We now wrap _withStackFrame() around wider sections of code, including
_loadStylesheet() which handles parse errors, so that the @use/@import
stack frames are available.
In addition to being useful for users of Sass, this will make it
possible for core Sass functions to produce warnings without needing
an explicit reference to the evaluator.
The automatic @charset adding is useful in general, but there are
consistently cases where it trips up naïve downstream tools. This
option makes it easier for users to control when it occurs.
This adds a --no-unicode option to disable Unicode span rendering,
decouples repl highlighting from SourceSpan.highlight, and updates
tests to work with the new error highlighting.
It also tightly scopes source spans for statements with children.
Previously, source spans for these nodes extended all the way through
any whitespace that followed the node. This led to messy-looking
multiline span highlights with dart-lang/source_span#25.
Now, StylesheetParser.children doesn't consume trailing whitespace.
Instead, we add a helper method StylesheetParser._withChildren that
parses children, creates the appropriate span, and then consumes the
trailing whitespace.
- Documentation comments are simply identified by starting with a triple-slash "///".
- Adjacent comments in indented syntax are now coalesced into a single comment.
This introduces two changes:
1. It changes the epsilon within which two numbers are considered
equal to be an order of magnitude smaller than the numeric
precision. Ruby Sass has always done this, and Dart Sass should
have but did not until now.
2. It parses the component of a number after the decimal point using
double.parse() to avoid accumulating floating point errors.
Always include the error location in JS error messages
I was trying to match Node Sass's behavior by having Error.formatted
property have more detail than Error.message, but our errors rely on
source snippets for context so this just ended up making them
confusing.
This allows us to accurately track the source spans for parenthesized
expressions, which in turn allows us to print accurate error
indications.
Adding a new class for this more accurately represents the structure
of the expression, but it also involves an extra allocation during
parsing and an extra level of nesting during evaluation which could
have a small but real performance impact.
We could alternatively add a package-internal setter for
Expression.span, and update the source span for parenthesized
expressions after they're initially parsed. However, this has its own
downsides: it adds complexity and mutability to the object model; and
many expression classes currently use lazily-generated spans, so
making them settable would require adding extra slots on those
classes.
I decided to go with the extra class because it only adds overhead
when parentheses are actually used in practice, as opposed to adding
overhead to every list/color/etc. The runtime overhead is also likely
to be mitigated if at any point we add a constant-folding step.
