Imported Upstream version 60upstream/60

1 files changed, 100 insertions, 0 deletions

diff --git a/src/cmd/godoc/snippet.go b/src/cmd/godoc/snippet.go
new file mode 100755
index 000000000..68e27d9a0
--- /dev/null
+++ b/src/cmd/godoc/snippet.go
@@ -0,0 +1,100 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains the infrastructure to create a code
+// snippet for search results.
+//
+// Note: At the moment, this only creates HTML snippets.
+
+package main
+
+import (
+	"bytes"
+	"go/ast"
+	"go/token"
+	"fmt"
+)
+
+type Snippet struct {
+	Line int
+	Text string // HTML-escaped
+}
+
+func newSnippet(fset *token.FileSet, decl ast.Decl, id *ast.Ident) *Snippet {
+	// TODO instead of pretty-printing the node, should use the original source instead
+	var buf1 bytes.Buffer
+	writeNode(&buf1, fset, decl)
+	// wrap text with <pre> tag
+	var buf2 bytes.Buffer
+	buf2.WriteString("<pre>")
+	FormatText(&buf2, buf1.Bytes(), -1, true, id.Name, nil)
+	buf2.WriteString("</pre>")
+	return &Snippet{fset.Position(id.Pos()).Line, buf2.String()}
+}
+
+func findSpec(list []ast.Spec, id *ast.Ident) ast.Spec {
+	for _, spec := range list {
+		switch s := spec.(type) {
+		case *ast.ImportSpec:
+			if s.Name == id {
+				return s
+			}
+		case *ast.ValueSpec:
+			for _, n := range s.Names {
+				if n == id {
+					return s
+				}
+			}
+		case *ast.TypeSpec:
+			if s.Name == id {
+				return s
+			}
+		}
+	}
+	return nil
+}
+
+func genSnippet(fset *token.FileSet, d *ast.GenDecl, id *ast.Ident) *Snippet {
+	s := findSpec(d.Specs, id)
+	if s == nil {
+		return nil //  declaration doesn't contain id - exit gracefully
+	}
+
+	// only use the spec containing the id for the snippet
+	dd := &ast.GenDecl{d.Doc, d.Pos(), d.Tok, d.Lparen, []ast.Spec{s}, d.Rparen}
+
+	return newSnippet(fset, dd, id)
+}
+
+func funcSnippet(fset *token.FileSet, d *ast.FuncDecl, id *ast.Ident) *Snippet {
+	if d.Name != id {
+		return nil //  declaration doesn't contain id - exit gracefully
+	}
+
+	// only use the function signature for the snippet
+	dd := &ast.FuncDecl{d.Doc, d.Recv, d.Name, d.Type, nil}
+
+	return newSnippet(fset, dd, id)
+}
+
+// NewSnippet creates a text snippet from a declaration decl containing an
+// identifier id. Parts of the declaration not containing the identifier
+// may be removed for a more compact snippet.
+//
+func NewSnippet(fset *token.FileSet, decl ast.Decl, id *ast.Ident) (s *Snippet) {
+	switch d := decl.(type) {
+	case *ast.GenDecl:
+		s = genSnippet(fset, d, id)
+	case *ast.FuncDecl:
+		s = funcSnippet(fset, d, id)
+	}
+
+	// handle failure gracefully
+	if s == nil {
+		var buf bytes.Buffer
+		fmt.Fprintf(&buf, `<span class="alert">could not generate a snippet for <span class="highlight">%s</span></span>`, id.Name)
+		s = &Snippet{fset.Position(id.Pos()).Line, buf.String()}
+	}
+	return
+}