dev: simplify sort results processors

pkg/result/processors/sort_results.go

@@ -1,10 +1,9 @@
 package processors
 
 import (
-	"errors"
+	"cmp"
 	"fmt"
 	"slices"
-	"sort"
 	"strings"
 
 	"github.com/golangci/golangci-lint/pkg/config"
@@ -22,24 +21,32 @@ const (
 	orderNameSeverity = "severity"
 )
 
+const (
+	less = iota - 1
+	equal
+	greater
+)
+
 var _ Processor = (*SortResults)(nil)
 
+type issueComparator func(a, b *result.Issue) int
+
 type SortResults struct {
-	cmps map[string]*comparator
+	cmps map[string][]issueComparator
 
 	cfg *config.Output
 }
 
 func NewSortResults(cfg *config.Config) *SortResults {
 	return &SortResults{
-		cmps: map[string]*comparator{
+		cmps: map[string][]issueComparator{
 			// For sorting we are comparing (in next order):
 			// file names, line numbers, position, and finally - giving up.
-			orderNameFile: byFileName().SetNext(byLine().SetNext(byColumn())),
+			orderNameFile: {byFileName, byLine, byColumn},
 			// For sorting we are comparing: linter name
-			orderNameLinter: byLinter(),
+			orderNameLinter: {byLinter},
 			// For sorting we are comparing: severity
-			orderNameSeverity: bySeverity(),
+			orderNameSeverity: {bySeverity},
 		},
 		cfg: &cfg.Output,
 	}
@@ -57,171 +64,54 @@ func (p SortResults) Process(issues []result.Issue) ([]result.Issue, error) {
 		p.cfg.SortOrder = []string{orderNameFile}
 	}
 
-	var cmps []*comparator
+	var cmps []issueComparator
+
 	for _, name := range p.cfg.SortOrder {
 		c, ok := p.cmps[name]
 		if !ok {
 			return nil, fmt.Errorf("unsupported sort-order name %q", name)
 		}
 
-		cmps = append(cmps, c)
+		cmps = append(cmps, c...)
 	}
 
-	cmp, err := mergeComparators(cmps)
-	if err != nil {
-		return nil, err
-	}
+	comp := mergeComparators(cmps...)
 
-	sort.Slice(issues, func(i, j int) bool {
-		return cmp.Compare(&issues[i], &issues[j]) == less
+	slices.SortFunc(issues, func(a, b result.Issue) int {
+		return comp(&a, &b)
 	})
 
 	return issues, nil
 }
 
 func (SortResults) Finish() {}
 
-type compareResult int
-
-const (
-	less compareResult = iota - 1
-	equal
-	greater
-	none
-)
-
-func (c compareResult) isNeutral() bool {
-	// return true if compare result is incomparable or equal.
-	return c == none || c == equal
-}
-
-func (c compareResult) String() string {
-	switch c {
-	case less:
-		return "less"
-	case equal:
-		return "equal"
-	case greater:
-		return "greater"
-	default:
-		return "none"
-	}
-}
-
-// comparator describes how to implement compare for two "issues".
-type comparator struct {
-	name    string
-	compare func(a, b *result.Issue) compareResult
-	next    *comparator
-}
-
-func (cmp *comparator) Next() *comparator { return cmp.next }
-
-func (cmp *comparator) SetNext(c *comparator) *comparator {
-	cmp.next = c
-	return cmp
+func byFileName(a, b *result.Issue) int {
+	return strings.Compare(a.FilePath(), b.FilePath())
 }
 
-func (cmp *comparator) String() string {
-	s := cmp.name
-	if cmp.Next() != nil {
-		s += " > " + cmp.Next().String()
-	}
-
-	return s
+func byLine(a, b *result.Issue) int {
+	return numericCompare(a.Line(), b.Line())
 }
 
-func (cmp *comparator) Compare(a, b *result.Issue) compareResult {
-	res := cmp.compare(a, b)
-	if !res.isNeutral() {
-		return res
-	}
-
-	if next := cmp.Next(); next != nil {
-		return next.Compare(a, b)
-	}
-
-	return res
+func byColumn(a, b *result.Issue) int {
+	return numericCompare(a.Column(), b.Column())
 }
 
-func byFileName() *comparator {
-	return &comparator{
-		name: "byFileName",
-		compare: func(a, b *result.Issue) compareResult {
-			return compareResult(strings.Compare(a.FilePath(), b.FilePath()))
-		},
-	}
+func byLinter(a, b *result.Issue) int {
+	return strings.Compare(a.FromLinter, b.FromLinter)
 }
 
-func byLine() *comparator {
-	return &comparator{
-		name: "byLine",
-		compare: func(a, b *result.Issue) compareResult {
-			return numericCompare(a.Line(), b.Line())
-		},
-	}
+func bySeverity(a, b *result.Issue) int {
+	return severityCompare(a.Severity, b.Severity)
 }
 
-func byColumn() *comparator {
-	return &comparator{
-		name: "byColumn",
-		compare: func(a, b *result.Issue) compareResult {
-			return numericCompare(a.Column(), b.Column())
-		},
-	}
-}
-
-func byLinter() *comparator {
-	return &comparator{
-		name: "byLinter",
-		compare: func(a, b *result.Issue) compareResult {
-			return compareResult(strings.Compare(a.FromLinter, b.FromLinter))
-		},
-	}
-}
-
-func bySeverity() *comparator {
-	return &comparator{
-		name: "bySeverity",
-		compare: func(a, b *result.Issue) compareResult {
-			return severityCompare(a.Severity, b.Severity)
-		},
-	}
-}
-
-func mergeComparators(cmps []*comparator) (*comparator, error) {
-	if len(cmps) == 0 {
-		return nil, errors.New("no comparator")
-	}
-
-	for i := range len(cmps) - 1 {
-		findComparatorTip(cmps[i]).SetNext(cmps[i+1])
-	}
-
-	return cmps[0], nil
-}
-
-func findComparatorTip(cmp *comparator) *comparator {
-	if cmp.Next() != nil {
-		return findComparatorTip(cmp.Next())
-	}
-
-	return cmp
-}
-
-func severityCompare(a, b string) compareResult {
+func severityCompare(a, b string) int {
 	// The position inside the slice define the importance (lower to higher).
 	classic := []string{"low", "medium", "high", "warning", "error"}
 
 	if slices.Contains(classic, a) && slices.Contains(classic, b) {
-		switch {
-		case slices.Index(classic, a) > slices.Index(classic, b):
-			return greater
-		case slices.Index(classic, a) < slices.Index(classic, b):
-			return less
-		default:
-			return equal
-		}
+		return cmp.Compare(slices.Index(classic, a), slices.Index(classic, b))
 	}
 
 	if slices.Contains(classic, a) {
@@ -232,28 +122,27 @@ func severityCompare(a, b string) compareResult {
 		return less
 	}
 
-	return compareResult(strings.Compare(a, b))
+	return strings.Compare(a, b)
 }
 
-func numericCompare(a, b int) compareResult {
-	var (
-		isValuesInvalid  = a < 0 || b < 0
-		isZeroValuesBoth = a == 0 && b == 0
-		isEqual          = a == b
-		isZeroValueInA   = b > 0 && a == 0
-		isZeroValueInB   = a > 0 && b == 0
-	)
-
-	switch {
-	case isZeroValuesBoth || isEqual:
+func numericCompare(a, b int) int {
+	// Negative values and zeros are skipped (equal) because they either invalid or  "neutral" (default int value).
+	if a <= 0 || b <= 0 {
 		return equal
-	case isValuesInvalid || isZeroValueInA || isZeroValueInB:
-		return none
-	case a > b:
-		return greater
-	case a < b:
-		return less
 	}
 
-	return equal
+	return cmp.Compare(a, b)
+}
+
+func mergeComparators(comps ...issueComparator) issueComparator {
+	return func(a, b *result.Issue) int {
+		for _, comp := range comps {
+			i := comp(a, b)
+			if i != equal {
+				return i
+			}
+		}
+
+		return equal
+	}
 }