This adds CSS parser error reporting for parsing of custom properties
and normal properties that have variable references.
When re-parsing a normal property that had a variable reference, we
report any parse error to be at the beginning of the property value.
This is because it is difficult to keep track of where exactly each
variable substitution came from to point to the particular value
that would have caused the parse error. For example, with this:
:root {
var-a: 1px 2px;
var-b: 3px var(a);
}
p {
margin: var(a) var(b);
}
we would end up resolving the value of 'margin' to:
" 1px 2px 3px 1px 2px"
In this string, the parse error occurs when we encounter the final
"2px", but by this point we don't know where that value came from.
So instead we just point to the line on which 'margin' was declared.
We extend ErrorReporter with an OutputError overload that takes the
specific line and column number to use in the error report to get this
right, and we store the line and column number for each token stream
we parse on the nsCSSValueTokenStream object.
This re-parses property values at computed value time if
they had a specified value that was a token stream. We add
a function nsRuleNode::ResolveVariableReferences that looks
at all the values in the nsRuleData and calls in to a new
nsCSSParser::ParsePropertyWithVariableReferences function if they have a
token stream value.
We add a nsCSSExpandedDataBlock::MapRuleInfoInto function that will
take the re-parsed property value and copy it back into the nsRuleData.
nsRuleNode::ResolveVariableReferences returns whether any variables
were attempted to be resolved, so that nsRuleNode::WalkRuleTree wil
recompute the rule detail in case any became 'inherit'.
Patch co-authored by Emmanuele Bassi <ebassi@gmail.com>
This defines a CSSVariableDeclarations class that holds a set of
variable declarations. This is at the specified value stage, so values
can either be 'initial', 'inherit' or a token stream (which is what you
normally have). The variables are stored in a hash table. Although
it's a bit of a hack, we store 'initial' and 'inherit' using special
string values that can't be valid token streams (we use "!" and ";").
Declaration objects now can have two CSSVariableDeclarations objects
on them, to store normal and !important variable declarations. So that
we keep preserving the order of declarations on the object, we inflate
mOrder to store uint32_ts, where values from eCSSProperty_COUNT onwards
represent custom properties. mVariableOrder stores the names of the
variables corresponding to those entries in mOrder.
We also add a new nsCSSProperty value, eCSSPropertyExtra_variable, which
is used to represent any custom property name.
nsCSSProps::LookupProperty can return this value.
The changes to nsCSSParser are straightforward. Custom properties
are parsed and checked for syntactic validity (e.g. "var(a,)" being
invalid) and stored on the Declaration. We use nsCSSScanner's
recording ability to grab the unparsed CSS string corresponding to
the variable's value.
