View Source Styler.Style behaviour (Styler v0.10.1)

A Style takes AST and returns a transformed version of that AST.

Because these transformations involve traversing trees (the "T" in "AST"), we wrap the AST in a structure called a Zipper to facilitate walking the trees.

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Callbacks

run will be used with Zipper.traverse_while/3, meaning it will be executed on every node of the AST.

Functions

Set the line of all comments with line in range_start..range_end to instead have line range_start

Returns true if the ast represents an empty map

Ensure the parent node can have multiple children.

Sets :line, :closing, and :last to all be on line and deletes :newlines

Change the line of all comments with line in range by adding delta to it. A positive delta will move the lines further down a file, while a negative delta will move them up.

Traverses an ast node, updating all nodes' meta with meta_fun

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@type context() :: %{comment: [map()], file: :stdin | String.t()}

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run will be used with Zipper.traverse_while/3, meaning it will be executed on every node of the AST.

You can skip traversing parts of the tree by returning a Zipper that's further along in the traversal, for example by calling Zipper.skip(zipper) to skip an entire subtree you know is of no interest to your Style.

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displace_comments(comments, range)

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Set the line of all comments with line in range_start..range_end to instead have line range_start

Returns true if the ast represents an empty map

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ensure_block_parent(zipper)

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Ensure the parent node can have multiple children.

If a context-changing node (a do end block or an -> arrow block) is encountered the child is wrapped in a :__block__

Other nodes (pipes, assignments) can only have a fixed number of children. This function will recursively traverse up the zipper until it's found the parents of those nodes.

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set_line(ast_node, line)

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Sets :line, :closing, and :last to all be on line and deletes :newlines

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shift_comments(comments, range, delta)

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Change the line of all comments with line in range by adding delta to it. A positive delta will move the lines further down a file, while a negative delta will move them up.

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shift_line(ast_node, delta)

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update_all_meta(node, meta_fun)

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Traverses an ast node, updating all nodes' meta with meta_fun