/
TreeBuilder.java
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/
TreeBuilder.java
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package org.kobjects.expressionparser.demo.cas;
import org.kobjects.expressionparser.ExpressionParser;
import org.kobjects.expressionparser.OperatorType;
import org.kobjects.expressionparser.Processor;
import org.kobjects.expressionparser.Tokenizer;
import org.kobjects.expressionparser.demo.cas.tree.Node;
import org.kobjects.expressionparser.demo.cas.tree.NodeFactory;
import org.kobjects.expressionparser.demo.cas.tree.UnaryFunction;
import org.kobjects.expressionparser.demo.cas.tree.Variable;
import java.util.List;
import java.util.Scanner;
import java.util.regex.Pattern;
public class TreeBuilder extends Processor<Node> {
@Override
public Node infixOperator(Tokenizer tokenizer, String name, Node left, Node right) {
switch (name.charAt(0)) {
case '+': return NodeFactory.add(left, right);
case '-':
case '−': return NodeFactory.sub(left, right);
case '/':
case ':':
case '÷': return NodeFactory.div(left, right);
case '*':
case '×':
case '⋅': return NodeFactory.mul(left, right);
case '^': return NodeFactory.pow(left, right);
}
throw new UnsupportedOperationException("Unsupported infix operator: " + name);
}
public Node implicitOperator(Tokenizer tokenizer, boolean strong, Node left, Node right) {
return infixOperator(tokenizer, "⋅", left, right);
}
@Override
public Node prefixOperator(Tokenizer tokenizer, String name, Node argument) {
if (name.equals("-") || name.equals("−")) {
return NodeFactory.neg(argument);
}
if (name.equals("+")) {
return argument;
}
return NodeFactory.f(name, argument);
}
@Override
public Node numberLiteral(Tokenizer tokenizer, String value) {
return NodeFactory.c(Double.parseDouble(value));
}
@Override
public Node identifier(Tokenizer tokenizer, String name) {
return NodeFactory.var(name);
}
@Override
public Node group(Tokenizer tokenizer, String paren, List<Node> elements) {
return elements.get(0);
}
@Override
public Node call(Tokenizer tokenizer, String identifier, String bracket, List<Node> arguments) {
if (identifier.equals("derive")) {
if (arguments.size() != 2) {
throw new IllegalArgumentException("Two parameters expected for derive.");
}
if (!(arguments.get(1) instanceof Variable)) {
throw new IllegalArgumentException("Second derive parameter must be a variable.");
}
return NodeFactory.derive(arguments.get(0), arguments.get(1).toString());
}
return super.call(tokenizer, identifier, bracket, arguments);
}
@Override
public Node apply(Tokenizer tokenizer, Node base, String bracket, List<Node> arguments) {
throw new UnsupportedOperationException();
}
public static ExpressionParser<Node> createParser() {
ExpressionParser<Node> parser = new ExpressionParser<Node>(new TreeBuilder()) {
@Override
public Node parse(String expression) {
Tokenizer tokenizer = new ExpressionTokenizer(new Scanner(expression), this.getSymbols());
tokenizer.nextToken();
Node result = parse(tokenizer);
if (tokenizer.currentType != Tokenizer.TokenType.EOF) {
throw tokenizer.exception("EOF expected.", null);
}
return result;
}
};
parser.addCallBrackets("(", ",", ")");
parser.addGroupBrackets("(", null, ")");
parser.addOperators(OperatorType.INFIX_RTL, Node.PRECEDENCE_POWER, "^");
parser.addOperators(OperatorType.PREFIX, Node.PRECEDENCE_SIGNUM, "+", "-", "−");
parser.setImplicitOperatorPrecedence(true, Node.PRECEDENCE_IMPLICIT_MULTIPLICATION);
for (String name : UnaryFunction.DEFINITIONS.keySet()) {
parser.addOperators(
OperatorType.PREFIX, Node.PRECEDENCE_UNARY_FUNCTION, name);
}
parser.addOperators(OperatorType.INFIX, Node.PRECEDENCE_MULTIPLICATIVE,
"*", "×", "⋅", "/", ":", "÷");
parser.addOperators(OperatorType.INFIX, Node.PRECEDENCE_ADDITIVE,
"+", "-", "−");
return parser;
}
static class ExpressionTokenizer extends Tokenizer {
static final Pattern EXPONENT_PATTERN = Pattern.compile("\\G\\s*[⁰¹²³⁴⁵⁶⁷⁸⁹]+");
String pendingExponent;
public ExpressionTokenizer(Scanner scanner, Iterable<String> symbols) {
super(scanner, symbols);
}
@Override
public TokenType nextToken() {
if (pendingExponent != null) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < pendingExponent.length(); i++) {
sb.append("⁰¹²³⁴⁵⁶⁷⁸⁹".indexOf(pendingExponent.charAt(i)));
}
leadingWhitespace = "";
currentType = TokenType.NUMBER;
currentValue = sb.toString();
pendingExponent = null;
return currentType;
}
String value = scanner.findWithinHorizon(EXPONENT_PATTERN, 0);
if (value != null) {
currentPosition += currentValue.length();
if (value.charAt(0) <= ' ') {
pendingExponent = value.trim();
leadingWhitespace = value.substring(0, value.length() - pendingExponent.length());
currentPosition += leadingWhitespace.length();
} else {
pendingExponent = value;
leadingWhitespace = "";
}
currentType = TokenType.SYMBOL;
currentValue = "^";
return currentType;
}
return super.nextToken();
}
}
}