Is there a rule for detecting errors in Lex / Yacc analysis?

Question

Should we catch errors when parsing a general-purpose language as early as possible (in Lex) or where is it more convenient and provide us with more information (in Yacc)? How do different languages ​​solve this problem?

Answer 1

In general, the more complex the error, the more difficult the code to approve the error . Lexers and parsers are fairly simple (in practice) and therefore catch simple errors.

• Lexers pick up invalid character sequences that must make up the token
• , Bison/Yacc, , .

. /, . /, , , .

, / ( ) AST .

:

a.b();
ab();

lexer/parser - , . ?

• , , .

• ID , , .

.

, . .

Answer 2

, . Token, char, ​​ . , , , .