present/code.go - tools - Git at Google

 // 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 present

 import (
 	"bufio"
 	"bytes"
 	"fmt"
 	"html/template"
 	"path/filepath"
 	"regexp"
 	"strconv"
 	"strings"
 )

 // PlayEnabled specifies whether runnable playground snippets should be
 // displayed in the present user interface.
 var PlayEnabled = false

 // TODO(adg): replace the PlayEnabled flag with something less spaghetti-like.
 // Instead this will probably be determined by a template execution Context
 // value that contains various global metadata required when rendering
 // templates.

 // NotesEnabled specifies whether presenter notes should be displayed in the
 // present user interface.
 var NotesEnabled = false

 func init() {
 	Register("code", parseCode)
 	Register("play", parseCode)
 }

 type Code struct {
 	Cmd      string // original command from present source
 	Text     template.HTML
 	Play     bool   // runnable code
 	Edit     bool   // editable code
 	FileName string // file name
 	Ext      string // file extension
 	Raw      []byte // content of the file
 }

 func (c Code) PresentCmd() string   { return c.Cmd }
 func (c Code) TemplateName() string { return "code" }

 // The input line is a .code or .play entry with a file name and an optional HLfoo marker on the end.
 // Anything between the file and HL (if any) is an address expression, which we treat as a string here.
 // We pick off the HL first, for easy parsing.
 var (
 	highlightRE = regexp.MustCompile(`\s+HL([a-zA-Z0-9_]+)?$`)
 	hlCommentRE = regexp.MustCompile(`(.+) // HL(.*)$`)
 	codeRE      = regexp.MustCompile(`\.(code|play)\s+((?:(?:-edit|-numbers)\s+)*)([^\s]+)(?:\s+(.*))?$`)
 )

 // parseCode parses a code present directive. Its syntax:
 //   .code [-numbers] [-edit] <filename> [address] [highlight]
 // The directive may also be ".play" if the snippet is executable.
 func parseCode(ctx *Context, sourceFile string, sourceLine int, cmd string) (Elem, error) {
 	cmd = strings.TrimSpace(cmd)
 	origCmd := cmd

 	// Pull off the HL, if any, from the end of the input line.
 	highlight := ""
 	if hl := highlightRE.FindStringSubmatchIndex(cmd); len(hl) == 4 {
 		if hl[2] < 0 || hl[3] < 0 {
 			return nil, fmt.Errorf("%s:%d invalid highlight syntax", sourceFile, sourceLine)
 		}
 		highlight = cmd[hl[2]:hl[3]]
 		cmd = cmd[:hl[2]-2]
 	}

 	// Parse the remaining command line.
 	// Arguments:
 	// args[0]: whole match
 	// args[1]:  .code/.play
 	// args[2]: flags ("-edit -numbers")
 	// args[3]: file name
 	// args[4]: optional address
 	args := codeRE.FindStringSubmatch(cmd)
 	if len(args) != 5 {
 		return nil, fmt.Errorf("%s:%d: syntax error for .code/.play invocation", sourceFile, sourceLine)
 	}
 	command, flags, file, addr := args[1], args[2], args[3], strings.TrimSpace(args[4])
 	play := command == "play" && PlayEnabled

 	// Read in code file and (optionally) match address.
 	filename := filepath.Join(filepath.Dir(sourceFile), file)
 	textBytes, err := ctx.ReadFile(filename)
 	if err != nil {
 		return nil, fmt.Errorf("%s:%d: %v", sourceFile, sourceLine, err)
 	}
 	lo, hi, err := addrToByteRange(addr, 0, textBytes)
 	if err != nil {
 		return nil, fmt.Errorf("%s:%d: %v", sourceFile, sourceLine, err)
 	}
 	if lo > hi {
 		// The search in addrToByteRange can wrap around so we might
 		// end up with the range ending before its starting point
 		hi, lo = lo, hi
 	}

 	// Acme pattern matches can stop mid-line,
 	// so run to end of line in both directions if not at line start/end.
 	for lo > 0 && textBytes[lo-1] != '\n' {
 		lo--
 	}
 	if hi > 0 {
 		for hi < len(textBytes) && textBytes[hi-1] != '\n' {
 			hi++
 		}
 	}

 	lines := codeLines(textBytes, lo, hi)

 	data := &codeTemplateData{
 		Lines:   formatLines(lines, highlight),
 		Edit:    strings.Contains(flags, "-edit"),
 		Numbers: strings.Contains(flags, "-numbers"),
 	}

 	// Include before and after in a hidden span for playground code.
 	if play {
 		data.Prefix = textBytes[:lo]
 		data.Suffix = textBytes[hi:]
 	}

 	var buf bytes.Buffer
 	if err := codeTemplate.Execute(&buf, data); err != nil {
 		return nil, err
 	}
 	return Code{
 		Cmd:      origCmd,
 		Text:     template.HTML(buf.String()),
 		Play:     play,
 		Edit:     data.Edit,
 		FileName: filepath.Base(filename),
 		Ext:      filepath.Ext(filename),
 		Raw:      rawCode(lines),
 	}, nil
 }

 // formatLines returns a new slice of codeLine with the given lines
 // replacing tabs with spaces and adding highlighting where needed.
 func formatLines(lines []codeLine, highlight string) []codeLine {
 	formatted := make([]codeLine, len(lines))
 	for i, line := range lines {
 		// Replace tabs with spaces, which work better in HTML.
 		line.L = strings.Replace(line.L, "\t", "    ", -1)

 		// Highlight lines that end with "// HL[highlight]"
 		// and strip the magic comment.
 		if m := hlCommentRE.FindStringSubmatch(line.L); m != nil {
 			line.L = m[1]
 			line.HL = m[2] == highlight
 		}

 		formatted[i] = line
 	}
 	return formatted
 }

 // rawCode returns the code represented by the given codeLines without any kind
 // of formatting.
 func rawCode(lines []codeLine) []byte {
 	b := new(bytes.Buffer)
 	for _, line := range lines {
 		b.WriteString(line.L)
 		b.WriteByte('\n')
 	}
 	return b.Bytes()
 }

 type codeTemplateData struct {
 	Lines          []codeLine
 	Prefix, Suffix []byte
 	Edit, Numbers  bool
 }

 var leadingSpaceRE = regexp.MustCompile(`^[ \t]*`)

 var codeTemplate = template.Must(template.New("code").Funcs(template.FuncMap{
 	"trimSpace":    strings.TrimSpace,
 	"leadingSpace": leadingSpaceRE.FindString,
 }).Parse(codeTemplateHTML))

 const codeTemplateHTML = `
 {{with .Prefix}}<pre style="display: none"><span>{{printf "%s" .}}</span></pre>{{end -}}

 <pre{{if .Edit}} contenteditable="true" spellcheck="false"{{end}}{{if .Numbers}} class="numbers"{{end}}>{{/*
 	*/}}{{range .Lines}}<span num="{{.N}}">{{/*
 	*/}}{{if .HL}}{{leadingSpace .L}}<b>{{trimSpace .L}}</b>{{/*
 	*/}}{{else}}{{.L}}{{end}}{{/*
 */}}</span>
 {{end}}</pre>
 {{with .Suffix}}<pre style="display: none"><span>{{printf "%s" .}}</span></pre>{{end -}}
 `

 // codeLine represents a line of code extracted from a source file.
 type codeLine struct {
 	L  string // The line of code.
 	N  int    // The line number from the source file.
 	HL bool   // Whether the line should be highlighted.
 }

 // codeLines takes a source file and returns the lines that
 // span the byte range specified by start and end.
 // It discards lines that end in "OMIT".
 func codeLines(src []byte, start, end int) (lines []codeLine) {
 	startLine := 1
 	for i, b := range src {
 		if i == start {
 			break
 		}
 		if b == '\n' {
 			startLine++
 		}
 	}
 	s := bufio.NewScanner(bytes.NewReader(src[start:end]))
 	for n := startLine; s.Scan(); n++ {
 		l := s.Text()
 		if strings.HasSuffix(l, "OMIT") {
 			continue
 		}
 		lines = append(lines, codeLine{L: l, N: n})
 	}
 	// Trim leading and trailing blank lines.
 	for len(lines) > 0 && len(lines[0].L) == 0 {
 		lines = lines[1:]
 	}
 	for len(lines) > 0 && len(lines[len(lines)-1].L) == 0 {
 		lines = lines[:len(lines)-1]
 	}
 	return
 }

 func parseArgs(name string, line int, args []string) (res []interface{}, err error) {
 	res = make([]interface{}, len(args))
 	for i, v := range args {
 		if len(v) == 0 {
 			return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
 		}
 		switch v[0] {
 		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
 			n, err := strconv.Atoi(v)
 			if err != nil {
 				return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
 			}
 			res[i] = n
 		case '/':
 			if len(v) < 2 || v[len(v)-1] != '/' {
 				return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
 			}
 			res[i] = v
 		case '$':
 			res[i] = "$"
 		case '_':
 			if len(v) == 1 {
 				// Do nothing; "_" indicates an intentionally empty parameter.
 				break
 			}
 			fallthrough
 		default:
 			return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
 		}
 	}
 	return
 }
	// 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 present

	import (
	"bufio"
	"bytes"
	"fmt"
	"html/template"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	)

	// PlayEnabled specifies whether runnable playground snippets should be
	// displayed in the present user interface.
	var PlayEnabled = false

	// TODO(adg): replace the PlayEnabled flag with something less spaghetti-like.
	// Instead this will probably be determined by a template execution Context
	// value that contains various global metadata required when rendering
	// templates.

	// NotesEnabled specifies whether presenter notes should be displayed in the
	// present user interface.
	var NotesEnabled = false

	func init() {
	Register("code", parseCode)
	Register("play", parseCode)
	}

	type Code struct {
	Cmd string // original command from present source
	Text template.HTML
	Play bool // runnable code
	Edit bool // editable code
	FileName string // file name
	Ext string // file extension
	Raw []byte // content of the file
	}

	func (c Code) PresentCmd() string { return c.Cmd }
	func (c Code) TemplateName() string { return "code" }

	// The input line is a .code or .play entry with a file name and an optional HLfoo marker on the end.
	// Anything between the file and HL (if any) is an address expression, which we treat as a string here.
	// We pick off the HL first, for easy parsing.
	var (
	highlightRE = regexp.MustCompile(`\s+HL([a-zA-Z0-9_]+)?$`)
	hlCommentRE = regexp.MustCompile(`(.+) // HL(.*)$`)
	codeRE = regexp.MustCompile(`\.(code\|play)\s+((?:(?:-edit\|-numbers)\s+))([^\s]+)(?:\s+(.))?$`)
	)

	// parseCode parses a code present directive. Its syntax:
	// .code [-numbers] [-edit] <filename> [address] [highlight]
	// The directive may also be ".play" if the snippet is executable.
	func parseCode(ctx *Context, sourceFile string, sourceLine int, cmd string) (Elem, error) {
	cmd = strings.TrimSpace(cmd)
	origCmd := cmd

	// Pull off the HL, if any, from the end of the input line.
	highlight := ""
	if hl := highlightRE.FindStringSubmatchIndex(cmd); len(hl) == 4 {
	if hl[2] < 0 \|\| hl[3] < 0 {
	return nil, fmt.Errorf("%s:%d invalid highlight syntax", sourceFile, sourceLine)
	}
	highlight = cmd[hl[2]:hl[3]]
	cmd = cmd[:hl[2]-2]
	}

	// Parse the remaining command line.
	// Arguments:
	// args[0]: whole match
	// args[1]: .code/.play
	// args[2]: flags ("-edit -numbers")
	// args[3]: file name
	// args[4]: optional address
	args := codeRE.FindStringSubmatch(cmd)
	if len(args) != 5 {
	return nil, fmt.Errorf("%s:%d: syntax error for .code/.play invocation", sourceFile, sourceLine)
	}
	command, flags, file, addr := args[1], args[2], args[3], strings.TrimSpace(args[4])
	play := command == "play" && PlayEnabled

	// Read in code file and (optionally) match address.
	filename := filepath.Join(filepath.Dir(sourceFile), file)
	textBytes, err := ctx.ReadFile(filename)
	if err != nil {
	return nil, fmt.Errorf("%s:%d: %v", sourceFile, sourceLine, err)
	}
	lo, hi, err := addrToByteRange(addr, 0, textBytes)
	if err != nil {
	return nil, fmt.Errorf("%s:%d: %v", sourceFile, sourceLine, err)
	}
	if lo > hi {
	// The search in addrToByteRange can wrap around so we might
	// end up with the range ending before its starting point
	hi, lo = lo, hi
	}

	// Acme pattern matches can stop mid-line,
	// so run to end of line in both directions if not at line start/end.
	for lo > 0 && textBytes[lo-1] != '\n' {
	lo--
	}
	if hi > 0 {
	for hi < len(textBytes) && textBytes[hi-1] != '\n' {
	hi++
	}
	}

	lines := codeLines(textBytes, lo, hi)

	data := &codeTemplateData{
	Lines: formatLines(lines, highlight),
	Edit: strings.Contains(flags, "-edit"),
	Numbers: strings.Contains(flags, "-numbers"),
	}

	// Include before and after in a hidden span for playground code.
	if play {
	data.Prefix = textBytes[:lo]
	data.Suffix = textBytes[hi:]
	}

	var buf bytes.Buffer
	if err := codeTemplate.Execute(&buf, data); err != nil {
	return nil, err
	}
	return Code{
	Cmd: origCmd,
	Text: template.HTML(buf.String()),
	Play: play,
	Edit: data.Edit,
	FileName: filepath.Base(filename),
	Ext: filepath.Ext(filename),
	Raw: rawCode(lines),
	}, nil
	}

	// formatLines returns a new slice of codeLine with the given lines
	// replacing tabs with spaces and adding highlighting where needed.
	func formatLines(lines []codeLine, highlight string) []codeLine {
	formatted := make([]codeLine, len(lines))
	for i, line := range lines {
	// Replace tabs with spaces, which work better in HTML.
	line.L = strings.Replace(line.L, "\t", " ", -1)

	// Highlight lines that end with "// HL[highlight]"
	// and strip the magic comment.
	if m := hlCommentRE.FindStringSubmatch(line.L); m != nil {
	line.L = m[1]
	line.HL = m[2] == highlight
	}

	formatted[i] = line
	}
	return formatted
	}

	// rawCode returns the code represented by the given codeLines without any kind
	// of formatting.
	func rawCode(lines []codeLine) []byte {
	b := new(bytes.Buffer)
	for _, line := range lines {
	b.WriteString(line.L)
	b.WriteByte('\n')
	}
	return b.Bytes()
	}

	type codeTemplateData struct {
	Lines []codeLine
	Prefix, Suffix []byte
	Edit, Numbers bool
	}

	var leadingSpaceRE = regexp.MustCompile(`^[ \t]*`)

	var codeTemplate = template.Must(template.New("code").Funcs(template.FuncMap{
	"trimSpace": strings.TrimSpace,
	"leadingSpace": leadingSpaceRE.FindString,
	}).Parse(codeTemplateHTML))

	const codeTemplateHTML = `
	{{with .Prefix}}<pre style="display: none"><span>{{printf "%s" .}}</span></pre>{{end -}}

	<pre{{if .Edit}} contenteditable="true" spellcheck="false"{{end}}{{if .Numbers}} class="numbers"{{end}}>{{/*
	/}}{{range .Lines}}<span num="{{.N}}">{{/
	/}}{{if .HL}}{{leadingSpace .L}}<b>{{trimSpace .L}}</b>{{/
	/}}{{else}}{{.L}}{{end}}{{/
	*/}}</span>
	{{end}}</pre>
	{{with .Suffix}}<pre style="display: none"><span>{{printf "%s" .}}</span></pre>{{end -}}
	`

	// codeLine represents a line of code extracted from a source file.
	type codeLine struct {
	L string // The line of code.
	N int // The line number from the source file.
	HL bool // Whether the line should be highlighted.
	}

	// codeLines takes a source file and returns the lines that
	// span the byte range specified by start and end.
	// It discards lines that end in "OMIT".
	func codeLines(src []byte, start, end int) (lines []codeLine) {
	startLine := 1
	for i, b := range src {
	if i == start {
	break
	}
	if b == '\n' {
	startLine++
	}
	}
	s := bufio.NewScanner(bytes.NewReader(src[start:end]))
	for n := startLine; s.Scan(); n++ {
	l := s.Text()
	if strings.HasSuffix(l, "OMIT") {
	continue
	}
	lines = append(lines, codeLine{L: l, N: n})
	}
	// Trim leading and trailing blank lines.
	for len(lines) > 0 && len(lines[0].L) == 0 {
	lines = lines[1:]
	}
	for len(lines) > 0 && len(lines[len(lines)-1].L) == 0 {
	lines = lines[:len(lines)-1]
	}
	return
	}

	func parseArgs(name string, line int, args []string) (res []interface{}, err error) {
	res = make([]interface{}, len(args))
	for i, v := range args {
	if len(v) == 0 {
	return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
	}
	switch v[0] {
	case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
	n, err := strconv.Atoi(v)
	if err != nil {
	return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
	}
	res[i] = n
	case '/':
	if len(v) < 2 \|\| v[len(v)-1] != '/' {
	return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
	}
	res[i] = v
	case '$':
	res[i] = "$"
	case '_':
	if len(v) == 1 {
	// Do nothing; "_" indicates an intentionally empty parameter.
	break
	}
	fallthrough
	default:
	return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
	}
	}
	return
	}