spellcheck: support transpositions aka Damerau-Levenshtein (PR other/69968)

gcc/fortran/ChangeLog:
	PR other/69968
	* misc.c (gfc_closest_fuzzy_match): Update for renaming of
	levenshtein_distance to get_edit_distance.

gcc/ChangeLog:
	PR other/69968
	* spellcheck-tree.c (levenshtein_distance): Rename to...
	(get_edit_distance): ...this, and update for underlying renaming.
	* spellcheck-tree.h (levenshtein_distance): Rename to...
	(get_edit_distance): ...this.
	* spellcheck.c (levenshtein_distance): Rename to...
	(get_edit_distance): ...this.  Convert from Levenshtein distance
	to Damerau-Levenshtein distance by supporting transpositions of
	adjacent characters.  Rename "v1" to "v_next" and "v0" to
	"v_one_ago".
	(selftest::levenshtein_distance_unit_test_oneway): Rename to...
	(selftest::test_edit_distance_unit_test_oneway): ...this, and
	update for underlying renaming.
	(selftest::levenshtein_distance_unit_test): Rename to...
	(selftest::test_get_edit_distance_unit): ...this, and update for
	underlying renaming.
	(selftest::test_find_closest_string): Add example from PR 69968
	where transposition helps
	(selftest::test_metric_conditions): Update for renaming.
	(selftest::test_metric_conditions): Likewise.
	(selftest::spellcheck_c_tests): Likewise.
	* spellcheck.h (levenshtein_distance): Rename both overloads to...
	(get_edit_distance): ...this.
	(best_match::consider): Update for renaming.

gcc/testsuite/ChangeLog:
	PR other/69968
	* gcc.dg/spellcheck-transposition.c: New test.

From-SVN: r261521

gcc/ChangeLog

+2018-06-12  David Malcolm  <dmalcolm@redhat.com>
+
+	PR other/69968
+	* spellcheck-tree.c (levenshtein_distance): Rename to...
+	(get_edit_distance): ...this, and update for underlying renaming.
+	* spellcheck-tree.h (levenshtein_distance): Rename to...
+	(get_edit_distance): ...this.
+	* spellcheck.c (levenshtein_distance): Rename to...
+	(get_edit_distance): ...this.  Convert from Levenshtein distance
+	to Damerau-Levenshtein distance by supporting transpositions of
+	adjacent characters.  Rename "v1" to "v_next" and "v0" to
+	"v_one_ago".
+	(selftest::levenshtein_distance_unit_test_oneway): Rename to...
+	(selftest::test_edit_distance_unit_test_oneway): ...this, and
+	update for underlying renaming.
+	(selftest::levenshtein_distance_unit_test): Rename to...
+	(selftest::test_get_edit_distance_unit): ...this, and update for
+	underlying renaming.
+	(selftest::test_find_closest_string): Add example from PR 69968
+	where transposition helps
+	(selftest::test_metric_conditions): Update for renaming.
+	(selftest::test_metric_conditions): Likewise.
+	(selftest::spellcheck_c_tests): Likewise.
+	* spellcheck.h (levenshtein_distance): Rename both overloads to...
+	(get_edit_distance): ...this.
+	(best_match::consider): Update for renaming.
+
 2018-06-12  Martin Sebor  <msebor@redhat.com>
 
 	PR tree-optimization/85259

gcc/fortran/ChangeLog

+2018-06-12  David Malcolm  <dmalcolm@redhat.com>
+
+	PR other/69968
+	* misc.c (gfc_closest_fuzzy_match): Update for renaming of
+	levenshtein_distance to get_edit_distance.
+
 2018-06-12  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/44491

gcc/fortran/misc.c

@@ -286,7 +286,7 @@ get_c_kind(const char *c_kind_name, CInteropKind_t kinds_table[])
 
 
 /* For a given name TYPO, determine the best candidate from CANDIDATES
-   perusing Levenshtein distance.  Frees CANDIDATES before returning.  */
+   using get_edit_distance.  Frees CANDIDATES before returning.  */
 
 const char *
 gfc_closest_fuzzy_match (const char *typo, char **candidates)
@@ -299,7 +299,7 @@ gfc_closest_fuzzy_match (const char *typo, char **candidates)
 
   while (cand && *cand)
     {
-      edit_distance_t dist = levenshtein_distance (typo, tl, *cand,
+      edit_distance_t dist = get_edit_distance (typo, tl, *cand,
 	  strlen (*cand));
       if (dist < best_distance)
 	{

gcc/spellcheck-tree.c

@@ -27,18 +27,18 @@ along with GCC; see the file COPYING3.  If not see
 #include "selftest.h"
 #include "stringpool.h"
 
-/* Calculate Levenshtein distance between two identifiers.  */
+/* Calculate edit distance between two identifiers.  */
 
 edit_distance_t
-levenshtein_distance (tree ident_s, tree ident_t)
+get_edit_distance (tree ident_s, tree ident_t)
 {
   gcc_assert (TREE_CODE (ident_s) == IDENTIFIER_NODE);
   gcc_assert (TREE_CODE (ident_t) == IDENTIFIER_NODE);
 
-  return levenshtein_distance (IDENTIFIER_POINTER (ident_s),
-			       IDENTIFIER_LENGTH (ident_s),
-			       IDENTIFIER_POINTER (ident_t),
-			       IDENTIFIER_LENGTH (ident_t));
+  return get_edit_distance (IDENTIFIER_POINTER (ident_s),
+			    IDENTIFIER_LENGTH (ident_s),
+			    IDENTIFIER_POINTER (ident_t),
+			    IDENTIFIER_LENGTH (ident_t));
 }
 
 /* Given TARGET, an identifier, and CANDIDATES, a vec of identifiers,

gcc/spellcheck-tree.h

@@ -25,7 +25,7 @@ along with GCC; see the file COPYING3.  If not see
 /* spellcheck-tree.c  */
 
 extern edit_distance_t
-levenshtein_distance (tree ident_s, tree ident_t);
+get_edit_distance (tree ident_s, tree ident_t);
 
 extern tree
 find_closest_identifier (tree target, const auto_vec<tree> *candidates);

gcc/spellcheck.h

@@ -25,11 +25,11 @@ const edit_distance_t MAX_EDIT_DISTANCE = UINT_MAX;
 
 /* spellcheck.c  */
 extern edit_distance_t
-levenshtein_distance (const char *s, int len_s,
-		      const char *t, int len_t);
+get_edit_distance (const char *s, int len_s,
+		   const char *t, int len_t);
 
 extern edit_distance_t
-levenshtein_distance (const char *s, const char *t);
+get_edit_distance (const char *s, const char *t);
 
 extern const char *
 find_closest_string (const char *target,
@@ -73,7 +73,7 @@ struct edit_distance_traits<const char *>
 
    This type accumulates the best possible match against GOAL_TYPE for
    a sequence of elements of CANDIDATE_TYPE, whilst minimizing the
-   number of calls to levenshtein_distance and to
+   number of calls to get_edit_distance and to
    edit_distance_traits<T>::get_length.  */
 
 template <typename GOAL_TYPE, typename CANDIDATE_TYPE>
@@ -126,9 +126,9 @@ class best_match
     /* Otherwise, compute the distance and see if the candidate
        has beaten the previous best value.  */
     edit_distance_t dist
-      = levenshtein_distance (m_goal, m_goal_len,
-			      candidate_traits::get_string (candidate),
-			      candidate_len);
+      = get_edit_distance (m_goal, m_goal_len,
+			   candidate_traits::get_string (candidate),
+			   candidate_len);
     if (dist < m_best_distance)
       {
 	m_best_distance = dist;

gcc/testsuite/ChangeLog

+2018-06-12  David Malcolm  <dmalcolm@redhat.com>
+
+	PR other/69968
+	* gcc.dg/spellcheck-transposition.c: New test.
+
 2018-06-12  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/44491

gcc/testsuite/gcc.dg/spellcheck-transposition.c

+/* PR other/69968.  */
+
+struct {
+  int coordx, coordy, coordz;
+  int coordx1, coordy1, coordz1;
+} c;
+
+/* Consider the misspelling "coorzd1".
+
+   With Levenshtein distance, the misspelling has an edit distance of 2
+   to all 6 of the fields (e.g. via a deletion and a substitution for the
+   first three, and via deletion and insertion for the second three).
+   
+   With Damerau-Levenshtein, the misspelling has an edit distance of 1
+   via transposition to "coordz1", and 2 to the other fields.  */
+
+void foo (void)
+{
+  c.coorzd1 = c.coordy; /* { dg-error "has no member named 'coorzd1'; did you mean 'coordz1'" } */
+}