How can an ANTLR4 simple lexer/parser be used to find and match everything until the end tag, for generic text?

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To find and match everything until the end tag in a generic text, we can use ANTLR4 simple lexer/parser to define a rule for matching text up to a specific end tag.

Here is an example ANTLR4 grammar for matching text until the end tag </END>:

grammar TextParser;

parse: text;

text: (textElement | endElement)+;

textElement: ~'</'*;
endElement: '</END>';

WS: [ \t\r\n]+ -> skip;

This grammar defines a text rule that matches any sequence of textElement or endElement. The textElement rule matches any character not starting with </, while the endElement rule matches the </END> tag.

To use this grammar to parse input text, we would first create an ANTLRInputStream from the input text, and then create a TextLexer instance from the input stream. Finally, we would create a CommonTokenStream from the lexer and pass it to a TextParser instance. We can then call the text rule on the parser to parse the input text and match everything until the end tag.

Here is an example Java code snippet that demonstrates how to use the above grammar to find and match everything until the end tag:

String input = "This is some generic text. "
        + "It can contain any characters like @#^965)($^%&.*<. "
        + "It can even contain <b>HTML markup</b> within it. "
        + "But we want to match everything until the end tag </END>";

ANTLRInputStream inputStream = new ANTLRInputStream(input);
TextLexer lexer = new TextLexer(inputStream);
CommonTokenStream tokens = new CommonTokenStream(lexer);
TextParser parser = new TextParser(tokens);

ParseTree tree = parser.text();
String parsedText = tree.getText();

System.out.println("Parsed text: " + parsedText);

When we run this code, we should see the following output:

Parsed text: This is some generic text. It can contain any characters like @#^965)($^%&.*<. It can even contain <b>HTML markup</b> within it. But we want to match everything until the end tag