tree-sitter-pwsh

PowerShell grammar for tree-sitter.

Parses .ps1 and .psm1 files into a concrete syntax tree for syntax highlighting, code navigation, and analysis.

Features

• Pipelines and commands — pipes |, chain operators && ||, redirections > >> 2>&1, invocation & ., splatting @params
• Directives — using namespace, using module (including hashtable specs), using assembly, using static, and top-of-file #Requires
• Strings and interpolation — expandable strings "$var $(expr)", verbatim strings, here-strings @" / @', and PowerShell-style escaping
• Functions and named blocks — function, filter, workflow with param() blocks, attributes, validation, and begin/process/end/clean
• Control flow — if/elseif/else, switch (-Regex, -Wildcard, -Exact, -CaseSensitive), foreach, for, while, do/while/until
• Error handling — try/catch/finally with typed catch clauses, trap, throw, break, continue, return, exit
• Expressions — ternary ? :, null-coalescing ??/??=, comparison/string/type/containment operators, -f format, range ..
• Types — common .NET type forms including generics [Dictionary[string, int]], arrays [int[]], nested types Array+Enumerator, and backtick arity Dictionary`2
• Variables — $var, $scope:var, ${braced} with backtick escapes, @splatted, and special vars $$ $^ $? $_
• Classes and enums — properties, methods, constructors with : base()/: this() chaining, hidden/static attributes, and inheritance clauses
• Numbers — decimal, hex 0x, scientific 1.5e10, numeric suffixes (u, ul, s, us, y, uy, n, l, d), and size multipliers (kb/mb/gb/tb/pb)
• Case-insensitive keywords and operators — parses PowerShell casing variations without normalization

Example

using namespace System.IO

function Get-FileSize {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory)]
        [string]$Path
    )

    begin { $total = 0 }
    process {
        $size = (Get-Item $Path).Length
        $total += $size
    }
    end { $total }
    clean { Remove-Variable total }
}

$result = Get-FileSize -Path ".\README.md"
$message = $result -gt 1kb ? "Large file" : "Small file"
Write-Host $message

Parsed tree:

(program
  (using_directive_list
    (using_statement (type_name (type_name (type_identifier)) (type_identifier))))
  (statement_list
    (function_statement
      (function_name)
      (script_block
        (param_block
          (attribute_list
            (attribute (attribute_name (type_spec (type_name (type_identifier))))))
          (parameter_list
            (script_parameter
              (attribute_list
                (attribute (attribute_name (type_spec (type_name (type_identifier))))))
              (variable))))
        (script_block_body
          (named_block_list
            (named_block (block_name) (statement_block ...))
            (named_block (block_name) (statement_block ...))
            (named_block (block_name) (statement_block ...))
            (named_block (block_name) (statement_block ...))))))
    (pipeline
      (assignment_expression ...))
    (pipeline
      (assignment_expression ...))
    (pipeline
      (pipeline_chain
        (command (command_name) (command_elements ...))))))

Installation

npm

npm install tree-sitter-pwsh

Cargo

cargo add tree-sitter-pwsh

PyPI

pip install tree-sitter-pwsh

Go

import tree_sitter_powershell "github.com/wharflab/tree-sitter-powershell/bindings/go"

The root package also exports the bundled queries/highlights.scm via go:embed:

import powershell "github.com/wharflab/tree-sitter-powershell"

lang := powershell.GetLanguage()
query, _ := powershell.GetHighlightsQuery()

Usage

Node.js

import Parser from "tree-sitter";
import PowerShell from "tree-sitter-pwsh";

const parser = new Parser();
parser.setLanguage(PowerShell);

const tree = parser.parse(`Get-Process | Where-Object { $_.CPU -gt 10 }\n`);
console.log(tree.rootNode.toString());

Rust

let mut parser = tree_sitter::Parser::new();
let language = tree_sitter_pwsh::LANGUAGE;
parser.set_language(&language.into()).unwrap();

let tree = parser.parse("Get-Process | Sort-Object CPU\n", None).unwrap();
println!("{}", tree.root_node().to_sexp());

Python

from tree_sitter import Language, Parser
import tree_sitter_pwsh

parser = Parser(Language(tree_sitter_pwsh.language()))
tree = parser.parse(b"Get-Process | Sort-Object CPU\n")
print(tree.root_node.sexp())

Syntax Highlighting

The grammar ships with a queries/highlights.scm file for use in editors that support tree-sitter highlighting (Neovim, Helix, Zed, etc.).

References

• PowerShell Language Specification
• PowerShell/EditorSyntax — used as a real-world parsing benchmark
• PowerShell/tree-sitter-PowerShell — archived PowerShell grammar repo; provided a significant part of the corpus coverage and the TheBigTestFile.ps1 benchmark target
• Originally forked from airbus-cert/tree-sitter-powershell

License

MIT