diff options
Diffstat (limited to 'vendor/github.com/google/go-cmp/cmp/options.go')
| -rw-r--r-- | vendor/github.com/google/go-cmp/cmp/options.go | 552 |
1 files changed, 552 insertions, 0 deletions
diff --git a/vendor/github.com/google/go-cmp/cmp/options.go b/vendor/github.com/google/go-cmp/cmp/options.go new file mode 100644 index 000000000..e57b9eb53 --- /dev/null +++ b/vendor/github.com/google/go-cmp/cmp/options.go @@ -0,0 +1,552 @@ +// Copyright 2017, The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package cmp + +import ( + "fmt" + "reflect" + "regexp" + "strings" + + "github.com/google/go-cmp/cmp/internal/function" +) + +// Option configures for specific behavior of Equal and Diff. In particular, +// the fundamental Option functions (Ignore, Transformer, and Comparer), +// configure how equality is determined. +// +// The fundamental options may be composed with filters (FilterPath and +// FilterValues) to control the scope over which they are applied. +// +// The cmp/cmpopts package provides helper functions for creating options that +// may be used with Equal and Diff. +type Option interface { + // filter applies all filters and returns the option that remains. + // Each option may only read s.curPath and call s.callTTBFunc. + // + // An Options is returned only if multiple comparers or transformers + // can apply simultaneously and will only contain values of those types + // or sub-Options containing values of those types. + filter(s *state, t reflect.Type, vx, vy reflect.Value) applicableOption +} + +// applicableOption represents the following types: +// Fundamental: ignore | validator | *comparer | *transformer +// Grouping: Options +type applicableOption interface { + Option + + // apply executes the option, which may mutate s or panic. + apply(s *state, vx, vy reflect.Value) +} + +// coreOption represents the following types: +// Fundamental: ignore | validator | *comparer | *transformer +// Filters: *pathFilter | *valuesFilter +type coreOption interface { + Option + isCore() +} + +type core struct{} + +func (core) isCore() {} + +// Options is a list of Option values that also satisfies the Option interface. +// Helper comparison packages may return an Options value when packing multiple +// Option values into a single Option. When this package processes an Options, +// it will be implicitly expanded into a flat list. +// +// Applying a filter on an Options is equivalent to applying that same filter +// on all individual options held within. +type Options []Option + +func (opts Options) filter(s *state, t reflect.Type, vx, vy reflect.Value) (out applicableOption) { + for _, opt := range opts { + switch opt := opt.filter(s, t, vx, vy); opt.(type) { + case ignore: + return ignore{} // Only ignore can short-circuit evaluation + case validator: + out = validator{} // Takes precedence over comparer or transformer + case *comparer, *transformer, Options: + switch out.(type) { + case nil: + out = opt + case validator: + // Keep validator + case *comparer, *transformer, Options: + out = Options{out, opt} // Conflicting comparers or transformers + } + } + } + return out +} + +func (opts Options) apply(s *state, _, _ reflect.Value) { + const warning = "ambiguous set of applicable options" + const help = "consider using filters to ensure at most one Comparer or Transformer may apply" + var ss []string + for _, opt := range flattenOptions(nil, opts) { + ss = append(ss, fmt.Sprint(opt)) + } + set := strings.Join(ss, "\n\t") + panic(fmt.Sprintf("%s at %#v:\n\t%s\n%s", warning, s.curPath, set, help)) +} + +func (opts Options) String() string { + var ss []string + for _, opt := range opts { + ss = append(ss, fmt.Sprint(opt)) + } + return fmt.Sprintf("Options{%s}", strings.Join(ss, ", ")) +} + +// FilterPath returns a new Option where opt is only evaluated if filter f +// returns true for the current Path in the value tree. +// +// This filter is called even if a slice element or map entry is missing and +// provides an opportunity to ignore such cases. The filter function must be +// symmetric such that the filter result is identical regardless of whether the +// missing value is from x or y. +// +// The option passed in may be an Ignore, Transformer, Comparer, Options, or +// a previously filtered Option. +func FilterPath(f func(Path) bool, opt Option) Option { + if f == nil { + panic("invalid path filter function") + } + if opt := normalizeOption(opt); opt != nil { + return &pathFilter{fnc: f, opt: opt} + } + return nil +} + +type pathFilter struct { + core + fnc func(Path) bool + opt Option +} + +func (f pathFilter) filter(s *state, t reflect.Type, vx, vy reflect.Value) applicableOption { + if f.fnc(s.curPath) { + return f.opt.filter(s, t, vx, vy) + } + return nil +} + +func (f pathFilter) String() string { + return fmt.Sprintf("FilterPath(%s, %v)", function.NameOf(reflect.ValueOf(f.fnc)), f.opt) +} + +// FilterValues returns a new Option where opt is only evaluated if filter f, +// which is a function of the form "func(T, T) bool", returns true for the +// current pair of values being compared. If either value is invalid or +// the type of the values is not assignable to T, then this filter implicitly +// returns false. +// +// The filter function must be +// symmetric (i.e., agnostic to the order of the inputs) and +// deterministic (i.e., produces the same result when given the same inputs). +// If T is an interface, it is possible that f is called with two values with +// different concrete types that both implement T. +// +// The option passed in may be an Ignore, Transformer, Comparer, Options, or +// a previously filtered Option. +func FilterValues(f interface{}, opt Option) Option { + v := reflect.ValueOf(f) + if !function.IsType(v.Type(), function.ValueFilter) || v.IsNil() { + panic(fmt.Sprintf("invalid values filter function: %T", f)) + } + if opt := normalizeOption(opt); opt != nil { + vf := &valuesFilter{fnc: v, opt: opt} + if ti := v.Type().In(0); ti.Kind() != reflect.Interface || ti.NumMethod() > 0 { + vf.typ = ti + } + return vf + } + return nil +} + +type valuesFilter struct { + core + typ reflect.Type // T + fnc reflect.Value // func(T, T) bool + opt Option +} + +func (f valuesFilter) filter(s *state, t reflect.Type, vx, vy reflect.Value) applicableOption { + if !vx.IsValid() || !vx.CanInterface() || !vy.IsValid() || !vy.CanInterface() { + return nil + } + if (f.typ == nil || t.AssignableTo(f.typ)) && s.callTTBFunc(f.fnc, vx, vy) { + return f.opt.filter(s, t, vx, vy) + } + return nil +} + +func (f valuesFilter) String() string { + return fmt.Sprintf("FilterValues(%s, %v)", function.NameOf(f.fnc), f.opt) +} + +// Ignore is an Option that causes all comparisons to be ignored. +// This value is intended to be combined with FilterPath or FilterValues. +// It is an error to pass an unfiltered Ignore option to Equal. +func Ignore() Option { return ignore{} } + +type ignore struct{ core } + +func (ignore) isFiltered() bool { return false } +func (ignore) filter(_ *state, _ reflect.Type, _, _ reflect.Value) applicableOption { return ignore{} } +func (ignore) apply(s *state, _, _ reflect.Value) { s.report(true, reportByIgnore) } +func (ignore) String() string { return "Ignore()" } + +// validator is a sentinel Option type to indicate that some options could not +// be evaluated due to unexported fields, missing slice elements, or +// missing map entries. Both values are validator only for unexported fields. +type validator struct{ core } + +func (validator) filter(_ *state, _ reflect.Type, vx, vy reflect.Value) applicableOption { + if !vx.IsValid() || !vy.IsValid() { + return validator{} + } + if !vx.CanInterface() || !vy.CanInterface() { + return validator{} + } + return nil +} +func (validator) apply(s *state, vx, vy reflect.Value) { + // Implies missing slice element or map entry. + if !vx.IsValid() || !vy.IsValid() { + s.report(vx.IsValid() == vy.IsValid(), 0) + return + } + + // Unable to Interface implies unexported field without visibility access. + if !vx.CanInterface() || !vy.CanInterface() { + help := "consider using a custom Comparer; if you control the implementation of type, you can also consider using an Exporter, AllowUnexported, or cmpopts.IgnoreUnexported" + var name string + if t := s.curPath.Index(-2).Type(); t.Name() != "" { + // Named type with unexported fields. + name = fmt.Sprintf("%q.%v", t.PkgPath(), t.Name()) // e.g., "path/to/package".MyType + if _, ok := reflect.New(t).Interface().(error); ok { + help = "consider using cmpopts.EquateErrors to compare error values" + } + } else { + // Unnamed type with unexported fields. Derive PkgPath from field. + var pkgPath string + for i := 0; i < t.NumField() && pkgPath == ""; i++ { + pkgPath = t.Field(i).PkgPath + } + name = fmt.Sprintf("%q.(%v)", pkgPath, t.String()) // e.g., "path/to/package".(struct { a int }) + } + panic(fmt.Sprintf("cannot handle unexported field at %#v:\n\t%v\n%s", s.curPath, name, help)) + } + + panic("not reachable") +} + +// identRx represents a valid identifier according to the Go specification. +const identRx = `[_\p{L}][_\p{L}\p{N}]*` + +var identsRx = regexp.MustCompile(`^` + identRx + `(\.` + identRx + `)*$`) + +// Transformer returns an Option that applies a transformation function that +// converts values of a certain type into that of another. +// +// The transformer f must be a function "func(T) R" that converts values of +// type T to those of type R and is implicitly filtered to input values +// assignable to T. The transformer must not mutate T in any way. +// +// To help prevent some cases of infinite recursive cycles applying the +// same transform to the output of itself (e.g., in the case where the +// input and output types are the same), an implicit filter is added such that +// a transformer is applicable only if that exact transformer is not already +// in the tail of the Path since the last non-Transform step. +// For situations where the implicit filter is still insufficient, +// consider using cmpopts.AcyclicTransformer, which adds a filter +// to prevent the transformer from being recursively applied upon itself. +// +// The name is a user provided label that is used as the Transform.Name in the +// transformation PathStep (and eventually shown in the Diff output). +// The name must be a valid identifier or qualified identifier in Go syntax. +// If empty, an arbitrary name is used. +func Transformer(name string, f interface{}) Option { + v := reflect.ValueOf(f) + if !function.IsType(v.Type(), function.Transformer) || v.IsNil() { + panic(fmt.Sprintf("invalid transformer function: %T", f)) + } + if name == "" { + name = function.NameOf(v) + if !identsRx.MatchString(name) { + name = "λ" // Lambda-symbol as placeholder name + } + } else if !identsRx.MatchString(name) { + panic(fmt.Sprintf("invalid name: %q", name)) + } + tr := &transformer{name: name, fnc: reflect.ValueOf(f)} + if ti := v.Type().In(0); ti.Kind() != reflect.Interface || ti.NumMethod() > 0 { + tr.typ = ti + } + return tr +} + +type transformer struct { + core + name string + typ reflect.Type // T + fnc reflect.Value // func(T) R +} + +func (tr *transformer) isFiltered() bool { return tr.typ != nil } + +func (tr *transformer) filter(s *state, t reflect.Type, _, _ reflect.Value) applicableOption { + for i := len(s.curPath) - 1; i >= 0; i-- { + if t, ok := s.curPath[i].(Transform); !ok { + break // Hit most recent non-Transform step + } else if tr == t.trans { + return nil // Cannot directly use same Transform + } + } + if tr.typ == nil || t.AssignableTo(tr.typ) { + return tr + } + return nil +} + +func (tr *transformer) apply(s *state, vx, vy reflect.Value) { + step := Transform{&transform{pathStep{typ: tr.fnc.Type().Out(0)}, tr}} + vvx := s.callTRFunc(tr.fnc, vx, step) + vvy := s.callTRFunc(tr.fnc, vy, step) + step.vx, step.vy = vvx, vvy + s.compareAny(step) +} + +func (tr transformer) String() string { + return fmt.Sprintf("Transformer(%s, %s)", tr.name, function.NameOf(tr.fnc)) +} + +// Comparer returns an Option that determines whether two values are equal +// to each other. +// +// The comparer f must be a function "func(T, T) bool" and is implicitly +// filtered to input values assignable to T. If T is an interface, it is +// possible that f is called with two values of different concrete types that +// both implement T. +// +// The equality function must be: +// • Symmetric: equal(x, y) == equal(y, x) +// • Deterministic: equal(x, y) == equal(x, y) +// • Pure: equal(x, y) does not modify x or y +func Comparer(f interface{}) Option { + v := reflect.ValueOf(f) + if !function.IsType(v.Type(), function.Equal) || v.IsNil() { + panic(fmt.Sprintf("invalid comparer function: %T", f)) + } + cm := &comparer{fnc: v} + if ti := v.Type().In(0); ti.Kind() != reflect.Interface || ti.NumMethod() > 0 { + cm.typ = ti + } + return cm +} + +type comparer struct { + core + typ reflect.Type // T + fnc reflect.Value // func(T, T) bool +} + +func (cm *comparer) isFiltered() bool { return cm.typ != nil } + +func (cm *comparer) filter(_ *state, t reflect.Type, _, _ reflect.Value) applicableOption { + if cm.typ == nil || t.AssignableTo(cm.typ) { + return cm + } + return nil +} + +func (cm *comparer) apply(s *state, vx, vy reflect.Value) { + eq := s.callTTBFunc(cm.fnc, vx, vy) + s.report(eq, reportByFunc) +} + +func (cm comparer) String() string { + return fmt.Sprintf("Comparer(%s)", function.NameOf(cm.fnc)) +} + +// Exporter returns an Option that specifies whether Equal is allowed to +// introspect into the unexported fields of certain struct types. +// +// Users of this option must understand that comparing on unexported fields +// from external packages is not safe since changes in the internal +// implementation of some external package may cause the result of Equal +// to unexpectedly change. However, it may be valid to use this option on types +// defined in an internal package where the semantic meaning of an unexported +// field is in the control of the user. +// +// In many cases, a custom Comparer should be used instead that defines +// equality as a function of the public API of a type rather than the underlying +// unexported implementation. +// +// For example, the reflect.Type documentation defines equality to be determined +// by the == operator on the interface (essentially performing a shallow pointer +// comparison) and most attempts to compare *regexp.Regexp types are interested +// in only checking that the regular expression strings are equal. +// Both of these are accomplished using Comparers: +// +// Comparer(func(x, y reflect.Type) bool { return x == y }) +// Comparer(func(x, y *regexp.Regexp) bool { return x.String() == y.String() }) +// +// In other cases, the cmpopts.IgnoreUnexported option can be used to ignore +// all unexported fields on specified struct types. +func Exporter(f func(reflect.Type) bool) Option { + if !supportExporters { + panic("Exporter is not supported on purego builds") + } + return exporter(f) +} + +type exporter func(reflect.Type) bool + +func (exporter) filter(_ *state, _ reflect.Type, _, _ reflect.Value) applicableOption { + panic("not implemented") +} + +// AllowUnexported returns an Options that allows Equal to forcibly introspect +// unexported fields of the specified struct types. +// +// See Exporter for the proper use of this option. +func AllowUnexported(types ...interface{}) Option { + m := make(map[reflect.Type]bool) + for _, typ := range types { + t := reflect.TypeOf(typ) + if t.Kind() != reflect.Struct { + panic(fmt.Sprintf("invalid struct type: %T", typ)) + } + m[t] = true + } + return exporter(func(t reflect.Type) bool { return m[t] }) +} + +// Result represents the comparison result for a single node and +// is provided by cmp when calling Result (see Reporter). +type Result struct { + _ [0]func() // Make Result incomparable + flags resultFlags +} + +// Equal reports whether the node was determined to be equal or not. +// As a special case, ignored nodes are considered equal. +func (r Result) Equal() bool { + return r.flags&(reportEqual|reportByIgnore) != 0 +} + +// ByIgnore reports whether the node is equal because it was ignored. +// This never reports true if Equal reports false. +func (r Result) ByIgnore() bool { + return r.flags&reportByIgnore != 0 +} + +// ByMethod reports whether the Equal method determined equality. +func (r Result) ByMethod() bool { + return r.flags&reportByMethod != 0 +} + +// ByFunc reports whether a Comparer function determined equality. +func (r Result) ByFunc() bool { + return r.flags&reportByFunc != 0 +} + +// ByCycle reports whether a reference cycle was detected. +func (r Result) ByCycle() bool { + return r.flags&reportByCycle != 0 +} + +type resultFlags uint + +const ( + _ resultFlags = (1 << iota) / 2 + + reportEqual + reportUnequal + reportByIgnore + reportByMethod + reportByFunc + reportByCycle +) + +// Reporter is an Option that can be passed to Equal. When Equal traverses +// the value trees, it calls PushStep as it descends into each node in the +// tree and PopStep as it ascend out of the node. The leaves of the tree are +// either compared (determined to be equal or not equal) or ignored and reported +// as such by calling the Report method. +func Reporter(r interface { + // PushStep is called when a tree-traversal operation is performed. + // The PathStep itself is only valid until the step is popped. + // The PathStep.Values are valid for the duration of the entire traversal + // and must not be mutated. + // + // Equal always calls PushStep at the start to provide an operation-less + // PathStep used to report the root values. + // + // Within a slice, the exact set of inserted, removed, or modified elements + // is unspecified and may change in future implementations. + // The entries of a map are iterated through in an unspecified order. + PushStep(PathStep) + + // Report is called exactly once on leaf nodes to report whether the + // comparison identified the node as equal, unequal, or ignored. + // A leaf node is one that is immediately preceded by and followed by + // a pair of PushStep and PopStep calls. + Report(Result) + + // PopStep ascends back up the value tree. + // There is always a matching pop call for every push call. + PopStep() +}) Option { + return reporter{r} +} + +type reporter struct{ reporterIface } +type reporterIface interface { + PushStep(PathStep) + Report(Result) + PopStep() +} + +func (reporter) filter(_ *state, _ reflect.Type, _, _ reflect.Value) applicableOption { + panic("not implemented") +} + +// normalizeOption normalizes the input options such that all Options groups +// are flattened and groups with a single element are reduced to that element. +// Only coreOptions and Options containing coreOptions are allowed. +func normalizeOption(src Option) Option { + switch opts := flattenOptions(nil, Options{src}); len(opts) { + case 0: + return nil + case 1: + return opts[0] + default: + return opts + } +} + +// flattenOptions copies all options in src to dst as a flat list. +// Only coreOptions and Options containing coreOptions are allowed. +func flattenOptions(dst, src Options) Options { + for _, opt := range src { + switch opt := opt.(type) { + case nil: + continue + case Options: + dst = flattenOptions(dst, opt) + case coreOption: + dst = append(dst, opt) + default: + panic(fmt.Sprintf("invalid option type: %T", opt)) + } + } + return dst +} |