From 0126a1fd88fe40e3de18dd677e094b46e23d0cb9 Mon Sep 17 00:00:00 2001 From: Martin Angers Date: Sun, 13 Jun 2021 14:34:32 -0400 Subject: [PATCH] Implement Single and SingleMatcher --- example_test.go | 28 ++++++++++++++++++++++++++++ type.go | 49 ++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 76 insertions(+), 1 deletion(-) diff --git a/example_test.go b/example_test.go index bc97f05..924e8d1 100644 --- a/example_test.go +++ b/example_test.go @@ -80,3 +80,31 @@ func ExampleNewDocumentFromReader_string() { // Output: Header } + +func ExampleSingle() { + html := ` + + +
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+ + +` + doc, err := goquery.NewDocumentFromReader(strings.NewReader(html)) + if err != nil { + log.Fatal(err) + } + + // By default, the selector string selects all matching nodes + multiSel := doc.Find("div") + fmt.Println(multiSel.Text()) + + // Using goquery.Single, only the first match is selected + singleSel := doc.FindMatcher(goquery.Single("div")) + fmt.Println(singleSel.Text()) + + // Output: + // 123 + // 1 +} diff --git a/type.go b/type.go index 6ad51db..e3d0b68 100644 --- a/type.go +++ b/type.go @@ -7,7 +7,6 @@ import ( "net/url" "github.com/andybalholm/cascadia" - "golang.org/x/net/html" ) @@ -122,6 +121,30 @@ type Matcher interface { Filter([]*html.Node) []*html.Node } +// Single compiles a selector string to a Matcher that stops after the first +// match is found. +// +// By default, Selection.Find and other functions that accept a selector string +// will use all matches corresponding to that selector. By using the Matcher +// returned by Single, at most the first match will be used. +func Single(selector string) Matcher { + return singleMatcher{compileMatcher(selector)} +} + +// SingleMatcher returns a Matcher matches the same nodes as m, but that stops +// after the first match is found. +// +// By default, Selection.FindMatcher and other functions that accept a Matcher +// will use all corresponding matches. By using the Matcher returned by +// SingleMatcher, at most the first match will be used. +func SingleMatcher(m Matcher) Matcher { + if _, ok := m.(singleMatcher); ok { + // m is already a singleMatcher + return m + } + return singleMatcher{m} +} + // compileMatcher compiles the selector string s and returns // the corresponding Matcher. If s is an invalid selector string, // it returns a Matcher that fails all matches. @@ -133,6 +156,30 @@ func compileMatcher(s string) Matcher { return cs } +type singleMatcher struct { + Matcher +} + +func (m singleMatcher) MatchAll(n *html.Node) []*html.Node { + // Optimized version - stops finding at the first match (cascadia-compiled + // matchers all use this code path). + if mm, ok := m.Matcher.(interface{ MatchFirst(*html.Node) *html.Node }); ok { + node := mm.MatchFirst(n) + if node == nil { + return nil + } + return []*html.Node{node} + } + + // Fallback version, for e.g. test mocks that don't provide the MatchFirst + // method. + nodes := m.Matcher.MatchAll(n) + if len(nodes) > 0 { + return nodes[:1:1] + } + return nil +} + // invalidMatcher is a Matcher that always fails to match. type invalidMatcher struct{}