fix lexer to parse correctly quoted empty strings, #1825

spec/search/lexer.spec.js

@@ -87,14 +87,16 @@ describe("Lexer expression", () => {
             .toEqual(["#label", "*=*", "text"]);
     });
 
-    it("simple label operator with in quotes and without", () => {
+    it("simple label operator with in quotes", () => {
         expect(lex("#label*=*'text'").expressionTokens)
             .toEqual([
                 {token: "#label", inQuotes: false, startIndex: 0, endIndex: 5},
                 {token: "*=*", inQuotes: false, startIndex: 6, endIndex: 8},
                 {token: "text", inQuotes: true, startIndex: 10, endIndex: 13}
             ]);
+    });
 
+    it("simple label operator with param without quotes", () => {
         expect(lex("#label*=*text").expressionTokens)
             .toEqual([
                 {token: "#label", inQuotes: false, startIndex: 0, endIndex: 5},
@@ -103,6 +105,16 @@ describe("Lexer expression", () => {
             ]);
     });
 
+    it("simple label operator with empty string param", () => {
+        expect(lex("#label = ''").expressionTokens)
+            .toEqual([
+                {token: "#label", inQuotes: false, startIndex: 0, endIndex: 5},
+                {token: "=", inQuotes: false, startIndex: 7, endIndex: 7},
+                // weird case for empty strings which ends up with endIndex < startIndex :-(
+                {token: "", inQuotes: true, startIndex: 10, endIndex: 9}
+            ]);
+    });
+
     it("note. prefix also separates fulltext from expression", () => {
         expect(lex(`hello fulltext note.labels.capital = Prague`).expressionTokens.map(t => t.token))
             .toEqual(["note", ".", "labels", ".", "capital", "=", "prague"]);

src/services/search/services/lex.js

@@ -21,8 +21,8 @@ function lex(str) {
         }
     }
 
-    function finishWord(endIndex) {
-        if (currentWord === '') {
+    function finishWord(endIndex, createAlsoForEmptyWords = false) {
+        if (currentWord === '' && !createAlsoForEmptyWords) {
             return;
         }
 
@@ -71,7 +71,7 @@ function lex(str) {
                 }
             }
             else if (quotes === chr) {
-                finishWord(i - 1);
+                finishWord(i - 1, true);
 
                 quotes = false;
             }