| 1 | // Copyright 2018 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package analysis |
| 6 | |
| 7 | import ( |
| 8 | "fmt" |
| 9 | "reflect" |
| 10 | "strings" |
| 11 | "unicode" |
| 12 | ) |
| 13 | |
| 14 | // Validate reports an error if any of the analyzers are misconfigured. |
| 15 | // Checks include: |
| 16 | // that the name is a valid identifier; |
| 17 | // that the Doc is not empty; |
| 18 | // that the Run is non-nil; |
| 19 | // that the Requires graph is acyclic; |
| 20 | // that analyzer fact types are unique; |
| 21 | // that each fact type is a pointer. |
| 22 | func Validate(analyzers []*Analyzer) error { |
| 23 | // Map each fact type to its sole generating analyzer. |
| 24 | factTypes := make(map[reflect.Type]*Analyzer) |
| 25 | |
| 26 | // Traverse the Requires graph, depth first. |
| 27 | const ( |
| 28 | white = iota |
| 29 | grey |
| 30 | black |
| 31 | finished |
| 32 | ) |
| 33 | color := make(map[*Analyzer]uint8) |
| 34 | var visit func(a *Analyzer) error |
| 35 | visit = func(a *Analyzer) error { |
| 36 | if a == nil { |
| 37 | return fmt.Errorf("nil *Analyzer") |
| 38 | } |
| 39 | if color[a] == white { |
| 40 | color[a] = grey |
| 41 | |
| 42 | // names |
| 43 | if !validIdent(a.Name) { |
| 44 | return fmt.Errorf("invalid analyzer name %q", a) |
| 45 | } |
| 46 | |
| 47 | if a.Doc == "" { |
| 48 | return fmt.Errorf("analyzer %q is undocumented", a) |
| 49 | } |
| 50 | |
| 51 | if a.Run == nil { |
| 52 | return fmt.Errorf("analyzer %q has nil Run", a) |
| 53 | } |
| 54 | // fact types |
| 55 | for _, f := range a.FactTypes { |
| 56 | if f == nil { |
| 57 | return fmt.Errorf("analyzer %s has nil FactType", a) |
| 58 | } |
| 59 | t := reflect.TypeOf(f) |
| 60 | if prev := factTypes[t]; prev != nil { |
| 61 | return fmt.Errorf("fact type %s registered by two analyzers: %v, %v", |
| 62 | t, a, prev) |
| 63 | } |
| 64 | if t.Kind() != reflect.Ptr { |
| 65 | return fmt.Errorf("%s: fact type %s is not a pointer", a, t) |
| 66 | } |
| 67 | factTypes[t] = a |
| 68 | } |
| 69 | |
| 70 | // recursion |
| 71 | for _, req := range a.Requires { |
| 72 | if err := visit(req); err != nil { |
| 73 | return err |
| 74 | } |
| 75 | } |
| 76 | color[a] = black |
| 77 | } |
| 78 | |
| 79 | if color[a] == grey { |
| 80 | stack := []*Analyzer{a} |
| 81 | inCycle := map[string]bool{} |
| 82 | for len(stack) > 0 { |
| 83 | current := stack[len(stack)-1] |
| 84 | stack = stack[:len(stack)-1] |
| 85 | if color[current] == grey && !inCycle[current.Name] { |
| 86 | inCycle[current.Name] = true |
| 87 | stack = append(stack, current.Requires...) |
| 88 | } |
| 89 | } |
| 90 | return &CycleInRequiresGraphError{AnalyzerNames: inCycle} |
| 91 | } |
| 92 | |
| 93 | return nil |
| 94 | } |
| 95 | for _, a := range analyzers { |
| 96 | if err := visit(a); err != nil { |
| 97 | return err |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | // Reject duplicates among analyzers. |
| 102 | // Precondition: color[a] == black. |
| 103 | // Postcondition: color[a] == finished. |
| 104 | for _, a := range analyzers { |
| 105 | if color[a] == finished { |
| 106 | return fmt.Errorf("duplicate analyzer: %s", a.Name) |
| 107 | } |
| 108 | color[a] = finished |
| 109 | } |
| 110 | |
| 111 | return nil |
| 112 | } |
| 113 | |
| 114 | func validIdent(name string) bool { |
| 115 | for i, r := range name { |
| 116 | if !(r == '_' || unicode.IsLetter(r) || i > 0 && unicode.IsDigit(r)) { |
| 117 | return false |
| 118 | } |
| 119 | } |
| 120 | return name != "" |
| 121 | } |
| 122 | |
| 123 | type CycleInRequiresGraphError struct { |
| 124 | AnalyzerNames map[string]bool |
| 125 | } |
| 126 | |
| 127 | func (e *CycleInRequiresGraphError) Error() string { |
| 128 | var b strings.Builder |
| 129 | b.WriteString("cycle detected involving the following analyzers:") |
| 130 | for n := range e.AnalyzerNames { |
| 131 | b.WriteByte(' ') |
| 132 | b.WriteString(n) |
| 133 | } |
| 134 | return b.String() |
| 135 | } |
| 136 |
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