Dialects

A script is always parsed in a dialect. Pass one of the ShellDialect values to ParseText or ParseCommand, or in ShellParseOptions:

The dialects of a family share a parser. Features lists what a dialect supports, as ShellDialectFeatures flags, and HasFeature tests one. ShellDialect.TryParse reads a dialect from its name, and Name gives it:

var powerShell = ShellSyntaxTree.ParseText("Get-ChildItem -Recurse | Where-Object { $_.Length -gt 1kb }", ShellDialect.PowerShellCore);
Assert.Empty(powerShell.GetDiagnostics());

var cmd = ShellSyntaxTree.ParseText("@echo off\r\nif exist out (rmdir /s /q out)\r\n", ShellDialect.Cmd);
Assert.Empty(cmd.GetDiagnostics());

// [[ ]] is bash and zsh only: in sh, it is an ordinary command name
Assert.True(ShellDialect.Bash.HasFeature(ShellDialectFeatures.ExtendedTest));
Assert.False(ShellDialect.Sh.HasFeature(ShellDialectFeatures.ExtendedTest));

// Read a dialect from its name
Assert.True(ShellDialect.TryParse("pwsh", out var dialect));
Assert.Equal(ShellDialect.PowerShellCore, dialect);

A construct is parsed as one only in the dialects that have it. POSIX defines $((1+2)), so every POSIX dialect parses it as an arithmetic expansion, while the ((1+2)) arithmetic command is bash and zsh only, and stays plain text in sh.

One tree for every dialect

Every dialect builds the same kind of tree, with node types shared where the shells agree, such as ShellCommandSyntax, ShellPipelineSyntax or ShellWordSyntax, and node types of their own where they do not:

ShellSyntaxVisitor, ShellSyntaxWalker and ShellSyntaxRewriter cover the node types of every dialect, so one walker handles any script.