Implemented ExpressionProgram

libraries/lepton/include/ExpressionProgram.h

+#ifndef LEPTON_EXPRESSION_PROGRAM_H_
+#define LEPTON_EXPRESSION_PROGRAM_H_
+
+/* -------------------------------------------------------------------------- *
+ *                                   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 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 "ExpressionTreeNode.h"
+#include "windowsIncludes.h"
+#include <map>
+#include <string>
+#include <vector>
+
+namespace Lepton {
+
+/**
+ * An ExpressionProgram is a linear sequence of Operations for evaluating an expression.  The evaluation
+ * is done with a stack.  The arguments to each Operation are first taken off the stack in order, then it is
+ * evaluated and the result is pushed back onto the stack.  At the end, the stack contains a single value,
+ * which is the value of the expression.
+ *
+ * An ExpressionProgram is created by calling createProgram() on a ParsedExpression.  It can generally be evaluated
+ * more quickly than the ParsedExpression itself, so when you need to evaluate an expression many times, it is
+ * most efficient to create an ExpressionProgram from it.
+ */
+
+class LEPTON_EXPORT ExpressionProgram {
+public:
+    ExpressionProgram(const ExpressionProgram& program);
+    ~ExpressionProgram();
+    ExpressionProgram& operator=(const ExpressionProgram& program);
+    /**
+     * Get the number of Operations that make up this program.
+     */
+    int getNumOperations() const;
+    /**
+     * Get an Operation in this program.
+     */
+    const Operation& getOperation(int index) const;
+    /**
+     * Get the size of the stack needed to execute this program.  This is the largest number of elements present
+     * on the stack at any point during evaluation.
+     */
+    int getStackSize() const;
+    /**
+     * Evaluate the expression.  If the expression involves any variables, this method will throw an exception.
+     */
+    double evaluate() const;
+    /**
+     * Evaluate the expression.
+     *
+     * @param variables    a map specifying the values of all variables that appear in the expression.  If any
+     *                     variable appears in the expression but is not included in this map, an exception
+     *                     will be thrown.
+     */
+    double evaluate(const std::map<std::string, double>& variables) const;
+private:
+    friend class ParsedExpression;
+    ExpressionProgram(const ParsedExpression& expression);
+    void buildProgram(const ExpressionTreeNode& node);
+    std::vector<Operation*> operations;
+    int maxArgs, stackSize;
+};
+
+} // namespace Lepton
+
+#endif /*LEPTON_EXPRESSION_PROGRAM_H_*/

libraries/lepton/include/ParsedExpression.h

@@ -39,6 +39,8 @@
 
 namespace Lepton {
 
+class ExpressionProgram;
+
 /**
  * This class represents the result of parsing an expression.  It provides methods for working with the
  * expression in various ways, such as evaluating it, getting the tree representation of the expresson, etc.
@@ -50,7 +52,7 @@ public:
      * Create a ParsedExpression.  Normally you will not call this directly.  Instead, use the Parser class
      * to parse expression.
      */
-    ParsedExpression(ExpressionTreeNode rootNode);
+    ParsedExpression(const ExpressionTreeNode& rootNode);
     /**
      * Get the root node of the expression's abstract syntax tree.
      */
@@ -86,6 +88,10 @@ public:
      * @param variable     the variable with respect to which the derivate should be taken
      */
     ParsedExpression differentiate(const std::string& variable) const;
+    /**
+     * Create an ExpressionProgram that represents the same calculation as this expression.
+     */
+    ExpressionProgram createProgram() const;
 private:
     static double evaluate(const ExpressionTreeNode& node, const std::map<std::string, double>& variables);
     static ExpressionTreeNode preevaluateVariables(const ExpressionTreeNode& node, const std::map<std::string, double>& variables);

libraries/lepton/src/ExpressionProgram.cpp

+/* -------------------------------------------------------------------------- *
+ *                                   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 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;
+using namespace std;
+
+ExpressionProgram::ExpressionProgram(const ParsedExpression& expression) : maxArgs(0), stackSize(0) {
+    buildProgram(expression.getRootNode());
+    int currentStackSize = 0;
+    for (int 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 (int 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 (int i = 0; i < operations.size(); i++)
+        operations[i] = program.operations[i]->clone();
+    return *this;
+}
+
+void ExpressionProgram::buildProgram(const ExpressionTreeNode& node) {
+    for (int i = node.getChildren().size()-1; i >= 0; i--)
+        buildProgram(node.getChildren()[i]);
+    operations.push_back(node.getOperation().clone());
+}
+
+int ExpressionProgram::getNumOperations() const {
+    return operations.size();
+}
+
+const Operation& ExpressionProgram::getOperation(int index) const {
+    return *operations[index];
+}
+
+int ExpressionProgram::getStackSize() const {
+    return stackSize;
+}
+
+double ExpressionProgram::evaluate() const {
+    return evaluate(map<string, double>());
+}
+
+double ExpressionProgram::evaluate(const std::map<std::string, double>& variables) const {
+    vector<double> args(maxArgs);
+    vector<double> stack(stackSize);
+    int stackPointer = 0;
+    for (int i = 0; i < operations.size(); i++) {
+        int numArgs = operations[i]->getNumArguments();
+        for (int j = 0; j < numArgs; j++)
+            args[j] = stack[--stackPointer];
+        stack[stackPointer++] = operations[i]->evaluate(&args[0], variables);
+    }
+    return stack[0];
+}

libraries/lepton/src/ParsedExpression.cpp

@@ -30,6 +30,7 @@
  * -------------------------------------------------------------------------- */
 
 #include "ParsedExpression.h"
+#include "ExpressionProgram.h"
 #include "Operation.h"
 #include <limits>
 #include <vector>
@@ -37,7 +38,7 @@
 using namespace Lepton;
 using namespace std;
 
-ParsedExpression::ParsedExpression(ExpressionTreeNode rootNode) : rootNode(rootNode) {
+ParsedExpression::ParsedExpression(const ExpressionTreeNode& rootNode) : rootNode(rootNode) {
 }
 
 const ExpressionTreeNode& ParsedExpression::getRootNode() const {
@@ -105,6 +106,7 @@ ExpressionTreeNode ParsedExpression::substituteSimplerExpression(const Expressio
         children[i] = substituteSimplerExpression(node.getChildren()[i]);
     switch (node.getOperation().getId()) {
         case Operation::ADD:
+        {
             double first = getConstantValue(children[0]);
             double second = getConstantValue(children[1]);
             if (first == 0.0)
@@ -116,19 +118,23 @@ ExpressionTreeNode ParsedExpression::substituteSimplerExpression(const Expressio
             if (second == 1.0)
                 return ExpressionTreeNode(new Operation::Increment(), children[0]);
             break;
+        }
         case Operation::SUBTRACT:
-            first = getConstantValue(children[0]);
+        {
+            double first = getConstantValue(children[0]);
             if (first == 0.0)
                 return ExpressionTreeNode(new Operation::Negate(), children[1]);
-            second = getConstantValue(children[1]);
+            double second = getConstantValue(children[1]);
             if (second == 0.0)
                 return children[0];
             if (second == 1.0)
                 return ExpressionTreeNode(new Operation::Decrement(), children[0]);
             break;
+        }
         case Operation::MULTIPLY:
-            first = getConstantValue(children[0]);
-            second = getConstantValue(children[1]);
+        {
+            double first = getConstantValue(children[0]);
+            double second = getConstantValue(children[1]);
             if (first == 0.0 || second == 0.0)
                 return ExpressionTreeNode(new Operation::Constant(0.0));
             if (first == 1.0)
@@ -136,7 +142,9 @@ ExpressionTreeNode ParsedExpression::substituteSimplerExpression(const Expressio
             if (second == 1.0)
                 return children[0];
             break;
+        }
         case Operation::DIVIDE:
+        {
             double numerator = getConstantValue(children[0]);
             if (numerator = 0.0)
                 return ExpressionTreeNode(new Operation::Constant(0.0));
@@ -146,7 +154,9 @@ ExpressionTreeNode ParsedExpression::substituteSimplerExpression(const Expressio
             if (denominator == 1.0)
                 return children[0];
             break;
+        }
         case Operation::POWER:
+        {
             double base = getConstantValue(children[0]);
             if (base == 0.0)
                 return ExpressionTreeNode(new Operation::Constant(0.0));
@@ -165,6 +175,7 @@ ExpressionTreeNode ParsedExpression::substituteSimplerExpression(const Expressio
                 return ExpressionTreeNode(new Operation::Sqrt(), children[0]);
             break;
         }
+    }
     return ExpressionTreeNode(node.getOperation().clone(), children);
 }
 
@@ -185,6 +196,10 @@ double ParsedExpression::getConstantValue(const ExpressionTreeNode& node) {
     return numeric_limits<double>::quiet_NaN();
 }
 
+ExpressionProgram ParsedExpression::createProgram() const {
+    return ExpressionProgram(*this);
+}
+
 ostream& Lepton::operator<<(ostream& out, const ExpressionTreeNode& node) {
     out << node.getOperation().getName();
     if (node.getChildren().size() > 0) {