Module shell 

Shell command parsing backed by tree-sitter-bash.

Public API:

• parse_with_substitutions — decomposes a shell command into a recursive ParsedPipeline tree.
• has_output_redirection — mutation-detection for redirects.
• dump_ast — diagnostic output.

The parser uses tree-sitter-bash for a full AST, then walks it to produce segments joined by operators. Substitutions ($(), backticks, <(), >()) are recursively parsed into nested pipelines — the result is a tree that can be evaluated bottom-up (catamorphism).

Control flow handling

Shell keywords (for, if, while, case) are grammar structure, not commands. The walker recurses into their bodies and extracts the actual commands as segments.

Redirection propagation

When a control flow construct has output redirection (e.g. for ... done > file), it propagates to inner segments via ShellSegment::redirection.

Functions

dump_ast

Diagnostic: dump the tree-sitter AST and parsed pipeline.

has_output_redirection

Check whether command contains output redirection.

parse_with_substitutions

Parse a shell command into a recursive pipeline tree.