Add `const` for target index matcher (#11760)

Firestore/core/src/model/target_index_matcher.cc

@@ -51,7 +51,7 @@ TargetIndexMatcher::TargetIndexMatcher(const core::Target& target) {
   }
 }
 
-bool TargetIndexMatcher::ServedByIndex(const model::FieldIndex& index) {
+bool TargetIndexMatcher::ServedByIndex(const model::FieldIndex& index) const {
   HARD_ASSERT(index.collection_group() == collection_id_,
               "Collection IDs do not match");
 
@@ -118,7 +118,7 @@ bool TargetIndexMatcher::ServedByIndex(const model::FieldIndex& index) {
   return true;
 }
 
-model::FieldIndex TargetIndexMatcher::BuildTargetIndex() {
+model::FieldIndex TargetIndexMatcher::BuildTargetIndex() const {
   // We want to make sure only one segment created for one field. For example,
   // in case like a == 3 and a > 2, Index: {a ASCENDING} will only be created
   // once.
@@ -175,7 +175,8 @@ model::FieldIndex TargetIndexMatcher::BuildTargetIndex() {
                     std::move(segments), FieldIndex::InitialState());
 }
 
-bool TargetIndexMatcher::HasMatchingEqualityFilter(const Segment& segment) {
+bool TargetIndexMatcher::HasMatchingEqualityFilter(
+    const Segment& segment) const {
   for (const auto& filter : equality_filters_) {
     if (MatchesFilter(filter, segment)) {
       return true;
@@ -185,7 +186,8 @@ bool TargetIndexMatcher::HasMatchingEqualityFilter(const Segment& segment) {
 }
 
 bool TargetIndexMatcher::MatchesFilter(
-    const absl::optional<core::FieldFilter>& filter, const Segment& segment) {
+    const absl::optional<core::FieldFilter>& filter,
+    const Segment& segment) const {
   if (!filter.has_value()) {
     return false;
   }
@@ -193,7 +195,7 @@ bool TargetIndexMatcher::MatchesFilter(
 }
 
 bool TargetIndexMatcher::MatchesFilter(const FieldFilter& filter,
-                                       const Segment& segment) {
+                                       const Segment& segment) const {
   if (filter.field() != segment.field_path()) {
     return false;
   }
@@ -204,7 +206,7 @@ bool TargetIndexMatcher::MatchesFilter(const FieldFilter& filter,
 }
 
 bool TargetIndexMatcher::MatchesOrderBy(const OrderBy& order_by,
-                                        const Segment& segment) {
+                                        const Segment& segment) const {
   if (order_by.field() != segment.field_path()) {
     return false;
   }

Firestore/core/src/model/target_index_matcher.h

@@ -75,21 +75,21 @@ class TargetIndexMatcher {
    *   clauses cannot be skipped, but a continuous OrderBy suffix may be
    *   omitted.
    */
-  bool ServedByIndex(const model::FieldIndex& index);
+  bool ServedByIndex(const model::FieldIndex& index) const;
 
   /** Returns a full matched field index for this target. */
-  model::FieldIndex BuildTargetIndex();
+  model::FieldIndex BuildTargetIndex() const;
 
  private:
-  bool HasMatchingEqualityFilter(const model::Segment& segment);
+  bool HasMatchingEqualityFilter(const model::Segment& segment) const;
 
   bool MatchesFilter(const core::FieldFilter& filter,
-                     const model::Segment& segment);
+                     const model::Segment& segment) const;
   bool MatchesFilter(const absl::optional<core::FieldFilter>& filter,
-                     const model::Segment& segment);
+                     const model::Segment& segment) const;
 
   bool MatchesOrderBy(const core::OrderBy& order_by,
-                      const model::Segment& segment);
+                      const model::Segment& segment) const;
 
   // The collection ID (or collection group) of the query target.
   std::string collection_id_;