Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Browse files

added a sample on how to use the parser/walker to instrument some code

  • Loading branch information...
commit 6e89f5b2b9b0601408863df17291cbabf0f7f8a4 1 parent 6e751ef
@mishoo mishoo authored
Showing with 97 additions and 0 deletions.
  1. +97 −0 tmp/instrument.js
View
97 tmp/instrument.js
@@ -0,0 +1,97 @@
+// sample on how to use the parser and walker API to instrument some code
+
+var jsp = require("uglify-js").parser;
+var pro = require("uglify-js").uglify;
+
+function instrument(code) {
+ var ast = jsp.parse(code, false, true); // true for the third arg specifies that we want
+ // to have start/end tokens embedded in the
+ // statements
+ var w = pro.ast_walker();
+
+ // we're gonna need this to push elements that we're currently looking at, to avoid
+ // endless recursion.
+ var analyzing = [];
+ function do_stat() {
+ var ret;
+ if (this[0].start && analyzing.indexOf(this) < 0) {
+ // without the `analyzing' hack, w.walk(this) would re-enter here leading
+ // to infinite recursion
+ analyzing.push(this);
+ ret = [ "splice", // XXX: "block" is safer
+ [ [ "stat",
+ [ "call", [ "name", "trace" ],
+ [ [ "string", this[0].toString() ],
+ [ "num", this[0].start.line ],
+ [ "num", this[0].start.col ],
+ [ "num", this[0].end.line ],
+ [ "num", this[0].end.col ]]]],
+ w.walk(this) ]];
+ analyzing.pop(this);
+ }
+ return ret;
+ };
+ var new_ast = w.with_walkers({
+ "stat" : do_stat,
+ "label" : do_stat,
+ "break" : do_stat,
+ "continue" : do_stat,
+ "debugger" : do_stat,
+ "var" : do_stat,
+ "const" : do_stat,
+ "return" : do_stat,
+ "throw" : do_stat,
+ "try" : do_stat,
+ "defun" : do_stat,
+ "if" : do_stat,
+ "while" : do_stat,
+ "do" : do_stat,
+ "for" : do_stat,
+ "for-in" : do_stat,
+ "switch" : do_stat,
+ "with" : do_stat
+ }, function(){
+ return w.walk(ast);
+ });
+ return pro.gen_code(new_ast, { beautify: true });
+}
+
+
+
+
+////// test code follows.
+
+var code = instrument(test.toString());
+console.log(code);
+
+function test() {
+ // simple stats
+ a = 5;
+ c += a + b;
+ "foo";
+
+ // var
+ var foo = 5;
+ const bar = 6, baz = 7;
+
+ // switch block. note we can't track case lines the same way.
+ switch ("foo") {
+ case "foo":
+ return 1;
+ case "bar":
+ return 2;
+ }
+
+ // for/for in
+ for (var i = 0; i < 5; ++i) {
+ console.log("Hello " + i);
+ }
+ for (var i in [ 1, 2, 3]) {
+ console.log(i);
+ }
+
+ // note however that the following is broken. I guess we
+ // should add the block brackets in this case...
+ for (var i = 0; i < 5; ++i)
+ console.log("foo");
+}
Please sign in to comment.
Something went wrong with that request. Please try again.