blob: 7c5df801a610c16f47ad0e02bd10dd1499c82e2e [file] [log] [blame]
// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2019 Google Inc. All rights reserved.
// http://code.google.com/p/ceres-solver/
//
// 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 Google Inc. 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.
//
// Author: darius.rueckert@fau.de (Darius Rueckert)
#ifndef CERES_PUBLIC_CODEGEN_INTERNAL_EXPRESSION_GRAPH_H_
#define CERES_PUBLIC_CODEGEN_INTERNAL_EXPRESSION_GRAPH_H_
#include <vector>
#include "expression.h"
namespace ceres {
namespace internal {
// A directed, acyclic, unconnected graph containing all expressions of a
// program.
//
// The expression graph is stored linear in the expressions_ array. The order is
// identical to the execution order. Each expression can have multiple children
// and multiple parents.
// A is child of B <=> B has A as a parameter <=> B.DirectlyDependsOn(A)
// A is parent of B <=> A has B as a parameter <=> A.DirectlyDependsOn(B)
class ExpressionGraph {
public:
// Checks if A depends on B.
// -> B is a descendant of A
bool DependsOn(ExpressionId A, ExpressionId B) const;
bool operator==(const ExpressionGraph& other) const;
bool operator!=(const ExpressionGraph& other) const {
return !(*this == other);
}
Expression& ExpressionForId(ExpressionId id) { return expressions_[id]; }
const Expression& ExpressionForId(ExpressionId id) const {
return expressions_[id];
}
int Size() const { return expressions_.size(); }
// Erases the expression at "location". All expression after "location" are
// moved by one element to the front. References to moved expressions are
// updated. Removing an expression that is still referenced somewhere is
// undefined behaviour.
void Erase(ExpressionId location);
// Insert a new expression at "location" into the graph. All expression
// after "location" are moved by one element to the back. References to
// moved expressions are updated.
void Insert(ExpressionId location, const Expression& expression);
// Adds an Expression to the end of the expression list and creates a new
// variable for the result. The id of the result variable is returned so it
// can be used for further operations.
ExpressionId InsertBack(const Expression& expression);
// Finds the closing ENDIF expression for a given IF expression. Calling this
// method is only valid on IF expressions. If no suitable ENDIF is found,
// kInvalidExpressionId is returned. Example:
// <id> <expr> FindMatchingEndif(id)
// 0 IF 7
// 1 IF 3
// 2 ELSE -
// 3 ENDIF -
// 4 ELSE -
// 5 IF 6
// 6 ENDIF -
// 7 ENDIF -
ExpressionId FindMatchingEndif(ExpressionId id) const;
// Similar to FindMatchingEndif, but returns the matching ELSE expression. If
// no suitable ELSE is found, kInvalidExpressionId is returned.
// FindMatchingElse does not throw an error is this case, because IF without
// ELSE is allowed.
// <id> <expr> FindMatchingEndif(id)
// 0 IF 4
// 1 IF 2
// 2 ELSE -
// 3 ENDIF -
// 4 ELSE -
// 5 IF kInvalidEpressionId
// 6 ENDIF -
// 7 ENDIF -
ExpressionId FindMatchingElse(ExpressionId id) const;
private:
// All Expressions are referenced by an ExpressionId. The ExpressionId is
// the index into this array. Each expression has a list of ExpressionId as
// arguments. These references form the graph.
std::vector<Expression> expressions_;
};
// After calling this method, all operations on 'ExpressionRef' objects will
// be recorded into an ExpressionGraph. You can obtain this graph by calling
// StopRecordingExpressions.
//
// Performing expression operations before calling StartRecordingExpressions
// or calling StartRecodring. twice is an error.
void StartRecordingExpressions();
// Stops recording and returns all expressions that have been executed since
// the call to StartRecordingExpressions. The internal ExpressionGraph will be
// invalidated and a second consecutive call to this method results in an
// error.
ExpressionGraph StopRecordingExpressions();
// Returns a pointer to the active expression tree.
// Normal users should not use this functions.
ExpressionGraph* GetCurrentExpressionGraph();
} // namespace internal
} // namespace ceres
#endif // CERES_PUBLIC_CODEGEN_INTERNAL_EXPRESSION_GRAPH_H_