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 "flag" 9 "fmt" 10 "go/ast" 11 "go/token" 12 "go/types" 13 "reflect" 14 ) 15 16 // An Analyzer describes an analysis function and its options. 17 type Analyzer struct { 18 // The Name of the analyzer must be a valid Go identifier 19 // as it may appear in command-line flags, URLs, and so on. 20 Name string 21 22 // Doc is the documentation for the analyzer. 23 // The part before the first "\n\n" is the title 24 // (no capital or period, max ~60 letters). 25 Doc string 26 27 // URL holds an optional link to a web page with additional 28 // documentation for this analyzer. 29 URL string 30 31 // Flags defines any flags accepted by the analyzer. 32 // The manner in which these flags are exposed to the user 33 // depends on the driver which runs the analyzer. 34 Flags flag.FlagSet 35 36 // Run applies the analyzer to a package. 37 // It returns an error if the analyzer failed. 38 // 39 // On success, the Run function may return a result 40 // computed by the Analyzer; its type must match ResultType. 41 // The driver makes this result available as an input to 42 // another Analyzer that depends directly on this one (see 43 // Requires) when it analyzes the same package. 44 // 45 // To pass analysis results between packages (and thus 46 // potentially between address spaces), use Facts, which are 47 // serializable. 48 Run func(*Pass) (interface{}, error) 49 50 // RunDespiteErrors allows the driver to invoke 51 // the Run method of this analyzer even on a 52 // package that contains parse or type errors. 53 // The Pass.TypeErrors field may consequently be non-empty. 54 RunDespiteErrors bool 55 56 // Requires is a set of analyzers that must run successfully 57 // before this one on a given package. This analyzer may inspect 58 // the outputs produced by each analyzer in Requires. 59 // The graph over analyzers implied by Requires edges must be acyclic. 60 // 61 // Requires establishes a "horizontal" dependency between 62 // analysis passes (different analyzers, same package). 63 Requires []*Analyzer 64 65 // ResultType is the type of the optional result of the Run function. 66 ResultType reflect.Type 67 68 // FactTypes indicates that this analyzer imports and exports 69 // Facts of the specified concrete types. 70 // An analyzer that uses facts may assume that its import 71 // dependencies have been similarly analyzed before it runs. 72 // Facts must be pointers. 73 // 74 // FactTypes establishes a "vertical" dependency between 75 // analysis passes (same analyzer, different packages). 76 FactTypes []Fact 77 } 78 79 func (a *Analyzer) String() string { return a.Name } 80 81 // A Pass provides information to the Run function that 82 // applies a specific analyzer to a single Go package. 83 // 84 // It forms the interface between the analysis logic and the driver 85 // program, and has both input and an output components. 86 // 87 // As in a compiler, one pass may depend on the result computed by another. 88 // 89 // The Run function should not call any of the Pass functions concurrently. 90 type Pass struct { 91 Analyzer *Analyzer // the identity of the current analyzer 92 93 // syntax and type information 94 Fset *token.FileSet // file position information 95 Files []*ast.File // the abstract syntax tree of each file 96 OtherFiles []string // names of non-Go files of this package 97 IgnoredFiles []string // names of ignored source files in this package 98 Pkg *types.Package // type information about the package 99 TypesInfo *types.Info // type information about the syntax trees 100 TypesSizes types.Sizes // function for computing sizes of types 101 TypeErrors []types.Error // type errors (only if Analyzer.RunDespiteErrors) 102 103 // Report reports a Diagnostic, a finding about a specific location 104 // in the analyzed source code such as a potential mistake. 105 // It may be called by the Run function. 106 Report func(Diagnostic) 107 108 // ResultOf provides the inputs to this analysis pass, which are 109 // the corresponding results of its prerequisite analyzers. 110 // The map keys are the elements of Analysis.Required, 111 // and the type of each corresponding value is the required 112 // analysis's ResultType. 113 ResultOf map[*Analyzer]interface{} 114 115 // -- facts -- 116 117 // ImportObjectFact retrieves a fact associated with obj. 118 // Given a value ptr of type *T, where *T satisfies Fact, 119 // ImportObjectFact copies the value to *ptr. 120 // 121 // ImportObjectFact panics if called after the pass is complete. 122 // ImportObjectFact is not concurrency-safe. 123 ImportObjectFact func(obj types.Object, fact Fact) bool 124 125 // ImportPackageFact retrieves a fact associated with package pkg, 126 // which must be this package or one of its dependencies. 127 // See comments for ImportObjectFact. 128 ImportPackageFact func(pkg *types.Package, fact Fact) bool 129 130 // ExportObjectFact associates a fact of type *T with the obj, 131 // replacing any previous fact of that type. 132 // 133 // ExportObjectFact panics if it is called after the pass is 134 // complete, or if obj does not belong to the package being analyzed. 135 // ExportObjectFact is not concurrency-safe. 136 ExportObjectFact func(obj types.Object, fact Fact) 137 138 // ExportPackageFact associates a fact with the current package. 139 // See comments for ExportObjectFact. 140 ExportPackageFact func(fact Fact) 141 142 // AllPackageFacts returns a new slice containing all package 143 // facts of the analysis's FactTypes in unspecified order. 144 AllPackageFacts func() []PackageFact 145 146 // AllObjectFacts returns a new slice containing all object 147 // facts of the analysis's FactTypes in unspecified order. 148 AllObjectFacts func() []ObjectFact 149 150 /* Further fields may be added in future. */ 151 } 152 153 // PackageFact is a package together with an associated fact. 154 type PackageFact struct { 155 Package *types.Package 156 Fact Fact 157 } 158 159 // ObjectFact is an object together with an associated fact. 160 type ObjectFact struct { 161 Object types.Object 162 Fact Fact 163 } 164 165 // Reportf is a helper function that reports a Diagnostic using the 166 // specified position and formatted error message. 167 func (pass *Pass) Reportf(pos token.Pos, format string, args ...interface{}) { 168 msg := fmt.Sprintf(format, args...) 169 pass.Report(Diagnostic{Pos: pos, Message: msg}) 170 } 171 172 // The Range interface provides a range. It's equivalent to and satisfied by 173 // ast.Node. 174 type Range interface { 175 Pos() token.Pos // position of first character belonging to the node 176 End() token.Pos // position of first character immediately after the node 177 } 178 179 // ReportRangef is a helper function that reports a Diagnostic using the 180 // range provided. ast.Node values can be passed in as the range because 181 // they satisfy the Range interface. 182 func (pass *Pass) ReportRangef(rng Range, format string, args ...interface{}) { 183 msg := fmt.Sprintf(format, args...) 184 pass.Report(Diagnostic{Pos: rng.Pos(), End: rng.End(), Message: msg}) 185 } 186 187 func (pass *Pass) String() string { 188 return fmt.Sprintf("%s@%s", pass.Analyzer.Name, pass.Pkg.Path()) 189 } 190 191 // A Fact is an intermediate fact produced during analysis. 192 // 193 // Each fact is associated with a named declaration (a types.Object) or 194 // with a package as a whole. A single object or package may have 195 // multiple associated facts, but only one of any particular fact type. 196 // 197 // A Fact represents a predicate such as "never returns", but does not 198 // represent the subject of the predicate such as "function F" or "package P". 199 // 200 // Facts may be produced in one analysis pass and consumed by another 201 // analysis pass even if these are in different address spaces. 202 // If package P imports Q, all facts about Q produced during 203 // analysis of that package will be available during later analysis of P. 204 // Facts are analogous to type export data in a build system: 205 // just as export data enables separate compilation of several passes, 206 // facts enable "separate analysis". 207 // 208 // Each pass (a, p) starts with the set of facts produced by the 209 // same analyzer a applied to the packages directly imported by p. 210 // The analysis may add facts to the set, and they may be exported in turn. 211 // An analysis's Run function may retrieve facts by calling 212 // Pass.Import{Object,Package}Fact and update them using 213 // Pass.Export{Object,Package}Fact. 214 // 215 // A fact is logically private to its Analysis. To pass values 216 // between different analyzers, use the results mechanism; 217 // see Analyzer.Requires, Analyzer.ResultType, and Pass.ResultOf. 218 // 219 // A Fact type must be a pointer. 220 // Facts are encoded and decoded using encoding/gob. 221 // A Fact may implement the GobEncoder/GobDecoder interfaces 222 // to customize its encoding. Fact encoding should not fail. 223 // 224 // A Fact should not be modified once exported. 225 type Fact interface { 226 AFact() // dummy method to avoid type errors 227 } 228