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package org.zwobble.hobgoblin.compiler.parser;
import org.zwobble.sourcetext.SourceCharacterIterator;
import org.zwobble.sourcetext.SourcePosition;
import org.zwobble.sourcetext.SourceRange;
import org.zwobble.sourcetext.SourceText;
import java.util.ArrayList;
import java.util.Optional;
class Tokenizer {
private Tokenizer() {
}
static Tokens tokenize(SourceText sourceText) {
var iterator = new CharacterIterator(sourceText);
var tokens = new ArrayList<Token>();
while (!iterator.isEnd()) {
if (trySkipWhitespace(iterator)) {
// Skip whitespace.
} else if (trySkipComment(iterator)) {
// Skip comments.
} else {
var token = tokenizeToken(iterator);
if (token.isPresent()) {
tokens.add(token.get());
} else {
throw ParseError.unexpectedTextError(
"token",
describeCharacter(iterator.peek()),
iterator.characterSourceRange()
);
}
}
}
var tokenEnd = new Token(TokenType.END, iterator.characterSourceRange());
return new Tokens(tokens, tokenEnd);
}
private static boolean trySkipComment(CharacterIterator iterator) {
if (!"//".contentEquals(iterator.peekSequence(2)) || "///".contentEquals(iterator.peekSequence(3))) {
return false;
}
skipToEndOfLine(iterator);
return true;
}
private static Optional<Token> tokenizeToken(CharacterIterator iterator) {
var identifierOrKeyword = tokenizeIdentifierOrKeyword(iterator);
if (identifierOrKeyword.isPresent()) {
return identifierOrKeyword;
}
var docComment = tokenizeDocComment(iterator);
if (docComment.isPresent()) {
return docComment;
}
var symbol = tokenizeSymbol(iterator);
if (symbol.isPresent()) {
return symbol;
}
throw ParseError.unexpectedTextError(
"token",
describeCharacter(iterator.peek()),
iterator.characterSourceRange()
);
}
private static boolean trySkipWhitespace(CharacterIterator iterator) {
var whitespace = false;
while (isWhitespace(iterator.peek())) {
iterator.skip();
whitespace = true;
}
return whitespace;
}
private static boolean isWhitespace(int character) {
return Character.isWhitespace(character);
}
private static Optional<Token> tokenizeDocComment(CharacterIterator iterator) {
if (!"///".contentEquals(iterator.peekSequence(3))) {
return Optional.empty();
}
var start = iterator.position();
skipToEndOfLine(iterator);
var end = iterator.position();
var token = new Token(TokenType.DOC_COMMENT, start.to(end));
return Optional.of(token);
}
private static void skipToEndOfLine(CharacterIterator iterator) {
while (!iterator.isEnd() && iterator.peek() != '\n') {
iterator.skip();
}
if (iterator.peek() == '\n') {
iterator.skip();
}
}
private static Optional<Token> tokenizeIdentifierOrKeyword(CharacterIterator iterator) {
if (!Character.isAlphabetic(iterator.peek())) {
return Optional.empty();
}
var start = iterator.position();
do {
iterator.skip();
} while (Character.isAlphabetic(iterator.peek()) || Character.isDigit(iterator.peek()));
var end = iterator.position();
var sourceRange = start.to(end);
TokenType tokenType;
if (CharSequence.compare(sourceRange.charSequence(), "enum") == 0) {
tokenType = TokenType.KEYWORD_ENUM;
} else if (CharSequence.compare(sourceRange.charSequence(), "field") == 0) {
tokenType = TokenType.KEYWORD_FIELD;
} else if (CharSequence.compare(sourceRange.charSequence(), "from") == 0) {
tokenType = TokenType.KEYWORD_FROM;
} else if (CharSequence.compare(sourceRange.charSequence(), "import") == 0) {
tokenType = TokenType.KEYWORD_IMPORT;
} else if (CharSequence.compare(sourceRange.charSequence(), "native") == 0) {
tokenType = TokenType.KEYWORD_NATIVE;
} else if (CharSequence.compare(sourceRange.charSequence(), "struct") == 0) {
tokenType = TokenType.KEYWORD_STRUCT;
} else if (CharSequence.compare(sourceRange.charSequence(), "sum") == 0) {
tokenType = TokenType.KEYWORD_SUM;
} else if (CharSequence.compare(sourceRange.charSequence(), "variant") == 0) {
tokenType = TokenType.KEYWORD_VARIANT;
} else {
tokenType = TokenType.IDENTIFIER;
}
var token = new Token(tokenType, start.to(end));
return Optional.of(token);
}
private static Optional<Token> tokenizeSymbol(CharacterIterator iterator) {
TokenType tokenType;
var start = iterator.position();
if ("..".contentEquals(iterator.peekSequence(2))) {
tokenType = TokenType.SYMBOL_DOT_DOT;
iterator.skip();
iterator.skip();
} else {
switch (iterator.peek()) {
case '{':
tokenType = TokenType.SYMBOL_BRACE_OPEN;
iterator.skip();
break;
case '}':
tokenType = TokenType.SYMBOL_BRACE_CLOSE;
iterator.skip();
break;
case ':':
tokenType = TokenType.SYMBOL_COLON;
iterator.skip();
break;
case ',':
tokenType = TokenType.SYMBOL_COMMA;
iterator.skip();
break;
case '.':
tokenType = TokenType.SYMBOL_DOT;
iterator.skip();
break;
case '/':
tokenType = TokenType.SYMBOL_FORWARD_SLASH;
iterator.skip();
break;
case '(':
tokenType = TokenType.SYMBOL_PAREN_OPEN;
iterator.skip();
break;
case ')':
tokenType = TokenType.SYMBOL_PAREN_CLOSE;
iterator.skip();
break;
case ';':
tokenType = TokenType.SYMBOL_SEMICOLON;
iterator.skip();
break;
case '[':
tokenType = TokenType.SYMBOL_SQUARE_OPEN;
iterator.skip();
break;
case ']':
tokenType = TokenType.SYMBOL_SQUARE_CLOSE;
iterator.skip();
break;
default:
return Optional.empty();
}
}
var end = iterator.position();
var token = new Token(tokenType, start.to(end));
return Optional.of(token);
}
private static String describeCharacter(int character) {
// TODO: handle characters that should be escaped
if (character == -1) {
return "end of document";
} else {
return String.format("'%s'", new String(new int[]{character}, 0, 1));
}
}
private static class CharacterIterator {
private final SourceCharacterIterator iterator;
CharacterIterator(SourceText sourceText) {
this.iterator = sourceText.characterIterator();
}
boolean isEnd() {
return this.iterator.isEnd();
}
SourceRange characterSourceRange() {
return this.iterator.characterSourceRange();
}
int peek() {
return this.iterator.peek();
}
CharSequence peekSequence(int length) {
if (length > this.iterator.remaining()) {
length = this.iterator.remaining();
}
return this.iterator.peekSequence(length);
}
void skip() {
this.iterator.skip();
}
public SourcePosition position() {
return this.iterator.position();
}
}
}
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