private static Context createMathContext()

in wayang-commons/wayang-core/src/main/java/org/apache/wayang/core/optimizer/costs/LoadProfileEstimators.java [411:447]

33 lines of code
11 McCabe index (conditional complexity)


    private static Context createMathContext(final EstimationContext context,
                                             final long[] inputCardinalities,
                                             final long[] outputCardinalities) {
        return new Context() {
            @Override
            public double getVariable(String variableName) throws EvaluationException {
                // Serve "in999" and "out999" variables directly from the cardinality arrays.
                if (variableName.startsWith("in") && variableName.length() > 2) {
                    int accu = 0;
                    int i;
                    for (i = 2; i < variableName.length(); i++) {
                        char c = variableName.charAt(i);
                        if (!Character.isDigit(c)) break;
                        accu = 10 * accu + (c - '0');
                    }
                    if (i == variableName.length()) return inputCardinalities[accu];
                } else if (variableName.startsWith("out") && variableName.length() > 3) {
                    int accu = 0;
                    int i;
                    for (i = 3; i < variableName.length(); i++) {
                        char c = variableName.charAt(i);
                        if (!Character.isDigit(c)) break;
                        accu = 10 * accu + (c - '0');
                    }
                    if (i == variableName.length()) return outputCardinalities[accu];
                }

                // Otherwise, ask the context for the property.
                return context.getDoubleProperty(variableName, Double.NaN);
            }

            @Override
            public ToDoubleFunction<double[]> getFunction(String functionName) throws EvaluationException {
                throw new EvaluationException("This context does not provide any functions.");
            }
        };
    }