1 files changed, 27 insertions, 0 deletions
diff --git a/extension/react-app/src/util/index.ts b/extension/react-app/src/util/index.ts
new file mode 100644
index 00000000..458f9d95
--- /dev/null
+++ b/extension/react-app/src/util/index.ts
@@ -0,0 +1,27 @@
+import { RangeInFile } from "../../../src/client";
+
+export function readRangeInVirtualFileSystem(
+  rangeInFile: RangeInFile,
+  filesystem: { [filepath: string]: string }
+): string | undefined {
+  const range = rangeInFile.range;
+
+  let data = filesystem[rangeInFile.filepath];
+  if (data === undefined) {
+    console.log("File not found");
+    return undefined;
+  } else {
+    let lines = data.toString().split("\n");
+    if (range.start.line === range.end.line) {
+      return lines[rangeInFile.range.start.line].slice(
+        rangeInFile.range.start.character,
+        rangeInFile.range.end.character
+      );
+    } else {
+      let firstLine = lines[range.start.line].slice(range.start.character);
+      let lastLine = lines[range.end.line].slice(0, range.end.character);
+      let middleLines = lines.slice(range.start.line + 1, range.end.line);
+      return [firstLine, ...middleLines, lastLine].join("\n");
+    }
+  }
+}