Factor out UrlPatternIndex from IndexedRuleset.

components/subresource_filter/core/common/flat/rules.fbs

Index: components/subresource_filter/core/common/flat/rules.fbs
diff --git a/components/subresource_filter/core/common/flat/rules.fbs b/components/subresource_filter/core/common/flat/rules.fbs
deleted file mode 100644
index fdeaea972ee2eb8212f1d4c4e7e305f2a6ccf649..0000000000000000000000000000000000000000
--- a/components/subresource_filter/core/common/flat/rules.fbs
+++ /dev/null
@@ -1,104 +0,0 @@
-namespace subresource_filter.flat;
-
-// Corresponds to subresource_filter::proto::UrlPatternType.
-enum UrlPatternType : ubyte {
-  SUBSTRING,
-  WILDCARDED,
-  REGEXP,
-}
-
-// Corresponds to subresource_filter::proto::AnchorType.
-enum AnchorType : ubyte {
-  NONE,
-  BOUNDARY,
-  SUBDOMAIN,
-}
-
-// URL rule matching options. These correspond to multiple fields of
-// subresource_filter::proto::UrlRule, but here, they are represented as flags
-// of the same bitmask to allow for compact storage.
-enum OptionFlag : ubyte (bit_flags) {
-  IS_WHITELIST,
-  APPLIES_TO_FIRST_PARTY,
-  APPLIES_TO_THIRD_PARTY,
-  IS_MATCH_CASE,
-}
-
-// The flat representation of a single URL rule. For more details regarding the
-// fields please see the comments to subresource_filter::proto::UrlRule.
-table UrlRule {
-  // Rule matching options, a bitmask consisting of OptionFlags.
-  options : ubyte;
-
-  // A bitmask of element types, same as proto::UrlRule::element_types. Enables
-  // all element types except POPUP by default.
-  // Note: Keep it equal to ELEMENT_TYPE_ALL-ELEMENT_TYPE_POPUP for compactness.
-  element_types : ushort = 6143;
-
-  // A bitmask of activation types, same as proto::UrlRule::activation_types.
-  // Disables all activation types by default.
-  activation_types : ubyte = 0;
-
-  // Use SUBSTRING as default, since it's the most used pattern type. Same as
-  // the corresponding proto::UrlRule::url_pattern_type.
-  url_pattern_type : UrlPatternType = SUBSTRING;
-
-  // Use NONE as default, since most of the rules are not anchored.
-  anchor_left : AnchorType = NONE;
-  anchor_right : AnchorType = NONE;
-
-  // The list of domains to be included/excluded from the filter's affected set.
-  domains_included : [string];
-  domains_excluded : [string];
-
-  // A URL pattern in the format defined by |url_pattern_type|.
-  url_pattern : string;
-}
-
-// Contains an N-gram (acting as a key in a hash table) and a list of URL rules
-// associated with that N-gram.
-table NGramToRules {
-  // A string consisting of N (up to 8) non-special characters, which are stored
-  // in the lowest N non-zero bytes, lower bytes corresponding to later symbols.
-  ngram : ulong;
-
-  // The list of rules containing |ngram| as a substring of their URL pattern.
-  rule_list : [UrlRule];
-}
-
-// A data structure used to select only a handful of URL rule candidates that
-// need to be matched against a certain resource URL.
-table UrlPatternIndex {
-  // The N of an N-gram index. Note: |n| should be between 1 and 8.
-  n : uint;
-
-  // A hash table with open addressing. The keys of the table are N-grams.
-  ngram_index : [NGramToRules];
-
-  // The slot that is pointed to by all empty slots of |ngram_index| hash table.
-  // Note: This is a workaround needed because null offsets are not allowed as
-  // elements of FlatBuffer arrays.
-  ngram_index_empty_slot : NGramToRules;
-
-  // A list storing the rules that doesn't contain any valid N-grams in their
-  // URL patterns. Contains all the REGEXP rules as well.
-  // TODO(pkalinnikov): Think about better implementation for the fallback
-  // index. Possibly make it a hash map and maybe merge it with the N-gram
-  // index, since we can treat any sequence of characters shorter than N as an
-  // N-gram with zero bytes used for padding.
-  fallback_rules : [UrlRule];
-}
-
-// The top-level data structure used to store URL rules.
-table IndexedRuleset {
-  // The index of all blacklist URL rules.
-  blacklist_index : UrlPatternIndex;
-
-  // The index of all whitelist URL rules, except pure activation rules.
-  whitelist_index : UrlPatternIndex;
-
-  // The index of all whitelist URL rules with activation options.
-  activation_index : UrlPatternIndex;
-}
-
-root_type IndexedRuleset;