prometheus/promql/parser/prettier_rules.md

# Prettifying PromQL expressions
This files contains rules for prettifying PromQL expressions.

Note: The current version of prettier does not preserve comments.

### Keywords
`max_characters_per_line`: Maximum number of characters that will be allowed on a single line in a prettified PromQL expression.

### Rules
1. A node exceeding the `max_characters_per_line` will qualify for split unless
   1. It is a `MatrixSelector`
   2. It is a `VectorSelector`. Label sets in a `VectorSelector` will be in the same line as metric_name, separated by commas and a space
   Note: Label groupings like `by`, `without`, `on`, `ignoring` will remain on the same line as their parent node
2. Nodes that are nested within another node will be prettified only if they exceed the `max_characters_per_line`
3. Expressions like `sum(expression) without (label_matchers)` will be modified to `sum without(label_matchers) (expression)`
4. Functional call args will be split to different lines if they exceed the `max_characters_per_line`
Adds support for prettifying PromQL expression (#10544) * Implement Pretty() function for AST nodes. Signed-off-by: Harkishen-Singh <harkishensingh@hotmail.com> This commit adds .Pretty() for all nodes of PromQL AST. Each .Pretty() prettifies the node it belongs to, and under no circustance, the parent or child node is touch/prettified. Read more in the "Approach" part in `prettier.go` * Refactor functions between printer.go & prettier.go Signed-off-by: Harkishen-Singh <harkishensingh@hotmail.com> This commit removes redundancy between printer.go and prettier.go by taking out the common code into separate private functions. * Add more unit tests for Prettier. Signed-off-by: Harkishen-Singh <harkishensingh@hotmail.com> * Add support for spliting function calls with 1 arg & unary expressions. Signed-off-by: Harkishen-Singh <harkishensingh@hotmail.com> This commit does 2 things: 1. It adds support to split function calls that have 1 arg and exceeds the max_characters_per_line to multiple lines. 2. Splits Unary expressions that exceed the max_characters_per_line. This is done by formatting the child node and then removing the prefix indent, which is already applied before the unary operator. 2022-07-07 05:43:36 -07:00			`# Prettifying PromQL expressions`
			`This files contains rules for prettifying PromQL expressions.`

			`Note: The current version of prettier does not preserve comments.`

			`### Keywords`
			`max_characters_per_line`: Maximum number of characters that will be allowed on a single line in a prettified PromQL expression.

			`### Rules`
			1. A node exceeding the `max_characters_per_line` will qualify for split unless
			1. It is a `MatrixSelector`
			2. It is a `VectorSelector`. Label sets in a `VectorSelector` will be in the same line as metric_name, separated by commas and a space
			Note: Label groupings like `by`, `without`, `on`, `ignoring` will remain on the same line as their parent node
			2. Nodes that are nested within another node will be prettified only if they exceed the `max_characters_per_line`
			3. Expressions like `sum(expression) without (label_matchers)` will be modified to `sum without(label_matchers) (expression)`
			4. Functional call args will be split to different lines if they exceed the `max_characters_per_line`