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Merge pull request #125 from openconfig/min-max-elements
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Parse and semantic-check min-elements and max-elements.
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@wenovus
wenovus authored Oct 2, 2020
2 parents 22e20cc + e39889f commit 1e0cba5
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Showing 4 changed files with 303 additions and 55 deletions.
111 changes: 96 additions & 15 deletions pkg/yang/entry.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ import (
"errors"
"fmt"
"io"
"math"
"reflect"
"sort"
"strconv"
Expand Down Expand Up @@ -62,6 +63,14 @@ func (t TriState) String() string {
}
}

// deviationPresence stores whether certain attributes for a DeviateEntry-type
// Entry have been given deviation values. This is useful when the attribute
// doesn't have a presence indicator (e.g. non-pointers).
type deviationPresence struct {
hasMinElements bool
hasMaxElements bool
}

// An Entry represents a single node (directory or leaf) created from the
// AST. Directory entries have a non-nil Dir entry. Leaf nodes have a nil
// Dir entry. If Errors is not nil then the only other valid field is Node.
Expand Down Expand Up @@ -99,7 +108,10 @@ type Entry struct {
Augmented []*Entry `json:",omitempty"` // Augments merged into this entry.
Deviations []*DeviatedEntry `json:"-"` // Deviations associated with this entry.
Deviate map[deviationType][]*Entry `json:"-"`
Uses []*UsesStmt `json:",omitempty"` // Uses merged into this entry.
// deviationPresence tracks whether certain attributes for a DeviateEntry-type
// Entry have been given deviation values.
deviatePresence deviationPresence
Uses []*UsesStmt `json:",omitempty"` // Uses merged into this entry.

// Extra maps all the unsupported fields to their values
Extra map[string][]interface{} `json:"-"`
Expand All @@ -125,8 +137,8 @@ type RPCEntry struct {

// A ListAttr is associated with an Entry that represents a List node
type ListAttr struct {
MinElements *Value // leaf-list or list MUST have at least min-elements
MaxElements *Value // leaf-list or list has at most max-elements
MinElements uint64 // leaf-list or list MUST have at least min-elements
MaxElements uint64 // leaf-list or list has at most max-elements
OrderedBy *Value // order of entries determined by "system" or "user"
}

Expand Down Expand Up @@ -473,6 +485,30 @@ type DeviatedEntry struct {
*Entry
}

// semCheckMaxElements checks whether the max-element argument is valid, and returns the specified value.
func semCheckMaxElements(v *Value) (uint64, error) {
if v == nil || v.Name == "unbounded" {
return math.MaxUint64, nil
}
val, err := strconv.ParseUint(v.Name, 10, 64)
if err != nil {
return val, fmt.Errorf(`%s: invalid max-elements value %q (expect "unbounded" or a non-negative integer): %v`, Source(v), v.Name, err)
}
return val, nil
}

// semCheckMinElements checks whether the min-element argument is valid, and returns the specified value.
func semCheckMinElements(v *Value) (uint64, error) {
if v == nil {
return 0, nil
}
val, err := strconv.ParseUint(v.Name, 10, 64)
if err != nil {
return val, fmt.Errorf(`%s: invalid min-elements value %q (expect a non-negative integer): %v`, Source(v), v.Name, err)
}
return val, nil
}

// ToEntry expands node n into a directory Entry. Expansion is based on the
// YANG tags in the structure behind n. ToEntry must only be used
// with nodes that are directories, such as top level modules and sub-modules.
Expand Down Expand Up @@ -561,9 +597,14 @@ func ToEntry(n Node) (e *Entry) {

e := ToEntry(leaf)
e.ListAttr = &ListAttr{
MinElements: s.MinElements,
MaxElements: s.MaxElements,
OrderedBy: s.OrderedBy,
OrderedBy: s.OrderedBy,
}
var err error
if e.ListAttr.MaxElements, err = semCheckMaxElements(s.MaxElements); err != nil {
e.addError(err)
}
if e.ListAttr.MinElements, err = semCheckMinElements(s.MinElements); err != nil {
e.addError(err)
}
e.Prefix = getRootPrefix(e)
addExtraKeywordsToLeafEntry(n, e)
Expand All @@ -590,9 +631,14 @@ func ToEntry(n Node) (e *Entry) {
switch s := n.(type) {
case *List:
e.ListAttr = &ListAttr{
MinElements: s.MinElements,
MaxElements: s.MaxElements,
OrderedBy: s.OrderedBy,
OrderedBy: s.OrderedBy,
}
var err error
if e.ListAttr.MaxElements, err = semCheckMaxElements(s.MaxElements); err != nil {
e.addError(err)
}
if e.ListAttr.MinElements, err = semCheckMinElements(s.MinElements); err != nil {
e.addError(err)
}
case *Choice:
e.Kind = ChoiceEntry
Expand Down Expand Up @@ -882,10 +928,20 @@ func ToEntry(n Node) (e *Entry) {
e.ListAttr = &ListAttr{}
}

if name == "max-elements" {
e.ListAttr.MaxElements = v
} else {
e.ListAttr.MinElements = v
// Only record the deviation if the statement exists.
if v != nil {
var err error
if name == "max-elements" {
e.deviatePresence.hasMaxElements = true
if e.ListAttr.MaxElements, err = semCheckMaxElements(v); err != nil {
e.addError(err)
}
} else {
e.deviatePresence.hasMinElements = true
if e.ListAttr.MinElements, err = semCheckMinElements(v); err != nil {
e.addError(err)
}
}
}
case "units":
v, ok := fv.Interface().(*Value)
Expand Down Expand Up @@ -1032,15 +1088,15 @@ func (e *Entry) ApplyDeviate() []error {
deviatedNode.Mandatory = devSpec.Mandatory
}

if devSpec.ListAttr != nil && devSpec.ListAttr.MinElements != nil {
if devSpec.deviatePresence.hasMinElements {
if !deviatedNode.IsList() && !deviatedNode.IsLeafList() {
appendErr(fmt.Errorf("tried to deviate min-elements on a non-list type %s", deviatedNode.Kind))
continue
}
deviatedNode.ListAttr.MinElements = devSpec.ListAttr.MinElements
}

if devSpec.ListAttr != nil && devSpec.ListAttr.MaxElements != nil {
if devSpec.deviatePresence.hasMaxElements {
if !deviatedNode.IsList() && !deviatedNode.IsLeafList() {
appendErr(fmt.Errorf("tried to deviate max-elements on a non-list type %s", deviatedNode.Kind))
continue
Expand Down Expand Up @@ -1075,6 +1131,31 @@ func (e *Entry) ApplyDeviate() []error {
if devSpec.Mandatory != TSUnset {
devSpec.Mandatory = TSUnset
}

if devSpec.deviatePresence.hasMinElements {
if !deviatedNode.IsList() && !deviatedNode.IsLeafList() {
appendErr(fmt.Errorf("tried to deviate min-elements on a non-list type %s", deviatedNode.Kind))
continue
}
if deviatedNode.ListAttr.MinElements != devSpec.ListAttr.MinElements {
// Argument value must match:
// https://tools.ietf.org/html/rfc7950#section-7.20.3.2
appendErr(fmt.Errorf("min-element value %d differs from deviation's min-element value %d for entry %v", devSpec.ListAttr.MinElements, deviatedNode.ListAttr.MinElements, d.DeviatedPath))
}
deviatedNode.ListAttr.MinElements = 0
}

if devSpec.deviatePresence.hasMaxElements {
if !deviatedNode.IsList() && !deviatedNode.IsLeafList() {
appendErr(fmt.Errorf("tried to deviate max-elements on a non-list type %s", deviatedNode.Kind))
continue
}
if deviatedNode.ListAttr.MaxElements != devSpec.ListAttr.MaxElements {
appendErr(fmt.Errorf("max-element value %d differs from deviation's max-element value %d for entry %v", devSpec.ListAttr.MaxElements, deviatedNode.ListAttr.MaxElements, d.DeviatedPath))
}
deviatedNode.ListAttr.MaxElements = math.MaxUint64
}

default:
appendErr(fmt.Errorf("invalid deviation type %s", dt))
}
Expand Down
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