PHP Parser

This is a PHP parser written in PHP. It's purpose is to simplify static code analysis and manipulation.

Note: This project is work in progress. It is known to not function perfectly correct yet (see the "Known Issues" section at the end of this document).

Components

This package currently bundles several components:

• The Parser itself
• A NodeDumper to dump the nodes to a human readable string representation
• A PrettyPrinter to translate the node tree back to PHP

Parser and ParserDebug

Parsing is performed using Parser->parse(). This method accepts a Lexer as the first parameter and a error callback, i.e. a function that will be passed a message in case of an error, as second parameter. The parser returns an array of statement nodes. If an error occurs the parser instead returns false and sends an error message to the error callback.

$code = '<?php // some code';

$parser = new Parser;
$stmts = $parser->parse(
    new Lexer($code),
    function ($msg) {
        echo $msg;
    }
);

The ParserDebug class also parses a PHP code, but outputs a debug trace while doing so.

Node Tree

The output of the parser is an array of statement nodes. All nodes are instances of NodeAbstract. Furthermore nodes are divided into three categories:

• Node_Stmt: A statement
• Node_Expr: An expression
• Node_Scalar: A scalar (which is a string, a number, aso.) Node_Scalar inherits from Node_Expr.

Each node may have subnodes. For example Node_Expr_Plus has two subnodes, namely left and right, which represend the left hand side and right hand side expressions of the plus operation. Subnodes are accessed as normal properties:

$node->left

The subnodes which a certain node can have are documented as @property doccomments in the respective files.

NodeDumper

Nodes can be dumped into a string representation using the NodeDumper->dump method:

$code = <<<'CODE'
<?php
    function printLine($msg) {
        echo $msg, "\n";
    }

    printLine('Hallo World!!!');
CODE;

$parser = new Parser;
$stmts = $parser->parse(
    new Lexer($code),
    function ($msg) {
        echo $msg;
    }
);

if (false !== $stmts) {
    $nodeDumper = new NodeDumper;
    echo '<pre>' . htmlspecialchars($nodeDumper->dump($stmts)) . '</pre>';
}

This script will have an output similar to the following:

array(
    0: Stmt_Func(
        byRef: false
        name: printLine
        params: array(
            0: Stmt_FuncParam(
                type: null
                name: msg
                byRef: false
                default: null
            )
        )
        stmts: array(
            0: Stmt_Echo(
                exprs: array(
                    0: Variable(
                        name: msg
                    )
                    1: Scalar_String(
                        value:

                        isBinary: false
                        type: 1
                    )
                )
            )
        )
    )
    1: Expr_FuncCall(
        func: Name(
            parts: array(
                0: printLine
            )
        )
        args: array(
            0: Expr_FuncCallArg(
                value: Scalar_String(
                    value: Hallo World!!!
                    isBinary: false
                    type: 0
                )
                byRef: false
            )
        )
    )
)

PrettyPrinter

The pretty printer compiles nodes back to PHP code. "Pretty printing" here is just the formal name of the process and does not mean that the output is in any way pretty.

$prettyPrinter = new PrettyPrinter_Zend;
echo '<pre>' . htmlspecialchars($prettyPrinter->pStmts($stmts)) . '</pre>';

For the code mentioned in the above section this should create the output:

function printLine($msg)
{
    echo $msg, "\n";
}
printLine('Hallo World!!!');

Known Issues

• Parsing expressions of type a::$b[c]() (I.e. the method name is specifed by an array) currently does not work (causes 1 parse fail in test against Symfony Beta 3).
• When pretty printing strings and InlineHTML those are indented like any other code, thus causing extra whitespace to be inserted (causes 23 compare fails in test against Symfony Beta 3).