1 files changed, 52 insertions, 0 deletions
diff --git a/lib/internal/source_map/prepare_stack_trace.js b/lib/internal/source_map/prepare_stack_trace.js
new file mode 100644
index 0000000000..d6c5fce60a
--- /dev/null
+++ b/lib/internal/source_map/prepare_stack_trace.js
@@ -0,0 +1,52 @@
+'use strict';
+
+const debug = require('internal/util/debuglog').debuglog('source_map');
+const { findSourceMap } = require('internal/source_map/source_map_cache');
+const { overrideStackTrace } = require('internal/errors');
+
+// Create a prettified stacktrace, inserting context from source maps
+// if possible.
+const ErrorToString = Error.prototype.toString; // Capture original toString.
+const prepareStackTrace = (globalThis, error, trace) => {
+  // API for node internals to override error stack formatting
+  // without interfering with userland code.
+  // TODO(bcoe): add support for source-maps to repl.
+  if (overrideStackTrace.has(error)) {
+    const f = overrideStackTrace.get(error);
+    overrideStackTrace.delete(error);
+    return f(error, trace);
+  }
+
+  const { SourceMap } = require('internal/source_map/source_map');
+  const errorString = ErrorToString.call(error);
+
+  if (trace.length === 0) {
+    return errorString;
+  }
+  const preparedTrace = trace.map((t, i) => {
+    let str = i !== 0 ? '\n    at ' : '';
+    str = `${str}${t}`;
+    try {
+      const sourceMap = findSourceMap(t.getFileName(), error);
+      if (sourceMap && sourceMap.data) {
+        const sm = new SourceMap(sourceMap.data);
+        // Source Map V3 lines/columns use zero-based offsets whereas, in
+        // stack traces, they start at 1/1.
+        const [, , url, line, col] =
+                   sm.findEntry(t.getLineNumber() - 1, t.getColumnNumber() - 1);
+        if (url && line !== undefined && col !== undefined) {
+          str +=
+            `\n        -> ${url.replace('file://', '')}:${line + 1}:${col + 1}`;
+        }
+      }
+    } catch (err) {
+      debug(err.stack);
+    }
+    return str;
+  });
+  return `${errorString}\n    at ${preparedTrace.join('')}`;
+};
+
+module.exports = {
+  prepareStackTrace,
+};