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Diffstat (limited to 'vendor/github.com/google/go-cmp/cmp/compare.go')
| -rw-r--r-- | vendor/github.com/google/go-cmp/cmp/compare.go | 682 |
1 files changed, 682 insertions, 0 deletions
diff --git a/vendor/github.com/google/go-cmp/cmp/compare.go b/vendor/github.com/google/go-cmp/cmp/compare.go new file mode 100644 index 000000000..86d0903b8 --- /dev/null +++ b/vendor/github.com/google/go-cmp/cmp/compare.go @@ -0,0 +1,682 @@ +// 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 determines equality of values. +// +// This package is intended to be a more powerful and safer alternative to +// reflect.DeepEqual for comparing whether two values are semantically equal. +// It is intended to only be used in tests, as performance is not a goal and +// it may panic if it cannot compare the values. Its propensity towards +// panicking means that its unsuitable for production environments where a +// spurious panic may be fatal. +// +// The primary features of cmp are: +// +// • When the default behavior of equality does not suit the needs of the test, +// custom equality functions can override the equality operation. +// For example, an equality function may report floats as equal so long as they +// are within some tolerance of each other. +// +// • Types that have an Equal method may use that method to determine equality. +// This allows package authors to determine the equality operation for the types +// that they define. +// +// • If no custom equality functions are used and no Equal method is defined, +// equality is determined by recursively comparing the primitive kinds on both +// values, much like reflect.DeepEqual. Unlike reflect.DeepEqual, unexported +// fields are not compared by default; they result in panics unless suppressed +// by using an Ignore option (see cmpopts.IgnoreUnexported) or explicitly +// compared using the Exporter option. +package cmp + +import ( + "fmt" + "reflect" + "strings" + + "github.com/google/go-cmp/cmp/internal/diff" + "github.com/google/go-cmp/cmp/internal/flags" + "github.com/google/go-cmp/cmp/internal/function" + "github.com/google/go-cmp/cmp/internal/value" +) + +// Equal reports whether x and y are equal by recursively applying the +// following rules in the given order to x and y and all of their sub-values: +// +// • Let S be the set of all Ignore, Transformer, and Comparer options that +// remain after applying all path filters, value filters, and type filters. +// If at least one Ignore exists in S, then the comparison is ignored. +// If the number of Transformer and Comparer options in S is greater than one, +// then Equal panics because it is ambiguous which option to use. +// If S contains a single Transformer, then use that to transform the current +// values and recursively call Equal on the output values. +// If S contains a single Comparer, then use that to compare the current values. +// Otherwise, evaluation proceeds to the next rule. +// +// • If the values have an Equal method of the form "(T) Equal(T) bool" or +// "(T) Equal(I) bool" where T is assignable to I, then use the result of +// x.Equal(y) even if x or y is nil. Otherwise, no such method exists and +// evaluation proceeds to the next rule. +// +// • Lastly, try to compare x and y based on their basic kinds. +// Simple kinds like booleans, integers, floats, complex numbers, strings, and +// channels are compared using the equivalent of the == operator in Go. +// Functions are only equal if they are both nil, otherwise they are unequal. +// +// Structs are equal if recursively calling Equal on all fields report equal. +// If a struct contains unexported fields, Equal panics unless an Ignore option +// (e.g., cmpopts.IgnoreUnexported) ignores that field or the Exporter option +// explicitly permits comparing the unexported field. +// +// Slices are equal if they are both nil or both non-nil, where recursively +// calling Equal on all non-ignored slice or array elements report equal. +// Empty non-nil slices and nil slices are not equal; to equate empty slices, +// consider using cmpopts.EquateEmpty. +// +// Maps are equal if they are both nil or both non-nil, where recursively +// calling Equal on all non-ignored map entries report equal. +// Map keys are equal according to the == operator. +// To use custom comparisons for map keys, consider using cmpopts.SortMaps. +// Empty non-nil maps and nil maps are not equal; to equate empty maps, +// consider using cmpopts.EquateEmpty. +// +// Pointers and interfaces are equal if they are both nil or both non-nil, +// where they have the same underlying concrete type and recursively +// calling Equal on the underlying values reports equal. +// +// Before recursing into a pointer, slice element, or map, the current path +// is checked to detect whether the address has already been visited. +// If there is a cycle, then the pointed at values are considered equal +// only if both addresses were previously visited in the same path step. +func Equal(x, y interface{}, opts ...Option) bool { + s := newState(opts) + s.compareAny(rootStep(x, y)) + return s.result.Equal() +} + +// Diff returns a human-readable report of the differences between two values: +// y - x. It returns an empty string if and only if Equal returns true for the +// same input values and options. +// +// The output is displayed as a literal in pseudo-Go syntax. +// At the start of each line, a "-" prefix indicates an element removed from x, +// a "+" prefix to indicates an element added from y, and the lack of a prefix +// indicates an element common to both x and y. If possible, the output +// uses fmt.Stringer.String or error.Error methods to produce more humanly +// readable outputs. In such cases, the string is prefixed with either an +// 's' or 'e' character, respectively, to indicate that the method was called. +// +// Do not depend on this output being stable. If you need the ability to +// programmatically interpret the difference, consider using a custom Reporter. +func Diff(x, y interface{}, opts ...Option) string { + s := newState(opts) + + // Optimization: If there are no other reporters, we can optimize for the + // common case where the result is equal (and thus no reported difference). + // This avoids the expensive construction of a difference tree. + if len(s.reporters) == 0 { + s.compareAny(rootStep(x, y)) + if s.result.Equal() { + return "" + } + s.result = diff.Result{} // Reset results + } + + r := new(defaultReporter) + s.reporters = append(s.reporters, reporter{r}) + s.compareAny(rootStep(x, y)) + d := r.String() + if (d == "") != s.result.Equal() { + panic("inconsistent difference and equality results") + } + return d +} + +// rootStep constructs the first path step. If x and y have differing types, +// then they are stored within an empty interface type. +func rootStep(x, y interface{}) PathStep { + vx := reflect.ValueOf(x) + vy := reflect.ValueOf(y) + + // If the inputs are different types, auto-wrap them in an empty interface + // so that they have the same parent type. + var t reflect.Type + if !vx.IsValid() || !vy.IsValid() || vx.Type() != vy.Type() { + t = reflect.TypeOf((*interface{})(nil)).Elem() + if vx.IsValid() { + vvx := reflect.New(t).Elem() + vvx.Set(vx) + vx = vvx + } + if vy.IsValid() { + vvy := reflect.New(t).Elem() + vvy.Set(vy) + vy = vvy + } + } else { + t = vx.Type() + } + + return &pathStep{t, vx, vy} +} + +type state struct { + // These fields represent the "comparison state". + // Calling statelessCompare must not result in observable changes to these. + result diff.Result // The current result of comparison + curPath Path // The current path in the value tree + curPtrs pointerPath // The current set of visited pointers + reporters []reporter // Optional reporters + + // recChecker checks for infinite cycles applying the same set of + // transformers upon the output of itself. + recChecker recChecker + + // dynChecker triggers pseudo-random checks for option correctness. + // It is safe for statelessCompare to mutate this value. + dynChecker dynChecker + + // These fields, once set by processOption, will not change. + exporters []exporter // List of exporters for structs with unexported fields + opts Options // List of all fundamental and filter options +} + +func newState(opts []Option) *state { + // Always ensure a validator option exists to validate the inputs. + s := &state{opts: Options{validator{}}} + s.curPtrs.Init() + s.processOption(Options(opts)) + return s +} + +func (s *state) processOption(opt Option) { + switch opt := opt.(type) { + case nil: + case Options: + for _, o := range opt { + s.processOption(o) + } + case coreOption: + type filtered interface { + isFiltered() bool + } + if fopt, ok := opt.(filtered); ok && !fopt.isFiltered() { + panic(fmt.Sprintf("cannot use an unfiltered option: %v", opt)) + } + s.opts = append(s.opts, opt) + case exporter: + s.exporters = append(s.exporters, opt) + case reporter: + s.reporters = append(s.reporters, opt) + default: + panic(fmt.Sprintf("unknown option %T", opt)) + } +} + +// statelessCompare compares two values and returns the result. +// This function is stateless in that it does not alter the current result, +// or output to any registered reporters. +func (s *state) statelessCompare(step PathStep) diff.Result { + // We do not save and restore curPath and curPtrs because all of the + // compareX methods should properly push and pop from them. + // It is an implementation bug if the contents of the paths differ from + // when calling this function to when returning from it. + + oldResult, oldReporters := s.result, s.reporters + s.result = diff.Result{} // Reset result + s.reporters = nil // Remove reporters to avoid spurious printouts + s.compareAny(step) + res := s.result + s.result, s.reporters = oldResult, oldReporters + return res +} + +func (s *state) compareAny(step PathStep) { + // Update the path stack. + s.curPath.push(step) + defer s.curPath.pop() + for _, r := range s.reporters { + r.PushStep(step) + defer r.PopStep() + } + s.recChecker.Check(s.curPath) + + // Cycle-detection for slice elements (see NOTE in compareSlice). + t := step.Type() + vx, vy := step.Values() + if si, ok := step.(SliceIndex); ok && si.isSlice && vx.IsValid() && vy.IsValid() { + px, py := vx.Addr(), vy.Addr() + if eq, visited := s.curPtrs.Push(px, py); visited { + s.report(eq, reportByCycle) + return + } + defer s.curPtrs.Pop(px, py) + } + + // Rule 1: Check whether an option applies on this node in the value tree. + if s.tryOptions(t, vx, vy) { + return + } + + // Rule 2: Check whether the type has a valid Equal method. + if s.tryMethod(t, vx, vy) { + return + } + + // Rule 3: Compare based on the underlying kind. + switch t.Kind() { + case reflect.Bool: + s.report(vx.Bool() == vy.Bool(), 0) + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + s.report(vx.Int() == vy.Int(), 0) + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + s.report(vx.Uint() == vy.Uint(), 0) + case reflect.Float32, reflect.Float64: + s.report(vx.Float() == vy.Float(), 0) + case reflect.Complex64, reflect.Complex128: + s.report(vx.Complex() == vy.Complex(), 0) + case reflect.String: + s.report(vx.String() == vy.String(), 0) + case reflect.Chan, reflect.UnsafePointer: + s.report(vx.Pointer() == vy.Pointer(), 0) + case reflect.Func: + s.report(vx.IsNil() && vy.IsNil(), 0) + case reflect.Struct: + s.compareStruct(t, vx, vy) + case reflect.Slice, reflect.Array: + s.compareSlice(t, vx, vy) + case reflect.Map: + s.compareMap(t, vx, vy) + case reflect.Ptr: + s.comparePtr(t, vx, vy) + case reflect.Interface: + s.compareInterface(t, vx, vy) + default: + panic(fmt.Sprintf("%v kind not handled", t.Kind())) + } +} + +func (s *state) tryOptions(t reflect.Type, vx, vy reflect.Value) bool { + // Evaluate all filters and apply the remaining options. + if opt := s.opts.filter(s, t, vx, vy); opt != nil { + opt.apply(s, vx, vy) + return true + } + return false +} + +func (s *state) tryMethod(t reflect.Type, vx, vy reflect.Value) bool { + // Check if this type even has an Equal method. + m, ok := t.MethodByName("Equal") + if !ok || !function.IsType(m.Type, function.EqualAssignable) { + return false + } + + eq := s.callTTBFunc(m.Func, vx, vy) + s.report(eq, reportByMethod) + return true +} + +func (s *state) callTRFunc(f, v reflect.Value, step Transform) reflect.Value { + v = sanitizeValue(v, f.Type().In(0)) + if !s.dynChecker.Next() { + return f.Call([]reflect.Value{v})[0] + } + + // Run the function twice and ensure that we get the same results back. + // We run in goroutines so that the race detector (if enabled) can detect + // unsafe mutations to the input. + c := make(chan reflect.Value) + go detectRaces(c, f, v) + got := <-c + want := f.Call([]reflect.Value{v})[0] + if step.vx, step.vy = got, want; !s.statelessCompare(step).Equal() { + // To avoid false-positives with non-reflexive equality operations, + // we sanity check whether a value is equal to itself. + if step.vx, step.vy = want, want; !s.statelessCompare(step).Equal() { + return want + } + panic(fmt.Sprintf("non-deterministic function detected: %s", function.NameOf(f))) + } + return want +} + +func (s *state) callTTBFunc(f, x, y reflect.Value) bool { + x = sanitizeValue(x, f.Type().In(0)) + y = sanitizeValue(y, f.Type().In(1)) + if !s.dynChecker.Next() { + return f.Call([]reflect.Value{x, y})[0].Bool() + } + + // Swapping the input arguments is sufficient to check that + // f is symmetric and deterministic. + // We run in goroutines so that the race detector (if enabled) can detect + // unsafe mutations to the input. + c := make(chan reflect.Value) + go detectRaces(c, f, y, x) + got := <-c + want := f.Call([]reflect.Value{x, y})[0].Bool() + if !got.IsValid() || got.Bool() != want { + panic(fmt.Sprintf("non-deterministic or non-symmetric function detected: %s", function.NameOf(f))) + } + return want +} + +func detectRaces(c chan<- reflect.Value, f reflect.Value, vs ...reflect.Value) { + var ret reflect.Value + defer func() { + recover() // Ignore panics, let the other call to f panic instead + c <- ret + }() + ret = f.Call(vs)[0] +} + +// sanitizeValue converts nil interfaces of type T to those of type R, +// assuming that T is assignable to R. +// Otherwise, it returns the input value as is. +func sanitizeValue(v reflect.Value, t reflect.Type) reflect.Value { + // TODO(≥go1.10): Workaround for reflect bug (https://golang.org/issue/22143). + if !flags.AtLeastGo110 { + if v.Kind() == reflect.Interface && v.IsNil() && v.Type() != t { + return reflect.New(t).Elem() + } + } + return v +} + +func (s *state) compareStruct(t reflect.Type, vx, vy reflect.Value) { + var addr bool + var vax, vay reflect.Value // Addressable versions of vx and vy + + var mayForce, mayForceInit bool + step := StructField{&structField{}} + for i := 0; i < t.NumField(); i++ { + step.typ = t.Field(i).Type + step.vx = vx.Field(i) + step.vy = vy.Field(i) + step.name = t.Field(i).Name + step.idx = i + step.unexported = !isExported(step.name) + if step.unexported { + if step.name == "_" { + continue + } + // Defer checking of unexported fields until later to give an + // Ignore a chance to ignore the field. + if !vax.IsValid() || !vay.IsValid() { + // For retrieveUnexportedField to work, the parent struct must + // be addressable. Create a new copy of the values if + // necessary to make them addressable. + addr = vx.CanAddr() || vy.CanAddr() + vax = makeAddressable(vx) + vay = makeAddressable(vy) + } + if !mayForceInit { + for _, xf := range s.exporters { + mayForce = mayForce || xf(t) + } + mayForceInit = true + } + step.mayForce = mayForce + step.paddr = addr + step.pvx = vax + step.pvy = vay + step.field = t.Field(i) + } + s.compareAny(step) + } +} + +func (s *state) compareSlice(t reflect.Type, vx, vy reflect.Value) { + isSlice := t.Kind() == reflect.Slice + if isSlice && (vx.IsNil() || vy.IsNil()) { + s.report(vx.IsNil() && vy.IsNil(), 0) + return + } + + // NOTE: It is incorrect to call curPtrs.Push on the slice header pointer + // since slices represents a list of pointers, rather than a single pointer. + // The pointer checking logic must be handled on a per-element basis + // in compareAny. + // + // A slice header (see reflect.SliceHeader) in Go is a tuple of a starting + // pointer P, a length N, and a capacity C. Supposing each slice element has + // a memory size of M, then the slice is equivalent to the list of pointers: + // [P+i*M for i in range(N)] + // + // For example, v[:0] and v[:1] are slices with the same starting pointer, + // but they are clearly different values. Using the slice pointer alone + // violates the assumption that equal pointers implies equal values. + + step := SliceIndex{&sliceIndex{pathStep: pathStep{typ: t.Elem()}, isSlice: isSlice}} + withIndexes := func(ix, iy int) SliceIndex { + if ix >= 0 { + step.vx, step.xkey = vx.Index(ix), ix + } else { + step.vx, step.xkey = reflect.Value{}, -1 + } + if iy >= 0 { + step.vy, step.ykey = vy.Index(iy), iy + } else { + step.vy, step.ykey = reflect.Value{}, -1 + } + return step + } + + // Ignore options are able to ignore missing elements in a slice. + // However, detecting these reliably requires an optimal differencing + // algorithm, for which diff.Difference is not. + // + // Instead, we first iterate through both slices to detect which elements + // would be ignored if standing alone. The index of non-discarded elements + // are stored in a separate slice, which diffing is then performed on. + var indexesX, indexesY []int + var ignoredX, ignoredY []bool + for ix := 0; ix < vx.Len(); ix++ { + ignored := s.statelessCompare(withIndexes(ix, -1)).NumDiff == 0 + if !ignored { + indexesX = append(indexesX, ix) + } + ignoredX = append(ignoredX, ignored) + } + for iy := 0; iy < vy.Len(); iy++ { + ignored := s.statelessCompare(withIndexes(-1, iy)).NumDiff == 0 + if !ignored { + indexesY = append(indexesY, iy) + } + ignoredY = append(ignoredY, ignored) + } + + // Compute an edit-script for slices vx and vy (excluding ignored elements). + edits := diff.Difference(len(indexesX), len(indexesY), func(ix, iy int) diff.Result { + return s.statelessCompare(withIndexes(indexesX[ix], indexesY[iy])) + }) + + // Replay the ignore-scripts and the edit-script. + var ix, iy int + for ix < vx.Len() || iy < vy.Len() { + var e diff.EditType + switch { + case ix < len(ignoredX) && ignoredX[ix]: + e = diff.UniqueX + case iy < len(ignoredY) && ignoredY[iy]: + e = diff.UniqueY + default: + e, edits = edits[0], edits[1:] + } + switch e { + case diff.UniqueX: + s.compareAny(withIndexes(ix, -1)) + ix++ + case diff.UniqueY: + s.compareAny(withIndexes(-1, iy)) + iy++ + default: + s.compareAny(withIndexes(ix, iy)) + ix++ + iy++ + } + } +} + +func (s *state) compareMap(t reflect.Type, vx, vy reflect.Value) { + if vx.IsNil() || vy.IsNil() { + s.report(vx.IsNil() && vy.IsNil(), 0) + return + } + + // Cycle-detection for maps. + if eq, visited := s.curPtrs.Push(vx, vy); visited { + s.report(eq, reportByCycle) + return + } + defer s.curPtrs.Pop(vx, vy) + + // We combine and sort the two map keys so that we can perform the + // comparisons in a deterministic order. + step := MapIndex{&mapIndex{pathStep: pathStep{typ: t.Elem()}}} + for _, k := range value.SortKeys(append(vx.MapKeys(), vy.MapKeys()...)) { + step.vx = vx.MapIndex(k) + step.vy = vy.MapIndex(k) + step.key = k + if !step.vx.IsValid() && !step.vy.IsValid() { + // It is possible for both vx and vy to be invalid if the + // key contained a NaN value in it. + // + // Even with the ability to retrieve NaN keys in Go 1.12, + // there still isn't a sensible way to compare the values since + // a NaN key may map to multiple unordered values. + // The most reasonable way to compare NaNs would be to compare the + // set of values. However, this is impossible to do efficiently + // since set equality is provably an O(n^2) operation given only + // an Equal function. If we had a Less function or Hash function, + // this could be done in O(n*log(n)) or O(n), respectively. + // + // Rather than adding complex logic to deal with NaNs, make it + // the user's responsibility to compare such obscure maps. + const help = "consider providing a Comparer to compare the map" + panic(fmt.Sprintf("%#v has map key with NaNs\n%s", s.curPath, help)) + } + s.compareAny(step) + } +} + +func (s *state) comparePtr(t reflect.Type, vx, vy reflect.Value) { + if vx.IsNil() || vy.IsNil() { + s.report(vx.IsNil() && vy.IsNil(), 0) + return + } + + // Cycle-detection for pointers. + if eq, visited := s.curPtrs.Push(vx, vy); visited { + s.report(eq, reportByCycle) + return + } + defer s.curPtrs.Pop(vx, vy) + + vx, vy = vx.Elem(), vy.Elem() + s.compareAny(Indirect{&indirect{pathStep{t.Elem(), vx, vy}}}) +} + +func (s *state) compareInterface(t reflect.Type, vx, vy reflect.Value) { + if vx.IsNil() || vy.IsNil() { + s.report(vx.IsNil() && vy.IsNil(), 0) + return + } + vx, vy = vx.Elem(), vy.Elem() + if vx.Type() != vy.Type() { + s.report(false, 0) + return + } + s.compareAny(TypeAssertion{&typeAssertion{pathStep{vx.Type(), vx, vy}}}) +} + +func (s *state) report(eq bool, rf resultFlags) { + if rf&reportByIgnore == 0 { + if eq { + s.result.NumSame++ + rf |= reportEqual + } else { + s.result.NumDiff++ + rf |= reportUnequal + } + } + for _, r := range s.reporters { + r.Report(Result{flags: rf}) + } +} + +// recChecker tracks the state needed to periodically perform checks that +// user provided transformers are not stuck in an infinitely recursive cycle. +type recChecker struct{ next int } + +// Check scans the Path for any recursive transformers and panics when any +// recursive transformers are detected. Note that the presence of a +// recursive Transformer does not necessarily imply an infinite cycle. +// As such, this check only activates after some minimal number of path steps. +func (rc *recChecker) Check(p Path) { + const minLen = 1 << 16 + if rc.next == 0 { + rc.next = minLen + } + if len(p) < rc.next { + return + } + rc.next <<= 1 + + // Check whether the same transformer has appeared at least twice. + var ss []string + m := map[Option]int{} + for _, ps := range p { + if t, ok := ps.(Transform); ok { + t := t.Option() + if m[t] == 1 { // Transformer was used exactly once before + tf := t.(*transformer).fnc.Type() + ss = append(ss, fmt.Sprintf("%v: %v => %v", t, tf.In(0), tf.Out(0))) + } + m[t]++ + } + } + if len(ss) > 0 { + const warning = "recursive set of Transformers detected" + const help = "consider using cmpopts.AcyclicTransformer" + set := strings.Join(ss, "\n\t") + panic(fmt.Sprintf("%s:\n\t%s\n%s", warning, set, help)) + } +} + +// dynChecker tracks the state needed to periodically perform checks that +// user provided functions are symmetric and deterministic. +// The zero value is safe for immediate use. +type dynChecker struct{ curr, next int } + +// Next increments the state and reports whether a check should be performed. +// +// Checks occur every Nth function call, where N is a triangular number: +// 0 1 3 6 10 15 21 28 36 45 55 66 78 91 105 120 136 153 171 190 ... +// See https://en.wikipedia.org/wiki/Triangular_number +// +// This sequence ensures that the cost of checks drops significantly as +// the number of functions calls grows larger. +func (dc *dynChecker) Next() bool { + ok := dc.curr == dc.next + if ok { + dc.curr = 0 + dc.next++ + } + dc.curr++ + return ok +} + +// makeAddressable returns a value that is always addressable. +// It returns the input verbatim if it is already addressable, +// otherwise it creates a new value and returns an addressable copy. +func makeAddressable(v reflect.Value) reflect.Value { + if v.CanAddr() { + return v + } + vc := reflect.New(v.Type()).Elem() + vc.Set(v) + return vc +} |