Full-file syntax highlighting for diff pages (#33766)

Fix #33358, fix #21970

This adds a step in the `GitDiffForRender` that does syntax highlighting for the
entire file and then only references lines from that syntax highlighted
code. This allows things like multi-line comments to be syntax
highlighted correctly.

---------

Co-authored-by: wxiaoguang <[email protected]>

modules/git/blob.go

@@ -7,6 +7,7 @@ package git
 import (
 	"bytes"
 	"encoding/base64"
+	"errors"
 	"io"
 
 	"code.gitea.io/gitea/modules/typesniffer"
@@ -34,8 +35,9 @@ func (b *Blob) GetBlobContent(limit int64) (string, error) {
 	return string(buf), err
 }
 
-// GetBlobLineCount gets line count of the blob
-func (b *Blob) GetBlobLineCount() (int, error) {
+// GetBlobLineCount gets line count of the blob.
+// It will also try to write the content to w if it's not nil, then we could pre-fetch the content without reading it again.
+func (b *Blob) GetBlobLineCount(w io.Writer) (int, error) {
 	reader, err := b.DataAsync()
 	if err != nil {
 		return 0, err
@@ -44,20 +46,20 @@ func (b *Blob) GetBlobLineCount() (int, error) {
 	buf := make([]byte, 32*1024)
 	count := 1
 	lineSep := []byte{'\n'}
-
-	c, err := reader.Read(buf)
-	if c == 0 && err == io.EOF {
-		return 0, nil
-	}
 	for {
+		c, err := reader.Read(buf)
+		if w != nil {
+			if _, err := w.Write(buf[:c]); err != nil {
+				return count, err
+			}
+		}
 		count += bytes.Count(buf[:c], lineSep)
 		switch {
-		case err == io.EOF:
+		case errors.Is(err, io.EOF):
 			return count, nil
 		case err != nil:
 			return count, err
 		}
-		c, err = reader.Read(buf)
 	}
 }
 

modules/highlight/highlight.go

@@ -11,6 +11,7 @@ import (
 	gohtml "html"
 	"html/template"
 	"io"
+	"path"
 	"path/filepath"
 	"strings"
 	"sync"
@@ -83,7 +84,7 @@ func Code(fileName, language, code string) (output template.HTML, lexerName stri
 	}
 
 	if lexer == nil {
-		if val, ok := highlightMapping[filepath.Ext(fileName)]; ok {
+		if val, ok := highlightMapping[path.Ext(fileName)]; ok {
 			// use mapped value to find lexer
 			lexer = lexers.Get(val)
 		}

routers/api/v1/repo/pull.go

@@ -1591,8 +1591,7 @@ func GetPullRequestFiles(ctx *context.APIContext) {
 	maxLines := setting.Git.MaxGitDiffLines
 
 	// FIXME: If there are too many files in the repo, may cause some unpredictable issues.
-	// FIXME: it doesn't need to call "GetDiff" to do various parsing and highlighting
-	diff, err := gitdiff.GetDiff(ctx, baseGitRepo,
+	diff, err := gitdiff.GetDiffForAPI(ctx, baseGitRepo,
 		&gitdiff.DiffOptions{
 			BeforeCommitID:     startCommitID,
 			AfterCommitID:      endCommitID,

routers/web/repo/blame.go

@@ -97,7 +97,7 @@ func RefBlame(ctx *context.Context) {
 		return
 	}
 
-	ctx.Data["NumLines"], err = blob.GetBlobLineCount()
+	ctx.Data["NumLines"], err = blob.GetBlobLineCount(nil)
 	if err != nil {
 		ctx.NotFound(err)
 		return

routers/web/repo/commit.go

@@ -314,7 +314,7 @@ func Diff(ctx *context.Context) {
 		maxLines, maxFiles = -1, -1
 	}
 
-	diff, err := gitdiff.GetDiff(ctx, gitRepo, &gitdiff.DiffOptions{
+	diff, err := gitdiff.GetDiffForRender(ctx, gitRepo, &gitdiff.DiffOptions{
 		AfterCommitID:      commitID,
 		SkipTo:             ctx.FormString("skip-to"),
 		MaxLines:           maxLines,

routers/web/repo/compare.go

@@ -614,7 +614,7 @@ func PrepareCompareDiff(
 
 	fileOnly := ctx.FormBool("file-only")
 
-	diff, err := gitdiff.GetDiff(ctx, ci.HeadGitRepo,
+	diff, err := gitdiff.GetDiffForRender(ctx, ci.HeadGitRepo,
 		&gitdiff.DiffOptions{
 			BeforeCommitID:     beforeCommitID,
 			AfterCommitID:      headCommitID,

routers/web/repo/pull.go

@@ -749,7 +749,7 @@ func viewPullFiles(ctx *context.Context, specifiedStartCommit, specifiedEndCommi
 		diffOptions.BeforeCommitID = startCommitID
 	}
 
-	diff, err := gitdiff.GetDiff(ctx, gitRepo, diffOptions, files...)
+	diff, err := gitdiff.GetDiffForRender(ctx, gitRepo, diffOptions, files...)
 	if err != nil {
 		ctx.ServerError("GetDiff", err)
 		return