use gotextdiff

misc/stdlib_diff/filediff.go

@@ -4,57 +4,143 @@ import (
 	"fmt"
 	"os"
 	"strings"
+
+	"github.com/hexops/gotextdiff"
+	"github.com/hexops/gotextdiff/myers"
+	"github.com/hexops/gotextdiff/span"
 )
 
 // FileDiff is a struct for comparing differences between two files.
 type FileDiff struct {
-	Src       []string // Lines of the source file.
-	Dst       []string // Lines of the destination file.
-	Algorithm          // Algorithm used for comparison.
+	Src        string   // Name of the source file.
+	Dst        string   // Name of the destination file.
+	srcContent string   // Content of the source file.
+	dstContent string   // Content of the destination file.
+	srcLines   []string // Lines of the source file.
+	dstLines   []string // Lines of the destination file.
+
 }
 
 // LineDifferrence represents a difference in a line during file comparison.
 type LineDifferrence struct {
 	Line      string    // The line content.
 	Operation operation // The operation performed on the line (e.g., "add", "delete", "equal").
+	Number    int
 }
 
 // NewFileDiff creates a new FileDiff instance for comparing differences between
 // the specified source and destination files. It initializes the source and
 // destination file lines .
 func NewFileDiff(srcPath, dstPath string) (*FileDiff, error) {
-	src, err := getFileLines(srcPath)
+	src, err := getFileContent(srcPath)
 	if err != nil {
 		return nil, fmt.Errorf("can't read src file: %w", err)
 	}
 
-	dst, err := getFileLines(dstPath)
+	dst, err := getFileContent(dstPath)
 	if err != nil {
 		return nil, fmt.Errorf("can't read dst file: %w", err)
 	}
 
 	return &FileDiff{
-		Src:       src,
-		Dst:       dst,
-		Algorithm: NewMyers(src, dst),
+		srcContent: src,
+		dstContent: dst,
+		srcLines:   strings.Split(src, "\n"),
+		dstLines:   strings.Split(dst, "\n"),
+		Src:        srcPath,
+		Dst:        dstPath,
 	}, nil
 }
 
 // Differences returns the differences in lines between the source and
 // destination files using the configured diff algorithm.
 func (f *FileDiff) Differences() (src, dst []LineDifferrence) {
-	return f.Diff()
+	var (
+		srcIndex, dstIndex       int
+		insertCount, deleteCount int
+		dstDiff, srcDiff         []LineDifferrence
+	)
+
+	if len(f.dstContent) == 0 {
+		return f.destEmpty()
+	}
+
+	if len(f.srcContent) == 0 {
+		return f.srcEmpty()
+	}
+
+	/* printUntil prints all the lines thar are equal
+	because they do not appear on the computed edits from gotextdiff
+	so we need to add them manually looping always from the current value of
+	srcIndex until the line before the start of the hunk computed diff, hunk.FromLine-1
+
+	We need to print all the lines before each hunk and then ensure the end of the file is printed too
+	*/
+	printUntil := func(until int) {
+		for i := srcIndex; i < until; i++ {
+			dstDiff = append(dstDiff, LineDifferrence{Line: f.srcLines[srcIndex], Operation: equal, Number: dstIndex + 1})
+			srcDiff = append(srcDiff, LineDifferrence{Line: f.srcLines[srcIndex], Operation: equal, Number: srcIndex + 1})
+			srcIndex++
+			dstIndex++
+		}
+	}
+
+	edits := myers.ComputeEdits(span.URIFromPath(f.Src), f.srcContent, f.dstContent)
+	unified := gotextdiff.ToUnified(f.Src, f.Dst, f.srcContent, edits)
+	for _, hunk := range unified.Hunks {
+		printUntil(hunk.FromLine - 1)
+
+		for _, line := range hunk.Lines {
+			switch line.Kind {
+			case gotextdiff.Insert:
+				insertCount++
+				dstIndex++
+				dstDiff = append(dstDiff, LineDifferrence{Line: line.Content, Operation: insert, Number: dstIndex})
+
+			case gotextdiff.Equal:
+				srcIndex++
+				dstIndex++
+				dstDiff = append(dstDiff, LineDifferrence{Line: line.Content, Operation: equal, Number: dstIndex})
+				srcDiff = append(srcDiff, LineDifferrence{Line: line.Content, Operation: equal, Number: srcIndex})
+
+			case gotextdiff.Delete:
+				srcIndex++
+				deleteCount++
+				srcDiff = append(srcDiff, LineDifferrence{Line: line.Content, Operation: delete, Number: srcIndex})
+			}
+		}
+	}
+
+	printUntil(len(f.srcLines))
+	return srcDiff, dstDiff
+}
+
+func (f *FileDiff) destEmpty() ([]LineDifferrence, []LineDifferrence) {
+	srcDiff := []LineDifferrence{}
+	for index, line := range f.srcLines {
+		srcDiff = append(srcDiff, LineDifferrence{Line: line, Operation: delete, Number: index + 1})
+	}
+
+	return srcDiff, make([]LineDifferrence, 0)
+}
+
+func (f *FileDiff) srcEmpty() ([]LineDifferrence, []LineDifferrence) {
+	destDiff := []LineDifferrence{}
+	for index, line := range f.dstLines {
+		destDiff = append(destDiff, LineDifferrence{Line: line, Operation: insert, Number: index + 1})
+	}
+
+	return make([]LineDifferrence, 0), destDiff
 }
 
-// getFileLines reads and returns the lines of a file given its path.
-func getFileLines(p string) ([]string, error) {
+// getFileContent reads and returns the lines of a file given its path.
+func getFileContent(p string) (string, error) {
 	data, err := os.ReadFile(p)
 	if err != nil {
 		if os.IsNotExist(err) {
-			return nil, nil
+			return "", nil
 		}
-		return nil, err
+		return "", err
 	}
-	lines := strings.Split(strings.ReplaceAll(string(data), "\r\n", "\n"), "\n")
-	return lines, nil
+	return strings.ReplaceAll(string(data), "\t", "    "), nil
 }

misc/stdlib_diff/go.mod

@@ -1,3 +1,5 @@
 module github.com/gnolang/gno/misc/stdlib_diff
 
 go 1.21.0
+
+require github.com/hexops/gotextdiff v1.0.3

misc/stdlib_diff/templates/package_diff_template.html

@@ -3,16 +3,20 @@
     {{- range .}}
     {{- if eq .Operation 1}}
     <div style="display: flex; color: #07ca07;">
-    <span style="user-select: none;">-</span><p>{{.Line}}</p> 
+    <span style="user-select: none; min-width: 50px;">{{.Number}} </span><p>{{.Line}}</p> 
     </div>
     {{- else if eq .Operation 2}}
     <div style="display: flex; color: red;">
-        <span style="user-select: none;">+</span><p>{{.Line}}</p> 
+        <span style="user-select: none; min-width: 50px;">{{.Number}} </span><p>{{.Line}}</p> 
+    </div>
+
+    {{- else if eq .Operation 3}}
+    <div div style="display: flex;">
+        <span style="user-select: none; min-width: 50px;">{{.Number}}</span>
+        <p style="opacity: 0.75;">{{.Line}}</p>
     </div>
-    {{- else if eq .Line ""}}
-    <br />
     {{- else}}
-    <p style="opacity: 0.75;">{{.Line}}</p>
+    <span style="user-select: none;"></span><p>{{.Line}}</p> 
     {{- end}}
     {{- end}}
 </div>