MatcherAction.java 文件源码

void init(String newMatchExpression, Matcher newMatcher) {
        this.matcher = newMatcher;
        this.matchExpression = newMatchExpression;
        setVerbose(newMatcher.getVerbose());

        InitErrorListener errorListener = new InitErrorListener();

        CodePointCharStream input = CharStreams.fromString(this.matchExpression);
        UserAgentTreeWalkerLexer lexer = new UserAgentTreeWalkerLexer(input);

        lexer.addErrorListener(errorListener);

        CommonTokenStream tokens = new CommonTokenStream(lexer);
        UserAgentTreeWalkerParser parser = new UserAgentTreeWalkerParser(tokens);

        parser.addErrorListener(errorListener);

//        parser.setTrace(true);
        ParserRuleContext requiredPattern = parseWalkerExpression(parser);

        if (requiredPattern == null) {
            throw new InvalidParserConfigurationException("NO pattern ?!?!?");
        }

        // We couldn't ditch the double quotes around the fixed values in the parsing phase.
        // So we ditch them here. We simply walk the tree and modify some of the tokens.
        new UnQuoteValues().visit(requiredPattern);

        // Now we create an evaluator instance
        evaluator = new TreeExpressionEvaluator(requiredPattern, matcher, verbose);

        // Is a fixed value (i.e. no events will ever be fired)?
        String fixedValue = evaluator.getFixedValue();
        if (fixedValue != null) {
            setFixedValue(fixedValue);
            mustHaveMatches = false;
            matches = new MatchesList(0);
            return; // Not interested in any patterns
        }

        mustHaveMatches = !evaluator.usesIsNull();

        int informs = calculateInformPath("agent", requiredPattern);

        // If this is based on a variable we do not need any matches from the hashmap.
        if (mustHaveMatches && informs == 0) {
            mustHaveMatches = false;
        }

        int listSize = 0;
        if (informs > 0) {
            listSize = 1;
        }
        this.matches = new MatchesList(listSize);
    }