Geometry Nodes: support custom delimiter in Import CSV node

Previously, only `,` was a valid delimiter, but it's also common to have e.g.
tab or semicolon. Only single characters are supported as delimiters. A few
characters are not allowed because they have other meanings: `\n`, `\r`, `"`,
`\\`.

Note: The best way to get a tab character is the use the Special Characters node
currently.

Pull Request: https://projects.blender.org/blender/blender/pulls/135468

source/blender/io/csv/IO_csv.hh

@@ -18,6 +18,7 @@ namespace blender::io::csv {
 struct CSVImportParams {
   /** Full path to the source CSV file to import. */
   char filepath[FILE_MAX];
+  char delimiter = ',';
 
   ReportList *reports = nullptr;
 };

source/blender/io/csv/importer/csv_reader.cc

@@ -281,6 +281,7 @@ PointCloud *import_csv_as_pointcloud(const CSVImportParams &import_params)
   LinearAllocator<> allocator;
   Array<ColumnInfo> columns_info;
   csv_parse::CsvParseOptions parse_options;
+  parse_options.delimiter = import_params.delimiter;
 
   const auto parse_header = [&](const csv_parse::CsvRecord &record) {
     columns_info.reinitialize(record.size());

source/blender/nodes/geometry/nodes/node_geo_import_csv.cc

@@ -20,6 +20,7 @@ static void node_declare(NodeDeclarationBuilder &b)
       .path_filter("*.csv")
       .hide_label()
       .description("Path to a CSV file");
+  b.add_input<decl::String>("Delimiter").default_value(",");
 
   b.add_output<decl::Geometry>("Point Cloud");
 }
@@ -33,8 +34,21 @@ static void node_geo_exec(GeoNodeExecParams params)
     params.set_default_remaining_outputs();
     return;
   }
+  const std::string delimiter = params.extract_input<std::string>("Delimiter");
+  if (delimiter.size() != 1) {
+    params.error_message_add(NodeWarningType::Error, TIP_("Delimiter must be a single character"));
+    params.set_default_remaining_outputs();
+    return;
+  }
+  if (ELEM(delimiter[0], '\n', '\r', '"', '\\')) {
+    params.error_message_add(NodeWarningType::Error,
+                             TIP_("Delimiter must not be \\n, \\r, \" or \\"));
+    params.set_default_remaining_outputs();
+    return;
+  }
 
   blender::io::csv::CSVImportParams import_params{};
+  import_params.delimiter = delimiter[0];
   STRNCPY(import_params.filepath, path->c_str());
 
   ReportList reports;