Update grammar

x-pack/plugin/esql/src/main/antlr/EsqlBaseLexer.g4

@@ -34,13 +34,15 @@ WS
     : [ \r\n\t]+ -> channel(HIDDEN)
     ;
 
-fragment INDEX_UNQUOTED_IDENTIFIER_PART
-    : ~[=`|,[\]/ \t\r\n]
+// in 8.14 ` were not allowed
+// this has been relaxed in 8.15 since " is used for quoting
+fragment UNQUOTED_SOURCE_PART
+    : ~["=|,[\]/ \t\r\n]
     | '/' ~[*/] // allow single / but not followed by another / or * which would start a comment
     ;
 
-INDEX_UNQUOTED_IDENTIFIER
-    : INDEX_UNQUOTED_IDENTIFIER_PART+
+UNQUOTED_SOURCE
+    : UNQUOTED_SOURCE_PART+
     ;
 
 //
@@ -199,12 +201,10 @@ FROM_OPENING_BRACKET : OPENING_BRACKET -> type(OPENING_BRACKET);
 FROM_CLOSING_BRACKET : CLOSING_BRACKET -> type(CLOSING_BRACKET);
 FROM_COMMA : COMMA -> type(COMMA);
 FROM_ASSIGN : ASSIGN -> type(ASSIGN);
-
 METADATA : 'metadata';
 
-FROM_INDEX_UNQUOTED_IDENTIFIER
-    : INDEX_UNQUOTED_IDENTIFIER -> type(INDEX_UNQUOTED_IDENTIFIER)
-    ;
+FROM_UNQUOTED_SOURCE : UNQUOTED_SOURCE -> type(UNQUOTED_SOURCE);
+FROM_QUOTED_SOURCE : QUOTED_STRING -> type(QUOTED_STRING);
 
 FROM_LINE_COMMENT
     : LINE_COMMENT -> channel(HIDDEN)
@@ -295,6 +295,9 @@ ENRICH_POLICY_NAME
     : (ENRICH_POLICY_NAME_BODY+ COLON)? ENRICH_POLICY_NAME_BODY+
     ;
 
+ENRICH_UNQUOTED_SOURCE : UNQUOTED_SOURCE -> type(UNQUOTED_SOURCE);
+ENRICH_QUOTED_SOURCE : QUOTED_STRING -> type(QUOTED_STRING);
+
 ENRICH_MODE_UNQUOTED_VALUE
     : ENRICH_POLICY_NAME -> type(ENRICH_POLICY_NAME)
     ;
@@ -347,9 +350,8 @@ LOOKUP_COMMA : COMMA -> type(COMMA);
 LOOKUP_DOT: DOT -> type(DOT);
 LOOKUP_ON : ON -> type(ON), pushMode(LOOKUP_FIELD_MODE);
 
-LOOKUP_INDEX_UNQUOTED_IDENTIFIER
-    : INDEX_UNQUOTED_IDENTIFIER -> type(INDEX_UNQUOTED_IDENTIFIER)
-    ;
+LOOKUP_UNQUOTED_SOURCE: UNQUOTED_SOURCE -> type(UNQUOTED_SOURCE);
+LOOKUP_QUOTED_SOURCE : QUOTED_STRING -> type(QUOTED_STRING);
 
 LOOKUP_LINE_COMMENT
     : LINE_COMMENT -> channel(HIDDEN)
@@ -476,9 +478,8 @@ SETTING_WS
 mode METRICS_MODE;
 METRICS_PIPE : PIPE -> type(PIPE), popMode;
 
-METRICS_INDEX_UNQUOTED_IDENTIFIER
-    : INDEX_UNQUOTED_IDENTIFIER -> type(INDEX_UNQUOTED_IDENTIFIER), popMode, pushMode(CLOSING_METRICS_MODE)
-    ;
+METRICS_UNQUOTED_SOURCE: UNQUOTED_SOURCE -> type(UNQUOTED_SOURCE), popMode, pushMode(CLOSING_METRICS_MODE);
+METRICS_QUOTED_SOURCE : QUOTED_STRING -> type(QUOTED_STRING), popMode, pushMode(CLOSING_METRICS_MODE);
 
 METRICS_LINE_COMMENT
     : LINE_COMMENT -> channel(HIDDEN)

x-pack/plugin/esql/src/main/antlr/EsqlBaseParser.g4

@@ -106,11 +106,12 @@ field
     ;
 
 fromCommand
-    : FROM indexIdentifier (COMMA indexIdentifier)* metadata?
+    : FROM indexString (COMMA indexString)* metadata?
     ;
 
-indexIdentifier
-    : INDEX_UNQUOTED_IDENTIFIER
+indexString
+    : UNQUOTED_SOURCE
+    | QUOTED_STRING
     ;
 
 metadata
@@ -119,15 +120,15 @@ metadata
     ;
 
 metadataOption
-    : METADATA indexIdentifier (COMMA indexIdentifier)*
+    : METADATA UNQUOTED_SOURCE (COMMA UNQUOTED_SOURCE)*
     ;
 
 deprecated_metadata
     : OPENING_BRACKET metadataOption CLOSING_BRACKET
     ;
 
 metricsCommand
-    : METRICS indexIdentifier (COMMA indexIdentifier)* aggregates=fields? (BY grouping=fields)?
+    : METRICS indexString (COMMA indexString)* aggregates=fields? (BY grouping=fields)?
     ;
 
 evalCommand
@@ -275,5 +276,5 @@ enrichWithClause
     ;
 
 lookupCommand
-    : LOOKUP tableName=INDEX_UNQUOTED_IDENTIFIER ON matchFields=qualifiedNamePatterns
+    : LOOKUP tableName=indexString ON matchFields=qualifiedNamePatterns
     ;

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/parser/AbstractBuilder.java

@@ -25,23 +25,26 @@ public Source visitTerminal(TerminalNode node) {
     }
 
     static String unquoteString(Source source) {
-        String text = source.text();
-        if (text == null) {
+        return unquoteString(source.text());
+    }
+
+    static String unquoteString(String string) {
+        if (string == null) {
             return null;
         }
 
         // unescaped strings can be interpreted directly
-        if (text.startsWith("\"\"\"")) {
-            return text.substring(3, text.length() - 3);
+        if (string.startsWith("\"\"\"")) {
+            return string.substring(3, string.length() - 3);
         }
 
-        text = text.substring(1, text.length() - 1);
+        string = string.substring(1, string.length() - 1);
         StringBuilder sb = new StringBuilder();
 
-        for (int i = 0; i < text.length();) {
-            if (text.charAt(i) == '\\') {
+        for (int i = 0; i < string.length();) {
+            if (string.charAt(i) == '\\') {
                 // ANTLR4 Grammar guarantees there is always a character after the `\`
-                switch (text.charAt(++i)) {
+                switch (string.charAt(++i)) {
                     case 't' -> sb.append('\t');
                     case 'n' -> sb.append('\n');
                     case 'r' -> sb.append('\r');
@@ -51,11 +54,11 @@ static String unquoteString(Source source) {
                     // will be interpreted as regex, so we have to escape it
                     default ->
                         // unknown escape sequence, pass through as-is, e.g: `...\w...`
-                        sb.append('\\').append(text.charAt(i));
+                        sb.append('\\').append(string.charAt(i));
                 }
                 i++;
             } else {
-                sb.append(text.charAt(i++));
+                sb.append(string.charAt(i++));
             }
         }
         return sb.toString();