gecko/layout/style/generate-stylestructlist.py
Xidorn Quan 36da0194c4 Bug 1122781 part 1 - Declare and statically check dependencies of style structs. r=dbaron
When a cyclic dependency is introduced, build will stop at generating style struct list.
For example, if you make Visibility depend on Font while Font also depend on Visibility, it would print lines like:

ERROR: Cannot resolve style struct dependencies
Resolved items: Variables Color Quotes UserInterface UIReset Table XUL
There exist cyclic dependencies in the following structs: Font List Text Visibility TableBorder SVG Background Position TextReset Display Content Margin Padding Border Outline SVGReset Column

--HG--
extra : source : bebfb64bb4a82ff51b21978998f1a0871a1c5cad
2015-02-07 13:25:21 +11:00

229 lines
8.2 KiB
Python

#!/usr/bin/env python
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
# This script generates nsStyleStructList.h, which contains macro invocations
# that can be used for three things:
#
# 1. To generate code for each inherited style struct.
# 2. To generate code for each reset style struct.
# 3. To generate a tree of nested if statements that can be used to run
# some code on each style struct.
#
# As an example, if we assume that we have only four style structs, the
# generated tree of nested if statements looks like this:
#
# if (STYLE_STRUCT_TEST < 4) {
# if (STYLE_STRUCT_TEST < 2) {
# if (STYLE_STRUCT_TEST == 0) {
# ... code for style struct with id 0 ...
# } else {
# ... code for style struct with id 1 ...
# }
# } else {
# if (STYLE_STRUCT_TEST == 2) {
# ... code for style struct with id 2 ...
# } else {
# ... code for style struct with id 3 ...
# }
# }
# }
#
# The TOPLEVELBRANCHES variable controls how widely we branch on the outermost
# if statement. In the example above, it splits the search space in 2, but with
# a larger number of style structs to test -- particularly when the number is
# closer to one power of two than the next higher one -- the average number of
# comparisons can be reduced by splitting the top level check into more than 2.
import math
NORMAL_DEP = ["Variables"]
COLOR_DEP = ["Color"]
LENGTH_DEP = ["Font", "Visibility"]
# List of style structs and their corresponding Check callback functions,
# if any.
STYLE_STRUCTS = [("INHERITED",) + x for x in [
# Inherited style structs.
("Font", "CheckFontCallback", NORMAL_DEP + ["Visibility"]),
("Color", "CheckColorCallback", NORMAL_DEP),
("List", "nullptr", NORMAL_DEP + LENGTH_DEP),
("Text", "CheckTextCallback", NORMAL_DEP + LENGTH_DEP + COLOR_DEP),
("Visibility", "nullptr", NORMAL_DEP),
("Quotes", "nullptr", NORMAL_DEP),
("UserInterface", "nullptr", NORMAL_DEP),
("TableBorder", "nullptr", NORMAL_DEP + LENGTH_DEP),
("SVG", "nullptr", NORMAL_DEP + LENGTH_DEP + COLOR_DEP),
("Variables", "CheckVariablesCallback",[]),
]] + [("RESET",) + x for x in [
# Reset style structs.
("Background", "nullptr", NORMAL_DEP + LENGTH_DEP + COLOR_DEP),
("Position", "nullptr", NORMAL_DEP + LENGTH_DEP),
("TextReset", "nullptr", NORMAL_DEP + LENGTH_DEP + COLOR_DEP),
("Display", "nullptr", NORMAL_DEP + LENGTH_DEP),
("Content", "nullptr", NORMAL_DEP + LENGTH_DEP),
("UIReset", "nullptr", NORMAL_DEP),
("Table", "nullptr", NORMAL_DEP),
("Margin", "nullptr", NORMAL_DEP + LENGTH_DEP),
("Padding", "nullptr", NORMAL_DEP + LENGTH_DEP),
("Border", "nullptr", NORMAL_DEP + LENGTH_DEP + COLOR_DEP),
("Outline", "nullptr", NORMAL_DEP + LENGTH_DEP + COLOR_DEP),
("XUL", "nullptr", NORMAL_DEP),
("SVGReset", "nullptr", NORMAL_DEP + LENGTH_DEP + COLOR_DEP),
("Column", "nullptr", NORMAL_DEP + LENGTH_DEP + COLOR_DEP),
]]
# How widely to branch on the outermost if statement.
TOPLEVELBRANCHES = 4
# ---- Generate nsStyleStructList.h ----
count = len(STYLE_STRUCTS)
# Check for problems with style struct dependencies
resolved_items = []
# This whole loop tries to sort the style structs in topological order
# according to the dependencies. A topological order exists iff there
# are no cyclic dependencies between the style structs. It resolves one
# struct each iteration, and append the resolved one to |resolved_items|.
for i in range(count):
# This inner loop picks one style struct which does not have
# unsolved dependencies. If nothing can be picked, then we
# must have some cyclic dependencies.
for j in range(count):
_, name, _, dependencies = STYLE_STRUCTS[j]
if name in resolved_items:
continue
# Check whether all dependencies of this item have been placed
for dep in dependencies:
if dep not in resolved_items:
break
else:
resolved_items.append(name)
break
else:
import sys
print >>sys.stderr, "ERROR: Cannot resolve style struct dependencies"
print >>sys.stderr, "Resolved items:", " ".join(resolved_items)
unsolved_items = [name for _, name, _, _ in STYLE_STRUCTS
if name not in resolved_items]
print >>sys.stderr, "There exist cyclic dependencies between " +\
"the following structs:", " ".join(unsolved_items)
exit(1)
def nextPowerOf2(x):
return int(pow(2, math.ceil(math.log(x, 2))))
def printEntry(i):
print "STYLE_STRUCT_%s(%s, %s)" % STYLE_STRUCTS[i][:3]
for dep in STYLE_STRUCTS[i][3]:
print "STYLE_STRUCT_DEP(%s)" % (dep,)
print "STYLE_STRUCT_END()"
def printTestTree(min, max, depth, branches):
indent = " " * depth
if min == count - 1 and max >= count:
print " STYLE_STRUCT_TEST_CODE(%sNS_ASSERTION(STYLE_STRUCT_TEST == %d, \"out of range\");)" % (indent, min)
printEntry(min)
elif max - min == 2:
print " STYLE_STRUCT_TEST_CODE(%sif (STYLE_STRUCT_TEST == %d) {)" % (indent, min)
printEntry(min)
print " STYLE_STRUCT_TEST_CODE(%s} else {)" % indent
printEntry(min + 1)
print " STYLE_STRUCT_TEST_CODE(%s})" % indent
elif min < count:
mid = min + (max - min) / branches
print " STYLE_STRUCT_TEST_CODE(%sif (STYLE_STRUCT_TEST < %d) {)" % (indent, mid)
printTestTree(min, mid, depth + 1, 2)
for branch in range(1, branches):
lo = min + branch * (max - min) / branches
hi = min + (branch + 1) * (max - min) / branches
if lo >= count:
break
if branch == branches - 1 or hi >= count:
print " STYLE_STRUCT_TEST_CODE(%s} else {)" % indent
else:
print " STYLE_STRUCT_TEST_CODE(%s} else if (STYLE_STRUCT_TEST < %d) {)" % (indent, hi)
printTestTree(lo, hi, depth + 1, 2)
print " STYLE_STRUCT_TEST_CODE(%s})" % indent
HEADER = """/* THIS FILE IS AUTOGENERATED BY generate-stylestructlist.py - DO NOT EDIT */
// IWYU pragma: private, include "nsStyleStructFwd.h"
/*
* list of structs that contain the data provided by nsStyleContext, the
* internal API for computed style data for an element
*/
/*
* This file is intended to be used by different parts of the code, with
* the STYLE_STRUCT macro (or the STYLE_STRUCT_INHERITED and
* STYLE_STRUCT_RESET pair of macros) defined in different ways.
*/
#ifndef STYLE_STRUCT_INHERITED
#define STYLE_STRUCT_INHERITED(name, checkdata_cb) \\
STYLE_STRUCT(name, checkdata_cb)
#define UNDEF_STYLE_STRUCT_INHERITED
#endif
#ifndef STYLE_STRUCT_RESET
#define STYLE_STRUCT_RESET(name, checkdata_cb) \\
STYLE_STRUCT(name, checkdata_cb)
#define UNDEF_STYLE_STRUCT_RESET
#endif
#ifndef STYLE_STRUCT_DEP
#define STYLE_STRUCT_DEP(dep)
#define UNDEF_STYLE_STRUCT_DEP
#endif
#ifndef STYLE_STRUCT_END
#define STYLE_STRUCT_END()
#define UNDEF_STYLE_STRUCT_END
#endif
#ifdef STYLE_STRUCT_TEST
#define STYLE_STRUCT_TEST_CODE(c) c
#else
#define STYLE_STRUCT_TEST_CODE(c)
#endif
// The inherited structs are listed before the Reset structs.
// nsStyleStructID assumes this is the case, and callers other than
// nsStyleStructFwd.h that want the structs in id-order just define
// STYLE_STRUCT rather than including the file twice.
"""
FOOTER = """
#ifdef UNDEF_STYLE_STRUCT_INHERITED
#undef STYLE_STRUCT_INHERITED
#undef UNDEF_STYLE_STRUCT_INHERITED
#endif
#ifdef UNDEF_STYLE_STRUCT_RESET
#undef STYLE_STRUCT_RESET
#undef UNDEF_STYLE_STRUCT_RESET
#endif
#ifdef UNDEF_STYLE_STRUCT_DEP
#undef STYLE_STRUCT_DEP
#undef UNDEF_STYLE_STRUCT_DEP
#endif
#ifdef UNDEF_STYLE_STRUCT_END
#undef STYLE_STRUCT_END
#undef UNDEF_STYLE_STRUCT_END
#endif
#undef STYLE_STRUCT_TEST_CODE
"""
print HEADER
printTestTree(0, nextPowerOf2(count), 0, TOPLEVELBRANCHES)
print FOOTER