62c5d65374
Add Catalog.All(), Catalog.SearchResults(), AllSections(), Tokens() iterators. Use slices.SortFunc, slices.Clone, maps.Values, built-in min replacing min3, strings.SplitSeq for streaming, range-over-int in levenshtein and benchmarks. Co-Authored-By: Gemini <noreply@google.com> Co-Authored-By: Virgil <virgil@lethean.io>
93 lines
2.3 KiB
Go
93 lines
2.3 KiB
Go
// SPDX-Licence-Identifier: EUPL-1.2
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package help
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import "strings"
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// stem performs lightweight Porter-style suffix stripping on an English word.
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// Words shorter than 4 characters are returned unchanged. The result is
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// guaranteed to be at least 2 characters long.
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//
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// This is intentionally NOT the full Porter algorithm — it covers only the
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// most impactful suffix rules for a help-catalog search context.
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func stem(word string) string {
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if len(word) < 4 {
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return word
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}
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s := word
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// Step 1: plurals and verb inflections.
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s = stemInflectional(s)
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// Step 2: derivational suffixes (longest match first).
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s = stemDerivational(s)
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// Guard: result must be at least 2 characters.
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if len(s) < 2 {
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return word
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}
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return s
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}
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// stemInflectional handles plurals and -ed/-ing verb forms.
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func stemInflectional(s string) string {
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switch {
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case strings.HasSuffix(s, "sses"):
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return s[:len(s)-2] // -sses → -ss
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case strings.HasSuffix(s, "ies"):
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return s[:len(s)-2] // -ies → -i
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case strings.HasSuffix(s, "eed"):
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return s[:len(s)-1] // -eed → -ee
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case strings.HasSuffix(s, "ing"):
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r := s[:len(s)-3]
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if len(r) >= 2 {
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return r
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}
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case strings.HasSuffix(s, "ed"):
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r := s[:len(s)-2]
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if len(r) >= 2 {
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return r
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}
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case strings.HasSuffix(s, "s") && !strings.HasSuffix(s, "ss"):
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return s[:len(s)-1] // -s → "" (but not -ss)
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}
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return s
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}
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// stemDerivational strips common derivational suffixes.
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// Ordered longest-first so we match the most specific rule.
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func stemDerivational(s string) string {
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// Longest suffixes first (8+ chars).
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type rule struct {
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suffix string
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replacement string
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}
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rules := []rule{
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{"fulness", "ful"}, // -fulness → -ful
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{"ational", "ate"}, // -ational → -ate
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{"tional", "tion"}, // -tional → -tion
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{"ously", "ous"}, // -ously → -ous
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{"ively", "ive"}, // -ively → -ive
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{"ingly", "ing"}, // -ingly → -ing
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{"ation", "ate"}, // -ation → -ate
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{"ness", ""}, // -ness → ""
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{"ment", ""}, // -ment → ""
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{"ably", "able"}, // -ably → -able
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{"ally", "al"}, // -ally → -al
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{"izer", "ize"}, // -izer → -ize
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}
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for _, r := range rules {
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if strings.HasSuffix(s, r.suffix) {
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result := s[:len(s)-len(r.suffix)] + r.replacement
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if len(result) >= 2 {
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return result
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}
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return s // Guard: don't over-strip
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}
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}
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return s
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}
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