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c42a6189e5
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
171 lines
5.6 KiB
Python
171 lines
5.6 KiB
Python
#!/usr/bin/env python
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# This Source Code Form is subject to the terms of the Mozilla Public
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# License, v. 2.0. If a copy of the MPL was not distributed with this
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# file, You can obtain one at http://mozilla.org/MPL/2.0/.
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# This script generates nsStyleStructList.h, which contains macro invocations
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# that can be used for three things:
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#
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# 1. To generate code for each inherited style struct.
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# 2. To generate code for each reset style struct.
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# 3. To generate a tree of nested if statements that can be used to run
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# some code on each style struct.
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#
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# As an example, if we assume that we have only four style structs, the
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# generated tree of nested if statements looks like this:
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#
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# if (STYLE_STRUCT_TEST < 4) {
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# if (STYLE_STRUCT_TEST < 2) {
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# if (STYLE_STRUCT_TEST == 0) {
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# ... code for style struct with id 0 ...
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# } else {
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# ... code for style struct with id 1 ...
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# }
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# } else {
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# if (STYLE_STRUCT_TEST == 2) {
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# ... code for style struct with id 2 ...
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# } else {
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# ... code for style struct with id 3 ...
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# }
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# }
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# }
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#
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# The TOPLEVELBRANCHES variable controls how widely we branch on the outermost
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# if statement. In the example above, it splits the search space in 2, but with
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# a larger number of style structs to test -- particularly when the number is
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# closer to one power of two than the next higher one -- the average number of
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# comparisons can be reduced by splitting the top level check into more than 2.
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import math
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# List of style structs and their corresponding Check callback functions,
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# if any.
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STYLE_STRUCTS = [("INHERITED",) + x for x in [
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# Inherited style structs.
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("Font", "CheckFontCallback"),
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("Color", "CheckColorCallback"),
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("List", "nullptr"),
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("Text", "CheckTextCallback"),
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("Visibility", "nullptr"),
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("Quotes", "nullptr"),
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("UserInterface", "nullptr"),
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("TableBorder", "nullptr"),
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("SVG", "nullptr"),
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("Variables", "CheckVariablesCallback"),
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]] + [("RESET",) + x for x in [
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# Reset style structs.
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("Background", "nullptr"),
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("Position", "nullptr"),
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("TextReset", "nullptr"),
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("Display", "nullptr"),
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("Content", "nullptr"),
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("UIReset", "nullptr"),
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("Table", "nullptr"),
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("Margin", "nullptr"),
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("Padding", "nullptr"),
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("Border", "nullptr"),
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("Outline", "nullptr"),
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("XUL", "nullptr"),
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("SVGReset", "nullptr"),
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("Column", "nullptr"),
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]]
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# How widely to branch on the outermost if statement.
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TOPLEVELBRANCHES = 4
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# ---- Generate nsStyleStructList.h ----
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count = len(STYLE_STRUCTS)
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def nextPowerOf2(x):
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return int(pow(2, math.ceil(math.log(x, 2))))
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def printEntry(i):
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print "STYLE_STRUCT_%s(%s, %s)" % STYLE_STRUCTS[i]
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def printTestTree(min, max, depth, branches):
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indent = " " * depth
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if min == count - 1 and max >= count:
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print " STYLE_STRUCT_TEST_CODE(%sNS_ASSERTION(STYLE_STRUCT_TEST == %d, \"out of range\");)" % (indent, min)
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printEntry(min)
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elif max - min == 2:
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print " STYLE_STRUCT_TEST_CODE(%sif (STYLE_STRUCT_TEST == %d) {)" % (indent, min)
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printEntry(min)
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print " STYLE_STRUCT_TEST_CODE(%s} else {)" % indent
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printEntry(min + 1)
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print " STYLE_STRUCT_TEST_CODE(%s})" % indent
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elif min < count:
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mid = min + (max - min) / branches
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print " STYLE_STRUCT_TEST_CODE(%sif (STYLE_STRUCT_TEST < %d) {)" % (indent, mid)
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printTestTree(min, mid, depth + 1, 2)
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for branch in range(1, branches):
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lo = min + branch * (max - min) / branches
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hi = min + (branch + 1) * (max - min) / branches
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if lo >= count:
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break
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if branch == branches - 1 or hi >= count:
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print " STYLE_STRUCT_TEST_CODE(%s} else {)" % indent
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else:
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print " STYLE_STRUCT_TEST_CODE(%s} else if (STYLE_STRUCT_TEST < %d) {)" % (indent, hi)
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printTestTree(lo, hi, depth + 1, 2)
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print " STYLE_STRUCT_TEST_CODE(%s})" % indent
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HEADER = """/* THIS FILE IS AUTOGENERATED BY generate-stylestructlist.py - DO NOT EDIT */
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// IWYU pragma: private, include "nsStyleStructFwd.h"
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/*
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* list of structs that contain the data provided by nsStyleContext, the
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* internal API for computed style data for an element
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*/
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/*
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* This file is intended to be used by different parts of the code, with
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* the STYLE_STRUCT macro (or the STYLE_STRUCT_INHERITED and
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* STYLE_STRUCT_RESET pair of macros) defined in different ways.
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*/
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#ifndef STYLE_STRUCT_INHERITED
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#define STYLE_STRUCT_INHERITED(name, checkdata_cb) \\
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STYLE_STRUCT(name, checkdata_cb)
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#define UNDEF_STYLE_STRUCT_INHERITED
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#endif
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#ifndef STYLE_STRUCT_RESET
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#define STYLE_STRUCT_RESET(name, checkdata_cb) \\
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STYLE_STRUCT(name, checkdata_cb)
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#define UNDEF_STYLE_STRUCT_RESET
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#endif
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#ifdef STYLE_STRUCT_TEST
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#define STYLE_STRUCT_TEST_CODE(c) c
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#else
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#define STYLE_STRUCT_TEST_CODE(c)
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#endif
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// The inherited structs are listed before the Reset structs.
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// nsStyleStructID assumes this is the case, and callers other than
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// nsStyleStructFwd.h that want the structs in id-order just define
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// STYLE_STRUCT rather than including the file twice.
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"""
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FOOTER = """
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#ifdef UNDEF_STYLE_STRUCT_INHERITED
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#undef STYLE_STRUCT_INHERITED
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#undef UNDEF_STYLE_STRUCT_INHERITED
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#endif
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#ifdef UNDEF_STYLE_STRUCT_RESET
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#undef STYLE_STRUCT_RESET
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#undef UNDEF_STYLE_STRUCT_RESET
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#endif
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#undef STYLE_STRUCT_TEST_CODE
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"""
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print HEADER
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printTestTree(0, nextPowerOf2(count), 0, TOPLEVELBRANCHES)
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print FOOTER
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