0ct0pu5/ladybird
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 2
ladybird/Libraries/LibJS/Lexer.cpp
Brian Gianforcaro dd112421b4 LibJS: Plumb line and column information through Lexer / Parser 
While debugging test failures, it's pretty frustrating to have to go do
printf debugging to figure out what test is failing right now. While
watching your JS Raytracer stream it seemed like this was pretty
furstrating as well. So I wanted to start working on improving the
diagnostics here.

In the future I hope we can eventually be able to plumb the info down
to the Error classes so any thrown exceptions will contain enough
metadata to know where they came from.
2020-04-05 12:43:39 +02:00

334 lines
13 KiB
C++
Raw Blame History

/*
* Copyright (c) 2020, Stephan Unverwerth <s.unverwerth@gmx.de>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "Lexer.h"
#include <AK/HashMap.h>
#include <AK/StringBuilder.h>
#include <ctype.h>
#include <stdio.h>
namespace JS {
HashMap<String, TokenType> Lexer::s_keywords;
HashMap<String, TokenType> Lexer::s_three_char_tokens;
HashMap<String, TokenType> Lexer::s_two_char_tokens;
HashMap<char, TokenType> Lexer::s_single_char_tokens;
Lexer::Lexer(StringView source)
: m_source(source)
, m_current_token(TokenType::Eof, StringView(nullptr), StringView(nullptr), 0, 0)
{
if (s_keywords.is_empty()) {
s_keywords.set("await", TokenType::Await);
s_keywords.set("break", TokenType::Break);
s_keywords.set("case", TokenType::Case);
s_keywords.set("catch", TokenType::Catch);
s_keywords.set("class", TokenType::Class);
s_keywords.set("const", TokenType::Const);
s_keywords.set("continue", TokenType::Continue);
s_keywords.set("default", TokenType::Default);
s_keywords.set("delete", TokenType::Delete);
s_keywords.set("do", TokenType::Do);
s_keywords.set("else", TokenType::Else);
s_keywords.set("false", TokenType::BoolLiteral);
s_keywords.set("finally", TokenType::Finally);
s_keywords.set("for", TokenType::For);
s_keywords.set("function", TokenType::Function);
s_keywords.set("if", TokenType::If);
s_keywords.set("in", TokenType::In);
s_keywords.set("instanceof", TokenType::Instanceof);
s_keywords.set("interface", TokenType::Interface);
s_keywords.set("let", TokenType::Let);
s_keywords.set("new", TokenType::New);
s_keywords.set("null", TokenType::NullLiteral);
s_keywords.set("return", TokenType::Return);
s_keywords.set("switch", TokenType::Switch);
s_keywords.set("throw", TokenType::Throw);
s_keywords.set("true", TokenType::BoolLiteral);
s_keywords.set("try", TokenType::Try);
s_keywords.set("typeof", TokenType::Typeof);
s_keywords.set("var", TokenType::Var);
s_keywords.set("void", TokenType::Void);
s_keywords.set("while", TokenType::While);
s_keywords.set("yield", TokenType::Yield);
}
if (s_three_char_tokens.is_empty()) {
s_three_char_tokens.set("===", TokenType::EqualsEqualsEquals);
s_three_char_tokens.set("!==", TokenType::ExclamationMarkEqualsEquals);
s_three_char_tokens.set("**=", TokenType::AsteriskAsteriskEquals);
s_three_char_tokens.set("<<=", TokenType::ShiftLeftEquals);
s_three_char_tokens.set(">>=", TokenType::ShiftRightEquals);
s_three_char_tokens.set(">>>", TokenType::UnsignedShiftRight);
}
if (s_two_char_tokens.is_empty()) {
s_two_char_tokens.set("=>", TokenType::Arrow);
s_two_char_tokens.set("+=", TokenType::PlusEquals);
s_two_char_tokens.set("-=", TokenType::MinusEquals);
s_two_char_tokens.set("*=", TokenType::AsteriskEquals);
s_two_char_tokens.set("/=", TokenType::SlashEquals);
s_two_char_tokens.set("%=", TokenType::PercentEquals);
s_two_char_tokens.set("&=", TokenType::AmpersandEquals);
s_two_char_tokens.set("|=", TokenType::PipeEquals);
s_two_char_tokens.set("&&", TokenType::DoubleAmpersand);
s_two_char_tokens.set("||", TokenType::DoublePipe);
s_two_char_tokens.set("??", TokenType::DoubleQuestionMark);
s_two_char_tokens.set("**", TokenType::DoubleAsterisk);
s_two_char_tokens.set("==", TokenType::EqualsEquals);
s_two_char_tokens.set("<=", TokenType::LessThanEquals);
s_two_char_tokens.set(">=", TokenType::GreaterThanEquals);
s_two_char_tokens.set("!=", TokenType::ExclamationMarkEquals);
s_two_char_tokens.set("--", TokenType::MinusMinus);
s_two_char_tokens.set("++", TokenType::PlusPlus);
s_two_char_tokens.set("<<", TokenType::ShiftLeft);
s_two_char_tokens.set(">>", TokenType::ShiftRight);
s_two_char_tokens.set("?.", TokenType::QuestionMarkPeriod);
}
if (s_single_char_tokens.is_empty()) {
s_single_char_tokens.set('&', TokenType::Ampersand);
s_single_char_tokens.set('*', TokenType::Asterisk);
s_single_char_tokens.set('[', TokenType::BracketOpen);
s_single_char_tokens.set(']', TokenType::BracketClose);
s_single_char_tokens.set('^', TokenType::Caret);
s_single_char_tokens.set(':', TokenType::Colon);
s_single_char_tokens.set(',', TokenType::Comma);
s_single_char_tokens.set('{', TokenType::CurlyOpen);
s_single_char_tokens.set('}', TokenType::CurlyClose);
s_single_char_tokens.set('=', TokenType::Equals);
s_single_char_tokens.set('!', TokenType::ExclamationMark);
s_single_char_tokens.set('-', TokenType::Minus);
s_single_char_tokens.set('(', TokenType::ParenOpen);
s_single_char_tokens.set(')', TokenType::ParenClose);
s_single_char_tokens.set('%', TokenType::Percent);
s_single_char_tokens.set('.', TokenType::Period);
s_single_char_tokens.set('|', TokenType::Pipe);
s_single_char_tokens.set('+', TokenType::Plus);
s_single_char_tokens.set('?', TokenType::QuestionMark);
s_single_char_tokens.set(';', TokenType::Semicolon);
s_single_char_tokens.set('/', TokenType::Slash);
s_single_char_tokens.set('~', TokenType::Tilde);
s_single_char_tokens.set('<', TokenType::LessThan);
s_single_char_tokens.set('>', TokenType::GreaterThan);
}
consume();
}
void Lexer::consume()
{
if (m_position >= m_source.length()) {
m_position = m_source.length() + 1;
m_current_char = EOF;
return;
}
if (m_current_char == '\n') {
m_line_number++;
m_line_column = 1;
} else {
m_line_column++;
}
m_current_char = m_source[m_position++];
}
bool Lexer::is_eof() const
{
return m_current_char == EOF;
}
bool Lexer::is_identifier_start() const
{
return isalpha(m_current_char) || m_current_char == '_' || m_current_char == '$';
}
bool Lexer::is_identifier_middle() const
{
return is_identifier_start() || isdigit(m_current_char);
}
bool Lexer::is_line_comment_start() const
{
return m_current_char == '/' && m_position < m_source.length() && m_source[m_position] == '/';
}
bool Lexer::is_block_comment_start() const
{
return m_current_char == '/' && m_position < m_source.length() && m_source[m_position] == '*';
}
bool Lexer::is_block_comment_end() const
{
return m_current_char == '*' && m_position < m_source.length() && m_source[m_position] == '/';
}
void Lexer::syntax_error(const char* msg)
{
m_has_errors = true;
fprintf(stderr, "Syntax Error: %s (line: %zu, column: %zu)\n", msg, m_line_number, m_line_column);
}
Token Lexer::next()
{
size_t trivia_start = m_position;
// consume whitespace and comments
while (true) {
if (isspace(m_current_char)) {
do {
consume();
} while (isspace(m_current_char));
} else if (is_line_comment_start()) {
consume();
do {
consume();
} while (!is_eof() && m_current_char != '\n');
} else if (is_block_comment_start()) {
consume();
do {
consume();
} while (!is_eof() && !is_block_comment_end());
consume(); // consume *
consume(); // consume /
} else {
break;
}
}
size_t value_start = m_position;
auto token_type = TokenType::Invalid;
if (is_identifier_start()) {
// identifier or keyword
do {
consume();
} while (is_identifier_middle());
StringView value = m_source.substring_view(value_start - 1, m_position - value_start);
auto it = s_keywords.find(value);
if (it == s_keywords.end()) {
token_type = TokenType::Identifier;
} else {
token_type = it->value;
}
} else if (isdigit(m_current_char)) {
consume();
while (m_current_char == '.' || isdigit(m_current_char)) {
consume();
}
token_type = TokenType::NumericLiteral;
} else if (m_current_char == '"' || m_current_char == '\'') {
char stop_char = m_current_char;
consume();
while (m_current_char != stop_char && m_current_char != '\n' && !is_eof()) {
if (m_current_char == '\\') {
consume();
}
consume();
}
if (m_current_char != stop_char) {
syntax_error("unterminated string literal");
token_type = TokenType::UnterminatedStringLiteral;
} else {
consume();
token_type = TokenType::StringLiteral;
}
} else if (m_current_char == EOF) {
token_type = TokenType::Eof;
} else {
// There is only one four-char operator: >>>=
bool found_four_char_token = false;
if (m_position + 2 < m_source.length()) {
if (m_current_char == '>'
&& m_source[m_position] == '>'
&& m_source[m_position + 1] == '>'
&& m_source[m_position + 2] == '=') {
found_four_char_token = true;
consume();
consume();
consume();
consume();
token_type = TokenType::UnsignedShiftRightEquals;
}
}
bool found_three_char_token = false;
if (!found_four_char_token && m_position + 1 < m_source.length()) {
char second_char = m_source[m_position];
char third_char = m_source[m_position + 1];
char three_chars[] { (char)m_current_char, second_char, third_char, 0 };
auto it = s_three_char_tokens.find(three_chars);
if (it != s_three_char_tokens.end()) {
found_three_char_token = true;
consume();
consume();
consume();
token_type = it->value;
}
}
bool found_two_char_token = false;
if (!found_four_char_token && !found_three_char_token && m_position < m_source.length()) {
char second_char = m_source[m_position];
char two_chars[] { (char)m_current_char, second_char, 0 };
auto it = s_two_char_tokens.find(two_chars);
if (it != s_two_char_tokens.end()) {
found_two_char_token = true;
consume();
consume();
token_type = it->value;
}
}
bool found_one_char_token = false;
if (!found_four_char_token && !found_three_char_token && !found_two_char_token) {
auto it = s_single_char_tokens.find(m_current_char);
if (it != s_single_char_tokens.end()) {
found_one_char_token = true;
consume();
token_type = it->value;
}
}
if (!found_four_char_token && !found_three_char_token && !found_two_char_token && !found_one_char_token) {
consume();
token_type = TokenType::Invalid;
}
}
m_current_token = Token(
token_type,
m_source.substring_view(trivia_start - 1, value_start - trivia_start),
m_source.substring_view(value_start - 1, m_position - value_start),
m_line_number,
m_line_column);
return m_current_token;
}
}
Reference in a new issue View git blame Copy permalink