Parser: When u flag is set, throw error on invalid unicode escape

Author: Golmote

src/parser/__tests__/parser-basic-test.js

@@ -1068,4 +1068,10 @@ describe('basic', () => {
     });
   });
 
+  it('throws error on invalid Unicode escape', () => {
+    expect(() => parser.parse('/\\p/u')).toThrowError(SyntaxError);
+    expect(() => parser.parse('/\\e/u')).toThrowError(SyntaxError);
+    expect(() => parser.parse('/\\g/u')).toThrowError(SyntaxError);
+  });
+
 });

src/parser/generated/regexp-tree.js

@@ -360,7 +360,13 @@ const lexRules = [[/^#[^\n]+/, function() { /* skip comments */ }],
 [/^\\x[0-9a-fA-F]{2}/, function() { return 'HEX_CODE' }],
 [/^\\[tnrdDsSwWvf]/, function() { return 'META_CHAR' }],
 [/^\\\//, function() { return 'ESC_CHAR' }],
-[/^\\[^*?+\[()]/, function() { return 'ESC_CHAR' }],
+[/^\\[^*?+\[()]/, function() { 
+                                        const s = this.getCurrentState();
+                                        if (s === 'u' || s === 'xu' || s === 'u_class') {
+                                            throw new SyntaxError(`invalid Unicode escape ${yytext}`);
+                                        }
+                                        return 'ESC_CHAR';
+                                     }],
 [/^\\[*?+\[()]/, function() { return 'ESC_CHAR' }],
 [/^\(/, function() { return 'CHAR' }],
 [/^\)/, function() { return 'CHAR' }],

src/parser/regexp.bnf

@@ -103,7 +103,14 @@ GROUP_NAME              ([\w$]|\\'u'[0-9a-fA-F]{4}|\\'u{'[0-9a-fA-F]{1,}'}')+
 
 {ESC}'/'                            return 'ESC_CHAR'
 
-{ESC}{CHAR}                         return 'ESC_CHAR'
+{ESC}{CHAR}                         {
+                                        const s = this.getCurrentState();
+                                        if (s === 'u' || s === 'xu' || s === 'u_class') {
+                                            throw new SyntaxError(`invalid Unicode escape ${yytext}`);
+                                        }
+                                        return 'ESC_CHAR';
+                                    }
+
 {ESC}[*?+\[()]                      return 'ESC_CHAR'
 
 <class,u_class>'('                  return 'CHAR'