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// Copyright 2012 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.
package doc
import (
"go/doc/comment"
"strings"
"unicode"
)
// firstSentence returns the first sentence in s.
// The sentence ends after the first period followed by space and
// not preceded by exactly one uppercase letter.
func firstSentence(s string) string {
var ppp, pp, p rune
for i, q := range s {
if q == '\n' || q == '\r' || q == '\t' {
q = ' '
}
if q == ' ' && p == '.' && (!unicode.IsUpper(pp) || unicode.IsUpper(ppp)) {
return s[:i]
}
if p == '。' || p == '．' {
return s[:i]
}
ppp, pp, p = pp, p, q
}
return s
}
// Synopsis returns a cleaned version of the first sentence in text.
//
// Deprecated: New programs should use [Package.Synopsis] instead,
// which handles links in text properly.
func Synopsis(text string) string {
var p Package
return p.Synopsis(text)
}
// IllegalPrefixes is a list of lower-case prefixes that identify
// a comment as not being a doc comment.
// This helps to avoid misinterpreting the common mistake
// of a copyright notice immediately before a package statement
// as being a doc comment.
var IllegalPrefixes = []string{
"copyright",
"all rights",
"author",
}
// Synopsis returns a cleaned version of the first sentence in text.
// That sentence ends after the first period followed by space and not
// preceded by exactly one uppercase letter, or at the first paragraph break.
// The result string has no \n, \r, or \t characters and uses only single
// spaces between words. If text starts with any of the IllegalPrefixes,
// the result is the empty string.
func (p *Package) Synopsis(text string) string {
text = firstSentence(text)
lower := strings.ToLower(text)
for _, prefix := range IllegalPrefixes {
if strings.HasPrefix(lower, prefix) {
return ""
}
}
pr := p.Printer()
pr.TextWidth = -1
d := p.Parser().Parse(text)
if len(d.Content) == 0 {
return ""
}
if _, ok := d.Content[0].(*comment.Paragraph); !ok {
return ""
}
d.Content = d.Content[:1] // might be blank lines, code blocks, etc in “first sentence”
return strings.TrimSpace(string(pr.Text(d)))
}
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