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LibJS: Replace 'size_t line, size_t column' with 'Optional<Position>'

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This is a bit nicer for two reasons:

- The absence of line number/column information isn't based on 'values
  are zero' anymore but on Optional's value
- When reporting syntax errors with position information other than the
  current token's position we had to store line and column ourselves,
  like this:

      auto foo_start_line = m_parser_state.m_current_token.line_number();
      auto foo_start_column = m_parser_state.m_current_token.line_column();
      ...
      syntax_error("...", foo_start_line, foo_start_column);

  Which now becomes:

      auto foo_start= position();
      ...
      syntax_error("...", foo_start);

  This makes it easier to report correct positions for syntax errors
  that only emerge a few tokens later :^)
This commit is contained in:
Linus Groh 2020-11-02 21:03:19 +00:00 • committed by Andreas Kling
parent ed5469c1c2
commit e07a39c816
2 changed files with 34 additions and 29 deletions
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21
Libraries/LibJS/Parser.h
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@ -100,21 +100,25 @@ public:
NonnullRefPtr<Expression> parse_property_key();
NonnullRefPtr<AssignmentExpression> parse_assignment_expression(AssignmentOp, NonnullRefPtr<Expression> lhs, int min_precedence, Associativity);
struct Error {
String message;
struct Position {
size_t line;
size_t column;
};
struct Error {
String message;
Optional<Position> position;
String to_string() const
{
if (line == 0 || column == 0)
if (!position.has_value())
return message;
return String::formatted("{} (line: {}, column: {})", message, line, column);
return String::formatted("{} (line: {}, column: {})", message, position.value().line, position.value().column);
}
String source_location_hint(const StringView& source, const char spacer = ' ', const char indicator = '^') const
{
if (line == 0 || column == 0)
if (!position.has_value())
return {};
// We need to modify the source to match what the lexer considers one line - normalizing
// line terminators to \n is easier than splitting using all different LT characters.
@ -124,9 +128,9 @@ public:
source_string.replace(LINE_SEPARATOR, "\n");
source_string.replace(PARAGRAPH_SEPARATOR, "\n");
StringBuilder builder;
builder.append(source_string.split_view('\n', true)[line - 1]);
builder.append(source_string.split_view('\n', true)[position.value().line - 1]);
builder.append('\n');
for (size_t i = 0; i < column - 1; ++i)
for (size_t i = 0; i < position.value().column - 1; ++i)
builder.append(spacer);
builder.append(indicator);
return builder.build();
@ -156,13 +160,14 @@ private:
bool match(TokenType type) const;
bool done() const;
void expected(const char* what);
void syntax_error(const String& message, size_t line = 0, size_t column = 0);
void syntax_error(const String& message, Optional<Position> = {});
Token consume();
Token consume(TokenType type);
Token consume_and_validate_numeric_literal();
void consume_or_insert_semicolon();
void save_state();
void load_state();
Position position() const;
struct ParserState {
Lexer m_lexer;