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Shell: Make the parser read consecutive sequences without recursing

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This fixes (the easy) part of #4976.
This commit is contained in:
AnotherTest 2021-01-16 23:20:52 +03:30 • committed by Andreas Kling
parent 212c90d68f
commit 2bd77bc93b
7 changed files with 130 additions and 100 deletions
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91
Userland/Shell/Parser.cpp
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@ -111,6 +111,11 @@ NonnullRefPtr<A> Parser::create(Args... args)
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';
@ -180,58 +185,70 @@ RefPtr<AST::Node> Parser::parse_toplevel()
{
auto rule_start = push_start();
if (auto sequence = parse_sequence())
return create<AST::Execute>(sequence.release_nonnull());
SequenceParseResult result;
NonnullRefPtrVector<AST::Node> sequence;
Vector<AST::Position> positions;
do {
result = parse_sequence();
if (result.entries.is_empty())
break;
return nullptr;
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)));
}
RefPtr<AST::Node> Parser::parse_sequence()
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();
{
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 var_decls;
return { move(left), {}, ShouldReadMoreSequences::No };
case ';':
case '\n': {
if (!var_decls)
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 };
auto rest = parse_sequence();
if (rest)
return create<AST::Sequence>(
var_decls.release_nonnull(),
rest.release_nonnull(),
AST::Position { pos_before_seps.offset, pos_after_seps.offset, pos_before_seps.line, pos_after_seps.line });
return var_decls;
return { move(left), { move(separator_position) }, ShouldReadMoreSequences::Yes };
}
default:
break;
}
auto first = parse_function_decl();
auto first_entry = parse_function_decl();
if (!first)
first = parse_or_logical_sequence();
Vector<AST::Position> separator_positions;
if (!first)
return var_decls;
if (!first_entry)
first_entry = parse_or_logical_sequence();
if (var_decls)
first = create<AST::Sequence>(
var_decls.release_nonnull(),
first.release_nonnull(),
AST::Position { pos_before_seps.offset, pos_before_seps.offset, pos_before_seps.line, pos_before_seps.line });
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);
@ -241,29 +258,19 @@ RefPtr<AST::Node> Parser::parse_sequence()
case '\n': {
consume_while(is_any_of("\n;"));
auto pos_after_seps = save_offset();
if (auto expr = parse_sequence()) {
return create<AST::Sequence>(
first.release_nonnull(),
expr.release_nonnull(),
AST::Position { pos_before_seps.offset, pos_after_seps.offset, pos_before_seps.line, pos_after_seps.line }); // Sequence
}
return first;
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>(first.release_nonnull()); // Execute Background
if (auto rest = parse_sequence())
return create<AST::Sequence>(
move(bg),
rest.release_nonnull(),
AST::Position { pos_before_seps.offset, pos_after_seps.offset, pos_before_seps.line, pos_before_seps.line }); // Sequence Background Sequence
return bg;
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 first;
return { move(left), move(separator_positions), ShouldReadMoreSequences::No };
}
}