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 testCompile() throws NoSuchMethodException {
// Creating a parameter for the expression tree.
ParameterExpression param = Expressions.parameter(String.class);
// Creating an expression for the method call and specifying its
// parameter.
MethodCallExpression methodCall =
Expressions.call(Integer.class, "valueOf", Collections.<Expression>singletonList(param));
// The following statement first creates an expression tree,
// then compiles it, and then runs it.
int x =
Expressions.<Function1<String, Integer>>lambda(
methodCall, new ParameterExpression[] {param})
.getFunction()
.apply("1234");
assertEquals(1234, x);
}
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);
}
public void testWrite() {
assertEquals(
"1 + 2.0F + 3L + Long.valueOf(4L)",
Expressions.toString(
Expressions.add(
Expressions.add(
Expressions.add(Expressions.constant(1), Expressions.constant(2F, Float.TYPE)),
Expressions.constant(3L, Long.TYPE)),
Expressions.constant(4L, Long.class))));
assertEquals(
"new java.math.BigDecimal(31415926L, 7)",
Expressions.toString(Expressions.constant(BigDecimal.valueOf(314159260, 8))));
// Parentheses needed, to override the left-associativity of +.
assertEquals(
"1 + (2 + 3)",
Expressions.toString(
Expressions.add(
Expressions.constant(1),
Expressions.add(Expressions.constant(2), Expressions.constant(3)))));
// No parentheses needed; higher precedence of * achieves the desired
// effect.
assertEquals(
"1 + 2 * 3",
Expressions.toString(
Expressions.add(
Expressions.constant(1),
Expressions.multiply(Expressions.constant(2), Expressions.constant(3)))));
assertEquals(
"1 * (2 + 3)",
Expressions.toString(
Expressions.multiply(
Expressions.constant(1),
Expressions.add(Expressions.constant(2), Expressions.constant(3)))));
// Parentheses needed, to overcome right-associativity of =.
assertEquals(
"(1 = 2) = 3",
Expressions.toString(
Expressions.assign(
Expressions.assign(Expressions.constant(1), Expressions.constant(2)),
Expressions.constant(3))));
// Ternary operator.
assertEquals(
"1 < 2 ? (3 < 4 ? 5 : 6) : 7 < 8 ? 9 : 10",
Expressions.toString(
Expressions.condition(
Expressions.lessThan(Expressions.constant(1), Expressions.constant(2)),
Expressions.condition(
Expressions.lessThan(Expressions.constant(3), Expressions.constant(4)),
Expressions.constant(5),
Expressions.constant(6)),
Expressions.condition(
Expressions.lessThan(Expressions.constant(7), Expressions.constant(8)),
Expressions.constant(9),
Expressions.constant(10)))));
assertEquals(
"0 + (double) (2 + 3)",
Expressions.toString(
Expressions.add(
Expressions.constant(0),
Expressions.convert_(
Expressions.add(Expressions.constant(2), Expressions.constant(3)),
Double.TYPE))));
assertEquals(
"a.empno",
Expressions.toString(
Expressions.field(Expressions.parameter(Linq4jTest.Employee.class, "a"), "empno")));
assertEquals(
"java.util.Collections.EMPTY_LIST",
Expressions.toString(Expressions.field(null, Collections.class, "EMPTY_LIST")));
final ParameterExpression paramX = Expressions.parameter(String.class, "x");
assertEquals(
"new net.hydromatic.linq4j.function.Function1() {\n"
+ " public int apply(String x) {\n"
+ " return x.length();\n"
+ " }\n"
+ " public Object apply(Object x) {\n"
+ " return apply(\n"
+ " (String) x);\n"
+ " }\n"
+ "}\n",
Expressions.toString(
Expressions.lambda(
Function1.class,
Expressions.call(paramX, "length", Collections.<Expression>emptyList()),
Arrays.asList(paramX))));
assertEquals(
"new String[] {\n" + " \"foo\",\n" + " null,\n" + " \"bar\\\"baz\"}",
Expressions.toString(
Expressions.newArrayInit(
String.class,
Arrays.<Expression>asList(
Expressions.constant("foo"),
Expressions.constant(null),
Expressions.constant("bar\"baz")))));
assertEquals(
"(int) ((String) (Object) \"foo\").length()",
Expressions.toString(
Expressions.convert_(
Expressions.call(
Expressions.convert_(
Expressions.convert_(Expressions.constant("foo"), Object.class),
String.class),
"length",
Collections.<Expression>emptyList()),
Integer.TYPE)));
// resolving a static method
assertEquals(
"Integer.valueOf(\"0123\")",
Expressions.toString(
Expressions.call(
Integer.class,
"valueOf",
Collections.<Expression>singletonList(Expressions.constant("0123")))));
// precedence of not and instanceof
assertEquals(
"!(o instanceof String)",
Expressions.toString(
Expressions.not(
Expressions.typeIs(Expressions.parameter(Object.class, "o"), String.class))));
// not not
assertEquals(
"!!(o instanceof String)",
Expressions.toString(
Expressions.not(
Expressions.not(
Expressions.typeIs(Expressions.parameter(Object.class, "o"), String.class)))));
}