refactoring of es6 test skeleton

src/public/app/services/attribute_parser.js

@@ -0,0 +1,100 @@
+function lexer(str) {
+    str = str.toLowerCase();
+
+    const expressionTokens = [];
+
+    let quotes = false;
+    let currentWord = '';
+
+    function isOperatorSymbol(chr) {
+        return ['=', '*', '>', '<', '!'].includes(chr);
+    }
+
+    function previousOperatorSymbol() {
+        if (currentWord.length === 0) {
+            return false;
+        }
+        else {
+            return isOperatorSymbol(currentWord[currentWord.length - 1]);
+        }
+    }
+
+    function finishWord() {
+        if (currentWord === '') {
+            return;
+        }
+
+        expressionTokens.push(currentWord);
+
+        currentWord = '';
+    }
+
+    for (let i = 0; i < str.length; i++) {
+        const chr = str[i];
+
+        if (chr === '\\') {
+            if ((i + 1) < str.length) {
+                i++;
+
+                currentWord += str[i];
+            }
+            else {
+                currentWord += chr;
+            }
+
+            continue;
+        }
+        else if (['"', "'", '`'].includes(chr)) {
+            if (!quotes) {
+                if (previousOperatorSymbol()) {
+                    finishWord();
+                }
+
+                quotes = chr;
+            }
+            else if (quotes === chr) {
+                quotes = false;
+
+                finishWord();
+            }
+            else {
+                // it's a quote but within other kind of quotes so it's valid as a literal character
+                currentWord += chr;
+            }
+            continue;
+        }
+        else if (!quotes) {
+            if (currentWord.length === 0 && (chr === '#' || chr === '~')) {
+                currentWord = chr;
+
+                continue;
+            }
+            else if (chr === ' ') {
+                finishWord();
+                continue;
+            }
+            else if (['(', ')', '.'].includes(chr)) {
+                finishWord();
+                currentWord += chr;
+                finishWord();
+                continue;
+            }
+            else if (previousOperatorSymbol() !== isOperatorSymbol(chr)) {
+                finishWord();
+
+                currentWord += chr;
+                continue;
+            }
+        }
+
+        currentWord += chr;
+    }
+
+    finishWord();
+
+    return expressionTokens;
+}
+
+export default {
+    lexer
+}