present: make code in slides editable only with -edit

Also added a suite of tests and fixed a minor bug that
caused a panic when the .code command specified HL with
no text after.

Fixes golang/go#17379.

Change-Id: I3c246523c3d4010bf76a467ee648475255090e1b
Reviewed-on: https://go-review.googlesource.com/30691
Reviewed-by: Rob Pike <r@golang.org>

cmd/present/templates/action.tmpl

@@ -28,7 +28,7 @@ It determines how the formatting actions are rendered.
 {{end}}
 
 {{define "code"}}
-  <div class="code{{if playable .}} playground{{end}}" contenteditable="true" spellcheck="false">{{.Text}}</div>
+  <div class="code{{if playable .}} playground{{end}}" {{if .Edit}}contenteditable="true" spellcheck="false"{{end}}>{{.Text}}</div>
 {{end}}
 
 {{define "image"}}

present/code.go

@@ -36,6 +36,7 @@ func init() {
 type Code struct {
 	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
@@ -61,6 +62,9 @@ func parseCode(ctx *Context, sourceFile string, sourceLine int, cmd string) (Ele
 	// 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]
 	}
@@ -127,6 +131,7 @@ func parseCode(ctx *Context, sourceFile string, sourceLine int, cmd string) (Ele
 	return Code{
 		Text:     template.HTML(buf.String()),
 		Play:     play,
+		Edit:     data.Edit,
 		FileName: filepath.Base(filename),
 		Ext:      filepath.Ext(filename),
 		Raw:      rawCode(lines),

present/code_test.go

@@ -0,0 +1,226 @@
+// 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 (
+	"fmt"
+	"html/template"
+	"strings"
+	"testing"
+)
+
+func TestParseCode(t *testing.T) {
+	// Enable play but revert the change at the end.
+	defer func(play bool) { PlayEnabled = play }(PlayEnabled)
+	PlayEnabled = true
+
+	helloTest := []byte(`
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("hello, test")
+}
+`)
+	helloTestHTML := template.HTML(`
+<pre><span num="2">package main</span>
+<span num="3"></span>
+<span num="4">import &#34;fmt&#34;</span>
+<span num="5"></span>
+<span num="6">func main() {</span>
+<span num="7">    fmt.Println(&#34;hello, test&#34;)</span>
+<span num="8">}</span>
+</pre>
+`)
+	helloTestHL := []byte(`
+package main
+
+import "fmt" // HLimport
+
+func main() { // HLfunc
+	fmt.Println("hello, test") // HL
+}
+`)
+	highlight := func(h template.HTML, s string) template.HTML {
+		return template.HTML(strings.Replace(string(h), s, "<b>"+s+"</b>", -1))
+	}
+	read := func(b []byte, err error) func(string) ([]byte, error) {
+		return func(string) ([]byte, error) { return b, err }
+	}
+
+	tests := []struct {
+		name       string
+		readFile   func(string) ([]byte, error)
+		sourceFile string
+		sourceLine int
+		cmd        string
+		err        string
+		Code
+	}{
+		{
+			name:       "all code, no play",
+			readFile:   read(helloTest, nil),
+			sourceFile: "main.go",
+			cmd:        ".code main.go",
+			Code: Code{
+				Ext:      ".go",
+				FileName: "main.go",
+				Raw:      helloTest,
+				Text:     helloTestHTML,
+			},
+		},
+		{
+			name:       "all code, play",
+			readFile:   read(helloTest, nil),
+			sourceFile: "main.go",
+			cmd:        ".play main.go",
+			Code: Code{
+				Ext:      ".go",
+				FileName: "main.go",
+				Play:     true,
+				Raw:      helloTest,
+				Text:     helloTestHTML,
+			},
+		},
+		{
+			name:       "all code, highlighted",
+			readFile:   read(helloTestHL, nil),
+			sourceFile: "main.go",
+			cmd:        ".code main.go",
+			Code: Code{
+				Ext:      ".go",
+				FileName: "main.go",
+				Raw:      helloTestHL,
+				Text:     highlight(helloTestHTML, "fmt.Println(&#34;hello, test&#34;)"),
+			},
+		},
+		{
+			name:       "highlight only func",
+			readFile:   read(helloTestHL, nil),
+			sourceFile: "main.go",
+			cmd:        ".code main.go HLfunc",
+			Code: Code{
+				Ext:      ".go",
+				FileName: "main.go",
+				Play:     false,
+				Raw:      []byte("package main\n\nimport \"fmt\" // HLimport\n\nfunc main() { // HLfunc\n\tfmt.Println(\"hello, test\") // HL\n}"),
+				Text:     highlight(helloTestHTML, "func main() {"),
+			},
+		},
+		{
+			name:       "bad highlight syntax",
+			readFile:   read(helloTest, nil),
+			sourceFile: "main.go",
+			cmd:        ".code main.go HL",
+			err:        "invalid highlight syntax",
+		},
+		{
+			name:       "error reading file",
+			readFile:   read(nil, fmt.Errorf("nope")),
+			sourceFile: "main.go",
+			cmd:        ".code main.go",
+			err:        "main.go:0: nope",
+		},
+		{
+			name:       "from func main to the end",
+			readFile:   read(helloTest, nil),
+			sourceFile: "main.go",
+			cmd:        ".code main.go /func main/,",
+			Code: Code{
+				Ext:      ".go",
+				FileName: "main.go",
+				Play:     false,
+				Raw:      []byte("func main() {\n\tfmt.Println(\"hello, test\")\n}"),
+				Text:     "<pre><span num=\"6\">func main() {</span>\n<span num=\"7\">    fmt.Println(&#34;hello, test&#34;)</span>\n<span num=\"8\">}</span>\n</pre>",
+			},
+		},
+		{
+			name:       "just func main",
+			readFile:   read(helloTest, nil),
+			sourceFile: "main.go",
+			cmd:        ".code main.go /func main/",
+			Code: Code{
+				Ext:      ".go",
+				FileName: "main.go",
+				Play:     false,
+				Raw:      []byte("func main() {"),
+				Text:     "<pre><span num=\"6\">func main() {</span>\n</pre>",
+			},
+		},
+		{
+			name:       "bad address",
+			readFile:   read(helloTest, nil),
+			sourceFile: "main.go",
+			cmd:        ".code main.go /function main/",
+			err:        "main.go:0: no match for function main",
+		},
+		{
+			name:       "all code with  numbers",
+			readFile:   read(helloTest, nil),
+			sourceFile: "main.go",
+			cmd:        ".code -numbers main.go",
+			Code: Code{
+				Ext:      ".go",
+				FileName: "main.go",
+				Raw:      helloTest,
+				// Replacing the first "<pre>"
+				Text: "<pre class=\"numbers\">" + helloTestHTML[6:],
+			},
+		},
+		{
+			name:       "all code editable",
+			readFile:   read(helloTest, nil),
+			sourceFile: "main.go",
+			cmd:        ".code -edit main.go",
+			Code: Code{
+				Ext:      ".go",
+				FileName: "main.go",
+				Raw:      helloTest,
+				Text:     "<pre contenteditable=\"true\" spellcheck=\"false\">" + helloTestHTML[6:],
+			},
+		},
+	}
+
+	trimHTML := func(t template.HTML) string { return strings.TrimSpace(string(t)) }
+	trimBytes := func(b []byte) string { return strings.TrimSpace(string(b)) }
+
+	for _, tt := range tests {
+		ctx := &Context{tt.readFile}
+		e, err := parseCode(ctx, tt.sourceFile, 0, tt.cmd)
+		if err != nil {
+			if tt.err == "" {
+				t.Errorf("%s: unexpected error %v", tt.name, err)
+			} else if !strings.Contains(err.Error(), tt.err) {
+				t.Errorf("%s: expected error %s; got %v", tt.name, tt.err, err)
+			}
+			continue
+		}
+		if tt.err != "" {
+			t.Errorf("%s: expected error %s; but got none", tt.name, tt.err)
+			continue
+		}
+		c, ok := e.(Code)
+		if !ok {
+			t.Errorf("%s: expected a Code value; got %T", tt.name, e)
+			continue
+		}
+		if c.FileName != tt.FileName {
+			t.Errorf("%s: expected FileName %s; got %s", tt.name, tt.FileName, c.FileName)
+		}
+		if c.Ext != tt.Ext {
+			t.Errorf("%s: expected Ext %s; got %s", tt.name, tt.Ext, c.Ext)
+		}
+		if c.Play != tt.Play {
+			t.Errorf("%s: expected Play %v; got %v", tt.name, tt.Play, c.Play)
+		}
+		if got, wants := trimBytes(c.Raw), trimBytes(tt.Raw); got != wants {
+			t.Errorf("%s: expected Raw \n%q\n; got \n%q\n", tt.name, wants, got)
+		}
+		if got, wants := trimHTML(c.Text), trimHTML(tt.Text); got != wants {
+			t.Errorf("%s: expected Text \n%q\n; got \n%q\n", tt.name, wants, got)
+		}
+	}
+}