# `mix ex_ast.replace`
[🔗](https://github.com/elixir-vibe/ex_ast/blob/v0.11.0/lib/mix/tasks/ex_ast.replace.ex#L1)

Replaces AST pattern matches in Elixir source files.

## Usage

    mix ex_ast.replace 'pattern' 'replacement' [path ...]

## Options

  * `--dry-run` — show changes without writing files
  * `--inside 'pattern'` — only replace inside ancestors matching this pattern
  * `--not-inside 'pattern'` — skip replacements inside ancestors matching this pattern
  * `--parent 'pattern'` / `--not-parent 'pattern'` — filter by direct semantic parent
  * `--ancestor 'pattern'` / `--not-ancestor 'pattern'` — filter by semantic ancestor
  * `--has-child 'pattern'` / `--not-has-child 'pattern'` — filter by direct semantic child
  * `--contains 'pattern'` / `--not-contains 'pattern'` — filter by semantic descendant
  * `--has-descendant 'pattern'` / `--not-has-descendant 'pattern'` — aliases for contains filters
  * `--has 'pattern'` / `--not-has 'pattern'` — aliases for contains filters
  * `--follows 'pattern'` / `--not-follows 'pattern'` — filter by earlier sibling
  * `--precedes 'pattern'` / `--not-precedes 'pattern'` — filter by later sibling
  * `--immediately-follows 'pattern'` / `--not-immediately-follows 'pattern'` — filter by previous sibling
  * `--immediately-precedes 'pattern'` / `--not-immediately-precedes 'pattern'` — filter by next sibling
  * `--first` / `--not-first`, `--last` / `--not-last`, `--nth n` / `--not-nth n` — filter by sibling position
  * `--comment text` / `--not-comment text` — filter by associated comments
  * `--comment-before text`, `--comment-after text`, `--comment-inside text`, `--comment-inline text` — filter by comment location

  Comment values are substrings by default. Use `/.../` or `~r/.../` for regexes, including flags like `/todo/i`.

## Examples

    mix ex_ast.replace 'IO.inspect(expr, _)' 'expr' lib/
    mix ex_ast.replace 'dbg(expr)' 'expr'
    mix ex_ast.replace --dry-run '%Step{id: "subject"}' 'SharedSteps.subject_step(@opts)'
    mix ex_ast.replace --not-inside 'test _ do _ end' 'IO.inspect(expr)' 'expr'
    mix ex_ast.replace 'IO.inspect(expr)' 'Logger.debug(inspect(expr))' lib/ --parent 'def _ do ... end'
    mix ex_ast.replace 'Repo.get!(schema, id)' 'Repo.fetch!(schema, id)' lib/ --contains 'Repo.transaction(_)' --not-contains 'IO.inspect(...)'
    mix ex_ast.replace 'Logger.debug(record)' 'Logger.info(record)' lib/ --immediately-precedes 'Repo.delete(record)'
    mix ex_ast.replace 'IO.inspect(expr)' 'dbg(expr)' lib/ --comment-inline temporary
    mix ex_ast.replace 'IO.inspect(expr)' 'dbg(expr)' lib/ --comment-inline '/temporary|debug/i'

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*Consult [api-reference.md](api-reference.md) for complete listing*