Parser

PHPTaqwim uses php-parser to generate an AST from the source code. The AST is then used to perform the analysis. The original AST is kept as is, but few additional properties are added to the nodes to make the analysis easier.

Version

PHPTaqwin uses a version of php-parse that has been compiled using vite node API and it ships with the extension. The reason being is that php-parse is transpiled using webpack, which is not compatible with vite. There was an undefined self error.

Additions

Traversal

Four methods are added to the nodes to traverse the AST:

• closest - returns the closest parent node of the given type
• parent - returns direct parent of node
• siblings - returns the siblings of the node
• find returns the first child node of the given type

Also, path property is added to the nodes. It is an array of node types from the root to the current node. Each key in the array is separated by a single pipe character |. The left side of the pipe is the node type, and the right side is the kind of the node.

For example:

[
  'children-0|if',
  'alternate|if',
  'alternate|block',
  'children-0|echo'
]

ifType

if nodes have an additional property ifType which is a string that represents the type of the if node. It can be one of the following:

• onlyif - if statement with no else or elseif
• if - if statement with either else or elseif
• elseif - elseif`statement
• else - else statement

AttrGroup and Attribute

AttrGroup and Attribute have few issues:

• loc is not accurate.
• source is not accurate or undefined. Using regex and string manipulation, the loc and source are fixed. Hopefully, once php-parser fixes the issue, the regex and string manipulation can be removed.

Loc position

• Loc position are transformed to zero-based instead of one-based
• There is a bug with noop loc position where they are the wrong match (start loc is for the end position and vice versa). This is fixed by swapping the start and end loc positions. For the bug see: https://github.com/glayzzle/php-parser/issues/1063

Types

PHPTaqwim is wrtten in TypeScript, but php-parser is not. While php-parser provides type definitions, they are not complete, or even consistent. PHPTaqwim adds additional types to the nodes to make the analysis easier. However, these types are temporary until hopefully php-parser adds them to their type definitions.

Online AST Explorer

To explore the AST you can do it online at AST Explorer, choose PHP as the language and php-parser as the parser.