "base/misc.hh"

MathExpr::MathExpr(std::string expr)
 : ops(
    std::array<OpSearch, uNeg + 1> {
      OpSearch {true, bAdd, 0, '+', [](double a, double b) { return a + b; }},
      OpSearch {true, bSub, 0, '-', [](double a, double b) { return a - b; }},
      OpSearch {true, bMul, 1, '*', [](double a, double b) { return a * b; }},
      OpSearch {true, bDiv, 1, '/', [](double a, double b) { return a / b; }},
      OpSearch {false,uNeg, 2, '-', [](double a, double b) { return -b; }},
      OpSearch {true, bPow, 3, '^', [](double a, double b) {
                 return std::pow(a,b); }
      },
    })
{
    // Cleanup
    expr.erase(remove_if(expr.begin(), expr.end(), isspace), expr.end());

    root = MathExpr::parse(expr);
    panic_if(!root, "Invalid expression\n");
}

/**
 * This function parses a string expression into an expression tree.
 * It will look for operators in priority order to recursively build the
 * tree, respecting parenthesization.
 * Constants can be expressed in any format accepted by std::stod, whereas
 * variables are essentially [A-Za-z0-9\.$\\]+
 */
MathExpr::Node *
MathExpr::parse(std::string expr) {
    if (expr.size() == 0)
        return NULL;

    // From low to high priority
    int par = 0;
    for (unsigned p = 0; p < MAX_PRIO; p++) {
        for (int i = expr.size() - 1; i >= 0; i--) {
            if (expr[i] == ')')
                par++;
            if (expr[i] == '(')
                par--;

            if (par < 0) return NULL;
            if (par > 0) continue;

            for (unsigned opt = 0; opt < ops.size(); opt++) {
                if (ops[opt].priority != p) continue;
                if (ops[opt].c == expr[i]) {
                    // Try to parse each side
                    Node *l = NULL;
                    if (ops[opt].binary)
                        l = parse(expr.substr(0, i));
                    Node *r = parse(expr.substr(i + 1));
                    if ((l && r) || (!ops[opt].binary && r)) {
                        // Match!
                        Node *n = new Node();
                        n->op = ops[opt].op;
                        n->l = l;
                        n->r = r;
                        return n;
                    }
                }
            }
        }
    }

    // Remove trivial parenthesis
    if (expr.size() >= 2 && expr[0] == '(' && expr[expr.size() - 1] == ')')
        return parse(expr.substr(1, expr.size() - 2));

    // Match a number
    {
        char *sptr;
        double v = strtod(expr.c_str(), &sptr);
        if (sptr != expr.c_str()) {
            Node *n = new Node();
            n->op = sValue;
            n->value = v;
            return n;
        }
    }

    // Match a variable
    {
        bool contains_non_alpha = false;
        for (auto & c: expr)
            contains_non_alpha = contains_non_alpha or
                !( (c >= 'a' && c <= 'z') ||
                   (c >= 'A' && c <= 'Z') ||
                   (c >= '0' && c <= '9') ||
                   c == '$' || c == '\\' || c == '.' || c == '_');

        if (!contains_non_alpha) {
            Node * n = new Node();
            n->op = sVariable;
            n->variable = expr;
            return n;
        }
    }

    return NULL;
}

double
MathExpr::eval(const Node *n, EvalCallback fn) const {
    if (!n)
        return 0;
    else if (n->op == sValue)
        return n->value;
    else if (n->op == sVariable)
        return fn(n->variable);

    for (auto & opt : ops)
        if (opt.op == n->op)
            return opt.fn( eval(n->l, fn), eval(n->r, fn) );

    panic("Invalid node!\n");
    return 0;
}

std::string
MathExpr::toStr(Node *n, std::string prefix) const {
    std::string ret;
    ret += prefix + "|-- " + n->toStr() + "\n";
    if (n->r)
        ret += toStr(n->r, prefix + "|   ");
    if (n->l)
        ret += toStr(n->l, prefix + "|   ");
    return ret;
}