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Parser error message improvements: better explanations and removed unused code

This commit is contained in:
Andy Clement 2008-08-15 00:26:11 +00:00
parent e78b9273f8
commit cf35116af7
1 changed files with 40 additions and 30 deletions
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70
org.springframework.expression/src/main/java/org/springframework/expression/spel/internal/SpringExpressionsParserExtender.java
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@ -20,6 +20,8 @@ import org.antlr.runtime.IntStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.Token;
import org.antlr.runtime.TokenStream;
import org.springframework.expression.spel.SpelException;
import org.springframework.expression.spel.SpelMessages;
import org.springframework.expression.spel.generated.SpringExpressionsParser;
public class SpringExpressionsParserExtender extends SpringExpressionsParser {
@ -29,35 +31,50 @@ public class SpringExpressionsParserExtender extends SpringExpressionsParser {
}
/**
* This method does not actually recover but can attempt to produce better error messages than a generic Antlr
* parser because it knows about grammar specifics. would do
* Override super type implementation and just include the character position rather than the line number since the
* expressions are nearly all going to be just one line.
*/
@Override
public void recoverFromMismatchedToken(IntStream input, RecognitionException re, int ttype, BitSet follow)
throws RecognitionException {
// CommonTokenStream tokStream = (CommonTokenStream) input;
// int prevToken = tokStream.LA(-1);
// int nextToken = tokStream.LA(1);
// String prevTokenText = tokStream.LT(-1).getText();
// String expectedToken = getTokenForId(ttype);
// Use token knowledge to log a more appropriate error:
// logger.error(ParserMessage.ERROR_NO_LEADING_ZERO, re.line, re.charPositionInLine);
throw re;
public String getErrorHeader(RecognitionException e) {
StringBuilder retval = new StringBuilder();
retval.append("(pos ").append(e.charPositionInLine).append("): ");
return retval.toString();
}
//
// /**
// * Similar to the BaseRecognizer getErrorMessage() but uses the ParserMessages class to get the text of the
// message
// */
// public void logError(RecognitionException re, String[] tokenNames) {
// logger.error(ELMessages.RECOGNITION_ERROR, re.line, re.charPositionInLine, re);
// }
@Override
public void recoverFromMismatchedSet(IntStream input, RecognitionException e, BitSet follow)
public void displayRecognitionError(String[] tokenNames, RecognitionException e) {
String message = getErrorMessage(e, tokenNames);
// TODO would something like this be worthwhile to improve messages?
// if (message.equals("no viable alternative at input '<EOF>'") && !paraphrase.isEmpty()) {
// // This means we ran out of input building something, that something is named in paraphrase
// message = "no more input data to process whilst constructing " + paraphrase.peek();
// }
SpelException parsingProblem = new SpelException(e.charPositionInLine, e, SpelMessages.PARSE_PROBLEM, message);
throw new InternalELException(parsingProblem);
}
/**
* Overridden purely because the base implementation does a System.err.println()
*/
@Override
public void recoverFromMismatchedToken(IntStream input, RecognitionException e, int ttype, BitSet follow)
throws RecognitionException {
throw e;
// if next token is what we are looking for then "delete" this token
if (input.LA(2) == ttype) {
reportError(e);
/*
* System.err.println("recoverFromMismatchedToken deleting "+input.LT(1)+ " since "+input.LT(2)+" is what we
* want");
*/
beginResync();
input.consume(); // simply delete extra token
endResync();
input.consume(); // move past ttype token as if all were ok
return;
}
if (!recoverFromMismatchedElement(input, e, follow)) {
throw e;
}
}
@Override
@ -67,11 +84,4 @@ public class SpringExpressionsParserExtender extends SpringExpressionsParser {
}
return super.getTokenErrorDisplay(t);
}
// private String getTokenForId(int id) {
// if (id == -1)
// return "EOF";
// return getTokenNames()[id];
// }
}