YQL-19747: Support LSP FilterText

LSP protocol has a property
```
/**
 * A string that should be used when filtering a set of
 * completion items. When omitted the label is used as the
 * filter text for this item.
 */
filterText?: string;
```

It is useful, e.g. when we prepend some punctuation
at a candidate content, but still want to filter by
prefix, ignoring that punctuation.

Related to https://nda.ya.ru/t/KCkzjhXS7G3Epg.
commit_hash:01f258218d312eef764350bd4d78da15acb8c9ea

5 files changed, 20 insertions, 7 deletions

diff --git a/yql/essentials/sql/v1/complete/analysis/global/column.cpp b/yql/essentials/sql/v1/complete/analysis/global/column.cpp
index 92665063690..9b6161dc3b8 100644
--- a/yql/essentials/sql/v1/complete/analysis/global/column.cpp
+++ b/yql/essentials/sql/v1/complete/analysis/global/column.cpp
@@ -49,7 +49,7 @@ namespace NSQLComplete {
             std::any visitTerminal(antlr4::tree::TerminalNode* node) override {
                 switch (node->getSymbol()->getType()) {
                     case SQLv1::TOKEN_ID_QUOTED:
-                        return Unquoted(GetText(node));
+                        return TString(Unquoted(GetText(node)));
                     case SQLv1::TOKEN_ID_PLAIN:
                         return GetText(node);
                 }
diff --git a/yql/essentials/sql/v1/complete/sql_complete.cpp b/yql/essentials/sql/v1/complete/sql_complete.cpp
index 282ceca41b1..fa84e749a8c 100644
--- a/yql/essentials/sql/v1/complete/sql_complete.cpp
+++ b/yql/essentials/sql/v1/complete/sql_complete.cpp
@@ -20,6 +20,14 @@
 
 namespace NSQLComplete {
 
+    TString TCandidate::FilterText() const {
+        TStringBuf text = Content;
+        if (IsQuoted(text)) {
+            text = Unquoted(text);
+        }
+        return ToLowerUTF8(text);
+    }
+
     class TSqlCompletionEngine: public ISqlCompletionEngine {
     public:
         TSqlCompletionEngine(
diff --git a/yql/essentials/sql/v1/complete/sql_complete.h b/yql/essentials/sql/v1/complete/sql_complete.h
index 3387019e25f..41fb67fc090 100644
--- a/yql/essentials/sql/v1/complete/sql_complete.h
+++ b/yql/essentials/sql/v1/complete/sql_complete.h
@@ -41,6 +41,8 @@ namespace NSQLComplete {
         size_t CursorShift = 0;
 
         friend bool operator==(const TCandidate& lhs, const TCandidate& rhs) = default;
+
+        TString FilterText() const;
     };
 
     struct TCompletion {
diff --git a/yql/essentials/sql/v1/complete/syntax/format.cpp b/yql/essentials/sql/v1/complete/syntax/format.cpp
index f85c93dd085..824ab0c7529 100644
--- a/yql/essentials/sql/v1/complete/syntax/format.cpp
+++ b/yql/essentials/sql/v1/complete/syntax/format.cpp
@@ -44,17 +44,19 @@ namespace NSQLComplete {
         return GetSqlGrammar().IsPlainIdentifier(content);
     }
 
+    bool IsQuoted(TStringBuf content) {
+        return 2 <= content.size() && content.front() == '`' && content.back() == '`';
+    }
+
     TString Quoted(TString content) {
         content.prepend('`');
         content.append('`');
         return content;
     }
 
-    TString Unquoted(TString content) {
-        Y_ENSURE(2 <= content.size() && content.front() == '`' && content.back() == '`');
-        content.erase(0, 1);
-        content.pop_back();
-        return content;
+    TStringBuf Unquoted(TStringBuf content) {
+        Y_ENSURE(IsQuoted(content));
+        return content.SubStr(1, content.size() - 2);
     }
 
 } // namespace NSQLComplete
diff --git a/yql/essentials/sql/v1/complete/syntax/format.h b/yql/essentials/sql/v1/complete/syntax/format.h
index ea3274ccf5d..4c5167ceaa1 100644
--- a/yql/essentials/sql/v1/complete/syntax/format.h
+++ b/yql/essentials/sql/v1/complete/syntax/format.h
@@ -7,7 +7,8 @@ namespace NSQLComplete {
 
     TString FormatKeywords(const TVector<TString>& seq);
     bool IsPlain(TStringBuf content);
+    bool IsQuoted(TStringBuf content);
     TString Quoted(TString content);
-    TString Unquoted(TString content);
+    TStringBuf Unquoted(TStringBuf content);
 
 } // namespace NSQLComplete