Antlr4 inconsistent tokenizing

Antlr4 inconsistent tokenizing

By : AssemberFriend
Date : November 20 2020, 01:01 AM
seems to work fine Assuming external_data_source_Expression contains the keyword AS, I would make a more specific rule of what external_data_source_Expression really means. The parser rule below should get you any number of columns and should handle the alias just fine. The capitalized rules below are the lexer rules. I didn't define what they all mean, but I suppose you can match them all to a string.
code :
  SELECT_KEYWORD external_data_source_Expression FROM_KEYWORD external_data_source_definition ;


  column_with_alias (',' column_with_alias)* ;


  'SELECT' ;

  'FROM' ;

  'AS' ;

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ANTLR4 Tokenizing a Huge Set of Keywords

ANTLR4 Tokenizing a Huge Set of Keywords

By : Krina Chudasama
Date : March 29 2020, 07:55 AM
wish of those help If you want each keyword to have its own token type, you can do the following:
code :
tokens {
private static final Map<String, Integer> KEYWORDS =
    new HashMap<String, Integer>();
static {
    KEYWORDS.put("keyword1", MyLanguageParser.Keyword1);
    KEYWORDS.put("keyword2", MyLanguageParser.Keyword2);

public static int getKeywordOrIdentifierType(String text) {
     Integer type = KEYWORDS.get(text);
     if (type == null) {
         return MyLanguageParser.Identifier;

     return type;
    :   [a-zA-Z_] [a-zA-Z0-9_]*
        {_type = MyLanguageKeywords.getKeywordOrIdentifierType(getText());}
Curbing ANTLR4 greediness (Building ANTLR4 Grammar for existing DSL)

Curbing ANTLR4 greediness (Building ANTLR4 Grammar for existing DSL)

By : Ben Danielmeier
Date : March 29 2020, 07:55 AM
wish helps you Instead of using .*? in your parser rules, try using ~'}'* to ensure that those rules won't try to read past the end of the rule.
Also, you skip whitespace in your lexer but use CHAR+ and DIGIT+ in your parser rules. This means the following are equivalent:
code :
true  in other cases
true  in  other cases
Inconsistent token handling in ANTLR4

Inconsistent token handling in ANTLR4

By : James Fitzy
Date : March 29 2020, 07:55 AM
should help you out The ANTLR4 book references a multi-mode example , One of the following is happening:
code :
OPEN  : '«' -> mode(ISLAND) ;
Antlr4 simple tokenizing failing

Antlr4 simple tokenizing failing

By : ye1088
Date : March 29 2020, 07:55 AM
it fixes the issue I have the following grammar to lex/parse a string, all i am wanting at this point is to tokenize by spaces : , With the posted grammar I don't have that error, but :
code :
$ a4 MyItems_op.g4 
warning(180): MyItems_op.g4:5:13: chars "'" used multiple times in set [' ']
$ javac M*.java
$ grun MyItems_op theseItems -tokens -diagnostics input.text
[@2,2:2=' ',<' '>,1:2]
FIELDTEXT : ~[' ']  ;
grammar MyItems;

@init {System.out.println("MyItems last update 0030");}
    :   item (SPACE item)*


SPACE     : ' ' ;
FIELDTEXT : ~[ \r\n]+ ;

NL  : [\r\n]+ -> skip ;        
$ alias
alias a4='java -jar /usr/local/lib/antlr-4.6-complete.jar'
$ a4 MyItems.g4 
$ javac M*.java
$ grun MyItems theseItems -tokens -diagnostics input.text 
[@1,2:2=' ',<' '>,1:2]
[@3,6:6=' ',<' '>,1:6]
MyItems last update 0030
$ hexdump -C input.text 
00000000  56 33 20 41 47 4c 20 56  34 34 35 0a              |V3 AGL V445.|
Tokenizing scientific notation in Antlr4 Lexer

Tokenizing scientific notation in Antlr4 Lexer

By : D4vid99
Date : March 29 2020, 07:55 AM
Hope this helps A vastly simplified version of my lexer rules (within a bigger grammar) are something like the following: , My recommendations are:
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