poshtree

Parse PowerShell into a syntax tree, walk it, and turn it back into source.

poshtree is a small PowerShell front-end for Rust. Under the hood it is a lexer feeding a recursive-descent parser, with an unparser for going the other way. It handles messy and deliberately obfuscated input without panicking, which makes it a useful base for formatters, linters, refactoring tools, or an editor integration that needs to know the shape of a script. The only dependency is regex.

Install

[dependencies]
poshtree = "0.1"

Or point at a local checkout:

[dependencies]
poshtree = { path = "../poshtree" }

Parse and walk

parse returns the parsed script block together with any recoverable errors. A malformed construct becomes an error node instead of aborting the parse, so you always get a tree back.

use poshtree::v1::{ast::AstNode, parser::parse};

let (tree, errors) = parse("$x = 1 + 2 | Write-Output");
assert!(errors.is_empty());

let root = AstNode::ScriptBlock(tree);
let mut count = 0;
root.walk(&mut |_| count += 1);
println!("{count} nodes");

Unparse (tree back to source)

let source = poshtree::unparse_source("$x = 1 + 2");
assert!(source.contains("$x"));

The result is meant to re-parse cleanly rather than match the original byte for byte. Whitespace and comments are not preserved.

Tokenize only

If you just want the token stream, skip the parser:

use poshtree::v1::lexer::tokenize;

let tokens = tokenize("Get-ChildItem -Path . -Recurse");
println!("{} tokens", tokens.len());

What is in the box

The common items are re-exported at the crate root: parse, parse_tokens, tokenize, AstNode, NodeInfo, ScriptBlock, Token, unparse, unparse_source, and dump_ast_to_ps1. Everything else lives under the v1 module (v1::ast, v1::lexer, v1::parser, v1::tokens).

Versioning

The tree types live under a v1 module. If the tree ever needs an incompatible redesign, it will arrive as a v2 module and v1 will keep working, so pinning to v1 is safe.

License

MIT. See LICENSE.