/* -------------------------------------------------------------------------- *
 *                                   Lepton                                   *
 * -------------------------------------------------------------------------- *
 * This is part of the Lepton expression parser originating from              *
 * Simbios, the NIH National Center for Physics-Based Simulation of           *
 * Biological Structures at Stanford, funded under the NIH Roadmap for        *
 * Medical Research, grant U54 GM072970. See https://simtk.org.               *
 *                                                                            *
 * Portions copyright (c) 2009-2013 Stanford University and the Authors.      *
 * Authors: Peter Eastman                                                     *
 * Contributors:                                                              *
 *                                                                            *
 * Permission is hereby granted, free of charge, to any person obtaining a    *
 * copy of this software and associated documentation files (the "Software"), *
 * to deal in the Software without restriction, including without limitation  *
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,   *
 * and/or sell copies of the Software, and to permit persons to whom the      *
 * Software is furnished to do so, subject to the following conditions:       *
 *                                                                            *
 * The above copyright notice and this permission notice shall be included in *
 * all copies or substantial portions of the Software.                        *
 *                                                                            *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,   *
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL    *
 * THE AUTHORS, CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,    *
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR      *
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE  *
 * USE OR OTHER DEALINGS IN THE SOFTWARE.                                     *
 * -------------------------------------------------------------------------- */

#include "ExpressionProgram.h"
#include "Operation.h"
#include "ParsedExpression.h"

using namespace Lepton;

ExpressionProgram::ExpressionProgram() : maxArgs(0), stackSize(0) {}

ExpressionProgram::ExpressionProgram(const ParsedExpression& expression) : maxArgs(0), stackSize(0)
{
	buildProgram(expression.getRootNode());
	int currentStackSize = 0;
	for (size_t i = 0; i < operations.size(); ++i)
	{
		int args = operations[i]->getNumArguments();
		if (args > maxArgs) { maxArgs = args; }
		currentStackSize += 1 - args;
		if (currentStackSize > stackSize) { stackSize = currentStackSize; }
	}
}

ExpressionProgram::~ExpressionProgram() { for (size_t i = 0; i < operations.size(); ++i) { delete operations[i]; } }

ExpressionProgram::ExpressionProgram(const ExpressionProgram& program) { *this = program; }

ExpressionProgram& ExpressionProgram::operator=(const ExpressionProgram& program)
{
	maxArgs   = program.maxArgs;
	stackSize = program.stackSize;
	operations.resize(program.operations.size());
	for (size_t i = 0; i < operations.size(); ++i) { operations[i] = program.operations[i]->clone(); }
	return *this;
}

void ExpressionProgram::buildProgram(const ExpressionTreeNode& node)
{
	for (size_t i = node.getChildren().size() - 1; i >= 0; i--) { buildProgram(node.getChildren()[i]); }
	operations.push_back(node.getOperation().clone());
}

int ExpressionProgram::getNumOperations() const { return int(operations.size()); }

const Operation& ExpressionProgram::getOperation(int index) const { return *operations[index]; }

int ExpressionProgram::getStackSize() const { return stackSize; }

double ExpressionProgram::evaluate() const { return evaluate(std::map<std::string, double>()); }

double ExpressionProgram::evaluate(const std::map<std::string, double>& variables) const
{
	std::vector<double> stack(stackSize + 1);
	int stackPointer = stackSize;
	for (size_t i = 0; i < operations.size(); ++i)
	{
		int numArgs   = operations[i]->getNumArguments();
		double result = operations[i]->evaluate(&stack[stackPointer], variables);
		stackPointer += numArgs - 1;
		stack[stackPointer] = result;
	}
	return stack[stackSize - 1];
}
