fix: '@text:prefix*' matching for fields. (#4868)

fixed: https://github.com/dragonflydb/dragonfly/issues/4691

src/core/search/lexer.lex

@@ -27,16 +27,16 @@
   using namespace std;
 
   Parser::symbol_type make_StringLit(string_view src, const Parser::location_type& loc);
-  Parser::symbol_type make_TagVal(string_view src, const Parser::location_type& loc);
+  Parser::symbol_type make_TagVal(string_view src, bool is_prefix, const Parser::location_type& loc);
 %}
 
-blank [ \t\r]
 dq    \"
 sq    \'
 esc_chars ['"\?\\abfnrtv]
 esc_seq \\{esc_chars}
-term_char [_]|\w
+term_char \w
 tag_val_char {term_char}|\\[,.<>{}\[\]\\\"\':;!@#$%^&*()\-+=~\/ ]
+asterisk_char \*
 
 
 %{
@@ -70,15 +70,16 @@ tag_val_char {term_char}|\\[,.<>{}\[\]\\\"\':;!@#$%^&*()\-+=~\/ ]
 [0-9]{1,9}                     return Parser::make_UINT32(str(), loc());
 [+-]?(([0-9]*[.])?[0-9]+|inf)  return Parser::make_DOUBLE(str(), loc());
 
-{dq}([^"]|{esc_seq})*{dq}  return make_StringLit(matched_view(1, 1), loc());
+{dq}([^"]|{esc_seq})*{dq}      return make_StringLit(matched_view(1, 1), loc());
-{sq}([^']|{esc_seq})*{sq}  return make_StringLit(matched_view(1, 1), loc());
+{sq}([^']|{esc_seq})*{sq}      return make_StringLit(matched_view(1, 1), loc());
 
-"$"{term_char}+ return ParseParam(str(), loc());
+"$"{term_char}+                return ParseParam(str(), loc());
-"@"{term_char}+ return Parser::make_FIELD(str(), loc());
+"@"{term_char}+                return Parser::make_FIELD(str(), loc());
-{term_char}+"*" return Parser::make_PREFIX(str(), loc());
+{term_char}+{asterisk_char}    return Parser::make_PREFIX(str(), loc());
 
-{term_char}+ return Parser::make_TERM(str(), loc());
+{term_char}+                   return Parser::make_TERM(str(), loc());
-{tag_val_char}+   return make_TagVal(str(), loc());
+{tag_val_char}+{asterisk_char} return make_TagVal(str(), true, loc());
+{tag_val_char}+                return make_TagVal(str(), false, loc());
 
 <<EOF>>    return Parser::make_YYEOF(loc());
 %%
@@ -91,12 +92,14 @@ Parser::symbol_type make_StringLit(string_view src, const Parser::location_type&
   return Parser::make_TERM(res, loc);
 }
 
-Parser::symbol_type make_TagVal(string_view src, const Parser::location_type& loc) {
+Parser::symbol_type make_TagVal(string_view src, bool is_prefix, const Parser::location_type& loc) {
   string res;
   res.reserve(src.size());
 
   bool escaped = false;
-  for (size_t i = 0; i < src.size(); ++i) {
+  size_t len = is_prefix ? src.size() - 1 : src.size(); // Exclude the '*' at the end for prefix
+
+  for (size_t i = 0; i < len; ++i) {
     if (escaped) {
       escaped = false;
     } else if (src[i] == '\\') {
@@ -104,7 +107,12 @@ Parser::symbol_type make_TagVal(string_view src, const Parser::location_type& lo
       continue;
     }
     res.push_back(src[i]);
+  }
 
+  // Add '*' back for prefix
+  if (is_prefix) {
+    res.push_back('*');
+    return Parser::make_PREFIX(res, loc);
   }
 
   return Parser::make_TAG_VAL(res, loc);

src/core/search/search_parser_test.cc

@@ -191,6 +191,36 @@ TEST_F(SearchParserTest, Scanner) {
   NEXT_EQ(TOK_DOUBLE, string, "33.3");
 }
 
+TEST_F(SearchParserTest, EscapedTagPrefixes) {
+  SetInput("@name:{escape\\-err*}");
+  NEXT_EQ(TOK_FIELD, string, "@name");
+  NEXT_TOK(TOK_COLON);
+  NEXT_TOK(TOK_LCURLBR);
+  NEXT_EQ(TOK_PREFIX, string, "escape-err*");
+  NEXT_TOK(TOK_RCURLBR);
+
+  SetInput("@name:{escape\\+pre*}");
+  NEXT_EQ(TOK_FIELD, string, "@name");
+  NEXT_TOK(TOK_COLON);
+  NEXT_TOK(TOK_LCURLBR);
+  NEXT_EQ(TOK_PREFIX, string, "escape+pre*");
+  NEXT_TOK(TOK_RCURLBR);
+
+  SetInput("@name:{escape\\.pre*}");
+  NEXT_EQ(TOK_FIELD, string, "@name");
+  NEXT_TOK(TOK_COLON);
+  NEXT_TOK(TOK_LCURLBR);
+  NEXT_EQ(TOK_PREFIX, string, "escape.pre*");
+  NEXT_TOK(TOK_RCURLBR);
+
+  SetInput("@name:{complex\\-escape\\+with\\.many\\*chars*}");
+  NEXT_EQ(TOK_FIELD, string, "@name");
+  NEXT_TOK(TOK_COLON);
+  NEXT_TOK(TOK_LCURLBR);
+  NEXT_EQ(TOK_PREFIX, string, "complex-escape+with.many*chars*");
+  NEXT_TOK(TOK_RCURLBR);
+}
+
 TEST_F(SearchParserTest, Parse) {
   EXPECT_EQ(0, Parse(" foo bar (baz) "));
   EXPECT_EQ(0, Parse(" -(foo) @foo:bar @ss:[1 2]"));
@@ -200,6 +230,8 @@ TEST_F(SearchParserTest, Parse) {
   EXPECT_EQ(0, Parse("@foo:{1|2.0|4|3.0}"));
   EXPECT_EQ(0, Parse("@foo:{1|hello|3.0|world|4}"));
 
+  EXPECT_EQ(0, Parse("@name:{escape\\-err*}"));
+
   EXPECT_EQ(1, Parse(" -(foo "));
   EXPECT_EQ(1, Parse(" foo:bar "));
   EXPECT_EQ(1, Parse(" @foo:@bar "));

src/server/search/search_family_test.cc

@@ -545,6 +545,16 @@ TEST_F(SearchFamilyTest, TagNumbers) {
   EXPECT_THAT(Run({"ft.search", "i1", "@number:{1|hello|2}"}), AreDocIds("d:1", "d:2"));
 }
 
+TEST_F(SearchFamilyTest, TagEscapeCharacters) {
+  EXPECT_EQ(Run({"ft.create", "item_idx", "ON", "JSON", "PREFIX", "1", "p", "SCHEMA", "$.name",
+                 "AS", "name", "TAG"}),
+            "OK");
+  EXPECT_EQ(Run({"json.set", "p:1", "$", "{\"name\":\"escape-error\"}"}), "OK");
+
+  auto resp = Run({"ft.search", "item_idx", "@name:{escape\\-err*}"});
+  EXPECT_THAT(resp, AreDocIds("p:1"));
+}
+
 TEST_F(SearchFamilyTest, Numbers) {
   for (unsigned i = 0; i <= 10; i++) {
     for (unsigned j = 0; j <= 10; j++) {