fix: Make prefix_order case insensitive when case=no. (#60)

See the history of this PR to see how prefixes.out has changed.

goldens/prefixes.in

@@ -1,42 +1,52 @@
 preferred prefixes putting 'build_target' before 'branch_name':
-build_specs {
-  # keep-sorted-test start prefix_order=build_target,branch_name
-  build_target: "//foo/baz"
-  branch_name: "dev"
-  build_target: "//foo/bar"
-  branch_name: "prod"
-  # keep-sorted-test end
-}
+  build_specs {
+    # keep-sorted-test start prefix_order=build_target,branch_name
+    build_target: "//foo/baz"
+    branch_name: "dev"
+    build_target: "//foo/bar"
+    branch_name: "prod"
+    # keep-sorted-test end
+  }
 
 Put the specified prefixes at the end:
-items = [
-  # keep-sorted-test start prefix_order=,FOO,BAR
-  FOO,
-  DING,
-  BAR
-  BATS,
-  # keep-sorted-test end
-]
+  items = [
+    # keep-sorted-test start prefix_order=,FOO,BAR
+    FOO,
+    DING,
+    BAR
+    BATS,
+    # keep-sorted-test end
+  ]
+
+Case insensitive put the specified prefixes at the end:
+  items = [
+    # keep-sorted-test start case=no prefix_order=,foo,bar
+    FOO,
+    DING,
+    BAR
+    BATS,
+    # keep-sorted-test end
+  ]
 
 Put a group of items in the beginning, another group at the end:
-// keep-sorted-test start prefix_order=INIT_,,FINAL_
-INIT_FOO,
-FINAL_FOO,
-INIT_BAR,
-FINAL_BAR,
-DO_STUFF,
-DO_MORE_STUFF,
-ZAP_THINGS
-// keep-sorted-test end
+  // keep-sorted-test start prefix_order=INIT_,,FINAL_
+  INIT_FOO,
+  FINAL_FOO,
+  INIT_BAR,
+  FINAL_BAR,
+  DO_STUFF,
+  DO_MORE_STUFF,
+  ZAP_THINGS
+  // keep-sorted-test end
 
 preferred prefixes with comments:
-build_specs {
-  # keep-sorted-test start prefix_order=build_target,branch_name
-  build_target: "//foo/baz"
-  # required for development.
-  branch_name: "dev"
-  # raise the bar!
-  build_target: "//foo/bar"
-  branch_name: "prod"
-  # keep-sorted-test end
-}
+  build_specs {
+    # keep-sorted-test start prefix_order=build_target,branch_name
+    build_target: "//foo/baz"
+    # required for development.
+    branch_name: "dev"
+    # raise the bar!
+    build_target: "//foo/bar"
+    branch_name: "prod"
+    # keep-sorted-test end
+  }

goldens/prefixes.out

@@ -1,42 +1,52 @@
 preferred prefixes putting 'build_target' before 'branch_name':
-build_specs {
-  # keep-sorted-test start prefix_order=build_target,branch_name
-  build_target: "//foo/bar"
-  build_target: "//foo/baz"
-  branch_name: "dev"
-  branch_name: "prod"
-  # keep-sorted-test end
-}
+  build_specs {
+    # keep-sorted-test start prefix_order=build_target,branch_name
+    build_target: "//foo/bar"
+    build_target: "//foo/baz"
+    branch_name: "dev"
+    branch_name: "prod"
+    # keep-sorted-test end
+  }
 
 Put the specified prefixes at the end:
-items = [
-  # keep-sorted-test start prefix_order=,FOO,BAR
-  BATS,
-  DING,
-  FOO,
-  BAR
-  # keep-sorted-test end
-]
+  items = [
+    # keep-sorted-test start prefix_order=,FOO,BAR
+    BATS,
+    DING,
+    FOO,
+    BAR
+    # keep-sorted-test end
+  ]
+
+Case insensitive put the specified prefixes at the end:
+  items = [
+    # keep-sorted-test start case=no prefix_order=,foo,bar
+    BATS,
+    DING,
+    FOO,
+    BAR
+    # keep-sorted-test end
+  ]
 
 Put a group of items in the beginning, another group at the end:
-// keep-sorted-test start prefix_order=INIT_,,FINAL_
-INIT_BAR,
-INIT_FOO,
-DO_MORE_STUFF,
-DO_STUFF,
-ZAP_THINGS,
-FINAL_BAR,
-FINAL_FOO
-// keep-sorted-test end
+  // keep-sorted-test start prefix_order=INIT_,,FINAL_
+  INIT_BAR,
+  INIT_FOO,
+  DO_MORE_STUFF,
+  DO_STUFF,
+  ZAP_THINGS,
+  FINAL_BAR,
+  FINAL_FOO
+  // keep-sorted-test end
 
 preferred prefixes with comments:
-build_specs {
-  # keep-sorted-test start prefix_order=build_target,branch_name
-  # raise the bar!
-  build_target: "//foo/bar"
-  build_target: "//foo/baz"
-  # required for development.
-  branch_name: "dev"
-  branch_name: "prod"
-  # keep-sorted-test end
-}
+  build_specs {
+    # keep-sorted-test start prefix_order=build_target,branch_name
+    # raise the bar!
+    build_target: "//foo/bar"
+    build_target: "//foo/baz"
+    # required for development.
+    branch_name: "dev"
+    branch_name: "prod"
+    # keep-sorted-test end
+  }

keepsorted/block.go

@@ -382,24 +382,20 @@ func (b block) lessFn() cmpFunc[lineGroup] {
 	//
 	// An empty prefix can be used to move "non-matching" entries to a position
 	// between other prefixes.
-	type prefixWeight struct {
-		prefix string
-		weight int
-	}
-	var prefixWeights []prefixWeight
+	prefixWeights := make(map[string]int)
 	for i, p := range b.metadata.opts.PrefixOrder {
-		prefixWeights = append(prefixWeights, prefixWeight{p, i - len(b.metadata.opts.PrefixOrder)})
+		prefixWeights[p] = i - len(b.metadata.opts.PrefixOrder)
 	}
 	// Sort prefixes longest -> shortest to find the most appropriate weight.
-	slices.SortStableFunc(prefixWeights, comparing(func(pw prefixWeight) int { return len(pw.prefix) }).reversed())
+	longestFirst := comparing(func(s string) int { return len(s) }).reversed()
+	prefixes := slices.SortedStableFunc(slices.Values(b.metadata.opts.PrefixOrder), longestFirst)
 
 	prefixOrder := comparing(func(lg lineGroup) int {
-		for _, w := range prefixWeights {
-			if lg.hasPrefix(w.prefix) {
-				return w.weight
-			}
+		p, ok := b.metadata.opts.hasPrefix(lg.joinedLines(), slices.Values(prefixes))
+		if !ok {
+			return 0
 		}
-		return 0
+		return prefixWeights[p]
 	})
 
 	// Combinations of switches (for example, case-insensitive and numeric

keepsorted/line_group.go

@@ -309,10 +309,6 @@ func (lg lineGroup) append(s string) {
 	lg.lines[len(lg.lines)-1] = lg.lines[len(lg.lines)-1] + s
 }
 
-func (lg lineGroup) hasPrefix(s string) bool {
-	return strings.HasPrefix(lg.joinedLines(), s)
-}
-
 func (lg lineGroup) hasSuffix(s string) bool {
 	return len(lg.lines) > 0 && strings.HasSuffix(lg.lines[len(lg.lines)-1], s)
 }

keepsorted/options.go

@@ -15,7 +15,6 @@
 package keepsorted
 
 import (
-	"cmp"
 	"errors"
 	"fmt"
 	"iter"
@@ -171,10 +170,9 @@ func parseBlockOptions(commentMarker, options string, defaults blockOptions) (_
 	if cm := guessCommentMarker(commentMarker); cm != "" {
 		ret.setCommentMarker(cm)
 	}
-	if len(ret.IgnorePrefixes) > 1 {
-		// Look at longer prefixes first, in case one of these prefixes is a prefix of another.
-		slices.SortFunc(ret.IgnorePrefixes, func(a string, b string) int { return cmp.Compare(len(b), len(a)) })
-	}
+	// Look at longer prefixes first, in case one of these prefixes is a prefix of another.
+	longestFirst := comparing(func(s string) int { return len(s) }).reversed()
+	slices.SortFunc(ret.IgnorePrefixes, longestFirst)
 
 	if warn := validate(&ret); len(warn) > 0 {
 		warns = append(warns, warn...)