cloudflare/pint
Publicmirrored from https://github.com/cloudflare/pintAvailable
internal/parser/decode.go
124lines · modecode
| 1 | package parser |
| 2 | |
| 3 | import ( |
| 4 | "encoding/json" |
| 5 | "errors" |
| 6 | "slices" |
| 7 | |
| 8 | promParser "github.com/prometheus/prometheus/promql/parser" |
| 9 | ) |
| 10 | |
| 11 | type PromQLExpr struct { |
| 12 | Value *YamlNode |
| 13 | SyntaxError error |
| 14 | Query *PromQLNode |
| 15 | } |
| 16 | |
| 17 | // PromQLNode is used to turn the parsed PromQL query expression into a tree. |
| 18 | // This allows us to walk the tree up & down and look for either parents |
| 19 | // or children of specific type. Which is useful if you, for example, |
| 20 | // want to check if all vector selectors are wrapped inside function |
| 21 | // calls etc. |
| 22 | type PromQLNode struct { |
| 23 | Parent *PromQLNode |
| 24 | Expr promParser.Node |
| 25 | Children []*PromQLNode |
| 26 | } |
| 27 | |
| 28 | func (pn PromQLNode) MarshalJSON() ([]byte, error) { |
| 29 | return json.Marshal(pn.Expr.String()) |
| 30 | } |
| 31 | |
| 32 | // Tree takes a parsed PromQL node and turns it into a Node |
| 33 | // instance with parent and children populated. |
| 34 | func tree(expr promParser.Node, parent *PromQLNode) *PromQLNode { |
| 35 | n := PromQLNode{ |
| 36 | Parent: parent, |
| 37 | Expr: expr, |
| 38 | Children: nil, |
| 39 | } |
| 40 | for _, child := range promParser.Children(expr) { |
| 41 | n.Children = append(n.Children, tree(child, &n)) |
| 42 | } |
| 43 | |
| 44 | return &n |
| 45 | } |
| 46 | |
| 47 | // WalkUpExpr allows to iterate a promQLNode node looking for |
| 48 | // parents of specific type. |
| 49 | // Prometheus parser returns interfaces which makes it more difficult |
| 50 | // to figure out what kind of node we're dealing with, hence this |
| 51 | // helper takes a type parameter it tries to cast. |
| 52 | // It starts by checking the node passed to it and then walks |
| 53 | // up by visiting all parent nodes. |
| 54 | func WalkUpExpr[T promParser.Node](node *PromQLNode) (nodes []*PromQLNode) { |
| 55 | if node == nil { |
| 56 | return nodes |
| 57 | } |
| 58 | if _, ok := node.Expr.(T); ok { |
| 59 | nodes = append(nodes, node) |
| 60 | } |
| 61 | if node.Parent != nil { |
| 62 | nodes = append(nodes, WalkUpExpr[T](node.Parent)...) |
| 63 | } |
| 64 | return nodes |
| 65 | } |
| 66 | |
| 67 | // WalkDownExpr works just like WalkUpExpr but it walks the tree |
| 68 | // down, visiting all children. |
| 69 | // It also starts by checking the node passed to it before walking |
| 70 | // down the tree. |
| 71 | func WalkDownExpr[T promParser.Node](node *PromQLNode) (nodes []*PromQLNode) { |
| 72 | if _, ok := node.Expr.(T); ok { |
| 73 | nodes = append(nodes, node) |
| 74 | } |
| 75 | for _, child := range node.Children { |
| 76 | nodes = append(nodes, WalkDownExpr[T](child)...) |
| 77 | } |
| 78 | return nodes |
| 79 | } |
| 80 | |
| 81 | // WalkUpParent works like WalkUpExpr but checks the parent |
| 82 | // (if present) instead of the node itself. |
| 83 | // It returns the nodes where the parent is of given type. |
| 84 | func WalkUpParent[T promParser.Node](node *PromQLNode) (nodes []*PromQLNode) { |
| 85 | if node == nil || node.Parent == nil { |
| 86 | return nodes |
| 87 | } |
| 88 | if _, ok := node.Parent.Expr.(T); ok { |
| 89 | nodes = append(nodes, node) |
| 90 | } |
| 91 | if node.Parent != nil { |
| 92 | nodes = append(nodes, WalkUpParent[T](node.Parent)...) |
| 93 | } |
| 94 | return nodes |
| 95 | } |
| 96 | |
| 97 | func DecodeExpr(expr string) (*PromQLNode, error) { |
| 98 | node, err := promParser.ParseExpr(expr) |
| 99 | if err != nil { |
| 100 | var errorList promParser.ParseErrors |
| 101 | if errors.As(err, &errorList) { |
| 102 | // Find the error pointing at the shortest query fragment. |
| 103 | slices.SortFunc(errorList, func(a, b promParser.ParseErr) int { |
| 104 | ar := a.PositionRange.End - a.PositionRange.Start |
| 105 | br := b.PositionRange.End - b.PositionRange.Start |
| 106 | switch { |
| 107 | case ar < br: |
| 108 | return -1 |
| 109 | case ar > br: |
| 110 | return 1 |
| 111 | default: |
| 112 | return 0 |
| 113 | } |
| 114 | }) |
| 115 | for _, el := range errorList { |
| 116 | if el.PositionRange.Start > 0 && el.PositionRange.End > 0 { |
| 117 | return nil, promParser.ParseErrors{el} |
| 118 | } |
| 119 | } |
| 120 | } |
| 121 | return nil, err |
| 122 | } |
| 123 | return tree(node, nil), nil |
| 124 | } |
| 125 | |