1 files changed, 86 insertions, 0 deletions
diff --git a/lib/src/csv.dart b/lib/src/csv.dart
new file mode 100644
index 0000000..ab2f0be
--- /dev/null
+++ b/lib/src/csv.dart
@@ -0,0 +1,86 @@
+/// A minimal RFC 4180 reader, for the `/csv` batch endpoint.
+///
+/// Values may contain commas and are then double-quoted with `""` escaping, so
+/// splitting on `,` corrupts every row that carries a street name like
+/// `Rua Um, Dois`. This is here because the Dart SDK ships no CSV parser and
+/// this library keeps its dependency list to one entry.
+library;
+
+const String _bom = '\u{FEFF}';
+
+/// Parses CSV text into records keyed by its header row.
+///
+/// A leading byte-order mark is dropped, `CRLF` and `LF` are both accepted, and
+/// a row shorter than the header has its remaining columns filled with the
+/// empty string. An empty input yields no records.
+List<Map<String, String>> parseCsv(String text) {
+  final rows = _parseRows(text.startsWith(_bom) ? text.substring(1) : text);
+  if (rows.isEmpty) {
+    return <Map<String, String>>[];
+  }
+
+  final header = rows.removeAt(0);
+  final records = <Map<String, String>>[];
+  for (final row in rows) {
+    if (row.length == 1 && row.first.isEmpty) {
+      continue;
+    }
+    final record = <String, String>{};
+    for (var i = 0; i < header.length; i++) {
+      record[header[i]] = i < row.length ? row[i] : '';
+    }
+    records.add(record);
+  }
+  return records;
+}
+
+List<List<String>> _parseRows(String text) {
+  final rows = <List<String>>[];
+  final field = StringBuffer();
+  var row = <String>[];
+  var quoted = false;
+  var started = false;
+
+  for (var i = 0; i < text.length; i++) {
+    final char = text[i];
+
+    if (quoted) {
+      if (char == '"') {
+        if (i + 1 < text.length && text[i + 1] == '"') {
+          field.write('"');
+          i++;
+        } else {
+          quoted = false;
+        }
+      } else {
+        field.write(char);
+      }
+      continue;
+    }
+
+    if (char == '"') {
+      quoted = true;
+      started = true;
+    } else if (char == ',') {
+      row.add(field.toString());
+      field.clear();
+      started = true;
+    } else if (char == '\n') {
+      row.add(field.toString());
+      field.clear();
+      rows.add(row);
+      row = <String>[];
+      started = false;
+    } else if (char != '\r') {
+      field.write(char);
+      started = true;
+    }
+  }
+
+  if (started || field.isNotEmpty || row.isNotEmpty) {
+    row.add(field.toString());
+    rows.add(row);
+  }
+
+  return rows;
+}