/
code.go
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/
code.go
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// Copyright 2013 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 web
import (
"bytes"
"fmt"
"html"
"html/template"
"log"
"regexp"
"strings"
"rsc.io/web/internal/texthtml"
)
func (s *siteDir) code(file string, arg ...interface{}) (_ template.HTML, err error) {
defer func() {
if r := recover(); r != nil {
err = fmt.Errorf("%v", r)
}
}()
_, text, _, cfg, err := s.locate("code", file, arg...)
if err != nil {
return "", err
}
cfg.GoComments = true
if cfg.HL == "" {
cfg.HL = "HL"
}
var buf bytes.Buffer
fmt.Fprintf(&buf, "<div class=\"code\">\n\n")
fmt.Fprintf(&buf, "<pre>")
// HTML-escape text and syntax-color comments like elsewhere.
buf.Write(texthtml.Format([]byte(text), cfg))
fmt.Fprintf(&buf, "</pre>\n")
fmt.Fprintf(&buf, "</div>\n\n")
return template.HTML(buf.String()), nil
}
func (s *siteDir) play(file string, arg ...interface{}) (_ template.HTML, err error) {
defer func() {
if r := recover(); r != nil {
err = fmt.Errorf("%v", r)
}
}()
before, text, after, cfg, err := s.locate("play", file, arg...)
if err != nil {
return "", err
}
cfg.Playground = true
var buf bytes.Buffer
fmt.Fprintf(&buf, "<div class=\"playground\">\n\n")
if before != "" {
fmt.Fprintf(&buf, "<pre style=\"display: none\"><span>%s</span>\n</pre>\n", html.EscapeString(before))
}
// HTML-escape text and syntax-color comments like elsewhere.
fmt.Fprintf(&buf, "<pre contenteditable=\"true\" spellcheck=\"false\">")
buf.Write(texthtml.Format([]byte(text), cfg))
fmt.Fprintf(&buf, "</pre>\n")
if after != "" {
fmt.Fprintf(&buf, "<pre style=\"display: none\"><span>%s</span>\n</pre>\n", html.EscapeString(after))
}
fmt.Fprintf(&buf, "</div>\n\n")
return template.HTML(buf.String()), nil
}
func (s *siteDir) locate(verb, file string, arg ...interface{}) (before, text, after string, cfg texthtml.Config, err error) {
btext, err := s.readFile(s.dir, file)
if err != nil {
return
}
text = string(btext)
if len(arg) > 0 {
if s, ok := arg[len(arg)-1].(string); ok && strings.HasPrefix(s, "HL") {
cfg.HL = s
arg = arg[:len(arg)-1]
}
}
if len(arg) > 0 {
if n, ok := arg[len(arg)-1].(int); ok {
if n == 0 {
n = -1
}
cfg.Line = n
arg = arg[:len(arg)-1]
}
}
switch len(arg) {
case 0:
// text is already whole file.
if cfg.Line == -1 {
cfg.Line = 1
}
case 1:
var n int
before, text, after, n = s.oneLine(file, text, arg[0])
if cfg.Line == -1 {
cfg.Line = n
}
case 2:
var n int
before, text, after, n = s.multipleLines(file, text, arg[0], arg[1])
if cfg.Line == -1 {
cfg.Line = n
}
default:
err = fmt.Errorf("incorrect code invocation: %s %q [%v, ...] (%d arguments)", verb, file, arg[0], len(arg))
return
}
// Trim leading and trailing blank lines from output.
text = strings.Trim(text, "\n")
if text != "" {
text += "\n"
}
// Replace tabs by spaces, which work better in HTML.
text = strings.Replace(text, "\t", " ", -1)
return
}
// Functions in this file panic on error, but the panic is recovered
// to an error by 'code'.
// 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 ""
}
// oneLine returns the single line generated by a two-argument code invocation.
func (s *Site) oneLine(file, body string, arg interface{}) (before, text, after string, num int) {
lines := strings.SplitAfter(body, "\n")
line, pattern, isInt := parseArg(arg, file, len(lines))
if !isInt {
line = match(file, 0, lines, pattern)
}
line--
return strings.Join(lines[:line], ""), lines[line], strings.Join(lines[line+1:], ""), line
}
// multipleLines returns the text generated by a three-argument code invocation.
func (s *Site) multipleLines(file, body string, arg1, arg2 interface{}) (before, text, after string, num int) {
lines := strings.SplitAfter(body, "\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", file, line1, line2)
}
for k := line1 - 1; k < line2; k++ {
if strings.HasSuffix(lines[k], "OMIT\n") {
lines[k] = ""
}
}
line1--
return strings.Join(lines[:line1], ""),
strings.Join(lines[line1:line2], ""),
strings.Join(lines[line2:], ""), line1
}
// 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
}
// 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("(?m)" + 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
}