monkeygems.c

/*
 * WARNING: This code has a few oversights, and is not really safe to use for production,
 *   etc. If you want to play with it in dev, though, it won't eat your children or anything.
 *
 * In particular, it doesn't necessarily choose the correct option if multiple items on the
 *   load path match the same require path. That wouldn't be hard, but I didn't get around to it.
 */

#include "ruby.h"
#include <string.h>
#include <stdio.h>

static long cached = 0;
static struct st_table *mapped_load_path_items;
static struct st_table *require_fullpaths;

VALUE monkeygems_require(VALUE obj, VALUE fname)
{
  int i, j;
  long load_path_item_size;
  char *glob;
  st_data_t data;
  VALUE load_path, files;
  char *entryFullpath;
  char *entryShortpath;
  char *stringName;
  load_path = rb_gv_get("$:");

  if (TYPE(fname) == T_STRING) {
    stringName = RSTRING_PTR(fname);
  } else {
    stringName = RSTRING_PTR(rb_funcall(fname, rb_intern("to_s"), 0));
  }

  if (RARRAY_LEN(load_path) > cached) {
    printf("*> Rebuilding cache: %ld -> %ld\n", cached, RARRAY_LEN(load_path));
    cached = RARRAY_LEN(load_path);
    for (i = 0; i < RARRAY_LEN(load_path); i++) {
      VALUE load_path_item = RARRAY_PTR(load_path)[i];
      if (TYPE(load_path_item) != T_STRING)
        load_path_item = rb_funcall(load_path_item, rb_intern("to_s"), 0);
      data = 0;
      st_lookup(mapped_load_path_items, (st_data_t)RSTRING_PTR(load_path_item), &data);
      if (data) continue;
      st_insert(mapped_load_path_items, (st_data_t)RSTRING_PTR(load_path_item), (st_data_t)1);
      if (RSTRING_PTR(load_path_item)[0] != '/') continue;
      load_path_item_size = RSTRING_LEN(load_path_item);

      glob = malloc(RSTRING_LEN(load_path_item) + 16);
      strcpy(glob, RSTRING_PTR(load_path_item));
      strcpy(glob + RSTRING_LEN(load_path_item), "/**/*.rb");
      files = rb_funcall(rb_cDir, rb_intern("glob"), 1, rb_str_new2(glob));
      free(glob);

      for (j = 0; j < RARRAY_LEN(files) ; j++) {
        entryFullpath = strdup(RSTRING_PTR(RARRAY_PTR(files)[j]));
        entryShortpath = malloc(strlen(entryFullpath));
        strcpy(entryShortpath, entryFullpath + load_path_item_size + 1);
        entryShortpath[strlen(entryShortpath) - 3] = 0;
        st_insert(require_fullpaths, (st_data_t)entryShortpath, (st_data_t)entryFullpath);
      }
    }
  }

  data = 0;
  if (st_lookup(require_fullpaths, (st_data_t)stringName, &data)) {
    return rb_f_require(obj, rb_str_new2((char *)data));
  } else {
    return rb_f_require(obj, fname);
  }
}

void Init_monkeygems()
{
  mapped_load_path_items = st_init_numtable();
  require_fullpaths = st_init_strtable();
  /*
   * Bundler resets require to `gem_original_require` to undo
   * rubygems' overwriting of require.
   *
   * So here we overwrite gem_original_require with our own extra
   * logic that we would like preserved after bundler takes over.
   *
   * *cue Inception theme*
   */
  rb_define_method(rb_mKernel, "gem_original_require", monkeygems_require, 1);
}