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package no.eliashaugsbakk.kompilator.tokenization;
import static java.lang.Character.isLetterOrDigit;
import static no.eliashaugsbakk.kompilator.tokenization.LexerState.IN_STRING;
import static no.eliashaugsbakk.kompilator.tokenization.LexerState.IN_WORD;
import static no.eliashaugsbakk.kompilator.tokenization.LexerState.NORMAL;
import static no.eliashaugsbakk.kompilator.tokenization.TokenType.EOF;
import static no.eliashaugsbakk.kompilator.tokenization.TokenType.IDENTIFIER;
import static no.eliashaugsbakk.kompilator.tokenization.TokenType.KEYWORD;
import static no.eliashaugsbakk.kompilator.tokenization.TokenType.LPAREN;
import static no.eliashaugsbakk.kompilator.tokenization.TokenType.RPAREN;
import static no.eliashaugsbakk.kompilator.tokenization.TokenType.SEMICOLON;
import static no.eliashaugsbakk.kompilator.tokenization.TokenType.STRING;
import java.util.ArrayList;
import java.util.List;
public class Lexer {
private int line = 1;
private int column = 0;
private final String input;
private int position = 0;
private final List<Token> tokens = new ArrayList<>();
private final StringBuilder wordBuffer = new StringBuilder();
LexerState state = NORMAL;
public Lexer(String input) {
this.input = input;
}
List<Token> tokenize() {
while (position < input.length()) {
char current = input.charAt(position);
if (current == '\n') {
line++;
column = 0;
} else {
column++;
}
if (state == IN_WORD) {
if (!isLetterOrDigit(current) || Character.isWhitespace(current)) {
state = NORMAL;
characterizeWord();
} else {
wordBuffer.append(current);
}
}
if (state == NORMAL) {
if (!Character.isWhitespace(current)) {
if (current == '"') {
state = IN_STRING;
} else if (isLetterOrDigit(current)) {
state = IN_WORD;
wordBuffer.append(current);
} else if (current == '(') {
tokens.add(new Token(LPAREN, Character.toString(current), line, column));
} else if (current == ')') {
tokens.add(new Token(RPAREN, Character.toString(current), line, column));
} else if (current == ';') {
tokens.add(new Token(SEMICOLON, Character.toString(current), line, column));
}
}
} else if (state == IN_STRING) {
if (current == '"') {
state = NORMAL;
tokens.add(new Token(STRING, wordBuffer.toString(), line, column));
wordBuffer.delete(0, wordBuffer.length());
} else {
wordBuffer.append(current);
}
}
position++;
}
tokens.add(new Token(EOF, "End of File", line, column));
return tokens;
}
private void characterizeWord() {
if (Keywords.KEYWORDS.contains(wordBuffer.toString())) {
tokens.add(new Token(KEYWORD, wordBuffer.toString(), line, column - wordBuffer.length()));
} else {
tokens.add(new Token(IDENTIFIER, wordBuffer.toString(), line, column - wordBuffer.length()));
}
wordBuffer.delete(0, wordBuffer.length());
}
}
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