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diff_refiner.go
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/
diff_refiner.go
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package uast
import (
"unicode/utf8"
"github.com/sergi/go-diff/diffmatchpatch"
"gopkg.in/bblfsh/sdk.v1/uast"
"gopkg.in/src-d/go-git.v4"
"gopkg.in/src-d/hercules.v6/internal/core"
"gopkg.in/src-d/hercules.v6/internal/plumbing"
)
// FileDiffRefiner uses UASTs to improve the human interpretability of diffs.
// It is a PipelineItem.
// The idea behind this algorithm is simple: in case of multiple choices which are equally
// optimal, choose the one which touches less AST nodes.
type FileDiffRefiner struct {
core.NoopMerger
}
// Name of this PipelineItem. Uniquely identifies the type, used for mapping keys, etc.
func (ref *FileDiffRefiner) Name() string {
return "FileDiffRefiner"
}
// Provides returns the list of names of entities which are produced by this PipelineItem.
// Each produced entity will be inserted into `deps` of dependent Consume()-s according
// to this list. Also used by core.Registry to build the global map of providers.
func (ref *FileDiffRefiner) Provides() []string {
arr := [...]string{plumbing.DependencyFileDiff}
return arr[:]
}
// Requires returns the list of names of entities which are needed by this PipelineItem.
// Each requested entity will be inserted into `deps` of Consume(). In turn, those
// entities are Provides() upstream.
func (ref *FileDiffRefiner) Requires() []string {
arr := [...]string{plumbing.DependencyFileDiff, DependencyUastChanges}
return arr[:]
}
// Features which must be enabled for this PipelineItem to be automatically inserted into the DAG.
func (ref *FileDiffRefiner) Features() []string {
arr := [...]string{FeatureUast}
return arr[:]
}
// ListConfigurationOptions returns the list of changeable public properties of this PipelineItem.
func (ref *FileDiffRefiner) ListConfigurationOptions() []core.ConfigurationOption {
return []core.ConfigurationOption{}
}
// Configure sets the properties previously published by ListConfigurationOptions().
func (ref *FileDiffRefiner) Configure(facts map[string]interface{}) error {
return nil
}
// Initialize resets the temporary caches and prepares this PipelineItem for a series of Consume()
// calls. The repository which is going to be analysed is supplied as an argument.
func (ref *FileDiffRefiner) Initialize(repository *git.Repository) error {
return nil
}
// Consume runs this PipelineItem on the next commit data.
// `deps` contain all the results from upstream PipelineItem-s as requested by Requires().
// Additionally, DependencyCommit is always present there and represents the analysed *object.Commit.
// This function returns the mapping with analysis results. The keys must be the same as
// in Provides(). If there was an error, nil is returned.
func (ref *FileDiffRefiner) Consume(deps map[string]interface{}) (map[string]interface{}, error) {
changesList := deps[DependencyUastChanges].([]Change)
changes := map[string]Change{}
for _, change := range changesList {
if change.Before != nil && change.After != nil {
changes[change.Change.To.Name] = change
}
}
diffs := deps[plumbing.DependencyFileDiff].(map[string]plumbing.FileDiffData)
result := map[string]plumbing.FileDiffData{}
for fileName, oldDiff := range diffs {
uastChange, exists := changes[fileName]
if !exists {
result[fileName] = oldDiff
continue
}
suspicious := map[int][2]int{}
line := 0
for i, diff := range oldDiff.Diffs {
if i == len(oldDiff.Diffs)-1 {
break
}
if diff.Type == diffmatchpatch.DiffInsert &&
oldDiff.Diffs[i+1].Type == diffmatchpatch.DiffEqual {
matched := 0
runesAdded := []rune(diff.Text)
runesEqual := []rune(oldDiff.Diffs[i+1].Text)
for ; matched < len(runesAdded) && matched < len(runesEqual) &&
runesAdded[matched] == runesEqual[matched]; matched++ {
}
if matched > 0 {
suspicious[i] = [2]int{line, matched}
}
}
if diff.Type != diffmatchpatch.DiffDelete {
line += utf8.RuneCountInString(diff.Text)
}
}
if len(suspicious) == 0 {
result[fileName] = oldDiff
continue
}
line2node := make([][]*uast.Node, oldDiff.NewLinesOfCode)
VisitEachNode(uastChange.After, func(node *uast.Node) {
if node.StartPosition != nil && node.EndPosition != nil {
for l := node.StartPosition.Line; l <= node.EndPosition.Line; l++ {
nodes := line2node[l-1] // line starts with 1
if nodes == nil {
nodes = []*uast.Node{}
}
line2node[l-1] = append(nodes, node)
}
}
})
newDiff := plumbing.FileDiffData{
OldLinesOfCode: oldDiff.OldLinesOfCode,
NewLinesOfCode: oldDiff.NewLinesOfCode,
Diffs: []diffmatchpatch.Diff{},
}
skipNext := false
for i, diff := range oldDiff.Diffs {
if skipNext {
skipNext = false
continue
}
info, exists := suspicious[i]
if !exists {
newDiff.Diffs = append(newDiff.Diffs, diff)
continue
}
line := info[0]
matched := info[1]
size := utf8.RuneCountInString(diff.Text)
n1 := countNodesInInterval(line2node, line, line+size)
n2 := countNodesInInterval(line2node, line+matched, line+size+matched)
if n1 <= n2 {
newDiff.Diffs = append(newDiff.Diffs, diff)
continue
}
skipNext = true
runes := []rune(diff.Text)
newDiff.Diffs = append(newDiff.Diffs, diffmatchpatch.Diff{
Type: diffmatchpatch.DiffEqual, Text: string(runes[:matched]),
})
newDiff.Diffs = append(newDiff.Diffs, diffmatchpatch.Diff{
Type: diffmatchpatch.DiffInsert, Text: string(runes[matched:]) + string(runes[:matched]),
})
runes = []rune(oldDiff.Diffs[i+1].Text)
if len(runes) > matched {
newDiff.Diffs = append(newDiff.Diffs, diffmatchpatch.Diff{
Type: diffmatchpatch.DiffEqual, Text: string(runes[matched:]),
})
}
}
result[fileName] = newDiff
}
return map[string]interface{}{plumbing.DependencyFileDiff: result}, nil
}
// Fork clones this PipelineItem.
func (ref *FileDiffRefiner) Fork(n int) []core.PipelineItem {
return core.ForkSamePipelineItem(ref, n)
}
// VisitEachNode is a handy routine to execute a callback on every node in the subtree,
// including the root itself. Depth first tree traversal.
func VisitEachNode(root *uast.Node, payload func(*uast.Node)) {
queue := []*uast.Node{}
queue = append(queue, root)
for len(queue) > 0 {
node := queue[len(queue)-1]
queue = queue[:len(queue)-1]
payload(node)
for _, child := range node.Children {
queue = append(queue, child)
}
}
}
func countNodesInInterval(occupiedMap [][]*uast.Node, start, end int) int {
nodes := map[*uast.Node]bool{}
for i := start; i < end; i++ {
for _, node := range occupiedMap[i] {
nodes[node] = true
}
}
return len(nodes)
}
func init() {
core.Registry.Register(&FileDiffRefiner{})
}