Commit Graph

3 Commits

Author SHA1 Message Date
Cameron McCormack
4fb5922824 Bug 773296 - Part 8: Resolve and compute CSS variables. r=dbaron
We add a new class CSSVariableResolver whose job is to take the
inherited computed variables and the specified variable declarations and
to perform cycle removal and resolution of the variables, storing the
result in the CSSVariableValues object on an nsStyleVariables.  We use
CSSVariableResolver in nsRuleNode::ComputeVariablesData.

The variable resolver does this:

  1. Asks the CSSVariableValues and CSSVariableDeclarations objects
     to add their variables to it.
  2. Calls in to a new nsCSSParser function
     EnumerateVariableReferences that informs the resolver which
     other variables a given variable references, and by doing so,
     builds a graph of variable dependencies.
  3. Removes variables involved in cyclic references using Tarjan's
     strongly connected component algorithm, setting those variables
     to have an invalid value.
  4. Calls in to a new nsCSSParser function ResolveVariableValue
     to resolve the remaining valid variables by substituting variable
     references.

We extend nsCSSParser::ParseValueWithVariables to take a callback
function to be invoked when encountering a variable reference.  This
lets EnumerateVariableReferences re-use ParseValueWithVariables.

CSSParserImpl::ResolveValueWithVariableReferences needs different
error handling behaviour from ParseValueWithVariables, so we don't
re-use it.

CSSParserImpl::AppendImpliedEOFCharacters is used to take the
value returned from nsCSSScanner::GetImpliedEOFCharacters while
resolving variable references that were declared using custom
properties that encountered EOF before being closed properly.

The SeparatorRequiredBetweenTokens helper function in nsCSSParser.cpp
implements the serialization rules in CSS Syntax Module Level 3:

https://dvcs.w3.org/hg/csswg/raw-file/3479cdefc59a/css-syntax/Overview.html#serialization
2013-12-12 13:09:41 +11:00
Cameron McCormack
82a5ba3c0f Bug 773296 - Part 4: Add style struct to store CSS variables. r=dbaron
This adds an nsStyleVariables on which computed variable values
will be stored.  We don't actually have any properties assigned to
nsStyleVariables; eCSSPropertyExtra_Variables which we added earlier
isn't a real property.  To avoid compiler errors for gVariableFlags
being a zero length array, we stick a dummy entry in there.

nsRuleNode::ComputeVariablesData does nothing for the moment.

nsStyleVariable nsChangeHint calculations always return 0, as later
we will compare the actual properties that reference variables to
see what changes are required for them.
2013-12-12 13:09:40 +11:00
Cameron McCormack
969c21f7eb Bug 873368 - Automatically generate nsStyleStructList.h. r=dbaron,ted 2013-07-16 14:32:25 +10:00