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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /layout/style/nsIStyleRule.h
parent49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff)
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Add m-esr52 at 52.6.0
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diff --git a/layout/style/nsIStyleRule.h b/layout/style/nsIStyleRule.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+/*
+ * internal abstract interface for objects providing immutable style
+ * information
+ */
+
+#ifndef nsIStyleRule_h___
+#define nsIStyleRule_h___
+
+#include <stdio.h>
+
+#include "nsCSSPropertyID.h"
+#include "nsISupports.h"
+
+class nsCSSValue;
+struct nsRuleData;
+
+// IID for the nsIStyleRule interface {f75f3f70-435d-43a6-a01b-65970489ca26}
+#define NS_ISTYLE_RULE_IID \
+{ 0xf75f3f70, 0x435d, 0x43a6, \
+ { 0xa0, 0x1b, 0x65, 0x97, 0x04, 0x89, 0xca, 0x26 } }
+
+/**
+ * An object implementing |nsIStyleRule| (henceforth, a rule) represents
+ * immutable stylistic information that either applies or does not apply
+ * to a given element. It belongs to an object or group of objects that
+ * implement |nsIStyleSheet| and |nsIStyleRuleProcessor| (henceforth, a
+ * sheet).
+ *
+ * A rule becomes relevant to the computation of style data when
+ * |nsIStyleRuleProcessor::RulesMatching| creates a rule node that
+ * points to the rule. (A rule node, |nsRuleNode|, is a node in the
+ * rule tree, which is a lexicographic tree indexed by rules. The path
+ * from the root of the rule tree to the |nsRuleNode| for a given
+ * |nsStyleContext| contains exactly the rules that match the element
+ * that the style context is for, in priority (weight, origin,
+ * specificity) order.)
+ *
+ * The computation of style data uses the rule tree, which calls
+ * |nsIStyleRule::MapRuleInfoInto| below.
+ *
+ * It is worth emphasizing that the data represented by a rule
+ * implementation are immutable. When the data need to be changed, a
+ * new rule object must be created. Failing to do this will lead to
+ * bugs in the handling of dynamic style changes, since the rule tree
+ * caches the results of |MapRuleInfoInto|.
+ *
+ * |nsIStyleRule| objects are owned by |nsRuleNode| objects (in addition
+ * to typically being owned by their sheet), which are in turn garbage
+ * collected (with the garbage collection roots being style contexts).
+ */
+
+
+class nsIStyleRule : public nsISupports {
+public:
+ NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISTYLE_RULE_IID)
+
+ /**
+ * |nsIStyleRule::MapRuleInfoInto| is a request to copy all stylistic
+ * data represented by the rule that:
+ * + are relevant for any structs in |aRuleData->mSIDs| (style
+ * struct ID bits)
+ * + are not already filled into the data struct
+ * into the appropriate data struct in |aRuleData|. It is important
+ * that only empty data are filled in, since the rule tree is walked
+ * from highest priority rule to least, so that the walk can stop if
+ * all needed data are found. Thus overwriting non-empty data will
+ * break CSS cascading rules.
+ */
+ virtual void MapRuleInfoInto(nsRuleData* aRuleData)=0;
+
+ /**
+ * Returns whether this style rule has any style data for inherited
+ * properties.
+ */
+ virtual bool MightMapInheritedStyleData() = 0;
+
+ /**
+ * Gets and sets given aProperty's value to aValue.
+ * Returns true, if aValue is filled in this rule.
+ */
+ virtual bool GetDiscretelyAnimatedCSSValue(nsCSSPropertyID aProperty,
+ nsCSSValue* aValue) = 0;
+
+#ifdef DEBUG
+ virtual void List(FILE* out = stdout, int32_t aIndent = 0) const = 0;
+#endif
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsIStyleRule, NS_ISTYLE_RULE_IID)
+
+#endif /* nsIStyleRule_h___ */