1/*
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17 *     from this software without specific prior written permission.
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19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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30 */
31
32// Usage: jjs javacastcounter.js -- <.java files>
33
34// This example demonstrates Nashorn Java.extend API
35// to subclass a Java class from script.
36
37// This example uses Javac Compiler and Tree API
38// to list type casts used in java source files.
39
40if (arguments.length == 0) {
41    print("Usage: jjs javacastcounter.js -- <.java files>");
42    exit(1);
43}
44
45// Java types used
46var ToolProvider = Java.type("javax.tools.ToolProvider");
47var TreeScanner = Java.type("com.sun.source.util.TreeScanner");
48var Trees = Java.type("com.sun.source.util.Trees");
49var StringArray = Java.type("java.lang.String[]");
50
51// get the system compiler tool
52var compiler = ToolProvider.systemJavaCompiler;
53
54// get standard file manager
55var fileMgr = compiler.getStandardFileManager(null, null, null);
56
57// make a list of compilation unit from command line argument file names
58// Using Java.to convert script array (arguments) to a Java String[]
59var compUnits = fileMgr.getJavaFileObjects(Java.to(arguments, StringArray));
60
61// create a new compilation task
62var task = compiler.getTask(null, fileMgr, null, null, null, compUnits);
63
64// SourcePositions object to get positions of AST nodes
65var sourcePositions = Trees.instance(task).sourcePositions;
66
67// Subclass TreeScanner class
68var CastCounter = Java.extend(TreeScanner);
69
70var counter = new CastCounter() {
71    // current CompilationUnitTree
72    compUnit: null,
73    // current LineMap (pos -> line, column)
74    lineMap: null,
75    // current compilation unit's file name
76    fileName: null,
77
78    // overrides of TreeScanner methods
79
80    visitCompilationUnit: function(node, p) {
81        // capture info about current Compilation unit
82        this.compUnit = node;
83        this.lineMap = node.lineMap;
84        this.fileName = node.sourceFile.name;
85
86        // Using Java.super API to call super class method here
87        return Java.super(counter).visitCompilationUnit(node, p);
88    },
89
90    visitTypeCast: function(node, p) {
91        // print information on this type cast node
92        var pos = sourcePositions.getStartPosition(this.compUnit, node);
93        var line = this.lineMap.getLineNumber(pos);
94        var col = this.lineMap.getColumnNumber(pos);
95        print(node + " @ " + this.fileName + ":" + line + ":" + col);
96
97        // count one more type cast
98        return 1;
99    },
100
101    reduce: function(r1, r2) {
102        return (r1 == null ? 0 : r1) + (r2 == null ? 0 : r2);
103    }
104};
105
106// print total number of type cast nodes seen
107print("Total casts:", counter.scan(task.parse(), null));
108