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ladybird/Userland/Shell/Parser.cpp
Andreas Kling 5d180d1f99 Everywhere: Rename ASSERT => VERIFY 
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)

Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.

We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
2021-02-23 20:56:54 +01:00

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/*
* Copyright (c) 2020, the SerenityOS developers.
* 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 "Parser.h"
#include "Shell.h"
#include <AK/AllOf.h>
#include <AK/TemporaryChange.h>
#include <ctype.h>
#include <stdio.h>
#include <unistd.h>
namespace Shell {
Parser::SavedOffset Parser::save_offset() const
{
return { m_offset, m_line };
}
char Parser::peek()
{
if (at_end())
return 0;
VERIFY(m_offset < m_input.length());
auto ch = m_input[m_offset];
if (ch == '\\' && m_input.length() > m_offset + 1 && m_input[m_offset + 1] == '\n') {
m_offset += 2;
++m_line.line_number;
m_line.line_column = 0;
return peek();
}
return ch;
}
char Parser::consume()
{
if (at_end())
return 0;
auto ch = peek();
++m_offset;
if (ch == '\n') {
++m_line.line_number;
m_line.line_column = 0;
} else {
++m_line.line_column;
}
return ch;
}
bool Parser::expect(char ch)
{
return expect(StringView { &ch, 1 });
}
bool Parser::expect(const StringView& expected)
{
auto offset_at_start = m_offset;
auto line_at_start = line();
if (expected.length() + m_offset > m_input.length())
return false;
for (size_t i = 0; i < expected.length(); ++i) {
if (peek() != expected[i]) {
restore_to(offset_at_start, line_at_start);
return false;
}
consume();
}
return true;
}
template<typename A, typename... Args>
NonnullRefPtr<A> Parser::create(Args... args)
{
return adopt(*new A(AST::Position { m_rule_start_offsets.last(), m_offset, m_rule_start_lines.last(), line() }, args...));
}
[[nodiscard]] OwnPtr<Parser::ScopedOffset> Parser::push_start()
{
return make<ScopedOffset>(m_rule_start_offsets, m_rule_start_lines, m_offset, m_line.line_number, m_line.line_column);
}
Parser::Offset Parser::current_position()
{
return Offset { m_offset, { m_line.line_number, m_line.line_column } };
}
static constexpr bool is_whitespace(char c)
{
return c == ' ' || c == '\t';
}
static constexpr bool is_digit(char c)
{
return c <= '9' && c >= '0';
}
static constexpr auto is_not(char c)
{
return [c](char ch) { return ch != c; };
}
static inline char to_byte(char a, char b)
{
char buf[3] { a, b, 0 };
return strtol(buf, nullptr, 16);
}
RefPtr<AST::Node> Parser::parse()
{
m_offset = 0;
m_line = { 0, 0 };
auto toplevel = parse_toplevel();
if (m_offset < m_input.length()) {
// Parsing stopped midway, this is a syntax error.
auto error_start = push_start();
while (!at_end())
consume();
auto syntax_error_node = create<AST::SyntaxError>("Unexpected tokens past the end");
if (!toplevel)
toplevel = move(syntax_error_node);
else if (!toplevel->is_syntax_error())
toplevel->set_is_syntax_error(*syntax_error_node);
}
return toplevel;
}
RefPtr<AST::Node> Parser::parse_as_single_expression()
{
auto input = Shell::escape_token_for_double_quotes(m_input);
Parser parser { input };
return parser.parse_expression();
}
NonnullRefPtrVector<AST::Node> Parser::parse_as_multiple_expressions()
{
NonnullRefPtrVector<AST::Node> nodes;
for (;;) {
consume_while(is_whitespace);
auto node = parse_expression();
if (!node)
node = parse_redirection();
if (!node)
return nodes;
nodes.append(node.release_nonnull());
}
return nodes;
}
RefPtr<AST::Node> Parser::parse_toplevel()
{
auto rule_start = push_start();
SequenceParseResult result;
NonnullRefPtrVector<AST::Node> sequence;
Vector<AST::Position> positions;
do {
result = parse_sequence();
if (result.entries.is_empty())
break;
sequence.append(move(result.entries));
positions.append(move(result.separator_positions));
} while (result.decision == ShouldReadMoreSequences::Yes);
if (sequence.is_empty())
return nullptr;
return create<AST::Execute>(
create<AST::Sequence>(move(sequence), move(positions)));
}
Parser::SequenceParseResult Parser::parse_sequence()
{
consume_while(is_any_of(" \t\n;")); // ignore whitespaces or terminators without effect.
NonnullRefPtrVector<AST::Node> left;
auto rule_start = push_start();
{
auto var_decls = parse_variable_decls();
if (var_decls)
left.append(var_decls.release_nonnull());
}
auto pos_before_seps = save_offset();
switch (peek()) {
case '}':
return { move(left), {}, ShouldReadMoreSequences::No };
case ';':
case '\n': {
if (left.is_empty())
break;
consume_while(is_any_of("\n;"));
auto pos_after_seps = save_offset();
AST::Position separator_position { pos_before_seps.offset, pos_after_seps.offset, pos_before_seps.line, pos_after_seps.line };
return { move(left), { move(separator_position) }, ShouldReadMoreSequences::Yes };
}
default:
break;
}
auto first_entry = parse_function_decl();
Vector<AST::Position> separator_positions;
if (!first_entry)
first_entry = parse_or_logical_sequence();
if (!first_entry)
return { move(left), {}, ShouldReadMoreSequences::No };
left.append(first_entry.release_nonnull());
separator_positions.empend(pos_before_seps.offset, pos_before_seps.offset, pos_before_seps.line, pos_before_seps.line);
consume_while(is_whitespace);
pos_before_seps = save_offset();
switch (peek()) {
case ';':
case '\n': {
consume_while(is_any_of("\n;"));
auto pos_after_seps = save_offset();
separator_positions.empend(pos_before_seps.offset, pos_after_seps.offset, pos_before_seps.line, pos_after_seps.line);
return { move(left), move(separator_positions), ShouldReadMoreSequences::Yes };
}
case '&': {
consume();
auto pos_after_seps = save_offset();
auto bg = create<AST::Background>(left.take_last()); // Execute Background
left.append(move(bg));
separator_positions.empend(pos_before_seps.offset, pos_after_seps.offset, pos_before_seps.line, pos_after_seps.line);
return { move(left), move(separator_positions), ShouldReadMoreSequences::Yes };
}
default:
return { move(left), move(separator_positions), ShouldReadMoreSequences::No };
}
}
RefPtr<AST::Node> Parser::parse_variable_decls()
{
auto rule_start = push_start();
consume_while(is_whitespace);
auto pos_before_name = save_offset();
auto var_name = consume_while(is_word_character);
if (var_name.is_empty())
return nullptr;
if (!expect('=')) {
restore_to(pos_before_name.offset, pos_before_name.line);
return nullptr;
}
auto name_expr = create<AST::BarewordLiteral>(move(var_name));
auto start = push_start();
auto expression = parse_expression();
if (!expression || expression->is_syntax_error()) {
restore_to(*start);
if (peek() == '(') {
consume();
auto command = parse_pipe_sequence();
if (!command)
restore_to(*start);
else if (!expect(')'))
command->set_is_syntax_error(*create<AST::SyntaxError>("Expected a terminating close paren", true));
expression = command;
}
}
if (!expression) {
if (is_whitespace(peek())) {
auto string_start = push_start();
expression = create<AST::StringLiteral>("");
} else {
restore_to(pos_before_name.offset, pos_before_name.line);
return nullptr;
}
}
Vector<AST::VariableDeclarations::Variable> variables;
variables.append({ move(name_expr), expression.release_nonnull() });
if (consume_while(is_whitespace).is_empty())
return create<AST::VariableDeclarations>(move(variables));
auto rest = parse_variable_decls();
if (!rest)
return create<AST::VariableDeclarations>(move(variables));
VERIFY(rest->is_variable_decls());
auto* rest_decl = static_cast<AST::VariableDeclarations*>(rest.ptr());
variables.append(rest_decl->variables());
return create<AST::VariableDeclarations>(move(variables));
}
RefPtr<AST::Node> Parser::parse_function_decl()
{
auto rule_start = push_start();
auto restore = [&] {
restore_to(*rule_start);
return nullptr;
};
consume_while(is_whitespace);
auto pos_before_name = save_offset();
auto function_name = consume_while(is_word_character);
auto pos_after_name = save_offset();
if (function_name.is_empty())
return restore();
if (!expect('('))
return restore();
Vector<AST::FunctionDeclaration::NameWithPosition> arguments;
for (;;) {
consume_while(is_whitespace);
if (expect(')'))
break;
auto name_offset = m_offset;
auto start_line = line();
auto arg_name = consume_while(is_word_character);
if (arg_name.is_empty()) {
// FIXME: Should this be a syntax error, or just return?
return restore();
}
arguments.append({ arg_name, { name_offset, m_offset, start_line, line() } });
}
consume_while(is_whitespace);
{
RefPtr<AST::Node> syntax_error;
{
auto obrace_error_start = push_start();
syntax_error = create<AST::SyntaxError>("Expected an open brace '{' to start a function body", true);
}
if (!expect('{')) {
return create<AST::FunctionDeclaration>(
AST::FunctionDeclaration::NameWithPosition {
move(function_name),
{ pos_before_name.offset, pos_after_name.offset, pos_before_name.line, pos_after_name.line } },
move(arguments),
move(syntax_error));
}
}
TemporaryChange controls { m_continuation_controls_allowed, false };
auto body = parse_toplevel();
{
RefPtr<AST::SyntaxError> syntax_error;
{
auto cbrace_error_start = push_start();
syntax_error = create<AST::SyntaxError>("Expected a close brace '}' to end a function body", true);
}
if (!expect('}')) {
if (body)
body->set_is_syntax_error(*syntax_error);
else
body = move(syntax_error);
return create<AST::FunctionDeclaration>(
AST::FunctionDeclaration::NameWithPosition {
move(function_name),
{ pos_before_name.offset, pos_after_name.offset, pos_before_name.line, pos_after_name.line } },
move(arguments),
move(body));
}
}
return create<AST::FunctionDeclaration>(
AST::FunctionDeclaration::NameWithPosition {
move(function_name),
{ pos_before_name.offset, pos_after_name.offset, pos_before_name.line, pos_after_name.line } },
move(arguments),
move(body));
}
RefPtr<AST::Node> Parser::parse_or_logical_sequence()
{
consume_while(is_whitespace);
auto rule_start = push_start();
auto and_sequence = parse_and_logical_sequence();
if (!and_sequence)
return nullptr;
consume_while(is_whitespace);
auto pos_before_or = save_offset();
if (!expect("||"))
return and_sequence;
auto pos_after_or = save_offset();
auto right_and_sequence = parse_and_logical_sequence();
if (!right_and_sequence)
right_and_sequence = create<AST::SyntaxError>("Expected an expression after '||'", true);
return create<AST::Or>(
and_sequence.release_nonnull(),
right_and_sequence.release_nonnull(),
AST::Position { pos_before_or.offset, pos_after_or.offset, pos_before_or.line, pos_after_or.line });
}
RefPtr<AST::Node> Parser::parse_and_logical_sequence()
{
consume_while(is_whitespace);
auto rule_start = push_start();
auto pipe_sequence = parse_pipe_sequence();
if (!pipe_sequence)
return nullptr;
consume_while(is_whitespace);
auto pos_before_and = save_offset();
if (!expect("&&"))
return pipe_sequence;
auto pos_after_end = save_offset();
auto right_and_sequence = parse_and_logical_sequence();
if (!right_and_sequence)
right_and_sequence = create<AST::SyntaxError>("Expected an expression after '&&'", true);
return create<AST::And>(
pipe_sequence.release_nonnull(),
right_and_sequence.release_nonnull(),
AST::Position { pos_before_and.offset, pos_after_end.offset, pos_before_and.line, pos_after_end.line });
}
RefPtr<AST::Node> Parser::parse_pipe_sequence()
{
auto rule_start = push_start();
auto left = parse_control_structure();
if (!left) {
if (auto cmd = parse_command())
left = cmd;
else
return nullptr;
}
consume_while(is_whitespace);
if (peek() != '|')
return left;
auto before_pipe = save_offset();
consume();
if (auto pipe_seq = parse_pipe_sequence()) {
return create<AST::Pipe>(left.release_nonnull(), pipe_seq.release_nonnull()); // Pipe
}
restore_to(before_pipe.offset, before_pipe.line);
return left;
}
RefPtr<AST::Node> Parser::parse_command()
{
auto rule_start = push_start();
consume_while(is_whitespace);
auto redir = parse_redirection();
if (!redir) {
auto list_expr = parse_list_expression();
if (!list_expr)
return nullptr;
auto cast = create<AST::CastToCommand>(list_expr.release_nonnull()); // Cast List Command
auto next_command = parse_command();
if (!next_command)
return cast;
return create<AST::Join>(move(cast), next_command.release_nonnull()); // Join List Command
}
auto command = parse_command();
if (!command)
return redir;
return create<AST::Join>(redir.release_nonnull(), command.release_nonnull()); // Join Command Command
}
RefPtr<AST::Node> Parser::parse_control_structure()
{
auto rule_start = push_start();
consume_while(is_whitespace);
if (auto control = parse_continuation_control())
return control;
if (auto for_loop = parse_for_loop())
return for_loop;
if (auto loop = parse_loop_loop())
return loop;
if (auto if_expr = parse_if_expr())
return if_expr;
if (auto subshell = parse_subshell())
return subshell;
if (auto match = parse_match_expr())
return match;
return nullptr;
}
RefPtr<AST::Node> Parser::parse_continuation_control()
{
if (!m_continuation_controls_allowed)
return nullptr;
auto rule_start = push_start();
if (expect("break")) {
{
auto break_end = push_start();
if (consume_while(is_any_of(" \t\n;")).is_empty()) {
restore_to(*rule_start);
return nullptr;
}
restore_to(*break_end);
}
return create<AST::ContinuationControl>(AST::ContinuationControl::Break);
}
if (expect("continue")) {
{
auto continue_end = push_start();
if (consume_while(is_any_of(" \t\n;")).is_empty()) {
restore_to(*rule_start);
return nullptr;
}
restore_to(*continue_end);
}
return create<AST::ContinuationControl>(AST::ContinuationControl::Continue);
}
return nullptr;
}
RefPtr<AST::Node> Parser::parse_for_loop()
{
auto rule_start = push_start();
if (!expect("for"))
return nullptr;
if (consume_while(is_any_of(" \t\n")).is_empty()) {
restore_to(*rule_start);
return nullptr;
}
auto variable_name = consume_while(is_word_character);
Optional<AST::Position> in_start_position;
if (variable_name.is_empty()) {
variable_name = "it";
} else {
consume_while(is_whitespace);
auto in_error_start = push_start();
if (!expect("in")) {
auto syntax_error = create<AST::SyntaxError>("Expected 'in' after a variable name in a 'for' loop", true);
return create<AST::ForLoop>(move(variable_name), move(syntax_error), nullptr); // ForLoop Var Iterated Block
}
in_start_position = AST::Position { in_error_start->offset, m_offset, in_error_start->line, line() };
}
consume_while(is_whitespace);
RefPtr<AST::Node> iterated_expression;
{
auto iter_error_start = push_start();
iterated_expression = parse_expression();
if (!iterated_expression)
iterated_expression = create<AST::SyntaxError>("Expected an expression in 'for' loop", true);
}
consume_while(is_any_of(" \t\n"));
{
auto obrace_error_start = push_start();
if (!expect('{')) {
auto syntax_error = create<AST::SyntaxError>("Expected an open brace '{' to start a 'for' loop body", true);
return create<AST::ForLoop>(move(variable_name), move(iterated_expression), move(syntax_error), move(in_start_position)); // ForLoop Var Iterated Block
}
}
TemporaryChange controls { m_continuation_controls_allowed, true };
auto body = parse_toplevel();
{
auto cbrace_error_start = push_start();
if (!expect('}')) {
auto error_start = push_start();
auto syntax_error = create<AST::SyntaxError>("Expected a close brace '}' to end a 'for' loop body", true);
if (body)
body->set_is_syntax_error(*syntax_error);
else
body = syntax_error;
}
}
return create<AST::ForLoop>(move(variable_name), move(iterated_expression), move(body), move(in_start_position)); // ForLoop Var Iterated Block
}
RefPtr<AST::Node> Parser::parse_loop_loop()
{
auto rule_start = push_start();
if (!expect("loop"))
return nullptr;
if (consume_while(is_any_of(" \t\n")).is_empty()) {
restore_to(*rule_start);
return nullptr;
}
{
auto obrace_error_start = push_start();
if (!expect('{')) {
auto syntax_error = create<AST::SyntaxError>("Expected an open brace '{' to start a 'loop' loop body", true);
return create<AST::ForLoop>(String::empty(), nullptr, move(syntax_error), Optional<AST::Position> {}); // ForLoop null null Block
}
}
TemporaryChange controls { m_continuation_controls_allowed, true };
auto body = parse_toplevel();
{
auto cbrace_error_start = push_start();
if (!expect('}')) {
auto error_start = push_start();
auto syntax_error = create<AST::SyntaxError>("Expected a close brace '}' to end a 'loop' loop body", true);
if (body)
body->set_is_syntax_error(*syntax_error);
else
body = syntax_error;
}
}
return create<AST::ForLoop>(String::empty(), nullptr, move(body), Optional<AST::Position> {}); // ForLoop null null Block
}
RefPtr<AST::Node> Parser::parse_if_expr()
{
auto rule_start = push_start();
if (!expect("if"))
return nullptr;
if (consume_while(is_any_of(" \t\n")).is_empty()) {
restore_to(*rule_start);
return nullptr;
}
RefPtr<AST::Node> condition;
{
auto cond_error_start = push_start();
condition = parse_or_logical_sequence();
if (!condition)
condition = create<AST::SyntaxError>("Expected a logical sequence after 'if'", true);
}
auto parse_braced_toplevel = [&]() -> RefPtr<AST::Node> {
RefPtr<AST::Node> body;
{
auto obrace_error_start = push_start();
if (!expect('{')) {
body = create<AST::SyntaxError>("Expected an open brace '{' to start an 'if' true branch", true);
}
}
if (!body)
body = parse_toplevel();
{
auto cbrace_error_start = push_start();
if (!expect('}')) {
auto error_start = push_start();
RefPtr<AST::SyntaxError> syntax_error = create<AST::SyntaxError>("Expected a close brace '}' to end an 'if' true branch", true);
if (body)
body->set_is_syntax_error(*syntax_error);
else
body = syntax_error;
}
}
return body;
};
consume_while(is_any_of(" \t\n"));
auto true_branch = parse_braced_toplevel();
auto end_before_else = m_offset;
auto line_before_else = line();
consume_while(is_any_of(" \t\n"));
Optional<AST::Position> else_position;
{
auto else_start = push_start();
if (expect("else"))
else_position = AST::Position { else_start->offset, m_offset, else_start->line, line() };
else
restore_to(end_before_else, line_before_else);
}
if (else_position.has_value()) {
consume_while(is_any_of(" \t\n"));
if (peek() == '{') {
auto false_branch = parse_braced_toplevel();
return create<AST::IfCond>(else_position, condition.release_nonnull(), move(true_branch), move(false_branch)); // If expr true_branch Else false_branch
}
auto else_if_branch = parse_if_expr();
return create<AST::IfCond>(else_position, condition.release_nonnull(), move(true_branch), move(else_if_branch)); // If expr true_branch Else If ...
}
return create<AST::IfCond>(else_position, condition.release_nonnull(), move(true_branch), nullptr); // If expr true_branch
}
RefPtr<AST::Node> Parser::parse_subshell()
{
auto rule_start = push_start();
if (!expect('{'))
return nullptr;
auto body = parse_toplevel();
{
auto cbrace_error_start = push_start();
if (!expect('}')) {
auto error_start = push_start();
RefPtr<AST::SyntaxError> syntax_error = create<AST::SyntaxError>("Expected a close brace '}' to end a subshell", true);
if (body)
body->set_is_syntax_error(*syntax_error);
else
body = syntax_error;
}
}
return create<AST::Subshell>(move(body));
}
RefPtr<AST::Node> Parser::parse_match_expr()
{
auto rule_start = push_start();
if (!expect("match"))
return nullptr;
if (consume_while(is_whitespace).is_empty()) {
restore_to(*rule_start);
return nullptr;
}
auto match_expression = parse_expression();
if (!match_expression) {
return create<AST::MatchExpr>(
create<AST::SyntaxError>("Expected an expression after 'match'", true),
String {}, Optional<AST::Position> {}, Vector<AST::MatchEntry> {});
}
consume_while(is_any_of(" \t\n"));
String match_name;
Optional<AST::Position> as_position;
auto as_start = m_offset;
auto as_line = line();
if (expect("as")) {
as_position = AST::Position { as_start, m_offset, as_line, line() };
if (consume_while(is_any_of(" \t\n")).is_empty()) {
auto node = create<AST::MatchExpr>(
match_expression.release_nonnull(),
String {}, move(as_position), Vector<AST::MatchEntry> {});
node->set_is_syntax_error(create<AST::SyntaxError>("Expected whitespace after 'as' in 'match'", true));
return node;
}
match_name = consume_while(is_word_character);
if (match_name.is_empty()) {
auto node = create<AST::MatchExpr>(
match_expression.release_nonnull(),
String {}, move(as_position), Vector<AST::MatchEntry> {});
node->set_is_syntax_error(create<AST::SyntaxError>("Expected an identifier after 'as' in 'match'", true));
return node;
}
}
consume_while(is_any_of(" \t\n"));
if (!expect('{')) {
auto node = create<AST::MatchExpr>(
match_expression.release_nonnull(),
move(match_name), move(as_position), Vector<AST::MatchEntry> {});
node->set_is_syntax_error(create<AST::SyntaxError>("Expected an open brace '{' to start a 'match' entry list", true));
return node;
}
consume_while(is_any_of(" \t\n"));
Vector<AST::MatchEntry> entries;
for (;;) {
auto entry = parse_match_entry();
consume_while(is_any_of(" \t\n"));
if (entry.options.is_empty())
break;
entries.append(entry);
}
consume_while(is_any_of(" \t\n"));
if (!expect('}')) {
auto node = create<AST::MatchExpr>(
match_expression.release_nonnull(),
move(match_name), move(as_position), move(entries));
node->set_is_syntax_error(create<AST::SyntaxError>("Expected a close brace '}' to end a 'match' entry list", true));
return node;
}
return create<AST::MatchExpr>(match_expression.release_nonnull(), move(match_name), move(as_position), move(entries));
}
AST::MatchEntry Parser::parse_match_entry()
{
auto rule_start = push_start();
NonnullRefPtrVector<AST::Node> patterns;
Vector<AST::Position> pipe_positions;
Optional<Vector<String>> match_names;
Optional<AST::Position> match_as_position;
auto pattern = parse_match_pattern();
if (!pattern)
return { {}, {}, {}, {}, create<AST::SyntaxError>("Expected a pattern in 'match' body", true) };
patterns.append(pattern.release_nonnull());
consume_while(is_any_of(" \t\n"));
auto previous_pipe_start_position = m_offset;
auto previous_pipe_start_line = line();
RefPtr<AST::SyntaxError> error;
while (expect('|')) {
pipe_positions.append({ previous_pipe_start_position, m_offset, previous_pipe_start_line, line() });
consume_while(is_any_of(" \t\n"));
auto pattern = parse_match_pattern();
if (!pattern) {
error = create<AST::SyntaxError>("Expected a pattern to follow '|' in 'match' body", true);
break;
}
consume_while(is_any_of(" \t\n"));
patterns.append(pattern.release_nonnull());
previous_pipe_start_line = line();
previous_pipe_start_position = m_offset;
}
consume_while(is_any_of(" \t\n"));
auto as_start_position = m_offset;
auto as_start_line = line();
if (expect("as")) {
match_as_position = AST::Position { as_start_position, m_offset, as_start_line, line() };
consume_while(is_any_of(" \t\n"));
if (!expect('(')) {
if (!error)
error = create<AST::SyntaxError>("Expected an explicit list of identifiers after a pattern 'as'");
} else {
match_names = Vector<String>();
for (;;) {
consume_while(is_whitespace);
auto name = consume_while(is_word_character);
if (name.is_empty())
break;
match_names.value().append(move(name));
}
if (!expect(')')) {
if (!error)
error = create<AST::SyntaxError>("Expected a close paren ')' to end the identifier list of pattern 'as'", true);
}
}
consume_while(is_any_of(" \t\n"));
}
if (!expect('{')) {
if (!error)
error = create<AST::SyntaxError>("Expected an open brace '{' to start a match entry body", true);
}
auto body = parse_toplevel();
if (!expect('}')) {
if (!error)
error = create<AST::SyntaxError>("Expected a close brace '}' to end a match entry body", true);
}
if (body && error)
body->set_is_syntax_error(*error);
else if (error)
body = error;
return { move(patterns), move(match_names), move(match_as_position), move(pipe_positions), move(body) };
}
RefPtr<AST::Node> Parser::parse_match_pattern()
{
return parse_expression();
}
RefPtr<AST::Node> Parser::parse_redirection()
{
auto rule_start = push_start();
auto pipe_fd = 0;
auto number = consume_while(is_digit);
if (number.is_empty()) {
pipe_fd = -1;
} else {
auto fd = number.to_int();
pipe_fd = fd.value_or(-1);
}
switch (peek()) {
case '>': {
consume();
if (peek() == '>') {
consume();
consume_while(is_whitespace);
pipe_fd = pipe_fd >= 0 ? pipe_fd : STDOUT_FILENO;
auto path = parse_expression();
if (!path) {
if (!at_end()) {
// Eat a character and hope the problem goes away
consume();
}
path = create<AST::SyntaxError>("Expected a path after redirection", true);
}
return create<AST::WriteAppendRedirection>(pipe_fd, path.release_nonnull()); // Redirection WriteAppend
}
if (peek() == '&') {
consume();
// FIXME: 'fd>&-' Syntax not the best. needs discussion.
if (peek() == '-') {
consume();
pipe_fd = pipe_fd >= 0 ? pipe_fd : STDOUT_FILENO;
return create<AST::CloseFdRedirection>(pipe_fd); // Redirection CloseFd
}
int dest_pipe_fd = 0;
auto number = consume_while(is_digit);
pipe_fd = pipe_fd >= 0 ? pipe_fd : STDOUT_FILENO;
if (number.is_empty()) {
dest_pipe_fd = -1;
} else {
auto fd = number.to_int();
dest_pipe_fd = fd.value_or(-1);
}
auto redir = create<AST::Fd2FdRedirection>(pipe_fd, dest_pipe_fd); // Redirection Fd2Fd
if (dest_pipe_fd == -1)
redir->set_is_syntax_error(*create<AST::SyntaxError>("Expected a file descriptor"));
return redir;
}
consume_while(is_whitespace);
pipe_fd = pipe_fd >= 0 ? pipe_fd : STDOUT_FILENO;
auto path = parse_expression();
if (!path) {
if (!at_end()) {
// Eat a character and hope the problem goes away
consume();
}
path = create<AST::SyntaxError>("Expected a path after redirection", true);
}
return create<AST::WriteRedirection>(pipe_fd, path.release_nonnull()); // Redirection Write
}
case '<': {
consume();
enum {
Read,
ReadWrite,
} mode { Read };
if (peek() == '>') {
mode = ReadWrite;
consume();
}
consume_while(is_whitespace);
pipe_fd = pipe_fd >= 0 ? pipe_fd : STDIN_FILENO;
auto path = parse_expression();
if (!path) {
if (!at_end()) {
// Eat a character and hope the problem goes away
consume();
}
path = create<AST::SyntaxError>("Expected a path after redirection", true);
}
if (mode == Read)
return create<AST::ReadRedirection>(pipe_fd, path.release_nonnull()); // Redirection Read
return create<AST::ReadWriteRedirection>(pipe_fd, path.release_nonnull()); // Redirection ReadWrite
}
default:
restore_to(*rule_start);
return nullptr;
}
}
RefPtr<AST::Node> Parser::parse_list_expression()
{
consume_while(is_whitespace);
auto rule_start = push_start();
Vector<NonnullRefPtr<AST::Node>> nodes;
do {
auto expr = parse_expression();
if (!expr)
break;
nodes.append(expr.release_nonnull());
} while (!consume_while(is_whitespace).is_empty());
if (nodes.is_empty())
return nullptr;
return create<AST::ListConcatenate>(move(nodes)); // Concatenate List
}
RefPtr<AST::Node> Parser::parse_expression()
{
auto rule_start = push_start();
if (m_rule_start_offsets.size() > max_allowed_nested_rule_depth)
return create<AST::SyntaxError>(String::formatted("Expression nested too deep (max allowed is {})", max_allowed_nested_rule_depth));
auto starting_char = peek();
auto read_concat = [&](auto&& expr) -> NonnullRefPtr<AST::Node> {
if (is_whitespace(peek()))
return move(expr);
if (auto next_expr = parse_expression())
return create<AST::Juxtaposition>(move(expr), next_expr.release_nonnull());
return move(expr);
};
if (strchr("&|)} ;<>\n", starting_char) != nullptr)
return nullptr;
if (m_extra_chars_not_allowed_in_barewords.contains_slow(starting_char))
return nullptr;
if (m_is_in_brace_expansion_spec && next_is(".."))
return nullptr;
if (isdigit(starting_char)) {
ScopedValueRollback offset_rollback { m_offset };
auto redir = parse_redirection();
if (redir)
return nullptr;
}
if (starting_char == '$') {
if (auto variable = parse_variable())
return read_concat(variable.release_nonnull());
if (auto inline_exec = parse_evaluate())
return read_concat(inline_exec.release_nonnull());
}
if (starting_char == '#')
return parse_comment();
if (starting_char == '(') {
consume();
auto list = parse_list_expression();
if (!expect(')')) {
restore_to(*rule_start);
return nullptr;
}
return read_concat(create<AST::CastToList>(move(list))); // Cast To List
}
if (starting_char == '!') {
if (auto designator = parse_history_designator())
return designator;
}
if (auto composite = parse_string_composite())
return read_concat(composite.release_nonnull());
return nullptr;
}
RefPtr<AST::Node> Parser::parse_string_composite()
{
auto rule_start = push_start();
if (auto string = parse_string()) {
if (auto next_part = parse_string_composite())
return create<AST::Juxtaposition>(string.release_nonnull(), next_part.release_nonnull()); // Concatenate String StringComposite
return string;
}
if (auto variable = parse_variable()) {
if (auto next_part = parse_string_composite())
return create<AST::Juxtaposition>(variable.release_nonnull(), next_part.release_nonnull()); // Concatenate Variable StringComposite
return variable;
}
if (auto glob = parse_glob()) {
if (auto next_part = parse_string_composite())
return create<AST::Juxtaposition>(glob.release_nonnull(), next_part.release_nonnull()); // Concatenate Glob StringComposite
return glob;
}
if (auto expansion = parse_brace_expansion()) {
if (auto next_part = parse_string_composite())
return create<AST::Juxtaposition>(expansion.release_nonnull(), next_part.release_nonnull()); // Concatenate BraceExpansion StringComposite
return expansion;
}
if (auto bareword = parse_bareword()) {
if (auto next_part = parse_string_composite())
return create<AST::Juxtaposition>(bareword.release_nonnull(), next_part.release_nonnull()); // Concatenate Bareword StringComposite
return bareword;
}
if (auto inline_command = parse_evaluate()) {
if (auto next_part = parse_string_composite())
return create<AST::Juxtaposition>(inline_command.release_nonnull(), next_part.release_nonnull()); // Concatenate Execute StringComposite
return inline_command;
}
return nullptr;
}
RefPtr<AST::Node> Parser::parse_string()
{
auto rule_start = push_start();
if (at_end())
return nullptr;
if (peek() == '"') {
consume();
auto inner = parse_doublequoted_string_inner();
if (!inner)
inner = create<AST::SyntaxError>("Unexpected EOF in string", true);
if (!expect('"')) {
inner = create<AST::DoubleQuotedString>(move(inner));
inner->set_is_syntax_error(*create<AST::SyntaxError>("Expected a terminating double quote", true));
return inner;
}
return create<AST::DoubleQuotedString>(move(inner)); // Double Quoted String
}
if (peek() == '\'') {
consume();
auto text = consume_while(is_not('\''));
bool is_error = false;
if (!expect('\''))
is_error = true;
auto result = create<AST::StringLiteral>(move(text)); // String Literal
if (is_error)
result->set_is_syntax_error(*create<AST::SyntaxError>("Expected a terminating single quote", true));
return move(result);
}
return nullptr;
}
RefPtr<AST::Node> Parser::parse_doublequoted_string_inner()
{
auto rule_start = push_start();
if (at_end())
return nullptr;
StringBuilder builder;
while (!at_end() && peek() != '"') {
if (peek() == '\\') {
consume();
if (at_end()) {
break;
}
auto ch = consume();
switch (ch) {
case '\\':
default:
builder.append(ch);
break;
case 'x': {
if (m_input.length() <= m_offset + 2)
break;
auto first_nibble = tolower(consume());
auto second_nibble = tolower(consume());
if (!isxdigit(first_nibble) || !isxdigit(second_nibble)) {
builder.append(first_nibble);
builder.append(second_nibble);
break;
}
builder.append(to_byte(first_nibble, second_nibble));
break;
}
case 'a':
builder.append('\a');
break;
case 'b':
builder.append('\b');
break;
case 'e':
builder.append('\x1b');
break;
case 'f':
builder.append('\f');
break;
case 'r':
builder.append('\r');
break;
case 'n':
builder.append('\n');
break;
}
continue;
}
if (peek() == '$') {
auto string_literal = create<AST::StringLiteral>(builder.to_string()); // String Literal
if (auto variable = parse_variable()) {
auto inner = create<AST::StringPartCompose>(
move(string_literal),
variable.release_nonnull()); // Compose String Variable
if (auto string = parse_doublequoted_string_inner()) {
return create<AST::StringPartCompose>(move(inner), string.release_nonnull()); // Compose Composition Composition
}
return inner;
}
if (auto evaluate = parse_evaluate()) {
auto composition = create<AST::StringPartCompose>(
move(string_literal),
evaluate.release_nonnull()); // Compose String Sequence
if (auto string = parse_doublequoted_string_inner()) {
return create<AST::StringPartCompose>(move(composition), string.release_nonnull()); // Compose Composition Composition
}
return composition;
}
}
builder.append(consume());
}
return create<AST::StringLiteral>(builder.to_string()); // String Literal
}
RefPtr<AST::Node> Parser::parse_variable()
{
auto rule_start = push_start();
if (at_end())
return nullptr;
if (peek() != '$')
return nullptr;
consume();
switch (peek()) {
case '$':
case '?':
case '*':
case '#':
return create<AST::SpecialVariable>(consume()); // Variable Special
default:
break;
}
auto name = consume_while(is_word_character);
if (name.length() == 0) {
restore_to(rule_start->offset, rule_start->line);
return nullptr;
}
return create<AST::SimpleVariable>(move(name)); // Variable Simple
}
RefPtr<AST::Node> Parser::parse_evaluate()
{
auto rule_start = push_start();
if (at_end())
return nullptr;
if (peek() != '$')
return nullptr;
consume();
if (peek() == '(') {
consume();
auto inner = parse_pipe_sequence();
if (!inner)
inner = create<AST::SyntaxError>("Unexpected EOF in list", true);
if (!expect(')'))
inner->set_is_syntax_error(*create<AST::SyntaxError>("Expected a terminating close paren", true));
return create<AST::Execute>(inner.release_nonnull(), true);
}
auto inner = parse_expression();
if (!inner) {
inner = create<AST::SyntaxError>("Expected a command", true);
} else {
if (inner->is_list()) {
auto execute_inner = create<AST::Execute>(inner.release_nonnull(), true);
inner = move(execute_inner);
} else {
auto dyn_inner = create<AST::DynamicEvaluate>(inner.release_nonnull());
inner = move(dyn_inner);
}
}
return inner;
}
RefPtr<AST::Node> Parser::parse_history_designator()
{
auto rule_start = push_start();
VERIFY(peek() == '!');
consume();
// Event selector
AST::HistorySelector selector;
RefPtr<AST::SyntaxError> syntax_error;
selector.event.kind = AST::HistorySelector::EventKind::StartingStringLookup;
selector.event.text_position = { m_offset, m_offset, m_line, m_line };
selector.word_selector_range = {
AST::HistorySelector::WordSelector {
AST::HistorySelector::WordSelectorKind::Index,
0,
{ m_offset, m_offset, m_line, m_line },
nullptr },
AST::HistorySelector::WordSelector {
AST::HistorySelector::WordSelectorKind::Last,
0,
{ m_offset, m_offset, m_line, m_line },
nullptr }
};
switch (peek()) {
case '!':
consume();
selector.event.kind = AST::HistorySelector::EventKind::IndexFromEnd;
selector.event.index = 0;
selector.event.text = "!";
break;
case '?':
consume();
selector.event.kind = AST::HistorySelector::EventKind::ContainingStringLookup;
[[fallthrough]];
default: {
TemporaryChange chars_change { m_extra_chars_not_allowed_in_barewords, { ':' } };
auto bareword = parse_bareword();
if (!bareword || !bareword->is_bareword()) {
restore_to(*rule_start);
return nullptr;
}
selector.event.text = static_ptr_cast<AST::BarewordLiteral>(bareword)->text();
selector.event.text_position = bareword->position();
auto it = selector.event.text.begin();
bool is_negative = false;
if (*it == '-') {
++it;
is_negative = true;
}
if (it != selector.event.text.end() && AK::all_of(it, selector.event.text.end(), is_digit)) {
if (is_negative)
selector.event.kind = AST::HistorySelector::EventKind::IndexFromEnd;
else
selector.event.kind = AST::HistorySelector::EventKind::IndexFromStart;
auto number = selector.event.text.to_int();
if (number.has_value())
selector.event.index = abs(number.value());
else
syntax_error = create<AST::SyntaxError>("History entry index value invalid or out of range");
}
break;
}
}
if (peek() != ':') {
auto node = create<AST::HistoryEvent>(move(selector));
if (syntax_error)
node->set_is_syntax_error(*syntax_error);
return node;
}
consume();
// Word selectors
auto parse_word_selector = [&]() -> Optional<AST::HistorySelector::WordSelector> {
auto rule_start = push_start();
auto c = peek();
if (isdigit(c)) {
auto num = consume_while(is_digit);
auto value = num.to_uint();
if (!value.has_value()) {
return AST::HistorySelector::WordSelector {
AST::HistorySelector::WordSelectorKind::Index,
0,
{ m_rule_start_offsets.last(), m_offset, m_rule_start_lines.last(), line() },
syntax_error ? NonnullRefPtr(*syntax_error) : create<AST::SyntaxError>("Word selector value invalid or out of range")
};
}
return AST::HistorySelector::WordSelector {
AST::HistorySelector::WordSelectorKind::Index,
value.value(),
{ m_rule_start_offsets.last(), m_offset, m_rule_start_lines.last(), line() },
syntax_error
};
}
if (c == '^') {
consume();
return AST::HistorySelector::WordSelector {
AST::HistorySelector::WordSelectorKind::Index,
0,
{ m_rule_start_offsets.last(), m_offset, m_rule_start_lines.last(), line() },
syntax_error
};
}
if (c == '$') {
consume();
return AST::HistorySelector::WordSelector {
AST::HistorySelector::WordSelectorKind::Last,
0,
{ m_rule_start_offsets.last(), m_offset, m_rule_start_lines.last(), line() },
syntax_error
};
}
return {};
};
auto start = parse_word_selector();
if (!start.has_value()) {
if (!syntax_error)
syntax_error = create<AST::SyntaxError>("Expected a word selector after ':' in a history event designator", true);
auto node = create<AST::HistoryEvent>(move(selector));
node->set_is_syntax_error(*syntax_error);
return node;
}
selector.word_selector_range.start = start.release_value();
if (peek() == '-') {
consume();
auto end = parse_word_selector();
if (!end.has_value()) {
if (!syntax_error)
syntax_error = create<AST::SyntaxError>("Expected a word selector after '-' in a history event designator word selector", true);
auto node = create<AST::HistoryEvent>(move(selector));
node->set_is_syntax_error(*syntax_error);
return node;
}
selector.word_selector_range.end = move(end);
} else {
selector.word_selector_range.end.clear();
}
auto node = create<AST::HistoryEvent>(move(selector));
if (syntax_error)
node->set_is_syntax_error(*syntax_error);
return node;
}
RefPtr<AST::Node> Parser::parse_comment()
{
if (at_end())
return nullptr;
if (peek() != '#')
return nullptr;
consume();
auto text = consume_while(is_not('\n'));
return create<AST::Comment>(move(text)); // Comment
}
RefPtr<AST::Node> Parser::parse_bareword()
{
auto rule_start = push_start();
StringBuilder builder;
auto is_acceptable_bareword_character = [&](char c) {
return strchr("\\\"'*$&#|(){} ?;<>\n", c) == nullptr
&& !m_extra_chars_not_allowed_in_barewords.contains_slow(c);
};
while (!at_end()) {
char ch = peek();
if (ch == '\\') {
consume();
if (!at_end()) {
ch = consume();
if (is_acceptable_bareword_character(ch))
builder.append('\\');
}
builder.append(ch);
continue;
}
if (m_is_in_brace_expansion_spec && next_is("..")) {
// Don't eat '..' in a brace expansion spec.
break;
}
if (is_acceptable_bareword_character(ch)) {
builder.append(consume());
continue;
}
break;
}
if (builder.is_empty())
return nullptr;
auto current_end = m_offset;
auto current_line = line();
auto string = builder.to_string();
if (string.starts_with('~')) {
String username;
RefPtr<AST::Node> tilde, text;
auto first_slash_index = string.index_of("/");
if (first_slash_index.has_value()) {
username = string.substring_view(1, first_slash_index.value() - 1);
string = string.substring_view(first_slash_index.value(), string.length() - first_slash_index.value());
} else {
username = string.substring_view(1, string.length() - 1);
string = "";
}
// Synthesize a Tilde Node with the correct positioning information.
{
restore_to(rule_start->offset, rule_start->line);
auto ch = consume();
VERIFY(ch == '~');
tilde = create<AST::Tilde>(move(username));
}
if (string.is_empty())
return tilde;
// Synthesize a BarewordLiteral Node with the correct positioning information.
{
auto text_start = push_start();
restore_to(current_end, current_line);
text = create<AST::BarewordLiteral>(move(string));
}
return create<AST::Juxtaposition>(tilde.release_nonnull(), text.release_nonnull()); // Juxtaposition Variable Bareword
}
if (string.starts_with("\\~")) {
// Un-escape the tilde, but only at the start (where it would be an expansion)
string = string.substring(1, string.length() - 1);
}
return create<AST::BarewordLiteral>(move(string)); // Bareword Literal
}
RefPtr<AST::Node> Parser::parse_glob()
{
auto rule_start = push_start();
auto bareword_part = parse_bareword();
if (at_end())
return bareword_part;
char ch = peek();
if (ch == '*' || ch == '?') {
auto saved_offset = save_offset();
consume();
StringBuilder textbuilder;
if (bareword_part) {
StringView text;
if (bareword_part->is_bareword()) {
auto bareword = static_cast<AST::BarewordLiteral*>(bareword_part.ptr());
text = bareword->text();
} else {
// FIXME: Allow composition of tilde+bareword with globs: '~/foo/bar/baz*'
restore_to(saved_offset.offset, saved_offset.line);
bareword_part->set_is_syntax_error(*create<AST::SyntaxError>(String::format("Unexpected %s inside a glob", bareword_part->class_name().characters())));
return bareword_part;
}
textbuilder.append(text);
}
textbuilder.append(ch);
auto glob_after = parse_glob();
if (glob_after) {
if (glob_after->is_glob()) {
auto glob = static_cast<AST::Glob*>(glob_after.ptr());
textbuilder.append(glob->text());
} else if (glob_after->is_bareword()) {
auto bareword = static_cast<AST::BarewordLiteral*>(glob_after.ptr());
textbuilder.append(bareword->text());
} else if (glob_after->is_tilde()) {
auto bareword = static_cast<AST::Tilde*>(glob_after.ptr());
textbuilder.append("~");
textbuilder.append(bareword->text());
} else {
return create<AST::SyntaxError>(String::formatted("Invalid node '{}' in glob position, escape shell special characters", glob_after->class_name()));
}
}
return create<AST::Glob>(textbuilder.to_string()); // Glob
}
return bareword_part;
}
RefPtr<AST::Node> Parser::parse_brace_expansion()
{
auto rule_start = push_start();
if (!expect('{'))
return nullptr;
if (auto spec = parse_brace_expansion_spec()) {
if (!expect('}'))
spec->set_is_syntax_error(create<AST::SyntaxError>("Expected a close brace '}' to end a brace expansion", true));
return spec;
}
restore_to(*rule_start);
return nullptr;
}
RefPtr<AST::Node> Parser::parse_brace_expansion_spec()
{
TemporaryChange is_in_brace_expansion { m_is_in_brace_expansion_spec, true };
TemporaryChange chars_change { m_extra_chars_not_allowed_in_barewords, { ',' } };
auto rule_start = push_start();
auto start_expr = parse_expression();
if (start_expr) {
if (expect("..")) {
if (auto end_expr = parse_expression()) {
if (end_expr->position().start_offset != start_expr->position().end_offset + 2)
end_expr->set_is_syntax_error(create<AST::SyntaxError>("Expected no whitespace between '..' and the following expression in brace expansion"));
return create<AST::Range>(start_expr.release_nonnull(), end_expr.release_nonnull());
}
return create<AST::Range>(start_expr.release_nonnull(), create<AST::SyntaxError>("Expected an expression to end range brace expansion with", true));
}
}
NonnullRefPtrVector<AST::Node> subexpressions;
if (start_expr)
subexpressions.append(start_expr.release_nonnull());
while (expect(',')) {
auto expr = parse_expression();
if (expr) {
subexpressions.append(expr.release_nonnull());
} else {
subexpressions.append(create<AST::StringLiteral>(""));
}
}
if (subexpressions.is_empty())
return nullptr;
return create<AST::BraceExpansion>(move(subexpressions));
}
StringView Parser::consume_while(Function<bool(char)> condition)
{
if (at_end())
return {};
auto start_offset = m_offset;
while (!at_end() && condition(peek()))
consume();
return m_input.substring_view(start_offset, m_offset - start_offset);
}
bool Parser::next_is(const StringView& next)
{
auto start = push_start();
auto res = expect(next);
restore_to(*start);
return res;
}
}
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