| // Copyright 2011 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. |
| |
| //go:build go1.16 |
| // +build go1.16 |
| |
| // Template support for writing HTML documents. |
| // Documents that include Template: true in their |
| // metadata are executed as input to text/template. |
| // |
| // This file defines functions for those templates to invoke. |
| |
| // The template uses the function "code" to inject program |
| // source into the output by extracting code from files and |
| // injecting them as HTML-escaped <pre> blocks. |
| // |
| // The syntax is simple: 1, 2, or 3 space-separated arguments: |
| // |
| // Whole file: |
| // {{code "foo.go"}} |
| // One line (here the signature of main): |
| // {{code "foo.go" `/^func.main/`}} |
| // Block of text, determined by start and end (here the body of main): |
| // {{code "foo.go" `/^func.main/` `/^}/` |
| // |
| // Patterns can be `/regular expression/`, a decimal number, or "$" |
| // to signify the end of the file. In multi-line matches, |
| // lines that end with the four characters |
| // OMIT |
| // are omitted from the output, making it easy to provide marker |
| // lines in the input that will not appear in the output but are easy |
| // to identify by pattern. |
| |
| package godoc |
| |
| import ( |
| "bytes" |
| "fmt" |
| "io/fs" |
| "log" |
| "regexp" |
| "strings" |
| |
| "golang.org/x/website/internal/texthtml" |
| ) |
| |
| // Functions in this file panic on error, but the panic is recovered |
| // to an error by 'code'. |
| |
| // contents reads and returns the content of the named file |
| // (from the virtual file system, so for example /doc refers to $GOROOT/doc). |
| func (p *Presentation) contents(name string) string { |
| file, err := fs.ReadFile(p.fs, toFS(name)) |
| if err != nil { |
| log.Panic(err) |
| } |
| return string(file) |
| } |
| |
| // stringFor returns a textual representation of the arg, formatted according to its nature. |
| func stringFor(arg interface{}) string { |
| switch arg := arg.(type) { |
| case int: |
| return fmt.Sprintf("%d", arg) |
| case string: |
| if len(arg) > 2 && arg[0] == '/' && arg[len(arg)-1] == '/' { |
| return fmt.Sprintf("%#q", arg) |
| } |
| return fmt.Sprintf("%q", arg) |
| default: |
| log.Panicf("unrecognized argument: %v type %T", arg, arg) |
| } |
| return "" |
| } |
| |
| func (p *Presentation) code(file string, arg ...interface{}) (s string, err error) { |
| defer func() { |
| if r := recover(); r != nil { |
| err = fmt.Errorf("%v", r) |
| } |
| }() |
| |
| text := p.contents(file) |
| var command string |
| switch len(arg) { |
| case 0: |
| // text is already whole file. |
| command = fmt.Sprintf("code %q", file) |
| case 1: |
| command = fmt.Sprintf("code %q %s", file, stringFor(arg[0])) |
| text = p.oneLine(file, text, arg[0]) |
| case 2: |
| command = fmt.Sprintf("code %q %s %s", file, stringFor(arg[0]), stringFor(arg[1])) |
| text = p.multipleLines(file, text, arg[0], arg[1]) |
| default: |
| return "", fmt.Errorf("incorrect code invocation: code %q [%v, ...] (%d arguments)", file, arg[0], len(arg)) |
| } |
| // Trim spaces from output. |
| text = strings.Trim(text, "\n") |
| // Replace tabs by spaces, which work better in HTML. |
| text = strings.Replace(text, "\t", " ", -1) |
| var buf bytes.Buffer |
| // HTML-escape text and syntax-color comments like elsewhere. |
| buf.Write(texthtml.Format([]byte(text), texthtml.Config{GoComments: true})) |
| // Include the command as a comment. |
| text = fmt.Sprintf("<pre><!--{{%s}}\n-->%s</pre>", command, buf.Bytes()) |
| return text, nil |
| } |
| |
| // parseArg returns the integer or string value of the argument and tells which it is. |
| func parseArg(arg interface{}, file string, max int) (ival int, sval string, isInt bool) { |
| switch n := arg.(type) { |
| case int: |
| if n <= 0 || n > max { |
| log.Panicf("%q:%d is out of range", file, n) |
| } |
| return n, "", true |
| case string: |
| return 0, n, false |
| } |
| log.Panicf("unrecognized argument %v type %T", arg, arg) |
| return |
| } |
| |
| // oneLine returns the single line generated by a two-argument code invocation. |
| func (p *Presentation) oneLine(file, text string, arg interface{}) string { |
| lines := strings.SplitAfter(p.contents(file), "\n") |
| line, pattern, isInt := parseArg(arg, file, len(lines)) |
| if isInt { |
| return lines[line-1] |
| } |
| return lines[match(file, 0, lines, pattern)-1] |
| } |
| |
| // multipleLines returns the text generated by a three-argument code invocation. |
| func (p *Presentation) multipleLines(file, text string, arg1, arg2 interface{}) string { |
| lines := strings.SplitAfter(p.contents(file), "\n") |
| line1, pattern1, isInt1 := parseArg(arg1, file, len(lines)) |
| line2, pattern2, isInt2 := parseArg(arg2, file, len(lines)) |
| if !isInt1 { |
| line1 = match(file, 0, lines, pattern1) |
| } |
| if !isInt2 { |
| line2 = match(file, line1, lines, pattern2) |
| } else if line2 < line1 { |
| log.Panicf("lines out of order for %q: %d %d", text, line1, line2) |
| } |
| for k := line1 - 1; k < line2; k++ { |
| if strings.HasSuffix(lines[k], "OMIT\n") { |
| lines[k] = "" |
| } |
| } |
| return strings.Join(lines[line1-1:line2], "") |
| } |
| |
| // match identifies the input line that matches the pattern in a code invocation. |
| // If start>0, match lines starting there rather than at the beginning. |
| // The return value is 1-indexed. |
| func match(file string, start int, lines []string, pattern string) int { |
| // $ matches the end of the file. |
| if pattern == "$" { |
| if len(lines) == 0 { |
| log.Panicf("%q: empty file", file) |
| } |
| return len(lines) |
| } |
| // /regexp/ matches the line that matches the regexp. |
| if len(pattern) > 2 && pattern[0] == '/' && pattern[len(pattern)-1] == '/' { |
| re, err := regexp.Compile(pattern[1 : len(pattern)-1]) |
| if err != nil { |
| log.Panic(err) |
| } |
| for i := start; i < len(lines); i++ { |
| if re.MatchString(lines[i]) { |
| return i + 1 |
| } |
| } |
| log.Panicf("%s: no match for %#q", file, pattern) |
| } |
| log.Panicf("unrecognized pattern: %q", pattern) |
| return 0 |
| } |