[英]How to emit a token in ANTLR4?
This is my grammar.g4
:这是我的
grammar.g4
:
FOO: 'x';
BAR: 'y'
{ /* here! */ };
I want tokens BAR
and FOO
to be emitted when the input contains y
.我希望在输入包含
y
时发出令牌BAR
和FOO
。 What should I write in the here!
我应该在
here!
写什么here!
part?部分? Please, don't suggest to rewrite the grammar, this is just a test sample, my real case is much more complex.
请不要建议重写语法,这只是一个测试样本,我的真实案例要复杂得多。
Here's a quick demo:这是一个快速演示:
grammar T;
@lexer::members {
private java.util.LinkedList<Token> tokens = new java.util.LinkedList<>();
@Override
public Token nextToken() {
return tokens.isEmpty() ? super.nextToken() : tokens.poll();
}
}
parse
: foo bar foo EOF
;
foo : FOO;
bar : BAR;
FOO : 'x';
BAR : 'y' {this.tokens.offer(new CommonToken(TLexer.FOO, "x"));};
SPACES : [ \t\r\n] -> skip;
Test with:测试:
TLexer lexer = new TLexer(CharStreams.fromString("x y"));
TParser parser = new TParser(new CommonTokenStream(lexer));
System.out.println(parser.parse().toStringTree(parser));
which will print:这将打印:
(parse (foo x) (bar y) (foo x) <EOF>)
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