105 lines
3.2 KiB
Java
105 lines
3.2 KiB
Java
package Lab3;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Stack;
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public class Lexer {
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public enum TokenType {
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NUMBER,
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OPERATOR,
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LPAREN,
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RPAREN,
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FUNCTION,
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COMMA,
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EOF
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}
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public static class Token {
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public TokenType type;
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public String value;
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public Token(TokenType type, String value) {
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this.type = type;
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this.value = value;
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}
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}
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public static List<Token> tokenize(String input) {
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List<Token> tokens = new ArrayList<>();
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input = input.replaceAll("\\s", "");
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int i = 0;
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while (i < input.length()) {
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char ch = input.charAt(i);
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if (Character.isDigit(ch)) {
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StringBuilder sb = new StringBuilder();
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while (i < input.length() && (Character.isDigit(input.charAt(i)) || input.charAt(i) == '.')) {
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sb.append(input.charAt(i));
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i++;
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}
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tokens.add(new Token(TokenType.NUMBER, sb.toString()));
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} else if (Character.isLetter(ch)) {
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StringBuilder sb = new StringBuilder();
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while (i < input.length() && Character.isLetter(input.charAt(i))) {
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sb.append(input.charAt(i));
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i++;
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}
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tokens.add(new Token(TokenType.FUNCTION, sb.toString()));
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} else {
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switch (ch) {
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case '(':
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tokens.add(new Token(TokenType.LPAREN, "("));
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i++;
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break;
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case ')':
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tokens.add(new Token(TokenType.RPAREN, ")"));
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i++;
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break;
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case ',':
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tokens.add(new Token(TokenType.COMMA, ","));
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i++;
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break;
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default:
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tokens.add(new Token(TokenType.OPERATOR, String.valueOf(ch)));
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i++;
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break;
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}
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}
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}
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tokens.add(new Token(TokenType.EOF, ""));
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if (!areParenthesesBalanced(tokens)) {
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throw new RuntimeException("Parentheses are not balanced.");
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}
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return tokens;
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}
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private static boolean areParenthesesBalanced(List<Token> tokens) {
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Stack<TokenType> stack = new Stack<>();
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for (Token token : tokens) {
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if (token.type == TokenType.LPAREN) {
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stack.push(TokenType.LPAREN);
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} else if (token.type == TokenType.RPAREN) {
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if (stack.isEmpty() || stack.pop() != TokenType.LPAREN) {
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return false;
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}
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}
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}
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return stack.isEmpty();
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}
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public static void main(String[] args) {
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String input = "(3 + 5) * loge(16)";
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try {
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List<Token> tokens = tokenize(input);
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for (Token token : tokens) {
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System.out.println(token.type + " : " + token.value);
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}
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} catch (RuntimeException e) {
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System.err.println(e.getMessage());
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}
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}
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}
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