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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta name="generator"
content="HTML Tidy for Linux/x86 (vers 1st February 2002), see www.w3.org" />
<title>JSwat - Testing Expressions</title>
</head>
<body bgcolor="#ffffff">
<h2>Testing Expressions</h2>
<h3>Introduction</h3>
<p>JSwat supports the evaluation of Java-like expressions. See the
built-in "Expression Evaluation" help screen to learn
more about them. In short, most of the expressions defined in the
JLS are supported.</p>
<h3>Test Cases</h3>
<table border="1" summary="expressions">
<tr>
<th>Expression</th>
<th>Result</th>
<th>Notes</th>
</tr>
<tr>
<td><code>123</code></td>
<td><code>123</code></td>
<td>numeric literals are returned as-is</td>
</tr>
<tr>
<td><code>true</code></td>
<td><code>true</code></td>
<td>boolean literals are returned as-is</td>
</tr>
<tr>
<td><code>null</code></td>
<td><code>null</code></td>
<td>null is returned as-is</td>
</tr>
<tr>
<td><code>"abc"</code></td>
<td><code>abc</code></td>
<td>string literals have their quotes removed</td>
</tr>
<tr>
<td><code>var</code></td>
<td>var's value</td>
<td>variable references are replaced with the variable
value</td>
</tr>
<tr>
<td><code>1 + 1</code></td>
<td><code>2</code></td>
<td>simple arithmetic expressions are evaluated</td>
</tr>
<tr>
<td><code>1 == 1</code></td>
<td><code>true</code></td>
<td>equality expression</td>
</tr>
<tr>
<td><code>i == 1</code></td>
<td><code>true</code> if i is one</td>
<td>variable and literal equality expression</td>
</tr>
<tr>
<td><code>1 != 1</code></td>
<td><code>false</code></td>
<td>equality expression</td>
</tr>
<tr>
<td><code>i != 1</code></td>
<td><code>true</code> if i is not one</td>
<td>variable and literal equality expression</td>
</tr>
<tr>
<td><code>2 > 1</code></td>
<td><code>true</code></td>
<td>relational expression</td>
</tr>
<tr>
<td><code>i > 1</code></td>
<td><code>true</code> if i is greater than one</td>
<td>variable to literal relational expression</td>
</tr>
<tr>
<td><code>2.2 >= 2.2</code></td>
<td><code>true</code></td>
<td>relational expression (with floating point operands)</td>
</tr>
<tr>
<td><code>1 + 2 * 3</code></td>
<td><code>7</code></td>
<td>operator precedence follows JLS</td>
</tr>
<tr>
<td><code>(1 + 2) * 3</code></td>
<td><code>9</code></td>
<td>parentheses override operator precedence</td>
</tr>
<tr>
<td><code>arr[1 + 1]</code></td>
<td>value of third element of arr (an array)</td>
<td>expressions as array indices</td>
</tr>
<tr>
<td><code>arr[meth(2 + 2)]</code></td>
<td>value of nth element of arr (an array)</td>
<td>method invocation as array index</td>
</tr>
<tr>
<td><code>meth(true, 2 * 3, null)</code></td>
<td>method return value</td>
<td>expressions as method arguments</td>
</tr>
<tr>
<td><code>meth(2 * (3 + 1), a == b, 255 & 32)</code></td>
<td>method return value</td>
<td>more complex method invocation</td>
</tr>
<tr>
<td><code>meth(a == b, meth2(123), 255 & 32)</code></td>
<td>method return value</td>
<td>nested method invocation</td>
</tr>
</table>
</body>
</html>
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