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package analysis
import (
"flag"
"fmt"
"go/ast"
"go/token"
"go/types"
"reflect"
)
// An Analyzer describes an analysis function and its options.
type Analyzer struct {
// The Name of the analyzer must be a valid Go identifier
// as it may appear in command-line flags, URLs, and so on.
Name string
// Doc is the documentation for the analyzer.
// The part before the first "\n\n" is the title
// (no capital or period, max ~60 letters).
Doc string
// Flags defines any flags accepted by the analyzer.
// The manner in which these flags are exposed to the user
// depends on the driver which runs the analyzer.
Flags flag.FlagSet
// Run applies the analyzer to a package.
// It returns an error if the analyzer failed.
//
// On success, the Run function may return a result
// computed by the Analyzer; its type must match ResultType.
// The driver makes this result available as an input to
// another Analyzer that depends directly on this one (see
// Requires) when it analyzes the same package.
//
// To pass analysis results between packages (and thus
// potentially between address spaces), use Facts, which are
// serializable.
Run func(*Pass) (interface{}, error)
// RunDespiteErrors allows the driver to invoke
// the Run method of this analyzer even on a
// package that contains parse or type errors.
RunDespiteErrors bool
// Requires is a set of analyzers that must run successfully
// before this one on a given package. This analyzer may inspect
// the outputs produced by each analyzer in Requires.
// The graph over analyzers implied by Requires edges must be acyclic.
//
// Requires establishes a "horizontal" dependency between
// analysis passes (different analyzers, same package).
Requires []*Analyzer
// ResultType is the type of the optional result of the Run function.
ResultType reflect.Type
// FactTypes indicates that this analyzer imports and exports
// Facts of the specified concrete types.
// An analyzer that uses facts may assume that its import
// dependencies have been similarly analyzed before it runs.
// Facts must be pointers.
//
// FactTypes establishes a "vertical" dependency between
// analysis passes (same analyzer, different packages).
FactTypes []Fact
}
func (a *Analyzer) String() string { return a.Name }
// A Pass provides information to the Run function that
// applies a specific analyzer to a single Go package.
//
// It forms the interface between the analysis logic and the driver
// program, and has both input and an output components.
//
// As in a compiler, one pass may depend on the result computed by another.
//
// The Run function should not call any of the Pass functions concurrently.
type Pass struct {
Analyzer *Analyzer // the identity of the current analyzer
// syntax and type information
Fset *token.FileSet // file position information
Files []*ast.File // the abstract syntax tree of each file
OtherFiles []string // names of non-Go files of this package
Pkg *types.Package // type information about the package
TypesInfo *types.Info // type information about the syntax trees
TypesSizes types.Sizes // function for computing sizes of types
// Report reports a Diagnostic, a finding about a specific location
// in the analyzed source code such as a potential mistake.
// It may be called by the Run function.
Report func(Diagnostic)
// ResultOf provides the inputs to this analysis pass, which are
// the corresponding results of its prerequisite analyzers.
// The map keys are the elements of Analysis.Required,
// and the type of each corresponding value is the required
// analysis's ResultType.
ResultOf map[*Analyzer]interface{}
// -- facts --
// ImportObjectFact retrieves a fact associated with obj.
// Given a value ptr of type *T, where *T satisfies Fact,
// ImportObjectFact copies the value to *ptr.
//
// ImportObjectFact panics if called after the pass is complete.
// ImportObjectFact is not concurrency-safe.
ImportObjectFact func(obj types.Object, fact Fact) bool
// ImportPackageFact retrieves a fact associated with package pkg,
// which must be this package or one of its dependencies.
// See comments for ImportObjectFact.
ImportPackageFact func(pkg *types.Package, fact Fact) bool
// ExportObjectFact associates a fact of type *T with the obj,
// replacing any previous fact of that type.
//
// ExportObjectFact panics if it is called after the pass is
// complete, or if obj does not belong to the package being analyzed.
// ExportObjectFact is not concurrency-safe.
ExportObjectFact func(obj types.Object, fact Fact)
// ExportPackageFact associates a fact with the current package.
// See comments for ExportObjectFact.
ExportPackageFact func(fact Fact)
// AllPackageFacts returns a new slice containing all package facts in unspecified order.
// WARNING: This is an experimental API and may change in the future.
AllPackageFacts func() []PackageFact
// AllObjectFacts returns a new slice containing all object facts in unspecified order.
// WARNING: This is an experimental API and may change in the future.
AllObjectFacts func() []ObjectFact
/* Further fields may be added in future. */
// For example, suggested or applied refactorings.
}
// PackageFact is a package together with an associated fact.
// WARNING: This is an experimental API and may change in the future.
type PackageFact struct {
Package *types.Package
Fact Fact
}
// ObjectFact is an object together with an associated fact.
// WARNING: This is an experimental API and may change in the future.
type ObjectFact struct {
Object types.Object
Fact Fact
}
// Reportf is a helper function that reports a Diagnostic using the
// specified position and formatted error message.
func (pass *Pass) Reportf(pos token.Pos, format string, args ...interface{}) {
msg := fmt.Sprintf(format, args...)
pass.Report(Diagnostic{Pos: pos, Message: msg})
}
// reportNodef is a helper function that reports a Diagnostic using the
// range denoted by the AST node.
//
// WARNING: This is an experimental API and may change in the future.
func (pass *Pass) reportNodef(node ast.Node, format string, args ...interface{}) {
msg := fmt.Sprintf(format, args...)
pass.Report(Diagnostic{Pos: node.Pos(), End: node.End(), Message: msg})
}
func (pass *Pass) String() string {
return fmt.Sprintf("%s@%s", pass.Analyzer.Name, pass.Pkg.Path())
}
// A Fact is an intermediate fact produced during analysis.
//
// Each fact is associated with a named declaration (a types.Object) or
// with a package as a whole. A single object or package may have
// multiple associated facts, but only one of any particular fact type.
//
// A Fact represents a predicate such as "never returns", but does not
// represent the subject of the predicate such as "function F" or "package P".
//
// Facts may be produced in one analysis pass and consumed by another
// analysis pass even if these are in different address spaces.
// If package P imports Q, all facts about Q produced during
// analysis of that package will be available during later analysis of P.
// Facts are analogous to type export data in a build system:
// just as export data enables separate compilation of several passes,
// facts enable "separate analysis".
//
// Each pass (a, p) starts with the set of facts produced by the
// same analyzer a applied to the packages directly imported by p.
// The analysis may add facts to the set, and they may be exported in turn.
// An analysis's Run function may retrieve facts by calling
// Pass.Import{Object,Package}Fact and update them using
// Pass.Export{Object,Package}Fact.
//
// A fact is logically private to its Analysis. To pass values
// between different analyzers, use the results mechanism;
// see Analyzer.Requires, Analyzer.ResultType, and Pass.ResultOf.
//
// A Fact type must be a pointer.
// Facts are encoded and decoded using encoding/gob.
// A Fact may implement the GobEncoder/GobDecoder interfaces
// to customize its encoding. Fact encoding should not fail.
//
// A Fact should not be modified once exported.
type Fact interface {
AFact() // dummy method to avoid type errors
}
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