search: simplify Deduper (#61139)

Apart from the expected deduping based on `Match.Key()`, `Deduper` kept track of the deduped results but none of the call sites ever read the results. On top of that, `Deduper` modified the matches passed to it via `Deduper.Add` which, looking at the call sites, I don't think was intentional, because all call sites keep track of results themselves. The test I fix in the second commit documents that behavior.

Notes:
- I also removed NewDedupingStream which was unused.

Test plan:
- updated unit test
- CI

Author: stefanhengl

internal/search/job/jobutil/select_test.go

@@ -45,73 +45,51 @@ func TestWithSelect(t *testing.T) {
 	}
 
 	autogold.Expect(`[
-  {
-    "Path": "pokeman/",
-    "PreciseLanguage": "",
-    "ChunkMatches": null,
-    "PathMatches": null,
-    "LimitHit": false
-  },
-  {
-    "Path": "digiman/",
-    "PreciseLanguage": "",
-    "ChunkMatches": null,
-    "PathMatches": null,
-    "LimitHit": false
-  }
-]`).Equal(t, test("file.directory"))
+	  {
+	    "Path": "pokeman/",
+	    "PreciseLanguage": "",
+	    "ChunkMatches": null,
+	    "PathMatches": null,
+	    "LimitHit": false
+	  },
+	  {
+	    "Path": "digiman/",
+	    "PreciseLanguage": "",
+	    "ChunkMatches": null,
+	    "PathMatches": null,
+	    "LimitHit": false
+	  }
+	]`).Equal(t, test("file.directory"))
 
 	autogold.Expect(`[
-  {
-    "Path": "pokeman/charmandar",
-    "PreciseLanguage": "",
-    "ChunkMatches": null,
-    "PathMatches": null,
-    "LimitHit": false
-  },
-  {
-    "Path": "pokeman/bulbosaur",
-    "PreciseLanguage": "",
-    "ChunkMatches": null,
-    "PathMatches": null,
-    "LimitHit": false
-  },
-  {
-    "Path": "digiman/ummm",
-    "PreciseLanguage": "",
-    "ChunkMatches": null,
-    "PathMatches": null,
-    "LimitHit": false
-  }
-]`).Equal(t, test("file"))
+	  {
+	    "Path": "pokeman/charmandar",
+	    "PreciseLanguage": "",
+	    "ChunkMatches": null,
+	    "PathMatches": null,
+	    "LimitHit": false
+	  },
+	  {
+	    "Path": "pokeman/bulbosaur",
+	    "PreciseLanguage": "",
+	    "ChunkMatches": null,
+	    "PathMatches": null,
+	    "LimitHit": false
+	  },
+	  {
+	    "Path": "digiman/ummm",
+	    "PreciseLanguage": "",
+	    "ChunkMatches": null,
+	    "PathMatches": null,
+	    "LimitHit": false
+	  }
+	]`).Equal(t, test("file"))
 
 	autogold.Expect(`[
   {
     "Path": "pokeman/charmandar",
     "PreciseLanguage": "",
     "ChunkMatches": [
-      {
-        "Content": "",
-        "ContentStart": [
-          0,
-          0,
-          0
-        ],
-        "Ranges": [
-          {
-            "start": [
-              0,
-              0,
-              0
-            ],
-            "end": [
-              0,
-              0,
-              0
-            ]
-          }
-        ]
-      },
       {
         "Content": "",
         "ContentStart": [

internal/search/result/BUILD.bazel

@@ -7,7 +7,6 @@ go_library(
         "commit.go",
         "commit_diff.go",
         "commit_json.go",
-        "deduper.go",
         "file.go",
         "highlight.go",
         "match.go",
@@ -43,7 +42,6 @@ go_test(
         "commit_diff_test.go",
         "commit_json_test.go",
         "commit_test.go",
-        "deduper_test.go",
         "file_test.go",
         "match_test.go",
         "merger_test.go",

internal/search/result/deduper.go

@@ -146,3 +146,19 @@ func (m Matches) ResultCount() int {
 	}
 	return count
 }
+
+// Deduper is a convenience type to deduplicate matches
+type Deduper map[Key]struct{}
+
+func NewDeduper() Deduper {
+	return make(map[Key]struct{})
+}
+
+func (d Deduper) Add(m Match) {
+	d[m.Key()] = struct{}{}
+}
+
+func (d Deduper) Seen(m Match) bool {
+	_, ok := d[m.Key()]
+	return ok
+}