public void testLambdaCallsBinaryOp() {
// A parameter for the lambda expression.
ParameterExpression paramExpr = Expressions.parameter(Integer.TYPE, "arg");
// This expression represents a lambda expression
// that adds 1 to the parameter value.
FunctionExpression lambdaExpr =
Expressions.lambda(
Expressions.add(paramExpr, Expressions.constant(2)), Arrays.asList(paramExpr));
// Print out the expression.
String s = Expressions.toString(lambdaExpr);
assertEquals(
"new net.hydromatic.linq4j.function.Function1() {\n"
+ " public int apply(Integer arg) {\n"
+ " return arg + 2;\n"
+ " }\n"
+ " public Object apply(Object arg) {\n"
+ " return apply(\n"
+ " (Integer) arg);\n"
+ " }\n"
+ "}\n",
s);
// Compile and run the lambda expression.
// The value of the parameter is 1.
int n = (Integer) lambdaExpr.compile().dynamicInvoke(1);
// This code example produces the following output:
//
// arg => (arg +2)
// 3
assertEquals(3, n);
}
public void testLambdaCallsTwoArgMethod() throws NoSuchMethodException {
// A parameter for the lambda expression.
ParameterExpression paramS = Expressions.parameter(String.class, "s");
ParameterExpression paramBegin = Expressions.parameter(Integer.TYPE, "begin");
ParameterExpression paramEnd = Expressions.parameter(Integer.TYPE, "end");
// This expression represents a lambda expression
// that adds 1 to the parameter value.
FunctionExpression lambdaExpr =
Expressions.lambda(
Expressions.call(
paramS,
String.class.getMethod("substring", Integer.TYPE, Integer.TYPE),
paramBegin,
paramEnd),
paramS,
paramBegin,
paramEnd);
// Compile and run the lambda expression.
String s = (String) lambdaExpr.compile().dynamicInvoke("hello world", 3, 7);
assertEquals("lo w", s);
}