erts: Refactor maps:from_list/1

1 files changed, 85 insertions, 78 deletions

diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index 69dd91d079..5e5e567642 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -69,6 +69,7 @@ static Eterm hashmap_to_list(Process *p, Eterm map);
 static Eterm hashmap_keys(Process *p, Eterm map);
 static Eterm hashmap_values(Process *p, Eterm map);
 static Eterm hashmap_delete(Process *p, Uint32 hx, Eterm key, Eterm node);
+static Eterm map_from_validated_list(Process *p, Eterm list, Uint size);
 
 /* erlang:map_size/1
  * the corresponding instruction is implemented in:
@@ -227,13 +228,8 @@ BIF_RETTYPE maps_get_2(BIF_ALIST_2) {
  */
 
 BIF_RETTYPE maps_from_list_1(BIF_ALIST_1) {
-    Eterm *kv, item = BIF_ARG_1;
-    Eterm *hp, *thp,*vs, *ks, keys, res;
-    map_t *mp;
-    Uint  size = 0, unused_size = 0;
-    Sint  c = 0;
-    Sint  idx = 0;
-
+    Eterm item = BIF_ARG_1, res, *kv;
+    Uint  size = 0;
     if (is_list(item) || is_nil(item)) {
 
 	/* Calculate size and check validity */
@@ -254,95 +250,106 @@ BIF_RETTYPE maps_from_list_1(BIF_ALIST_1) {
 	if (is_not_nil(item))
 	    goto error;
 
-	hp    = HAlloc(BIF_P, 3 + 1 + (2 * size));
-	thp   = hp;
-	keys  = make_tuple(hp);
-	*hp++ = make_arityval(size);
-	ks    = hp;
-	hp   += size;
-	mp    = (map_t*)hp;
-	res   = make_map(mp);
-	hp   += MAP_HEADER_SIZE;
-	vs    = hp;
+	BIF_RET(map_from_validated_list(BIF_P, BIF_ARG_1, size));
+    }
 
-	mp->thing_word = MAP_HEADER;
-	mp->size = size; /* set later, might shrink*/
-	mp->keys = keys;
+error:
 
-	if (size == 0)
-	    BIF_RET(res);
+    BIF_ERROR(BIF_P, BADARG);
+}
+
+static Eterm map_from_validated_list(Process *p, Eterm list, Uint size) {
+    Eterm *kv, item = list;
+    Eterm *hp, *thp,*vs, *ks, keys, res;
+    map_t *mp;
+    Uint  unused_size = 0;
+    Sint  c = 0;
+    Sint  idx = 0;
 
-	item  = BIF_ARG_1;
 
-	/* first entry */
-	kv    = tuple_val(CAR(list_val(item)));
-	ks[0] = kv[1];
-	vs[0] = kv[2];
-	size  = 1;
-	item  = CDR(list_val(item));
+    hp    = HAlloc(p, 3 + 1 + (2 * size));
+    thp   = hp;
+    keys  = make_tuple(hp);
+    *hp++ = make_arityval(size);
+    ks    = hp;
+    hp   += size;
+    mp    = (map_t*)hp;
+    res   = make_map(mp);
+    hp   += MAP_HEADER_SIZE;
+    vs    = hp;
 
-	/* insert sort key/value pairs */
-	while(is_list(item)) {
+    mp->thing_word = MAP_HEADER;
+    mp->size = size; /* set later, might shrink*/
+    mp->keys = keys;
 
-	    kv = tuple_val(CAR(list_val(item)));
+    if (size == 0)
+	return res;
 
-	    /* compare ks backwards
-	     * idx represent word index to be written (hole position).
-	     * We cannot copy the elements when searching since we might
-	     * have an equal key. So we search for just the index first =(
-	     *
-	     * It is perhaps faster to move the values in the first pass.
-	     * Check for uniqueness during insert phase and then have a
-	     * second phace compacting the map if duplicates are found
-	     * during insert. .. or do someother sort .. shell-sort perhaps.
-	     */
+    /* first entry */
+    kv    = tuple_val(CAR(list_val(item)));
+    ks[0] = kv[1];
+    vs[0] = kv[2];
+    size  = 1;
+    item  = CDR(list_val(item));
+
+    /* insert sort key/value pairs */
+    while(is_list(item)) {
+
+	kv = tuple_val(CAR(list_val(item)));
+
+	/* compare ks backwards
+	 * idx represent word index to be written (hole position).
+	 * We cannot copy the elements when searching since we might
+	 * have an equal key. So we search for just the index first =(
+	 *
+	 * It is perhaps faster to move the values in the first pass.
+	 * Check for uniqueness during insert phase and then have a
+	 * second phace compacting the map if duplicates are found
+	 * during insert. .. or do someother sort .. shell-sort perhaps.
+	 */
 
-	    idx = size;
+	idx = size;
 
-	    while(idx > 0 && (c = CMP_TERM(kv[1],ks[idx-1])) < 0) { idx--; }
+	while(idx > 0 && (c = CMP_TERM(kv[1],ks[idx-1])) < 0) { idx--; }
 
-	    if (c == 0) {
-		/* last compare was equal,
-		 * i.e. we have to release memory
-		 * and overwrite that key/value
-		 */
-		ks[idx-1] = kv[1];
-		vs[idx-1] = kv[2];
-		unused_size++;
-	    } else {
-		Uint i = size;
-		while(i > idx) {
-		    ks[i] = ks[i-1];
-		    vs[i] = vs[i-1];
-		    i--;
-		}
-		ks[idx] = kv[1];
-		vs[idx] = kv[2];
-		size++;
+	if (c == 0) {
+	    /* last compare was equal,
+	     * i.e. we have to release memory
+	     * and overwrite that key/value
+	     */
+	    ks[idx-1] = kv[1];
+	    vs[idx-1] = kv[2];
+	    unused_size++;
+	} else {
+	    Uint i = size;
+	    while(i > idx) {
+		ks[i] = ks[i-1];
+		vs[i] = vs[i-1];
+		i--;
 	    }
-	    item = CDR(list_val(item));
+	    ks[idx] = kv[1];
+	    vs[idx] = kv[2];
+	    size++;
 	}
+	item = CDR(list_val(item));
+    }
 
-	if (unused_size) {
-	    /* the key tuple is embedded in the heap
-	     * write a bignum to clear it.
-	     */
-	    /* release values as normal since they are on the top of the heap */
-
-	    ks[size] = make_pos_bignum_header(unused_size - 1);
-	    HRelease(BIF_P, vs + size + unused_size, vs + size);
-	}
+    if (unused_size) {
+	/* the key tuple is embedded in the heap
+	 * write a bignum to clear it.
+	 */
+	/* release values as normal since they are on the top of the heap */
 
-	*thp = make_arityval(size);
-	mp->size = size;
-	BIF_RET(res);
+	ks[size] = make_pos_bignum_header(unused_size - 1);
+	HRelease(p, vs + size + unused_size, vs + size);
     }
 
-error:
-
-    BIF_ERROR(BIF_P, BADARG);
+    *thp = make_arityval(size);
+    mp->size = size;
+    return res;
 }
 
+
 /* maps:is_key/2
  */