vikunja-api/vendor/honnef.co/go/tools/staticcheck/vrp/slice.go

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2018-12-31 02:18:41 +01:00
package vrp
// TODO(dh): most of the constraints have implementations identical to
// that of strings. Consider reusing them.
import (
"fmt"
"go/types"
"honnef.co/go/tools/ssa"
)
type SliceInterval struct {
Length IntInterval
}
func (s SliceInterval) Union(other Range) Range {
i, ok := other.(SliceInterval)
if !ok {
i = SliceInterval{EmptyIntInterval}
}
if s.Length.Empty() || !s.Length.IsKnown() {
return i
}
if i.Length.Empty() || !i.Length.IsKnown() {
return s
}
return SliceInterval{
Length: s.Length.Union(i.Length).(IntInterval),
}
}
func (s SliceInterval) String() string { return s.Length.String() }
func (s SliceInterval) IsKnown() bool { return s.Length.IsKnown() }
type SliceAppendConstraint struct {
aConstraint
A ssa.Value
B ssa.Value
}
type SliceSliceConstraint struct {
aConstraint
X ssa.Value
Lower ssa.Value
Upper ssa.Value
}
type ArraySliceConstraint struct {
aConstraint
X ssa.Value
Lower ssa.Value
Upper ssa.Value
}
type SliceIntersectionConstraint struct {
aConstraint
X ssa.Value
I IntInterval
}
type SliceLengthConstraint struct {
aConstraint
X ssa.Value
}
type MakeSliceConstraint struct {
aConstraint
Size ssa.Value
}
type SliceIntervalConstraint struct {
aConstraint
I IntInterval
}
func NewSliceAppendConstraint(a, b, y ssa.Value) Constraint {
return &SliceAppendConstraint{NewConstraint(y), a, b}
}
func NewSliceSliceConstraint(x, lower, upper, y ssa.Value) Constraint {
return &SliceSliceConstraint{NewConstraint(y), x, lower, upper}
}
func NewArraySliceConstraint(x, lower, upper, y ssa.Value) Constraint {
return &ArraySliceConstraint{NewConstraint(y), x, lower, upper}
}
func NewSliceIntersectionConstraint(x ssa.Value, i IntInterval, y ssa.Value) Constraint {
return &SliceIntersectionConstraint{NewConstraint(y), x, i}
}
func NewSliceLengthConstraint(x, y ssa.Value) Constraint {
return &SliceLengthConstraint{NewConstraint(y), x}
}
func NewMakeSliceConstraint(size, y ssa.Value) Constraint {
return &MakeSliceConstraint{NewConstraint(y), size}
}
func NewSliceIntervalConstraint(i IntInterval, y ssa.Value) Constraint {
return &SliceIntervalConstraint{NewConstraint(y), i}
}
func (c *SliceAppendConstraint) Operands() []ssa.Value { return []ssa.Value{c.A, c.B} }
func (c *SliceSliceConstraint) Operands() []ssa.Value {
ops := []ssa.Value{c.X}
if c.Lower != nil {
ops = append(ops, c.Lower)
}
if c.Upper != nil {
ops = append(ops, c.Upper)
}
return ops
}
func (c *ArraySliceConstraint) Operands() []ssa.Value {
ops := []ssa.Value{c.X}
if c.Lower != nil {
ops = append(ops, c.Lower)
}
if c.Upper != nil {
ops = append(ops, c.Upper)
}
return ops
}
func (c *SliceIntersectionConstraint) Operands() []ssa.Value { return []ssa.Value{c.X} }
func (c *SliceLengthConstraint) Operands() []ssa.Value { return []ssa.Value{c.X} }
func (c *MakeSliceConstraint) Operands() []ssa.Value { return []ssa.Value{c.Size} }
func (s *SliceIntervalConstraint) Operands() []ssa.Value { return nil }
func (c *SliceAppendConstraint) String() string {
return fmt.Sprintf("%s = append(%s, %s)", c.Y().Name(), c.A.Name(), c.B.Name())
}
func (c *SliceSliceConstraint) String() string {
var lname, uname string
if c.Lower != nil {
lname = c.Lower.Name()
}
if c.Upper != nil {
uname = c.Upper.Name()
}
return fmt.Sprintf("%s[%s:%s]", c.X.Name(), lname, uname)
}
func (c *ArraySliceConstraint) String() string {
var lname, uname string
if c.Lower != nil {
lname = c.Lower.Name()
}
if c.Upper != nil {
uname = c.Upper.Name()
}
return fmt.Sprintf("%s[%s:%s]", c.X.Name(), lname, uname)
}
func (c *SliceIntersectionConstraint) String() string {
return fmt.Sprintf("%s = %s.%t ⊓ %s", c.Y().Name(), c.X.Name(), c.Y().(*ssa.Sigma).Branch, c.I)
}
func (c *SliceLengthConstraint) String() string {
return fmt.Sprintf("%s = len(%s)", c.Y().Name(), c.X.Name())
}
func (c *MakeSliceConstraint) String() string {
return fmt.Sprintf("%s = make(slice, %s)", c.Y().Name(), c.Size.Name())
}
func (c *SliceIntervalConstraint) String() string { return fmt.Sprintf("%s = %s", c.Y().Name(), c.I) }
func (c *SliceAppendConstraint) Eval(g *Graph) Range {
l1 := g.Range(c.A).(SliceInterval).Length
var l2 IntInterval
switch r := g.Range(c.B).(type) {
case SliceInterval:
l2 = r.Length
case StringInterval:
l2 = r.Length
default:
return SliceInterval{}
}
if !l1.IsKnown() || !l2.IsKnown() {
return SliceInterval{}
}
return SliceInterval{
Length: l1.Add(l2),
}
}
func (c *SliceSliceConstraint) Eval(g *Graph) Range {
lr := NewIntInterval(NewZ(0), NewZ(0))
if c.Lower != nil {
lr = g.Range(c.Lower).(IntInterval)
}
ur := g.Range(c.X).(SliceInterval).Length
if c.Upper != nil {
ur = g.Range(c.Upper).(IntInterval)
}
if !lr.IsKnown() || !ur.IsKnown() {
return SliceInterval{}
}
ls := []Z{
ur.Lower.Sub(lr.Lower),
ur.Upper.Sub(lr.Lower),
ur.Lower.Sub(lr.Upper),
ur.Upper.Sub(lr.Upper),
}
// TODO(dh): if we don't truncate lengths to 0 we might be able to
// easily detect slices with high < low. we'd need to treat -∞
// specially, though.
for i, l := range ls {
if l.Sign() == -1 {
ls[i] = NewZ(0)
}
}
return SliceInterval{
Length: NewIntInterval(MinZ(ls...), MaxZ(ls...)),
}
}
func (c *ArraySliceConstraint) Eval(g *Graph) Range {
lr := NewIntInterval(NewZ(0), NewZ(0))
if c.Lower != nil {
lr = g.Range(c.Lower).(IntInterval)
}
var l int64
switch typ := c.X.Type().(type) {
case *types.Array:
l = typ.Len()
case *types.Pointer:
l = typ.Elem().(*types.Array).Len()
}
ur := NewIntInterval(NewZ(l), NewZ(l))
if c.Upper != nil {
ur = g.Range(c.Upper).(IntInterval)
}
if !lr.IsKnown() || !ur.IsKnown() {
return SliceInterval{}
}
ls := []Z{
ur.Lower.Sub(lr.Lower),
ur.Upper.Sub(lr.Lower),
ur.Lower.Sub(lr.Upper),
ur.Upper.Sub(lr.Upper),
}
// TODO(dh): if we don't truncate lengths to 0 we might be able to
// easily detect slices with high < low. we'd need to treat -∞
// specially, though.
for i, l := range ls {
if l.Sign() == -1 {
ls[i] = NewZ(0)
}
}
return SliceInterval{
Length: NewIntInterval(MinZ(ls...), MaxZ(ls...)),
}
}
func (c *SliceIntersectionConstraint) Eval(g *Graph) Range {
xi := g.Range(c.X).(SliceInterval)
if !xi.IsKnown() {
return c.I
}
return SliceInterval{
Length: xi.Length.Intersection(c.I),
}
}
func (c *SliceLengthConstraint) Eval(g *Graph) Range {
i := g.Range(c.X).(SliceInterval).Length
if !i.IsKnown() {
return NewIntInterval(NewZ(0), PInfinity)
}
return i
}
func (c *MakeSliceConstraint) Eval(g *Graph) Range {
i, ok := g.Range(c.Size).(IntInterval)
if !ok {
return SliceInterval{NewIntInterval(NewZ(0), PInfinity)}
}
if i.Lower.Sign() == -1 {
i.Lower = NewZ(0)
}
return SliceInterval{i}
}
func (c *SliceIntervalConstraint) Eval(*Graph) Range { return SliceInterval{c.I} }