Difference between revisions of "Antlr"
Jump to navigation
Jump to search
| Line 10: | Line 10: | ||
= Base Class Language Parser = | = Base Class Language Parser = | ||
The abstract base class LanguageParser has some help code that makes language development and debugging easier. | The abstract base class LanguageParser has some help code that makes language development and debugging easier. | ||
| + | |||
| + | === Example === | ||
| + | <source lang='java'> | ||
| + | /** | ||
| + | * example parser | ||
| + | * @author wf | ||
| + | * | ||
| + | */ | ||
| + | public class ExpLanguageParser extends LanguageParser { | ||
| + | private ExpParser parser; | ||
| + | ExpLexer lexer; | ||
| + | |||
| + | public ExpParser getParser() { | ||
| + | return parser; | ||
| + | } | ||
| + | |||
| + | @Override | ||
| + | protected ParseTree getRootContext(Parser parser) { | ||
| + | if (!(parser instanceof ExpParser)) { | ||
| + | throw new RuntimeException("wrong parser type for getRootContext, expected Rule but got "+parser.getClass().getName()); | ||
| + | } else { | ||
| + | ExpParser expParser=(ExpParser) parser; | ||
| + | return expParser.eval(); | ||
| + | } | ||
| + | } | ||
| + | |||
| + | @Override | ||
| + | protected ParseTree parse(ANTLRInputStream in, String inputText) | ||
| + | throws Exception { | ||
| + | lexer = new ExpLexer(in); | ||
| + | parser=new ExpParser(getTokens(lexer)); | ||
| + | ParseTree result=super.parse(lexer,getParser()); | ||
| + | return result; | ||
| + | } | ||
| + | |||
| + | @Override | ||
| + | public void showParseTree() { | ||
| + | super.showParseTree(getParser()); | ||
| + | } | ||
| + | |||
| + | } | ||
| + | </source> | ||
= Motivation = | = Motivation = | ||
Revision as of 14:32, 14 October 2017
ANTLR is a parser generator tool.
BITPlan has been using ANTLR in projects for a few years now and Wolfgang Fahl has been active in improving ANTLR see e.g. #Motivation
Library with helpers for ANTLR Language development com.bitplan.antlr
To simplify Parser development with ANTLR BITPlan has created a library with some helper code for ANTLR Language Development and published it as Open Source at:
Base Class Language Parser
The abstract base class LanguageParser has some help code that makes language development and debugging easier.
Example
/**
* example parser
* @author wf
*
*/
public class ExpLanguageParser extends LanguageParser {
private ExpParser parser;
ExpLexer lexer;
public ExpParser getParser() {
return parser;
}
@Override
protected ParseTree getRootContext(Parser parser) {
if (!(parser instanceof ExpParser)) {
throw new RuntimeException("wrong parser type for getRootContext, expected Rule but got "+parser.getClass().getName());
} else {
ExpParser expParser=(ExpParser) parser;
return expParser.eval();
}
}
@Override
protected ParseTree parse(ANTLRInputStream in, String inputText)
throws Exception {
lexer = new ExpLexer(in);
parser=new ExpParser(getTokens(lexer));
ParseTree result=super.parse(lexer,getParser());
return result;
}
@Override
public void showParseTree() {
super.showParseTree(getParser());
}
}