/*
* Encog(tm) Core v3.3 - Java Version
* http://www.heatonresearch.com/encog/
* https://github.com/encog/encog-java-core
* Copyright 2008-2014 Heaton Research, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* For more information on Heaton Research copyrights, licenses
* and trademarks visit:
* http://www.heatonresearch.com/copyright
*/
package org.encog.parse.expression.latex;
import org.encog.ml.ea.exception.EACompileError;
import org.encog.ml.prg.EncogProgram;
import org.encog.ml.prg.ProgramNode;
import org.encog.ml.prg.expvalue.ExpressionValue;
import org.encog.ml.prg.extension.NodeType;
import org.encog.ml.prg.extension.ProgramExtensionTemplate;
import org.encog.ml.prg.extension.StandardExtensions;
import org.encog.parse.expression.ExpressionNodeType;
// "x=\\frac{-b \\pm \\sqrt {b^2-4ac}}{2a}";
public class RenderLatexExpression {
private EncogProgram program;
public RenderLatexExpression() {
}
public String render(final EncogProgram theProgram) {
this.program = theProgram;
return renderNode(this.program.getRootNode());
}
private String handleConst(ProgramNode node) {
ExpressionValue v = node.getData()[0];
return v.toStringValue();
}
private String handleVar(ProgramNode node) {
int varIndex = (int)node.getData()[0].toIntValue();
return this.program.getVariables().getVariableName(varIndex);
}
private String handleFunction(ProgramNode node) {
ProgramExtensionTemplate temp = node.getTemplate();
StringBuilder result = new StringBuilder();
if (temp == StandardExtensions.EXTENSION_SQRT) {
result.append("\\sqrt{");
result.append(renderNode(node.getChildNode(0)));
result.append("}");
} else {
result.append(temp.getName());
result.append('(');
for (int i = 0; i < temp.getChildNodeCount(); i++) {
if (i > 0) {
result.append(',');
}
result.append(renderNode(node.getChildNode(i)));
}
result.append(')');
}
return result.toString();
}
private String handleOperator(ProgramNode node) {
ProgramExtensionTemplate temp = node.getTemplate();
StringBuilder result = new StringBuilder();
if (temp.getChildNodeCount() == 2) {
String a = renderNode(node.getChildNode(0));
String b = renderNode(node.getChildNode(1));
if (temp == StandardExtensions.EXTENSION_DIV) {
result.append("\\frac{");
result.append(b);
result.append("}{");
result.append(a);
result.append("}");
} else if (temp == StandardExtensions.EXTENSION_MUL) {
result.append("(");
result.append(b);
result.append("\\cdot ");
result.append(a);
result.append(")");
} else {
result.append("(");
result.append(b);
result.append(temp.getName());
result.append(a);
result.append(")");
}
} else if (temp.getChildNodeCount() == 1) {
String a = renderNode(node.getChildNode(0));
result.append("(");
result.append(temp.getName());
result.append(a);
result.append(")");
} else {
throw new EACompileError(
"An operator must have an arity of 1 or 2, probably should be made a function.");
}
return result.toString();
}
public ExpressionNodeType determineNodeType(ProgramNode node) {
if (node.getTemplate() == StandardExtensions.EXTENSION_CONST_SUPPORT) {
return ExpressionNodeType.ConstVal;
} else if (node.getTemplate() == StandardExtensions.EXTENSION_VAR_SUPPORT) {
return ExpressionNodeType.Variable;
} else if (node.getTemplate().getNodeType() == NodeType.OperatorLeft
|| node.getTemplate().getNodeType() == NodeType.OperatorRight) {
return ExpressionNodeType.Operator;
} else {
return ExpressionNodeType.Function;
}
}
private String renderNode(ProgramNode node) {
switch (determineNodeType(node)) {
case ConstVal:
return handleConst(node);
case Operator:
return handleOperator(node);
case Variable:
return handleVar(node);
case Function:
return handleFunction(node);
}
throw new EACompileError("Uknown node type: " + node.toString());
}
}