Demonstration

This section is intended as a quick introduction outlining what the current release of phc can do for you. It does not explain everything in detail.

The Source Program

Consider the following simple PHP script.

<?php
   function foo()
   {
      return 5;
   }

   $foo = foo();
   echo "foo is $foo<br>";
?>

Internally this program gets represented as an abstract syntax tree, as shown in figure Abstract syntax tree for the demo example.

Abstract syntax tree for the demo example

The Transform

Suppose we want to rename function foo to bar. This is done by the following plugin:

#include "AST_visitor.h"
#include "pass_manager/Plugin_pass.h"

class Rename_foo_to_bar : public Visitor
{
   void pre_method_name(METHOD_NAME* in)
   {
      if(*in->value == "foo")
         in->value = new String("bar");
   }
};

extern "C" void run_ast (AST::PHP_script* in, Pass_manager* pm, String* option)
{
    Rename_foo_to_bar f2b;
    php_script->visit(&f2b);
}

extern "C" void load (Pass_manager* pm, Plugin_pass* pass)
{
   pm->add_after_named_pass (pass, new String("ast"));
}

The Result

Running phc gives

<?php
   function bar()
   {
      return 5;
   }

   $foo = bar();
   echo "foo is " . $foo . "<br>";
?>

where the name of the function has been changed, while the name of the variable remained unaltered, as has the text "foo" inside the string. It’s that simple! Of course, in this example, it would have been quicker to do it by hand, but that’s not the point; the example shows how easy it is to operate on PHP scripts within the phc framework.