summaryrefslogtreecommitdiff
path: root/vendor/github.com/google/go-cmp/cmp/path.go
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/github.com/google/go-cmp/cmp/path.go')
-rw-r--r--vendor/github.com/google/go-cmp/cmp/path.go378
1 files changed, 378 insertions, 0 deletions
diff --git a/vendor/github.com/google/go-cmp/cmp/path.go b/vendor/github.com/google/go-cmp/cmp/path.go
new file mode 100644
index 000000000..c71003463
--- /dev/null
+++ b/vendor/github.com/google/go-cmp/cmp/path.go
@@ -0,0 +1,378 @@
+// 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"
+ "strings"
+ "unicode"
+ "unicode/utf8"
+
+ "github.com/google/go-cmp/cmp/internal/value"
+)
+
+// Path is a list of PathSteps describing the sequence of operations to get
+// from some root type to the current position in the value tree.
+// The first Path element is always an operation-less PathStep that exists
+// simply to identify the initial type.
+//
+// When traversing structs with embedded structs, the embedded struct will
+// always be accessed as a field before traversing the fields of the
+// embedded struct themselves. That is, an exported field from the
+// embedded struct will never be accessed directly from the parent struct.
+type Path []PathStep
+
+// PathStep is a union-type for specific operations to traverse
+// a value's tree structure. Users of this package never need to implement
+// these types as values of this type will be returned by this package.
+//
+// Implementations of this interface are
+// StructField, SliceIndex, MapIndex, Indirect, TypeAssertion, and Transform.
+type PathStep interface {
+ String() string
+
+ // Type is the resulting type after performing the path step.
+ Type() reflect.Type
+
+ // Values is the resulting values after performing the path step.
+ // The type of each valid value is guaranteed to be identical to Type.
+ //
+ // In some cases, one or both may be invalid or have restrictions:
+ // • For StructField, both are not interface-able if the current field
+ // is unexported and the struct type is not explicitly permitted by
+ // an Exporter to traverse unexported fields.
+ // • For SliceIndex, one may be invalid if an element is missing from
+ // either the x or y slice.
+ // • For MapIndex, one may be invalid if an entry is missing from
+ // either the x or y map.
+ //
+ // The provided values must not be mutated.
+ Values() (vx, vy reflect.Value)
+}
+
+var (
+ _ PathStep = StructField{}
+ _ PathStep = SliceIndex{}
+ _ PathStep = MapIndex{}
+ _ PathStep = Indirect{}
+ _ PathStep = TypeAssertion{}
+ _ PathStep = Transform{}
+)
+
+func (pa *Path) push(s PathStep) {
+ *pa = append(*pa, s)
+}
+
+func (pa *Path) pop() {
+ *pa = (*pa)[:len(*pa)-1]
+}
+
+// Last returns the last PathStep in the Path.
+// If the path is empty, this returns a non-nil PathStep that reports a nil Type.
+func (pa Path) Last() PathStep {
+ return pa.Index(-1)
+}
+
+// Index returns the ith step in the Path and supports negative indexing.
+// A negative index starts counting from the tail of the Path such that -1
+// refers to the last step, -2 refers to the second-to-last step, and so on.
+// If index is invalid, this returns a non-nil PathStep that reports a nil Type.
+func (pa Path) Index(i int) PathStep {
+ if i < 0 {
+ i = len(pa) + i
+ }
+ if i < 0 || i >= len(pa) {
+ return pathStep{}
+ }
+ return pa[i]
+}
+
+// String returns the simplified path to a node.
+// The simplified path only contains struct field accesses.
+//
+// For example:
+// MyMap.MySlices.MyField
+func (pa Path) String() string {
+ var ss []string
+ for _, s := range pa {
+ if _, ok := s.(StructField); ok {
+ ss = append(ss, s.String())
+ }
+ }
+ return strings.TrimPrefix(strings.Join(ss, ""), ".")
+}
+
+// GoString returns the path to a specific node using Go syntax.
+//
+// For example:
+// (*root.MyMap["key"].(*mypkg.MyStruct).MySlices)[2][3].MyField
+func (pa Path) GoString() string {
+ var ssPre, ssPost []string
+ var numIndirect int
+ for i, s := range pa {
+ var nextStep PathStep
+ if i+1 < len(pa) {
+ nextStep = pa[i+1]
+ }
+ switch s := s.(type) {
+ case Indirect:
+ numIndirect++
+ pPre, pPost := "(", ")"
+ switch nextStep.(type) {
+ case Indirect:
+ continue // Next step is indirection, so let them batch up
+ case StructField:
+ numIndirect-- // Automatic indirection on struct fields
+ case nil:
+ pPre, pPost = "", "" // Last step; no need for parenthesis
+ }
+ if numIndirect > 0 {
+ ssPre = append(ssPre, pPre+strings.Repeat("*", numIndirect))
+ ssPost = append(ssPost, pPost)
+ }
+ numIndirect = 0
+ continue
+ case Transform:
+ ssPre = append(ssPre, s.trans.name+"(")
+ ssPost = append(ssPost, ")")
+ continue
+ }
+ ssPost = append(ssPost, s.String())
+ }
+ for i, j := 0, len(ssPre)-1; i < j; i, j = i+1, j-1 {
+ ssPre[i], ssPre[j] = ssPre[j], ssPre[i]
+ }
+ return strings.Join(ssPre, "") + strings.Join(ssPost, "")
+}
+
+type pathStep struct {
+ typ reflect.Type
+ vx, vy reflect.Value
+}
+
+func (ps pathStep) Type() reflect.Type { return ps.typ }
+func (ps pathStep) Values() (vx, vy reflect.Value) { return ps.vx, ps.vy }
+func (ps pathStep) String() string {
+ if ps.typ == nil {
+ return "<nil>"
+ }
+ s := ps.typ.String()
+ if s == "" || strings.ContainsAny(s, "{}\n") {
+ return "root" // Type too simple or complex to print
+ }
+ return fmt.Sprintf("{%s}", s)
+}
+
+// StructField represents a struct field access on a field called Name.
+type StructField struct{ *structField }
+type structField struct {
+ pathStep
+ name string
+ idx int
+
+ // These fields are used for forcibly accessing an unexported field.
+ // pvx, pvy, and field are only valid if unexported is true.
+ unexported bool
+ mayForce bool // Forcibly allow visibility
+ paddr bool // Was parent addressable?
+ pvx, pvy reflect.Value // Parent values (always addressable)
+ field reflect.StructField // Field information
+}
+
+func (sf StructField) Type() reflect.Type { return sf.typ }
+func (sf StructField) Values() (vx, vy reflect.Value) {
+ if !sf.unexported {
+ return sf.vx, sf.vy // CanInterface reports true
+ }
+
+ // Forcibly obtain read-write access to an unexported struct field.
+ if sf.mayForce {
+ vx = retrieveUnexportedField(sf.pvx, sf.field, sf.paddr)
+ vy = retrieveUnexportedField(sf.pvy, sf.field, sf.paddr)
+ return vx, vy // CanInterface reports true
+ }
+ return sf.vx, sf.vy // CanInterface reports false
+}
+func (sf StructField) String() string { return fmt.Sprintf(".%s", sf.name) }
+
+// Name is the field name.
+func (sf StructField) Name() string { return sf.name }
+
+// Index is the index of the field in the parent struct type.
+// See reflect.Type.Field.
+func (sf StructField) Index() int { return sf.idx }
+
+// SliceIndex is an index operation on a slice or array at some index Key.
+type SliceIndex struct{ *sliceIndex }
+type sliceIndex struct {
+ pathStep
+ xkey, ykey int
+ isSlice bool // False for reflect.Array
+}
+
+func (si SliceIndex) Type() reflect.Type { return si.typ }
+func (si SliceIndex) Values() (vx, vy reflect.Value) { return si.vx, si.vy }
+func (si SliceIndex) String() string {
+ switch {
+ case si.xkey == si.ykey:
+ return fmt.Sprintf("[%d]", si.xkey)
+ case si.ykey == -1:
+ // [5->?] means "I don't know where X[5] went"
+ return fmt.Sprintf("[%d->?]", si.xkey)
+ case si.xkey == -1:
+ // [?->3] means "I don't know where Y[3] came from"
+ return fmt.Sprintf("[?->%d]", si.ykey)
+ default:
+ // [5->3] means "X[5] moved to Y[3]"
+ return fmt.Sprintf("[%d->%d]", si.xkey, si.ykey)
+ }
+}
+
+// Key is the index key; it may return -1 if in a split state
+func (si SliceIndex) Key() int {
+ if si.xkey != si.ykey {
+ return -1
+ }
+ return si.xkey
+}
+
+// SplitKeys are the indexes for indexing into slices in the
+// x and y values, respectively. These indexes may differ due to the
+// insertion or removal of an element in one of the slices, causing
+// all of the indexes to be shifted. If an index is -1, then that
+// indicates that the element does not exist in the associated slice.
+//
+// Key is guaranteed to return -1 if and only if the indexes returned
+// by SplitKeys are not the same. SplitKeys will never return -1 for
+// both indexes.
+func (si SliceIndex) SplitKeys() (ix, iy int) { return si.xkey, si.ykey }
+
+// MapIndex is an index operation on a map at some index Key.
+type MapIndex struct{ *mapIndex }
+type mapIndex struct {
+ pathStep
+ key reflect.Value
+}
+
+func (mi MapIndex) Type() reflect.Type { return mi.typ }
+func (mi MapIndex) Values() (vx, vy reflect.Value) { return mi.vx, mi.vy }
+func (mi MapIndex) String() string { return fmt.Sprintf("[%#v]", mi.key) }
+
+// Key is the value of the map key.
+func (mi MapIndex) Key() reflect.Value { return mi.key }
+
+// Indirect represents pointer indirection on the parent type.
+type Indirect struct{ *indirect }
+type indirect struct {
+ pathStep
+}
+
+func (in Indirect) Type() reflect.Type { return in.typ }
+func (in Indirect) Values() (vx, vy reflect.Value) { return in.vx, in.vy }
+func (in Indirect) String() string { return "*" }
+
+// TypeAssertion represents a type assertion on an interface.
+type TypeAssertion struct{ *typeAssertion }
+type typeAssertion struct {
+ pathStep
+}
+
+func (ta TypeAssertion) Type() reflect.Type { return ta.typ }
+func (ta TypeAssertion) Values() (vx, vy reflect.Value) { return ta.vx, ta.vy }
+func (ta TypeAssertion) String() string { return fmt.Sprintf(".(%v)", ta.typ) }
+
+// Transform is a transformation from the parent type to the current type.
+type Transform struct{ *transform }
+type transform struct {
+ pathStep
+ trans *transformer
+}
+
+func (tf Transform) Type() reflect.Type { return tf.typ }
+func (tf Transform) Values() (vx, vy reflect.Value) { return tf.vx, tf.vy }
+func (tf Transform) String() string { return fmt.Sprintf("%s()", tf.trans.name) }
+
+// Name is the name of the Transformer.
+func (tf Transform) Name() string { return tf.trans.name }
+
+// Func is the function pointer to the transformer function.
+func (tf Transform) Func() reflect.Value { return tf.trans.fnc }
+
+// Option returns the originally constructed Transformer option.
+// The == operator can be used to detect the exact option used.
+func (tf Transform) Option() Option { return tf.trans }
+
+// pointerPath represents a dual-stack of pointers encountered when
+// recursively traversing the x and y values. This data structure supports
+// detection of cycles and determining whether the cycles are equal.
+// In Go, cycles can occur via pointers, slices, and maps.
+//
+// The pointerPath uses a map to represent a stack; where descension into a
+// pointer pushes the address onto the stack, and ascension from a pointer
+// pops the address from the stack. Thus, when traversing into a pointer from
+// reflect.Ptr, reflect.Slice element, or reflect.Map, we can detect cycles
+// by checking whether the pointer has already been visited. The cycle detection
+// uses a separate stack for the x and y values.
+//
+// If a cycle is detected we need to determine whether the two pointers
+// should be considered equal. The definition of equality chosen by Equal
+// requires two graphs to have the same structure. To determine this, both the
+// x and y values must have a cycle where the previous pointers were also
+// encountered together as a pair.
+//
+// Semantically, this is equivalent to augmenting Indirect, SliceIndex, and
+// MapIndex with pointer information for the x and y values.
+// Suppose px and py are two pointers to compare, we then search the
+// Path for whether px was ever encountered in the Path history of x, and
+// similarly so with py. If either side has a cycle, the comparison is only
+// equal if both px and py have a cycle resulting from the same PathStep.
+//
+// Using a map as a stack is more performant as we can perform cycle detection
+// in O(1) instead of O(N) where N is len(Path).
+type pointerPath struct {
+ // mx is keyed by x pointers, where the value is the associated y pointer.
+ mx map[value.Pointer]value.Pointer
+ // my is keyed by y pointers, where the value is the associated x pointer.
+ my map[value.Pointer]value.Pointer
+}
+
+func (p *pointerPath) Init() {
+ p.mx = make(map[value.Pointer]value.Pointer)
+ p.my = make(map[value.Pointer]value.Pointer)
+}
+
+// Push indicates intent to descend into pointers vx and vy where
+// visited reports whether either has been seen before. If visited before,
+// equal reports whether both pointers were encountered together.
+// Pop must be called if and only if the pointers were never visited.
+//
+// The pointers vx and vy must be a reflect.Ptr, reflect.Slice, or reflect.Map
+// and be non-nil.
+func (p pointerPath) Push(vx, vy reflect.Value) (equal, visited bool) {
+ px := value.PointerOf(vx)
+ py := value.PointerOf(vy)
+ _, ok1 := p.mx[px]
+ _, ok2 := p.my[py]
+ if ok1 || ok2 {
+ equal = p.mx[px] == py && p.my[py] == px // Pointers paired together
+ return equal, true
+ }
+ p.mx[px] = py
+ p.my[py] = px
+ return false, false
+}
+
+// Pop ascends from pointers vx and vy.
+func (p pointerPath) Pop(vx, vy reflect.Value) {
+ delete(p.mx, value.PointerOf(vx))
+ delete(p.my, value.PointerOf(vy))
+}
+
+// isExported reports whether the identifier is exported.
+func isExported(id string) bool {
+ r, _ := utf8.DecodeRuneInString(id)
+ return unicode.IsUpper(r)
+}