This extension exposes the abstract syntax tree generated by PHP 7.

This extension is experimental and the representation of the syntax tree is not final.

API overview

Defines:

• ast\Node class
• ast\Node\Decl class
• ast\AST_* kind constants (mirroring zend_ast.h)
• ast\flags\* flags
• ast\parse_file(string $filename)
• ast\parse_code(string $code [, string $filename = "string code"])
• ast\get_kind_name(int $kind)
• ast\kind_uses_flags(int $kind)

Usage

The ast\parse_code() function accepts a source code string or the ast\parse_file() which accepts a filename containing PHP code (which is parsed in INITIAL mode, i.e. it should generally include an opening PHP tag) and returns an abstract syntax tree consisting of ast\Node objects. ast\Node is declared as follows:

namespace ast;
class Node {
    public $kind;
    public $flags;
    public $lineno;
    public $children;
}

The kind property specified the type of the node. It is an integral value, which corresponds to one of the ast\AST_* constants, for example ast\AST_STMT_LIST. You can retrieve the string name of an integral kind by passing it to ast\get_kind_name().

The flags property contains node specific flags. It is always defined, but for most nodes it is always zero. ast\kind_uses_flags() can be used to determine whether a certain kind has a meaningful flags value. Which nodes use which flags is explained in the "Flags" section below.

The lineno property specified the starting line number of the node.

The children property contains an array of child-nodes. These children can be either other ast\Node objects or plain values. The meaning of the children is node-specific and should be deduced from context or by looking at the parser definition.

Function and class declarations use ast\Node\Decl objects instead, which specify a number of additional properties:

namespace ast\Node;
use ast\Node;

class Decl extends Node {
    public $endLineno;
    public $name;
    public $docComment;
}

endLineno provides the end line number of the declaration, name contains the name of the function or class (can be null for anonymous classes) and docComment contains the preceding doc comment or null if no doc comment was used.

Simple usage example:

<?php

$code = <<<'EOC'
<?php
$var = 42;
EOC;

var_dump(ast\parse_code($code));

// Output:
object(ast\Node)#1 (4) {
  ["kind"]=>
  int(133)
  ["flags"]=>
  int(0)
  ["lineno"]=>
  int(1)
  ["children"]=>
  array(1) {
    [0]=>
    object(ast\Node)#2 (4) {
      ["kind"]=>
      int(517)
      ["flags"]=>
      int(0)
      ["lineno"]=>
      int(1)
      ["children"]=>
      array(2) {
        [0]=>
        object(ast\Node)#3 (4) {
          ["kind"]=>
          int(256)
          ["flags"]=>
          int(0)
          ["lineno"]=>
          int(1)
          ["children"]=>
          array(1) {
            [0]=>
            string(3) "var"
          }
        }
        [1]=>
        int(42)
      }
    }
  }
}

The util.php file defines an ast_dump() function, which can be used to create a more compact and human-readable dump of the AST structure:

<?php

require 'path/to/util.php';

$code = <<<'EOC'
<?php
$var = 42;
EOC;

echo ast_dump(ast\parse_code($code)), "\n";

// Output:
AST_STMT_LIST
    0: AST_ASSIGN
        0: AST_VAR
            0: "var"
        1: 42

To additionally show line numbers pass the AST_DUMP_LINENOS option as the second argument to ast_dump().

A more substantial AST dump can be found in the tests.

Flags

This section lists which flags are used by which AST node kinds. The "combinable" flags can be combined using bitwise or and should be checked by using $ast->flags & ast\flags\FOO. The "exclusive" flags are used standalone and should be checked using $ast->flags === ast\flags\BAR.

// Used by ast\AST_ARRAY_ELEM and ast\AST_CLOSURE_VAR (exclusive)
1 = by-reference

// Used by ast\AST_NAME (exclusive)
ast\flags\NAME_FQ (= 0)
ast\flags\NAME_NOT_FQ
ast\flags\NAME_RELATIVE

// Used by ast\AST_METHOD, ast\AST_PROP_DECL, ast\AST_TRAIT_ALIAS (combinable)
ast\flags\MODIFIER_PUBLIC
ast\flags\MOFIFIER_PROTECTED
ast\flags\MOFIFIER_PRIVATE
ast\flags\MOFIFIER_STATIC
ast\flags\MOFIFIER_ABSTRACT
ast\flags\MOFIFIER_FINAL

// Used by ast\AST_CLOSURE (combinable)
ast\flags\MODIFIER_STATIC

// Used by ast\AST_FUNC_DECL, ast\AST_METHOD, ast\AST_CLOSURE (combinable)
ast\flags\RETURNS_REF

// Used by ast\AST_CLASS (exclusive)
ast\flags\CLASS_ABSTRACT
ast\flags\CLASS_FINAL
ast\flags\CLASS_TRAIT
ast\flags\CLASS_INTERFACE

// Used by ast\AST_PARAM (exclusive)
ast\flags\PARAM_REF
ast\flags\PARAM_VARIADIC

// Used by ast\AST_TYPE (exclusive)
ast\flags\TYPE_ARRAY
ast\flags\TYPE_CALLABLE

// Used by ast\AST_CAST (exclusive)
ast\flags\TYPE_NULL
ast\flags\TYPE_BOOL
ast\flags\TYPE_LONG
ast\flags\TYPE_DOUBLE
ast\flags\TYPE_STRING
ast\flags\TYPE_ARRAY
ast\flags\TYPE_OBJECT

// Used by ast\AST_UNARY_OP (exclusive)
ast\flags\UNARY_BOOL_NOT
ast\flags\UNARY_BITWISE_NOT

// Used by ast\AST_BINARY_OP (exclusive)
ast\flags\BINARY_BOOL_XOR
ast\flags\BINARY_BITWISE_OR
ast\flags\BINARY_BITWISE_AND
ast\flags\BINARY_BITWISE_XOR
ast\flags\BINARY_CONCAT
ast\flags\BINARY_ADD
ast\flags\BINARY_SUB
ast\flags\BINARY_MUL
ast\flags\BINARY_DIV
ast\flags\BINARY_MOD
ast\flags\BINARY_POW
ast\flags\BINARY_SHIFT_LEFT
ast\flags\BINARY_SHIFT_RIGHT
ast\flags\BINARY_IS_IDENTICAL
ast\flags\BINARY_IS_NOT_IDENTICAL
ast\flags\BINARY_IS_EQUAL
ast\flags\BINARY_IS_NOT_EQUAL
ast\flags\BINARY_IS_SMALLER
ast\flags\BINARY_IS_SMALLER_OR_EQUAL
ast\flags\BINARY_SPACESHIP

// Used by ast\AST_ASSIGN_OP (exclusive)
ast\flags\ASSIGN_BITWISE_OR
ast\flags\ASSIGN_BITWISE_AND
ast\flags\ASSIGN_BITWISE_XOR
ast\flags\ASSIGN_CONCAT
ast\flags\ASSIGN_ADD
ast\flags\ASSIGN_SUB
ast\flags\ASSIGN_MUL
ast\flags\ASSIGN_DIV
ast\flags\ASSIGN_MOD
ast\flags\ASSIGN_POW
ast\flags\ASSIGN_SHIFT_LEFT
ast\flags\ASSIGN_SHIFT_RIGHT

// Used by ast\AST_MAGIC_CONST (exclusive)
// (Constants defined by ext\tokenizer)
T_LINE
T_FILE
T_DIR
T_TRAIT_C
T_METHOD_C
T_FUNC_C
T_NS_C
T_CLASS_C

// Used by ast\AST_USE, ast\AST_GROUP_USE and ast\AST_USE_ELEM (exclusive)
// (Constants defined by ext\tokenizer)
T_CLASS
T_FUNCTION
T_CONST

// Used by ast\AST_INCLUDE_OR_EVAL (exclusive)
ast\flags\???