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/*
* 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;
}
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