README.md

C interface to autocomplete-haskell

Running examples from the command line

The script run_examples.sh compiles the Haskell library, organizes to-be-exported FFI functions in a dependencies folder, and compiles the examples file examples/trie_examples.c:

sh run_examples.sh

c_library/examples/trie_examples.c

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

int main(void) {
  tries_init();

  // create an EmptyTrie
  HsStablePtr empty_trie = get_empty_trie();
  printf("get_empty_trie():\n");
  print_trie(empty_trie);

  // create a more interesting trie
  double weights[5] = {30.0, 12.0, 25.0, 20.0, 14.0};
  char* words[5] = {"an", "to", "ted", "a", "tea"};
  HsStablePtr mytrie = trie_from_arrays(weights, words, 5);
  printf("mytrie:\n");
  print_trie(mytrie);

  // get the next node when searching for "ted"
  printf("get_next_node(\"ted\", mytrie):\n");
  print_trie(get_next_node("ted", mytrie));

  // get the node for "te"
  printf("get_node(\"te\", mytrie):\n");
  print_trie(get_node("te", mytrie));

  // is "ted" in the trie?
  printf("is_in_trie(\"ted\", mytrie): %d\n", is_in_trie("ted", mytrie));

  // is "tedtalk" in the trie?
  printf("is_in_trie(\"tedtalk\", mytrie): %d\n",
         is_in_trie("tedtalk", mytrie));

  // what's the maximum weight in this trie?
  printf("get_max_weight(mytrie): %f\n", get_max_weight(mytrie));

  // insert some nodes
  double new_weights[2] = {5, 15};
  char* new_words[2] = {"in", "inn"};
  HsStablePtr mytrie_augmented = insert_words(new_weights, new_words,
                                              2, mytrie);
  printf("\nmytrie_augmented:\n");
  print_trie(mytrie_augmented);

  // remove a prefix
  mytrie_augmented = remove_prefix("in", mytrie_augmented);
  printf("\nmytrie_augmented after deleting \"in\"\n");
  print_trie(mytrie_augmented);

  // read in a trie
  HsStablePtr mytrie4 = read_terms("../Data/mytrie4.txt");
  printf("mytrie4 using read_terms:\n");
  print_trie(mytrie4);

  // use autocomplete
  double weights_out[3];
  char* words_out[3];
  autocomplete(weights_out, words_out, "t", mytrie4, 3);
  printf("autocomplete results:\n");

  for (int i = 0; i < 3; i++){
    printf("(%f, %s)\n", weights_out[i], words_out[i]);
  }

  // Request the same autocomplete results but use slowcomplete
  slowcomplete(weights_out, words_out, 5, "t", weights, words, 3);

  printf("\nslowcomplete results:\n");
  for (int i = 0; i < 3; i++){
    printf("(%f, %s)\n", weights_out[i], words_out[i]);
  }

  tries_end();
  return 0;
}

Expected output from the above C program

get_empty_trie():
EmptyTrie

mytrie:
a 20.0 30.0
   n 30.0 -1.0
t -1.0 25.0
   o 12.0 -1.0
   e -1.0 25.0
      a 14.0 -1.0
      d 25.0 -1.0


get_next_node("ted", mytrie):
t -1.0 25.0
   o 12.0 -1.0
   e -1.0 25.0
      a 14.0 -1.0
      d 25.0 -1.0


get_node("te", mytrie):
e -1.0 25.0
   a 14.0 -1.0
   d 25.0 -1.0


is_in_trie("ted", mytrie): 1
is_in_trie("tedtalk", mytrie): 0
get_max_weight(mytrie): 30.000000

mytrie_augmented:
a 20.0 30.0
   n 30.0 -1.0
t -1.0 25.0
   o 12.0 -1.0
   e -1.0 25.0
      a 14.0 -1.0
      d 25.0 -1.0
i -1.0 15.0
   n 5.0 15.0
      n 15.0 -1.0



mytrie_augmented after deleting "in"
a 20.0 30.0
   n 30.0 -1.0
t -1.0 25.0
   o 12.0 -1.0
   e -1.0 25.0
      a 14.0 -1.0
      d 25.0 -1.0
i -1.0 15.0
   n -1.0 15.0
      n 15.0 -1.0


mytrie4 using read_terms:
a 20.0 30.0
   n 30.0 -1.0
t -1.0 25.0
   o 12.0 -1.0
   e -1.0 25.0
      a 14.0 -1.0
      d 25.0 -1.0


autocomplete results:
(25.000000, ted)
(14.000000, tea)
(12.000000, to)

slowcomplete results:
(25.000000, ted)
(14.000000, tea)
(12.000000, to)

Unit tests

The script run_tests.sh compiles the Haskell library, organizes to-be-exported FFI functions in a dependencies folder, and compiles the unit test file test/test_tries.c:

sh run_tests.sh

Documentation (using doxygen)

Documentation for the C interface can be generated using doxygen. First, you will need to have doxygen installed. This can likely be accomplished using your OS package manager. For example, using homebrew,

brew install doxygen

Now, simply run doxygen on doxygen_config:

doxygen doxygen_config

Finally, open the generated html/files.html to see documentation for src/tries.c and src/tries.h. This can be done on macOS using the open command:

open html/files.html