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ladybird/Userland/Libraries/LibCpp/Lexer.cpp

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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "Lexer.h"
#include <AK/CharacterTypes.h>
#include <AK/DeprecatedString.h>
#include <AK/Function.h>
#include <AK/HashTable.h>
#include <AK/StdLibExtras.h>
namespace Cpp {
Lexer::Lexer(StringView input, size_t start_line)
: m_input(input)
, m_previous_position { start_line, 0 }
, m_position { start_line, 0 }
{
}
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++];
m_previous_position = m_position;
if (ch == '\n') {
m_position.line++;
m_position.column = 0;
} else {
m_position.column++;
}
return ch;
}
constexpr bool is_valid_first_character_of_identifier(char ch)
{
return is_ascii_alpha(ch) || ch == '_' || ch == '$';
}
constexpr bool is_valid_nonfirst_character_of_identifier(char ch)
{
return is_valid_first_character_of_identifier(ch) || is_ascii_digit(ch);
}
constexpr StringView s_known_keywords[] = {
"alignas"sv,
"alignof"sv,
"and"sv,
"and_eq"sv,
"asm"sv,
"bitand"sv,
"bitor"sv,
"break"sv,
"case"sv,
"catch"sv,
"class"sv,
"compl"sv,
"const"sv,
"const_cast"sv,
"constexpr"sv,
"continue"sv,
"decltype"sv,
"default"sv,
"delete"sv,
"do"sv,
"dynamic_cast"sv,
"else"sv,
"enum"sv,
"explicit"sv,
"export"sv,
"extern"sv,
"false"sv,
"final"sv,
"for"sv,
"friend"sv,
"goto"sv,
"if"sv,
"inline"sv,
"mutable"sv,
"namespace"sv,
"new"sv,
"noexcept"sv,
"not"sv,
"not_eq"sv,
"nullptr"sv,
"operator"sv,
"or"sv,
"or_eq"sv,
"override"sv,
"private"sv,
"protected"sv,
"public"sv,
"register"sv,
"reinterpret_cast"sv,
"return"sv,
"signed"sv,
"sizeof"sv,
"static"sv,
"static_assert"sv,
"static_cast"sv,
"struct"sv,
"switch"sv,
"template"sv,
"this"sv,
"thread_local"sv,
"throw"sv,
"true"sv,
"try"sv,
"typedef"sv,
"typeid"sv,
"typename"sv,
"union"sv,
"using"sv,
"virtual"sv,
"volatile"sv,
"while"sv,
"xor"sv,
"xor_eq"sv
};
constexpr StringView s_known_types[] = {
"Array"sv,
"Array"sv,
"Badge"sv,
"Bitmap"sv,
"ByteBuffer"sv,
"Bytes"sv,
"Checked"sv,
"CircularDeque"sv,
"CircularQueue"sv,
"Deque"sv,
"DoublyLinkedList"sv,
"Error"sv,
"ErrorOr"sv,
"FlyString"sv,
"Function"sv,
"HashMap"sv,
"HashTable"sv,
"IPv4Address"sv,
"IntrusiveList"sv,
"IntrusiveList"sv,
"JsonArray"sv,
"JsonObject"sv,
"JsonValue"sv,
"LexicalPath"sv,
"MappedFile"sv,
"NetworkOrdered"sv,
"NeverDestroyed"sv,
"NonnullOwnPtr"sv,
"NonnullRefPtr"sv,
"Optional"sv,
"OwnPtr"sv,
"ReadonlyBytes"sv,
"RedBlackTree"sv,
"RefPtr"sv,
"Result"sv,
"ScopeGuard"sv,
"Singleton"sv,
"SinglyLinkedList"sv,
"Span"sv,
"String"sv,
"StringBuilder"sv,
"StringImpl"sv,
"StringView"sv,
"Utf8View"sv,
"Variant"sv,
"Vector"sv,
"WeakPtr"sv,
"auto"sv,
"bool"sv,
"char"sv,
"char16_t"sv,
"char32_t"sv,
"char8_t"sv,
"double"sv,
"float"sv,
"i16"sv,
"i32"sv,
"i64"sv,
"i8"sv,
"int"sv,
"int"sv,
"long"sv,
"short"sv,
"signed"sv,
"u16"sv,
"u32"sv,
"u64"sv,
"u8"sv,
"unsigned"sv,
"void"sv,
"wchar_t"sv,
};
static bool is_keyword(StringView string)
{
static HashTable<DeprecatedString> keywords(array_size(s_known_keywords));
if (keywords.is_empty()) {
keywords.set_from(s_known_keywords);
}
return keywords.contains(string);
}
static bool is_known_type(StringView string)
{
static HashTable<DeprecatedString> types(array_size(s_known_types));
if (types.is_empty()) {
types.set_from(s_known_types);
}
return types.contains(string);
}
void Lexer::lex_impl(Function<void(Token)> callback)
{
size_t token_start_index = 0;
Position token_start_position;
auto emit_single_char_token = [&](auto type) {
callback(Token(type, m_position, m_position, m_input.substring_view(m_index, 1)));
consume();
};
auto begin_token = [&] {
token_start_index = m_index;
token_start_position = m_position;
};
auto commit_token = [&](auto type) {
if (m_options.ignore_whitespace && type == Token::Type::Whitespace)
return;
callback(Token(type, token_start_position, m_previous_position, m_input.substring_view(token_start_index, m_index - token_start_index)));
};
auto emit_token_equals = [&](auto type, auto equals_type) {
if (peek(1) == '=') {
begin_token();
consume();
consume();
commit_token(equals_type);
return;
}
emit_single_char_token(type);
};
auto match_escape_sequence = [&]() -> size_t {
switch (peek(1)) {
case '\'':
case '"':
case '?':
case '\\':
case 'a':
case 'b':
case 'f':
case 'n':
case 'r':
case 't':
case 'v':
return 2;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7': {
size_t octal_digits = 1;
for (size_t i = 0; i < 2; ++i) {
char next = peek(2 + i);
if (next < '0' || next > '7')
break;
++octal_digits;
}
return 1 + octal_digits;
}
case 'x': {
size_t hex_digits = 0;
while (is_ascii_hex_digit(peek(2 + hex_digits)))
++hex_digits;
return 2 + hex_digits;
}
case 'u':
case 'U': {
bool is_unicode = true;
size_t number_of_digits = peek(1) == 'u' ? 4 : 8;
for (size_t i = 0; i < number_of_digits; ++i) {
if (!is_ascii_hex_digit(peek(2 + i))) {
is_unicode = false;
break;
}
}
return is_unicode ? 2 + number_of_digits : 0;
}
default:
return 0;
}
};
auto match_string_prefix = [&](char quote) -> size_t {
if (peek() == quote)
return 1;
if (peek() == 'L' && peek(1) == quote)
return 2;
if (peek() == 'u') {
if (peek(1) == quote)
return 2;
if (peek(1) == '8' && peek(2) == quote)
return 3;
}
if (peek() == 'U' && peek(1) == quote)
return 2;
return 0;
};
while (m_index < m_input.length()) {
auto ch = peek();
if (is_ascii_space(ch)) {
begin_token();
while (is_ascii_space(peek()))
consume();
commit_token(Token::Type::Whitespace);
continue;
}
if (ch == '(') {
emit_single_char_token(Token::Type::LeftParen);
continue;
}
if (ch == ')') {
emit_single_char_token(Token::Type::RightParen);
continue;
}
if (ch == '{') {
emit_single_char_token(Token::Type::LeftCurly);
continue;
}
if (ch == '}') {
emit_single_char_token(Token::Type::RightCurly);
continue;
}
if (ch == '[') {
emit_single_char_token(Token::Type::LeftBracket);
continue;
}
if (ch == ']') {
emit_single_char_token(Token::Type::RightBracket);
continue;
}
if (ch == '<') {
begin_token();
consume();
if (peek() == '<') {
consume();
if (peek() == '=') {
consume();
commit_token(Token::Type::LessLessEquals);
continue;
}
commit_token(Token::Type::LessLess);
continue;
}
if (peek() == '=') {
consume();
commit_token(Token::Type::LessEquals);
continue;
}
if (peek() == '>') {
consume();
commit_token(Token::Type::LessGreater);
continue;
}
commit_token(Token::Type::Less);
continue;
}
if (ch == '>') {
begin_token();
consume();
if (peek() == '>') {
consume();
if (peek() == '=') {
consume();
commit_token(Token::Type::GreaterGreaterEquals);
continue;
}
commit_token(Token::Type::GreaterGreater);
continue;
}
if (peek() == '=') {
consume();
commit_token(Token::Type::GreaterEquals);
continue;
}
commit_token(Token::Type::Greater);
continue;
}
if (ch == ',') {
emit_single_char_token(Token::Type::Comma);
continue;
}
if (ch == '+') {
begin_token();
consume();
if (peek() == '+') {
consume();
commit_token(Token::Type::PlusPlus);
continue;
}
if (peek() == '=') {
consume();
commit_token(Token::Type::PlusEquals);
continue;
}
commit_token(Token::Type::Plus);
continue;
}
if (ch == '-') {
begin_token();
consume();
if (peek() == '-') {
consume();
commit_token(Token::Type::MinusMinus);
continue;
}
if (peek() == '=') {
consume();
commit_token(Token::Type::MinusEquals);
continue;
}
if (peek() == '>') {
consume();
if (peek() == '*') {
consume();
commit_token(Token::Type::ArrowAsterisk);
continue;
}
commit_token(Token::Type::Arrow);
continue;
}
commit_token(Token::Type::Minus);
continue;
}
if (ch == '*') {
emit_token_equals(Token::Type::Asterisk, Token::Type::AsteriskEquals);
continue;
}
if (ch == '%') {
emit_token_equals(Token::Type::Percent, Token::Type::PercentEquals);
continue;
}
if (ch == '^') {
emit_token_equals(Token::Type::Caret, Token::Type::CaretEquals);
continue;
}
if (ch == '!') {
emit_token_equals(Token::Type::ExclamationMark, Token::Type::ExclamationMarkEquals);
continue;
}
if (ch == '=') {
emit_token_equals(Token::Type::Equals, Token::Type::EqualsEquals);
continue;
}
if (ch == '&') {
begin_token();
consume();
if (peek() == '&') {
consume();
commit_token(Token::Type::AndAnd);
continue;
}
if (peek() == '=') {
consume();
commit_token(Token::Type::AndEquals);
continue;
}
commit_token(Token::Type::And);
continue;
}
if (ch == '|') {
begin_token();
consume();
if (peek() == '|') {
consume();
commit_token(Token::Type::PipePipe);
continue;
}
if (peek() == '=') {
consume();
commit_token(Token::Type::PipeEquals);
continue;
}
commit_token(Token::Type::Pipe);
continue;
}
if (ch == '~') {
emit_single_char_token(Token::Type::Tilde);
continue;
}
if (ch == '?') {
emit_single_char_token(Token::Type::QuestionMark);
continue;
}
if (ch == ':') {
begin_token();
consume();
if (peek() == ':') {
consume();
if (peek() == '*') {
consume();
commit_token(Token::Type::ColonColonAsterisk);
continue;
}
commit_token(Token::Type::ColonColon);
continue;
}
commit_token(Token::Type::Colon);
continue;
}
if (ch == ';') {
emit_single_char_token(Token::Type::Semicolon);
continue;
}
if (ch == '.') {
begin_token();
consume();
if (peek() == '*') {
consume();
commit_token(Token::Type::DotAsterisk);
continue;
}
commit_token(Token::Type::Dot);
continue;
}
if (ch == '#') {
begin_token();
consume();
while (AK::is_ascii_space(peek()))
consume();
size_t directive_start = m_index;
if (is_valid_first_character_of_identifier(peek()))
while (peek() && is_valid_nonfirst_character_of_identifier(peek()))
consume();
auto directive = StringView(m_input.characters_without_null_termination() + directive_start, m_index - directive_start);
if (directive == "include"sv) {
commit_token(Token::Type::IncludeStatement);
if (is_ascii_space(peek())) {
begin_token();
do {
consume();
} while (is_ascii_space(peek()));
commit_token(Token::Type::Whitespace);
}
begin_token();
if (peek() == '<' || peek() == '"') {
char closing = consume() == '<' ? '>' : '"';
while (peek() && peek() != closing && peek() != '\n')
consume();
if (peek() && consume() == '\n') {
commit_token(Token::Type::IncludePath);
continue;
}
commit_token(Token::Type::IncludePath);
begin_token();
}
} else {
while (peek()) {
if (peek() == '\\' && peek(1) == '\n') {
consume();
consume();
} else if (peek() == '\n') {
break;
} else {
consume();
}
}
commit_token(Token::Type::PreprocessorStatement);
}
continue;
}
if (ch == '/' && peek(1) == '/') {
begin_token();
while (peek() && peek() != '\n')
consume();
commit_token(Token::Type::Comment);
continue;
}
if (ch == '/' && peek(1) == '*') {
begin_token();
consume();
consume();
bool comment_block_ends = false;
while (peek()) {
if (peek() == '*' && peek(1) == '/') {
comment_block_ends = true;
break;
}
consume();
}
if (comment_block_ends) {
consume();
consume();
}
commit_token(Token::Type::Comment);
continue;
}
if (ch == '/') {
emit_token_equals(Token::Type::Slash, Token::Type::SlashEquals);
continue;
}
if (size_t prefix = match_string_prefix('"'); prefix > 0) {
begin_token();
for (size_t i = 0; i < prefix; ++i)
consume();
while (peek()) {
if (peek() == '\\') {
if (size_t escape = match_escape_sequence(); escape > 0) {
commit_token(Token::Type::DoubleQuotedString);
begin_token();
for (size_t i = 0; i < escape; ++i)
consume();
commit_token(Token::Type::EscapeSequence);
begin_token();
continue;
}
}
// If string is not terminated - stop before EOF
if (!peek(1))
break;
if (consume() == '"')
break;
}
commit_token(Token::Type::DoubleQuotedString);
continue;
}
if (size_t prefix = match_string_prefix('R'); prefix > 0 && peek(prefix) == '"') {
begin_token();
for (size_t i = 0; i < prefix + 1; ++i)
consume();
size_t prefix_start = m_index;
while (peek() && peek() != '(')
consume();
StringView prefix_string = m_input.substring_view(prefix_start, m_index - prefix_start);
while (peek()) {
if (consume() == '"') {
VERIFY(m_index >= prefix_string.length() + 2);
VERIFY(m_input[m_index - 1] == '"');
if (m_input[m_index - 1 - prefix_string.length() - 1] == ')') {
StringView suffix_string = m_input.substring_view(m_index - 1 - prefix_string.length(), prefix_string.length());
if (prefix_string == suffix_string)
break;
}
}
}
commit_token(Token::Type::RawString);
continue;
}
if (size_t prefix = match_string_prefix('\''); prefix > 0) {
begin_token();
for (size_t i = 0; i < prefix; ++i)
consume();
while (peek()) {
if (peek() == '\\') {
if (size_t escape = match_escape_sequence(); escape > 0) {
commit_token(Token::Type::SingleQuotedString);
begin_token();
for (size_t i = 0; i < escape; ++i)
consume();
commit_token(Token::Type::EscapeSequence);
begin_token();
continue;
}
}
if (consume() == '\'')
break;
}
commit_token(Token::Type::SingleQuotedString);
continue;
}
if (is_ascii_digit(ch) || (ch == '.' && is_ascii_digit(peek(1)))) {
begin_token();
consume();
auto type = ch == '.' ? Token::Type::Float : Token::Type::Integer;
bool is_hex = false;
bool is_binary = false;
auto match_exponent = [&]() -> size_t {
char ch = peek();
if (ch != 'e' && ch != 'E' && ch != 'p' && ch != 'P')
return 0;
type = Token::Type::Float;
size_t length = 1;
ch = peek(length);
if (ch == '+' || ch == '-') {
++length;
}
for (ch = peek(length); is_ascii_digit(ch); ch = peek(length)) {
++length;
}
return length;
};
auto match_type_literal = [&]() -> size_t {
size_t length = 0;
for (;;) {
char ch = peek(length);
if ((ch == 'u' || ch == 'U') && type == Token::Type::Integer) {
++length;
} else if ((ch == 'f' || ch == 'F') && !is_binary) {
type = Token::Type::Float;
++length;
} else if (ch == 'l' || ch == 'L') {
++length;
} else
return length;
}
};
if (peek() == 'b' || peek() == 'B') {
consume();
is_binary = true;
for (char ch = peek(); ch == '0' || ch == '1' || (ch == '\'' && peek(1) != '\''); ch = peek()) {
consume();
}
} else {
if (peek() == 'x' || peek() == 'X') {
consume();
is_hex = true;
}
for (char ch = peek(); (is_hex ? is_ascii_hex_digit(ch) : is_ascii_digit(ch)) || (ch == '\'' && peek(1) != '\'') || ch == '.'; ch = peek()) {
if (ch == '.') {
if (type == Token::Type::Integer) {
type = Token::Type::Float;
} else
break;
};
consume();
}
}
if (!is_binary) {
size_t length = match_exponent();
for (size_t i = 0; i < length; ++i)
consume();
}
size_t length = match_type_literal();
for (size_t i = 0; i < length; ++i)
consume();
commit_token(type);
continue;
}
if (is_valid_first_character_of_identifier(ch)) {
begin_token();
while (peek() && is_valid_nonfirst_character_of_identifier(peek()))
consume();
auto token_view = StringView(m_input.characters_without_null_termination() + token_start_index, m_index - token_start_index);
if (is_keyword(token_view))
commit_token(Token::Type::Keyword);
else if (is_known_type(token_view))
commit_token(Token::Type::KnownType);
else
commit_token(Token::Type::Identifier);
continue;
}
if (ch == '\\' && peek(1) == '\n') {
consume();
consume();
continue;
}
dbgln("Unimplemented token character: {}", ch);
emit_single_char_token(Token::Type::Unknown);
}
}
Vector<Token> Lexer::lex()
{
Vector<Token> tokens;
lex_impl([&](auto token) {
tokens.append(move(token));
});
return tokens;
}
}
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