[antlr-interest] What does ANTLR use the reserved char codes and Token IDs for?

[Ric Klaren]

On Sun, Nov 03, 2002 at 09:16:32PM -0000, micheal_jor wrote:
> ANTLR reserves the following character codes /u0000 to /u0003. What 
> are they used for?
> 
> On a similar note, the Token IDs 0 to 3 are also reserved. What are 
> they used for as well. I mean, if I come across a node in my AST with 
> these Token IDs, what does it represent?

Copy-paste:

static const int MIN_USER_TYPE = 4;
static const int NULL_TREE_LOOKAHEAD = 3;
static const int INVALID_TYPE = 0;
static const int EOF_TYPE = 1;
static const int SKIP = -1;

SKIP -> internally used for the skipping of tokens. When you set a token to
        type skip in the lexer.
EOF  -> end of file token.
INVALID_TYPE -> default value for token constructors
NULL_TREE_LOOKAHEAD -> eof kindoff but in treewalkers, used for the
                       ASTNULLtype sentinel.

HTH,

Ric
-- 
-----+++++*****************************************************+++++++++-------
    ---- Ric Klaren ----- klaren at cs.utwente.nl ----- +31 53 4893722  ----
-----+++++*****************************************************+++++++++-------
  Wo das Chaos auf die Ordnung trifft, gewinnt meist das Chaos, weil es
  besser organisiert ist. --- Friedrich Nietzsche


 

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