1 files changed, 258 insertions, 0 deletions
diff --git a/src/arrow/r/data-raw/codegen.R b/src/arrow/r/data-raw/codegen.R
new file mode 100644
index 000000000..46b02fd64
--- /dev/null
+++ b/src/arrow/r/data-raw/codegen.R
@@ -0,0 +1,258 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# This file is used to generate code in the files
+# src/arrowExports.cpp and R/arrowExports.R
+#
+# This is similar to what compileAttributes() would do,
+# with some arrow specific changes.
+#
+# Functions are decorated with [[arrow::export]]
+# and the generated code adds a layer of protection so that
+# the arrow package can be installed even when libarrow is not
+#
+# All the C++ code should be guarded by
+#
+# #if defined(ARROW_R_WITH_ARROW)
+# // [[arrow::export]]
+# std::shared_ptr<arrow::Array> some_function_using_arrow_api(){
+#     ...
+# }
+# #endif
+
+
+# Different flags can be used to export different features.
+# [[feature::export]]
+# maps to
+# #if defined(ARROW_R_WITH_FEATURE)
+# and each feature is written to its own set of export files.
+
+# Ensure that all machines are sorting the same way
+invisible(Sys.setlocale("LC_COLLATE", "C"))
+
+features <- c("arrow", "dataset", "parquet", "s3", "json")
+
+suppressPackageStartupMessages({
+  library(decor)
+  library(dplyr)
+  library(purrr)
+  library(glue)
+  library(vctrs)
+})
+
+get_exported_functions <- function(decorations, export_tag) {
+  out <- decorations %>%
+    filter(decoration %in% paste0(export_tag, "::export")) %>%
+    mutate(functions = map(context, decor:::parse_cpp_function)) %>%
+    { vec_cbind(., vec_rbind(!!!pull(., functions))) } %>%
+    select(-functions) %>%
+    mutate(decoration = sub("::export", "", decoration))
+  message(glue("*** > {n} functions decorated with [[{tags}::export]]", n = nrow(out), tags = paste0(export_tag, collapse = "|")))
+  out
+}
+
+glue_collapse_data <- function(data, ..., sep = ", ", last = "") {
+  res <- glue_collapse(glue_data(data, ...), sep = sep, last = last)
+  if (length(res) == 0) res <- ""
+  res
+}
+
+wrap_call <- function(name, return_type, args) {
+  call <- glue::glue('{name}({list_params})', list_params = glue_collapse_data(args, "{name}"))
+  if (return_type == "void") {
+    glue::glue("\t{call};\n\treturn R_NilValue;", .trim = FALSE)
+  } else {
+    glue::glue("\treturn cpp11::as_sexp({call});")
+  }
+}
+
+feature_available <- function(feat) {
+  glue::glue(
+'extern "C" SEXP _{feat}_available() {{
+return Rf_ScalarLogical(
+#if defined(ARROW_R_WITH_{toupper(feat)})
+  TRUE
+#else
+  FALSE
+#endif
+);
+}}
+')
+}
+
+write_if_modified <- function(code, file) {
+  old <- try(readLines(file), silent=TRUE)
+  new <- unclass(unlist(strsplit(code, "\n")))
+  # We don't care about changes in empty lines
+  if (!identical(old[nzchar(old)], new[nzchar(new)])) {
+    writeLines(con = file, code)
+    # To debug why they're different if you think they shouldn't be:
+    # print(waldo::compare(old[nzchar(old)], new[nzchar(new)]))
+    message(glue::glue("*** > generated file `{file}`"))
+  } else {
+    message(glue::glue("*** > `{file}` not modified"))
+  }
+}
+
+all_decorations <- cpp_decorations()
+arrow_exports <- get_exported_functions(all_decorations, features)
+
+arrow_classes <- c(
+  "Table" = "arrow::Table",
+  "RecordBatch" = "arrow::RecordBatch"
+)
+
+# This takes a cpp11 C wrapper and conditionally makes it available based on
+# a feature decoration
+ifdef_wrap <- function(cpp11_wrapped, name, sexp_signature, decoration) {
+  # if (identical(decoration, "arrow")) {
+  #   # Arrow is now required
+  #   return(cpp11_wrapped)
+  # }
+  glue('
+  #if defined(ARROW_R_WITH_{toupper(decoration)})
+  {cpp11_wrapped}
+  #else
+  extern "C" SEXP {sexp_signature}{{
+  \tRf_error("Cannot call {name}(). See https://arrow.apache.org/docs/r/articles/install.html for help installing Arrow C++ libraries. ");
+  }}
+  #endif
+  \n')
+}
+
+cpp_functions_definitions <- arrow_exports %>%
+  select(name, return_type, args, file, line, decoration) %>%
+  pmap_chr(function(name, return_type, args, file, line, decoration) {
+    sexp_params <- glue_collapse_data(args, "SEXP {name}_sexp")
+    sexp_signature <- glue('_arrow_{name}({sexp_params})')
+    cpp11_wrapped <- glue('
+      {return_type} {name}({real_params});
+      extern "C" SEXP {sexp_signature}{{
+      BEGIN_CPP11
+      {input_params}{return_line}{wrap_call(name, return_type, args)}
+      END_CPP11
+      }}',
+      sep = "\n",
+      real_params = glue_collapse_data(args, "{type} {name}"),
+      input_params = glue_collapse_data(args, "\tarrow::r::Input<{type}>::type {name}({name}_sexp);", sep = "\n"),
+      return_line = if (nrow(args)) "\n" else "")
+
+    glue::glue('
+    // {basename(file)}
+    {ifdef_wrap(cpp11_wrapped, name, sexp_signature, decoration)}
+    ',
+      sep = "\n",
+    )
+  }) %>%
+  glue_collapse(sep = "\n")
+
+cpp_functions_registration <- arrow_exports %>%
+  select(name, return_type, args) %>%
+  pmap_chr(function(name, return_type, args) {
+    glue('\t\t{{ "_arrow_{name}", (DL_FUNC) &_arrow_{name}, {nrow(args)}}}, ')
+  }) %>%
+  glue_collapse(sep = "\n")
+
+cpp_classes_finalizers <- map2(names(arrow_classes), arrow_classes, function(name, class) {
+  sexp_signature <- glue('_arrow_{name}__Reset(SEXP r6)')
+  cpp11_wrapped <- glue('
+    extern "C" SEXP {sexp_signature} {{
+    BEGIN_CPP11
+    arrow::r::r6_reset_pointer<{class}>(r6);
+    END_CPP11
+    return R_NilValue;
+    }}')
+  ifdef_wrap(cpp11_wrapped, name, sexp_signature, "arrow")
+}) %>%
+  glue_collapse(sep = "\n")
+
+classes_finalizers_registration <- glue('\t\t{{ "_arrow_{names(arrow_classes)}__Reset", (DL_FUNC) &_arrow_{names(arrow_classes)}__Reset, 1}}, ') %>%
+  glue_collapse(sep = "\n")
+
+cpp_file_header <- '// Generated by using data-raw/codegen.R -> do not edit by hand
+#include <cpp11.hpp>
+#include <cpp11/declarations.hpp>
+
+#include "./arrow_types.h"
+'
+
+arrow_exports_cpp <- paste0(
+glue::glue('
+{cpp_file_header}
+{cpp_functions_definitions}
+{cpp_classes_finalizers}
+\n'),
+glue::glue_collapse(glue::glue('
+{feature_available({features})}
+'), sep = '\n'),
+'
+static const R_CallMethodDef CallEntries[] = {
+',
+glue::glue_collapse(glue::glue('
+\t\t{{ "_{features}_available", (DL_FUNC)& _{features}_available, 0 }},
+'), sep = '\n'),
+glue::glue('\n
+{cpp_functions_registration}
+{classes_finalizers_registration}
+\t\t{{NULL, NULL, 0}}
+}};
+\n'),
+'extern "C" void R_init_arrow(DllInfo* dll){
+  R_registerRoutines(dll, NULL, CallEntries, NULL, NULL);
+  R_useDynamicSymbols(dll, FALSE);
+
+  #if defined(ARROW_R_WITH_ARROW) && defined(HAS_ALTREP)
+  arrow::r::altrep::Init_Altrep_classes(dll);
+  #endif
+
+}
+\n')
+
+write_if_modified(arrow_exports_cpp, "src/arrowExports.cpp")
+
+r_functions <- arrow_exports %>%
+  select(name, return_type, args) %>%
+  pmap_chr(function(name, return_type, args) {
+    params <- if (nrow(args)) {
+      paste0(", ", glue_collapse_data(args, "{name}"))
+    } else {
+      ""
+    }
+    call <- glue::glue('.Call(`_arrow_{name}`{params})')
+    if (return_type == "void") {
+      call <- glue::glue('invisible({call})')
+    }
+
+    glue::glue('
+    {name} <- function({list_params}) {{
+      {call}
+    }}
+
+    ',
+      list_params = glue_collapse_data(args, "{name}"),
+      sep = "\n",
+    )
+  }) %>%
+  glue_collapse(sep = "\n")
+
+arrow_exports_r <- glue::glue('
+# Generated by using data-raw/codegen.R -> do not edit by hand
+
+{r_functions}
+')
+
+write_if_modified(arrow_exports_r, "R/arrowExports.R")