Merge pull request #10 from Syuparn/fix-diff-logic

Syuparn · web-flow · commit 6cf24d280e7d · 2021-02-21T22:20:48.000+09:00
fix diff detection algorithm
diff --git a/main.go b/main.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"strings"
 	"text/template"
 )
 
@@ -74,8 +75,6 @@ func runREPLMode(tmplGen *template.Template) {
 	scanner := bufio.NewScanner(os.Stdin)
 	tmplStr := ""
 	lineNum := 1
-	// NOTE: save previous output length to print only diff added by the latest input
-	previousOutLen := 0
 
 	for {
 		// show prompt
@@ -89,7 +88,9 @@ func runREPLMode(tmplGen *template.Template) {
 		line := scanner.Text() + "\n"
 
 		// NOTE: whole history is necessary to refer previous variable statement
-		tmpl, err := tmplGen.Parse(tmplStr + line)
+		// HACK: insert "\034"(, which is not printable) to detect
+		//       output generated by the latest input line
+		tmpl, err := tmplGen.Parse(tmplStr + "\034" + line)
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "template error:\n%v\n", err)
 			continue
@@ -102,13 +103,17 @@ func runREPLMode(tmplGen *template.Template) {
 			continue
 		}
 		// print only added output, which corresponds to the latest input
-		// NOTE: break line is unneccessary because it already exists
-		outStr := out.String()
-		diffStr := outStr[previousOutLen:]
-		fmt.Print(diffStr)
+		splitted := strings.Split(out.String(), "\034")
+		if len(splitted) != 2 {
+			fmt.Fprintf(os.Stderr,
+				"runtime error:\nthere must be 1 internal delimiter \\034 (found %d)\n", len(splitted)-1)
+			continue
+		}
+
+		diffStr := splitted[1]
+		fmt.Println(diffStr)
 
 		tmplStr = tmplStr + line
-		previousOutLen = len(outStr)
 		lineNum++
 	}
 }
