public Object evaluate()

in impl/maven-core/src/main/java/org/apache/maven/plugin/PluginParameterExpressionEvaluatorV4.java [100:207]

• 77 lines of code
• 23 McCabe index (conditional complexity)

    public Object evaluate(String expr, Class<?> type) throws ExpressionEvaluationException {
        Object value = null;

        if (expr == null) {
            return null;
        }

        String expression = stripTokens(expr);
        if (expression.equals(expr)) {
            int index = expr.indexOf("${");
            if (index >= 0) {
                int lastIndex = expr.indexOf('}', index);
                if (lastIndex >= 0) {
                    String retVal = expr.substring(0, index);

                    if ((index > 0) && (expr.charAt(index - 1) == '$')) {
                        retVal += expr.substring(index + 1, lastIndex + 1);
                    } else {
                        Object subResult = evaluate(expr.substring(index, lastIndex + 1));

                        if (subResult != null) {
                            retVal += subResult;
                        } else {
                            retVal += "$" + expr.substring(index + 1, lastIndex + 1);
                        }
                    }

                    retVal += evaluate(expr.substring(lastIndex + 1));
                    return retVal;
                }
            }

            // Was not an expression
            return expression.replace("$$", "$");
        }

        Map<String, Object> objects = new HashMap<>();
        objects.put("session.", session);
        objects.put("project.", project);
        objects.put("mojo.", mojoExecution);
        objects.put("settings.", session.getSettings());
        for (Map.Entry<String, Object> ctx : objects.entrySet()) {
            if (expression.startsWith(ctx.getKey())) {
                try {
                    int pathSeparator = expression.indexOf('/');
                    if (pathSeparator > 0) {
                        String pathExpression = expression.substring(0, pathSeparator);
                        value = ReflectionValueExtractor.evaluate(pathExpression, ctx.getValue());
                        if (pathSeparator < expression.length() - 1) {
                            if (value instanceof Path path) {
                                value = path.resolve(expression.substring(pathSeparator + 1));
                            } else {
                                value = value + expression.substring(pathSeparator);
                            }
                        }
                    } else {
                        value = ReflectionValueExtractor.evaluate(expression, ctx.getValue());
                    }
                    break;
                } catch (Exception e) {
                    // TODO don't catch exception
                    throw new ExpressionEvaluationException(
                            "Error evaluating plugin parameter expression: " + expression, e);
                }
            }
        }

        /*
         * MNG-4312: We neither have reserved all of the above magic expressions nor is their set fixed/well-known (it
         * gets occasionally extended by newer Maven versions). This imposes the risk for existing plugins to
         * unintentionally use such a magic expression for an ordinary property. So here we check whether we
         * ended up with a magic value that is not compatible with the type of the configured mojo parameter (a string
         * could still be converted by the configurator so we leave those alone). If so, back off to evaluating the
         * expression from properties only.
         */
        if (value != null && type != null && !(value instanceof String) && !isTypeCompatible(type, value)) {
            value = null;
        }

        if (value == null) {
            // The CLI should win for defining properties

            if (properties != null) {
                // We will attempt to get nab a property as a way to specify a parameter
                // to a plugin. My particular case here is allowing the surefire plugin
                // to run a single test so I want to specify that class on the cli as
                // a parameter.

                value = properties.get(expression);
            }
        }

        if (value instanceof String val) {
            // TODO without #, this could just be an evaluate call...

            int exprStartDelimiter = val.indexOf("${");

            if (exprStartDelimiter >= 0) {
                if (exprStartDelimiter > 0) {
                    value = val.substring(0, exprStartDelimiter) + evaluate(val.substring(exprStartDelimiter));
                } else {
                    value = evaluate(val.substring(exprStartDelimiter));
                }
            }
        }

        return value;
    }