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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "Lexer.h"
#include <AK/CharacterTypes.h>
#include <AK/Vector.h>
namespace GUI::GML {
Lexer::Lexer(StringView input)
: m_input(input)
{
}
char Lexer::peek(size_t offset) const
{
if ((m_index + offset) >= m_input.length())
return 0;
return m_input[m_index + offset];
}
char Lexer::consume()
{
VERIFY(m_index < m_input.length());
char ch = m_input[m_index++];
if (ch == '\n') {
m_position.line++;
m_position.column = 0;
} else {
m_position.column++;
}
return ch;
}
constexpr bool is_valid_identifier_start(char ch)
{
return is_ascii_alpha(ch) || ch == '_';
}
constexpr bool is_valid_identifier_character(char ch)
{
return is_ascii_alphanumeric(ch) || ch == '_';
}
constexpr bool is_valid_class_character(char ch)
{
return is_ascii_alphanumeric(ch) || ch == '_' || ch == ':';
}
Vector<Token> Lexer::lex()
{
Vector<Token> tokens;
size_t token_start_index = 0;
Position token_start_position;
auto begin_token = [&] {
token_start_index = m_index;
token_start_position = m_position;
};
auto commit_token = [&](auto type) {
Token token;
token.m_view = m_input.substring_view(token_start_index, m_index - token_start_index);
token.m_type = type;
token.m_start = token_start_position;
token.m_end = m_position;
tokens.append(token);
};
auto consume_class = [&] {
begin_token();
consume();
commit_token(Token::Type::ClassMarker);
begin_token();
while (is_valid_class_character(peek()))
consume();
commit_token(Token::Type::ClassName);
};
while (m_index < m_input.length()) {
if (is_ascii_space(peek(0))) {
begin_token();
while (is_ascii_space(peek()))
consume();
continue;
}
// C++ style comments
if (peek(0) && peek(0) == '/' && peek(1) == '/') {
begin_token();
while (peek() && peek() != '\n')
consume();
commit_token(Token::Type::Comment);
continue;
}
if (peek(0) == '{') {
begin_token();
consume();
commit_token(Token::Type::LeftCurly);
continue;
}
if (peek(0) == '}') {
begin_token();
consume();
commit_token(Token::Type::RightCurly);
continue;
}
if (peek(0) == '@') {
consume_class();
continue;
}
if (is_valid_identifier_start(peek(0))) {
begin_token();
consume();
while (is_valid_identifier_character(peek(0)))
consume();
commit_token(Token::Type::Identifier);
continue;
}
if (peek(0) == ':') {
begin_token();
consume();
commit_token(Token::Type::Colon);
while (is_ascii_space(peek()))
consume();
if (peek(0) == '@') {
consume_class();
} else {
begin_token();
while (peek() && peek() != '\n')
consume();
commit_token(Token::Type::JsonValue);
}
continue;
}
consume();
commit_token(Token::Type::Unknown);
}
return tokens;
}
}
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