fix bug for empty rows

mousetail · Apr 8, 2024 · b7f5074 · b7f5074
1 parent dc4a6cf
commit b7f5074
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Showing 2 changed files with 17 additions and 5 deletions.
diff --git a/src/scripts/interpreter.ts b/src/scripts/interpreter.ts
@@ -286,9 +286,18 @@ export function step(o: ProgramState) {
     } else {
         throw new Error("Unexpected token: " + token + " Note: all symbols must be lower case");
     }
-    o.cursor[0] += o.cursor_direction[0];
-    o.cursor[1] += o.cursor_direction[1];
 
-    o.cursor[1] = (o.cursor[1] + o.program.length) % o.program.length;
-    o.cursor[0] = (o.cursor[0] + o.program[o.cursor[1]].length) % o.program[o.cursor[1]].length;
+    if (o.cursor_direction[0] != 0) {
+        o.cursor[0] += o.cursor_direction[0];
+
+        const row_length = o.program[o.cursor[1]].length;
+        if (row_length != 0) {
+            o.cursor[0] = (o.cursor[0] + row_length) % row_length;
+        }
+    }
+
+    if (o.cursor_direction[1] != 0) {
+        o.cursor[1] += o.cursor_direction[1];
+        o.cursor[1] = (o.cursor[1] + o.program.length) % o.program.length;
+    }
 }
diff --git a/src/scripts/main.ts b/src/scripts/main.ts
@@ -123,8 +123,11 @@ function text_with_cursor(program: number[][], cursor: [number, number]): (strin
     let text_before = text.slice(0, cursor[1]).map(i => i + '\n').join('') + text[cursor[1]].substring(0, cursor[0]);
     let text_after = text[cursor[1]].substring(cursor[0] + 1) + '\n' + text.slice(cursor[1] + 1).map(i => i + '\n').join('');
 
+    let cursor_content = text[cursor[1]][cursor[0]];
     let span = document.createElement('span');
-    span.innerText = text[cursor[1]][cursor[0]];
+    if (cursor_content != undefined) {
+        span.innerText = cursor_content;
+    }
     span.classList.add('cursor');
     return [
         text_before,