From de60b61b0ea7867bb1ded3768939cb8cf43f0e84 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Fri, 26 Feb 2021 02:18:13 -0500 Subject: cmd/golangorg: split out internal/codewalk [generated] This code is not likely to ever change, so it's nice to stash elsewhere. CL generated by the script below. [git-generate] cd cmd/golangorg rf ' mv codewalk.go golang.org/x/website/internal/codewalk ' cd ../../internal/codewalk rf ' mv CodewalkServer Server mv NewCodewalkServer NewServer mv Codewalk codewalk mv Codestep codestep ' Change-Id: If16a7dc9214a8d44ce42bc8e7e6ccd502b718c0e Reviewed-on: https://go-review.googlesource.com/c/website/+/317661 Trust: Russ Cox Run-TryBot: Russ Cox Website-Publish: Russ Cox Reviewed-by: Dmitri Shuralyov --- cmd/golangorg/codewalk.go | 529 ------------------------------------------ cmd/golangorg/handlers.go | 3 +- internal/codewalk/codewalk.go | 528 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 530 insertions(+), 530 deletions(-) delete mode 100644 cmd/golangorg/codewalk.go create mode 100644 internal/codewalk/codewalk.go diff --git a/cmd/golangorg/codewalk.go b/cmd/golangorg/codewalk.go deleted file mode 100644 index 00a5ea50..00000000 --- a/cmd/golangorg/codewalk.go +++ /dev/null @@ -1,529 +0,0 @@ -// Copyright 2010 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 - -// The /doc/codewalk/ tree is synthesized from codewalk descriptions, -// files named _content/doc/codewalk/*.xml. -// For an example and a description of the format, see -// http://golang.org/doc/codewalk/codewalk or run godoc -http=:6060 -// and see http://localhost:6060/doc/codewalk/codewalk . -// That page is itself a codewalk; the source code for it is -// _content/doc/codewalk/codewalk.xml. - -package main - -import ( - "encoding/xml" - "errors" - "fmt" - "html/template" - "io" - "io/fs" - "log" - "net/http" - "os" - "path" - pathpkg "path" - "regexp" - "sort" - "strconv" - "strings" - "unicode/utf8" - - "golang.org/x/website/internal/web" -) - -type CodewalkServer struct { - fsys fs.FS - site *web.Site -} - -func NewCodewalkServer(fsys fs.FS, site *web.Site) *CodewalkServer { - return &CodewalkServer{fsys, site} -} - -// Handler for /doc/codewalk/ and below. -func (s *CodewalkServer) ServeHTTP(w http.ResponseWriter, r *http.Request) { - relpath := path.Clean(r.URL.Path[1:]) - - r.ParseForm() - if f := r.FormValue("fileprint"); f != "" { - s.codewalkFileprint(w, r, f) - return - } - - // If directory exists, serve list of code walks. - dir, err := fs.Stat(s.fsys, relpath) - if err == nil && dir.IsDir() { - s.codewalkDir(w, r, relpath) - return - } - - // If file exists, serve using standard file server. - if err == nil { - s.site.ServeHTTP(w, r) - return - } - - // Otherwise append .xml and hope to find - // a codewalk description, but before trim - // the trailing /. - cw, err := s.loadCodewalk(relpath + ".xml") - if err != nil { - log.Print(err) - s.site.ServeError(w, r, err) - return - } - - // Canonicalize the path and redirect if changed - if redir(w, r) { - return - } - - s.site.ServePage(w, r, web.Page{ - Title: "Codewalk: " + cw.Title, - TabTitle: cw.Title, - Template: "codewalk.html", - Data: cw, - }) -} - -func redir(w http.ResponseWriter, r *http.Request) (redirected bool) { - canonical := pathpkg.Clean(r.URL.Path) - if !strings.HasSuffix(canonical, "/") { - canonical += "/" - } - if r.URL.Path != canonical { - url := *r.URL - url.Path = canonical - http.Redirect(w, r, url.String(), http.StatusMovedPermanently) - redirected = true - } - return -} - -// A Codewalk represents a single codewalk read from an XML file. -type Codewalk struct { - Title string `xml:"title,attr"` - File []string `xml:"file"` - Step []*Codestep `xml:"step"` -} - -// A Codestep is a single step in a codewalk. -type Codestep struct { - // Filled in from XML - Src string `xml:"src,attr"` - Title string `xml:"title,attr"` - XML string `xml:",innerxml"` - - // Derived from Src; not in XML. - Err error - File string - Lo int - LoByte int - Hi int - HiByte int - Data []byte -} - -func (c *Codestep) HTML() template.HTML { - return template.HTML(c.XML) -} - -// String method for printing in template. -// Formats file address nicely. -func (st *Codestep) String() string { - s := st.File - if st.Lo != 0 || st.Hi != 0 { - s += fmt.Sprintf(":%d", st.Lo) - if st.Lo != st.Hi { - s += fmt.Sprintf(",%d", st.Hi) - } - } - return s -} - -// loadCodewalk reads a codewalk from the named XML file. -func (s *CodewalkServer) loadCodewalk(filename string) (*Codewalk, error) { - f, err := s.fsys.Open(filename) - if err != nil { - return nil, err - } - defer f.Close() - cw := new(Codewalk) - d := xml.NewDecoder(f) - d.Entity = xml.HTMLEntity - err = d.Decode(cw) - if err != nil { - return nil, &os.PathError{Op: "parsing", Path: filename, Err: err} - } - - // Compute file list, evaluate line numbers for addresses. - m := make(map[string]bool) - for _, st := range cw.Step { - i := strings.Index(st.Src, ":") - if i < 0 { - i = len(st.Src) - } - filename := st.Src[0:i] - data, err := fs.ReadFile(s.fsys, filename) - if err != nil { - st.Err = err - continue - } - if i < len(st.Src) { - lo, hi, err := addrToByteRange(st.Src[i+1:], 0, data) - if err != nil { - st.Err = err - continue - } - // Expand match to line boundaries. - for lo > 0 && data[lo-1] != '\n' { - lo-- - } - for hi < len(data) && (hi == 0 || data[hi-1] != '\n') { - hi++ - } - st.Lo = byteToLine(data, lo) - st.Hi = byteToLine(data, hi-1) - } - st.Data = data - st.File = filename - m[filename] = true - } - - // Make list of files - cw.File = make([]string, len(m)) - i := 0 - for f := range m { - cw.File[i] = f - i++ - } - sort.Strings(cw.File) - - return cw, nil -} - -// codewalkDir serves the codewalk directory listing. -// It scans the directory for subdirectories or files named *.xml -// and prepares a table. -func (s *CodewalkServer) codewalkDir(w http.ResponseWriter, r *http.Request, relpath string) { - type elem struct { - Name string - Title string - } - - dir, err := fs.ReadDir(s.fsys, relpath) - if err != nil { - log.Print(err) - s.site.ServeError(w, r, err) - return - } - var v []interface{} - for _, fi := range dir { - name := fi.Name() - if fi.IsDir() { - v = append(v, &elem{name + "/", ""}) - } else if strings.HasSuffix(name, ".xml") { - cw, err := s.loadCodewalk(relpath + "/" + name) - if err != nil { - continue - } - v = append(v, &elem{name[0 : len(name)-len(".xml")], cw.Title}) - } - } - - s.site.ServePage(w, r, web.Page{ - Title: "Codewalks", - Template: "codewalkdir.html", - Data: v, - }) -} - -// codewalkFileprint serves requests with ?fileprint=f&lo=lo&hi=hi. -// The filename f has already been retrieved and is passed as an argument. -// Lo and hi are the numbers of the first and last line to highlight -// in the response. This format is used for the middle window pane -// of the codewalk pages. It is a separate iframe and does not get -// the usual godoc HTML wrapper. -func (s *CodewalkServer) codewalkFileprint(w http.ResponseWriter, r *http.Request, f string) { - relpath := strings.Trim(path.Clean(f), "/") - data, err := fs.ReadFile(s.fsys, relpath) - if err != nil { - log.Print(err) - s.site.ServeError(w, r, err) - return - } - lo, _ := strconv.Atoi(r.FormValue("lo")) - hi, _ := strconv.Atoi(r.FormValue("hi")) - if hi < lo { - hi = lo - } - lo = lineToByte(data, lo) - hi = lineToByte(data, hi+1) - - // Put the mark 4 lines before lo, so that the iframe - // shows a few lines of context before the highlighted - // section. - n := 4 - mark := lo - for ; mark > 0 && n > 0; mark-- { - if data[mark-1] == '\n' { - if n--; n == 0 { - break - } - } - } - - io.WriteString(w, `
`)
-	template.HTMLEscape(w, data[0:mark])
-	io.WriteString(w, "")
-	template.HTMLEscape(w, data[mark:lo])
-	if lo < hi {
-		io.WriteString(w, "
")
-		template.HTMLEscape(w, data[lo:hi])
-		io.WriteString(w, "
")
-	}
-	template.HTMLEscape(w, data[hi:])
-	io.WriteString(w, "
") -} - -// addrToByte evaluates the given address starting at offset start in data. -// It returns the lo and hi byte offset of the matched region within data. -// See https://9p.io/sys/doc/sam/sam.html Table II -// for details on the syntax. -func addrToByteRange(addr string, start int, data []byte) (lo, hi int, err error) { - var ( - dir byte - prevc byte - charOffset bool - ) - lo = start - hi = start - for addr != "" && err == nil { - c := addr[0] - switch c { - default: - err = errors.New("invalid address syntax near " + string(c)) - case ',': - if len(addr) == 1 { - hi = len(data) - } else { - _, hi, err = addrToByteRange(addr[1:], hi, data) - } - return - - case '+', '-': - if prevc == '+' || prevc == '-' { - lo, hi, err = addrNumber(data, lo, hi, prevc, 1, charOffset) - } - dir = c - - case '$': - lo = len(data) - hi = len(data) - if len(addr) > 1 { - dir = '+' - } - - case '#': - charOffset = true - - case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': - var i int - for i = 1; i < len(addr); i++ { - if addr[i] < '0' || addr[i] > '9' { - break - } - } - var n int - n, err = strconv.Atoi(addr[0:i]) - if err != nil { - break - } - lo, hi, err = addrNumber(data, lo, hi, dir, n, charOffset) - dir = 0 - charOffset = false - prevc = c - addr = addr[i:] - continue - - case '/': - var i, j int - Regexp: - for i = 1; i < len(addr); i++ { - switch addr[i] { - case '\\': - i++ - case '/': - j = i + 1 - break Regexp - } - } - if j == 0 { - j = i - } - pattern := addr[1:i] - lo, hi, err = addrRegexp(data, lo, hi, dir, pattern) - prevc = c - addr = addr[j:] - continue - } - prevc = c - addr = addr[1:] - } - - if err == nil && dir != 0 { - lo, hi, err = addrNumber(data, lo, hi, dir, 1, charOffset) - } - if err != nil { - return 0, 0, err - } - return lo, hi, nil -} - -// addrNumber applies the given dir, n, and charOffset to the address lo, hi. -// dir is '+' or '-', n is the count, and charOffset is true if the syntax -// used was #n. Applying +n (or +#n) means to advance n lines -// (or characters) after hi. Applying -n (or -#n) means to back up n lines -// (or characters) before lo. -// The return value is the new lo, hi. -func addrNumber(data []byte, lo, hi int, dir byte, n int, charOffset bool) (int, int, error) { - switch dir { - case 0: - lo = 0 - hi = 0 - fallthrough - - case '+': - if charOffset { - pos := hi - for ; n > 0 && pos < len(data); n-- { - _, size := utf8.DecodeRune(data[pos:]) - pos += size - } - if n == 0 { - return pos, pos, nil - } - break - } - // find next beginning of line - if hi > 0 { - for hi < len(data) && data[hi-1] != '\n' { - hi++ - } - } - lo = hi - if n == 0 { - return lo, hi, nil - } - for ; hi < len(data); hi++ { - if data[hi] != '\n' { - continue - } - switch n--; n { - case 1: - lo = hi + 1 - case 0: - return lo, hi + 1, nil - } - } - - case '-': - if charOffset { - // Scan backward for bytes that are not UTF-8 continuation bytes. - pos := lo - for ; pos > 0 && n > 0; pos-- { - if data[pos]&0xc0 != 0x80 { - n-- - } - } - if n == 0 { - return pos, pos, nil - } - break - } - // find earlier beginning of line - for lo > 0 && data[lo-1] != '\n' { - lo-- - } - hi = lo - if n == 0 { - return lo, hi, nil - } - for ; lo >= 0; lo-- { - if lo > 0 && data[lo-1] != '\n' { - continue - } - switch n--; n { - case 1: - hi = lo - case 0: - return lo, hi, nil - } - } - } - - return 0, 0, errors.New("address out of range") -} - -// addrRegexp searches for pattern in the given direction starting at lo, hi. -// The direction dir is '+' (search forward from hi) or '-' (search backward from lo). -// Backward searches are unimplemented. -func addrRegexp(data []byte, lo, hi int, dir byte, pattern string) (int, int, error) { - re, err := regexp.Compile(pattern) - if err != nil { - return 0, 0, err - } - if dir == '-' { - // Could implement reverse search using binary search - // through file, but that seems like overkill. - return 0, 0, errors.New("reverse search not implemented") - } - m := re.FindIndex(data[hi:]) - if len(m) > 0 { - m[0] += hi - m[1] += hi - } else if hi > 0 { - // No match. Wrap to beginning of data. - m = re.FindIndex(data) - } - if len(m) == 0 { - return 0, 0, errors.New("no match for " + pattern) - } - return m[0], m[1], nil -} - -// lineToByte returns the byte index of the first byte of line n. -// Line numbers begin at 1. -func lineToByte(data []byte, n int) int { - if n <= 1 { - return 0 - } - n-- - for i, c := range data { - if c == '\n' { - if n--; n == 0 { - return i + 1 - } - } - } - return len(data) -} - -// byteToLine returns the number of the line containing the byte at index i. -func byteToLine(data []byte, i int) int { - l := 1 - for j, c := range data { - if j == i { - return l - } - if c == '\n' { - l++ - } - } - return l -} diff --git a/cmd/golangorg/handlers.go b/cmd/golangorg/handlers.go index 6000ac34..85b985d1 100644 --- a/cmd/golangorg/handlers.go +++ b/cmd/golangorg/handlers.go @@ -14,6 +14,7 @@ import ( "net/http" "strings" + "golang.org/x/website/internal/codewalk" "golang.org/x/website/internal/env" "golang.org/x/website/internal/redirect" "golang.org/x/website/internal/web" @@ -73,7 +74,7 @@ func registerHandlers(site *web.Site) *http.ServeMux { } mux := http.NewServeMux() mux.Handle("/", site) - mux.Handle("/doc/codewalk/", NewCodewalkServer(fsys, site)) + mux.Handle("/doc/codewalk/", codewalk.NewServer(fsys, site)) mux.Handle("/fmt", http.HandlerFunc(fmtHandler)) mux.Handle("/x/", http.HandlerFunc(xHandler)) redirect.Register(mux) diff --git a/internal/codewalk/codewalk.go b/internal/codewalk/codewalk.go new file mode 100644 index 00000000..532a0922 --- /dev/null +++ b/internal/codewalk/codewalk.go @@ -0,0 +1,528 @@ +// Copyright 2010 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 + +// The /doc/codewalk/ tree is synthesized from codewalk descriptions, +// files named _content/doc/codewalk/*.xml. +// For an example and a description of the format, see +// http://golang.org/doc/codewalk/codewalk or run godoc -http=:6060 +// and see http://localhost:6060/doc/codewalk/codewalk . +// That page is itself a codewalk; the source code for it is +// _content/doc/codewalk/codewalk.xml. + +package codewalk + +import ( + "encoding/xml" + "errors" + "fmt" + "html/template" + "io" + "io/fs" + "log" + "net/http" + "os" + "path" + "regexp" + "sort" + "strconv" + "strings" + "unicode/utf8" + + "golang.org/x/website/internal/web" +) + +type Server struct { + fsys fs.FS + site *web.Site +} + +func NewServer(fsys fs.FS, site *web.Site) *Server { + return &Server{fsys, site} +} + +// Handler for /doc/codewalk/ and below. +func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) { + relpath := path.Clean(r.URL.Path[1:]) + + r.ParseForm() + if f := r.FormValue("fileprint"); f != "" { + s.codewalkFileprint(w, r, f) + return + } + + // If directory exists, serve list of code walks. + dir, err := fs.Stat(s.fsys, relpath) + if err == nil && dir.IsDir() { + s.codewalkDir(w, r, relpath) + return + } + + // If file exists, serve using standard file server. + if err == nil { + s.site.ServeHTTP(w, r) + return + } + + // Otherwise append .xml and hope to find + // a codewalk description, but before trim + // the trailing /. + cw, err := s.loadCodewalk(relpath + ".xml") + if err != nil { + log.Print(err) + s.site.ServeError(w, r, err) + return + } + + // Canonicalize the path and redirect if changed + if redir(w, r) { + return + } + + s.site.ServePage(w, r, web.Page{ + Title: "Codewalk: " + cw.Title, + TabTitle: cw.Title, + Template: "codewalk.html", + Data: cw, + }) +} + +func redir(w http.ResponseWriter, r *http.Request) (redirected bool) { + canonical := path.Clean(r.URL.Path) + if !strings.HasSuffix(canonical, "/") { + canonical += "/" + } + if r.URL.Path != canonical { + url := *r.URL + url.Path = canonical + http.Redirect(w, r, url.String(), http.StatusMovedPermanently) + redirected = true + } + return +} + +// A codewalk represents a single codewalk read from an XML file. +type codewalk struct { + Title string `xml:"title,attr"` + File []string `xml:"file"` + Step []*codestep `xml:"step"` +} + +// A codestep is a single step in a codewalk. +type codestep struct { + // Filled in from XML + Src string `xml:"src,attr"` + Title string `xml:"title,attr"` + XML string `xml:",innerxml"` + + // Derived from Src; not in XML. + Err error + File string + Lo int + LoByte int + Hi int + HiByte int + Data []byte +} + +func (c *codestep) HTML() template.HTML { + return template.HTML(c.XML) +} + +// String method for printing in template. +// Formats file address nicely. +func (st *codestep) String() string { + s := st.File + if st.Lo != 0 || st.Hi != 0 { + s += fmt.Sprintf(":%d", st.Lo) + if st.Lo != st.Hi { + s += fmt.Sprintf(",%d", st.Hi) + } + } + return s +} + +// loadCodewalk reads a codewalk from the named XML file. +func (s *Server) loadCodewalk(filename string) (*codewalk, error) { + f, err := s.fsys.Open(filename) + if err != nil { + return nil, err + } + defer f.Close() + cw := new(codewalk) + d := xml.NewDecoder(f) + d.Entity = xml.HTMLEntity + err = d.Decode(cw) + if err != nil { + return nil, &os.PathError{Op: "parsing", Path: filename, Err: err} + } + + // Compute file list, evaluate line numbers for addresses. + m := make(map[string]bool) + for _, st := range cw.Step { + i := strings.Index(st.Src, ":") + if i < 0 { + i = len(st.Src) + } + filename := st.Src[0:i] + data, err := fs.ReadFile(s.fsys, filename) + if err != nil { + st.Err = err + continue + } + if i < len(st.Src) { + lo, hi, err := addrToByteRange(st.Src[i+1:], 0, data) + if err != nil { + st.Err = err + continue + } + // Expand match to line boundaries. + for lo > 0 && data[lo-1] != '\n' { + lo-- + } + for hi < len(data) && (hi == 0 || data[hi-1] != '\n') { + hi++ + } + st.Lo = byteToLine(data, lo) + st.Hi = byteToLine(data, hi-1) + } + st.Data = data + st.File = filename + m[filename] = true + } + + // Make list of files + cw.File = make([]string, len(m)) + i := 0 + for f := range m { + cw.File[i] = f + i++ + } + sort.Strings(cw.File) + + return cw, nil +} + +// codewalkDir serves the codewalk directory listing. +// It scans the directory for subdirectories or files named *.xml +// and prepares a table. +func (s *Server) codewalkDir(w http.ResponseWriter, r *http.Request, relpath string) { + type elem struct { + Name string + Title string + } + + dir, err := fs.ReadDir(s.fsys, relpath) + if err != nil { + log.Print(err) + s.site.ServeError(w, r, err) + return + } + var v []interface{} + for _, fi := range dir { + name := fi.Name() + if fi.IsDir() { + v = append(v, &elem{name + "/", ""}) + } else if strings.HasSuffix(name, ".xml") { + cw, err := s.loadCodewalk(relpath + "/" + name) + if err != nil { + continue + } + v = append(v, &elem{name[0 : len(name)-len(".xml")], cw.Title}) + } + } + + s.site.ServePage(w, r, web.Page{ + Title: "Codewalks", + Template: "codewalkdir.html", + Data: v, + }) +} + +// codewalkFileprint serves requests with ?fileprint=f&lo=lo&hi=hi. +// The filename f has already been retrieved and is passed as an argument. +// Lo and hi are the numbers of the first and last line to highlight +// in the response. This format is used for the middle window pane +// of the codewalk pages. It is a separate iframe and does not get +// the usual godoc HTML wrapper. +func (s *Server) codewalkFileprint(w http.ResponseWriter, r *http.Request, f string) { + relpath := strings.Trim(path.Clean(f), "/") + data, err := fs.ReadFile(s.fsys, relpath) + if err != nil { + log.Print(err) + s.site.ServeError(w, r, err) + return + } + lo, _ := strconv.Atoi(r.FormValue("lo")) + hi, _ := strconv.Atoi(r.FormValue("hi")) + if hi < lo { + hi = lo + } + lo = lineToByte(data, lo) + hi = lineToByte(data, hi+1) + + // Put the mark 4 lines before lo, so that the iframe + // shows a few lines of context before the highlighted + // section. + n := 4 + mark := lo + for ; mark > 0 && n > 0; mark-- { + if data[mark-1] == '\n' { + if n--; n == 0 { + break + } + } + } + + io.WriteString(w, `
`)
+	template.HTMLEscape(w, data[0:mark])
+	io.WriteString(w, "")
+	template.HTMLEscape(w, data[mark:lo])
+	if lo < hi {
+		io.WriteString(w, "
")
+		template.HTMLEscape(w, data[lo:hi])
+		io.WriteString(w, "
")
+	}
+	template.HTMLEscape(w, data[hi:])
+	io.WriteString(w, "
") +} + +// addrToByte evaluates the given address starting at offset start in data. +// It returns the lo and hi byte offset of the matched region within data. +// See https://9p.io/sys/doc/sam/sam.html Table II +// for details on the syntax. +func addrToByteRange(addr string, start int, data []byte) (lo, hi int, err error) { + var ( + dir byte + prevc byte + charOffset bool + ) + lo = start + hi = start + for addr != "" && err == nil { + c := addr[0] + switch c { + default: + err = errors.New("invalid address syntax near " + string(c)) + case ',': + if len(addr) == 1 { + hi = len(data) + } else { + _, hi, err = addrToByteRange(addr[1:], hi, data) + } + return + + case '+', '-': + if prevc == '+' || prevc == '-' { + lo, hi, err = addrNumber(data, lo, hi, prevc, 1, charOffset) + } + dir = c + + case '$': + lo = len(data) + hi = len(data) + if len(addr) > 1 { + dir = '+' + } + + case '#': + charOffset = true + + case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': + var i int + for i = 1; i < len(addr); i++ { + if addr[i] < '0' || addr[i] > '9' { + break + } + } + var n int + n, err = strconv.Atoi(addr[0:i]) + if err != nil { + break + } + lo, hi, err = addrNumber(data, lo, hi, dir, n, charOffset) + dir = 0 + charOffset = false + prevc = c + addr = addr[i:] + continue + + case '/': + var i, j int + Regexp: + for i = 1; i < len(addr); i++ { + switch addr[i] { + case '\\': + i++ + case '/': + j = i + 1 + break Regexp + } + } + if j == 0 { + j = i + } + pattern := addr[1:i] + lo, hi, err = addrRegexp(data, lo, hi, dir, pattern) + prevc = c + addr = addr[j:] + continue + } + prevc = c + addr = addr[1:] + } + + if err == nil && dir != 0 { + lo, hi, err = addrNumber(data, lo, hi, dir, 1, charOffset) + } + if err != nil { + return 0, 0, err + } + return lo, hi, nil +} + +// addrNumber applies the given dir, n, and charOffset to the address lo, hi. +// dir is '+' or '-', n is the count, and charOffset is true if the syntax +// used was #n. Applying +n (or +#n) means to advance n lines +// (or characters) after hi. Applying -n (or -#n) means to back up n lines +// (or characters) before lo. +// The return value is the new lo, hi. +func addrNumber(data []byte, lo, hi int, dir byte, n int, charOffset bool) (int, int, error) { + switch dir { + case 0: + lo = 0 + hi = 0 + fallthrough + + case '+': + if charOffset { + pos := hi + for ; n > 0 && pos < len(data); n-- { + _, size := utf8.DecodeRune(data[pos:]) + pos += size + } + if n == 0 { + return pos, pos, nil + } + break + } + // find next beginning of line + if hi > 0 { + for hi < len(data) && data[hi-1] != '\n' { + hi++ + } + } + lo = hi + if n == 0 { + return lo, hi, nil + } + for ; hi < len(data); hi++ { + if data[hi] != '\n' { + continue + } + switch n--; n { + case 1: + lo = hi + 1 + case 0: + return lo, hi + 1, nil + } + } + + case '-': + if charOffset { + // Scan backward for bytes that are not UTF-8 continuation bytes. + pos := lo + for ; pos > 0 && n > 0; pos-- { + if data[pos]&0xc0 != 0x80 { + n-- + } + } + if n == 0 { + return pos, pos, nil + } + break + } + // find earlier beginning of line + for lo > 0 && data[lo-1] != '\n' { + lo-- + } + hi = lo + if n == 0 { + return lo, hi, nil + } + for ; lo >= 0; lo-- { + if lo > 0 && data[lo-1] != '\n' { + continue + } + switch n--; n { + case 1: + hi = lo + case 0: + return lo, hi, nil + } + } + } + + return 0, 0, errors.New("address out of range") +} + +// addrRegexp searches for pattern in the given direction starting at lo, hi. +// The direction dir is '+' (search forward from hi) or '-' (search backward from lo). +// Backward searches are unimplemented. +func addrRegexp(data []byte, lo, hi int, dir byte, pattern string) (int, int, error) { + re, err := regexp.Compile(pattern) + if err != nil { + return 0, 0, err + } + if dir == '-' { + // Could implement reverse search using binary search + // through file, but that seems like overkill. + return 0, 0, errors.New("reverse search not implemented") + } + m := re.FindIndex(data[hi:]) + if len(m) > 0 { + m[0] += hi + m[1] += hi + } else if hi > 0 { + // No match. Wrap to beginning of data. + m = re.FindIndex(data) + } + if len(m) == 0 { + return 0, 0, errors.New("no match for " + pattern) + } + return m[0], m[1], nil +} + +// lineToByte returns the byte index of the first byte of line n. +// Line numbers begin at 1. +func lineToByte(data []byte, n int) int { + if n <= 1 { + return 0 + } + n-- + for i, c := range data { + if c == '\n' { + if n--; n == 0 { + return i + 1 + } + } + } + return len(data) +} + +// byteToLine returns the number of the line containing the byte at index i. +func byteToLine(data []byte, i int) int { + l := 1 + for j, c := range data { + if j == i { + return l + } + if c == '\n' { + l++ + } + } + return l +} -- cgit v1.3