Merge pull request #687 from fadushin/interop-iolist-additions

Added interop_iolist_fold

This PR adds a function that supports traversal of values (integers and
binaries) in an IO list.

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

Author: bettio

src/libAtomVM/interop.c

@@ -176,19 +176,16 @@ term interop_proplist_get_value_default(term list, term key, term default_value)
     return default_value;
 }
 
-InteropFunctionResult interop_iolist_size(term t, size_t *size)
+inline InteropFunctionResult interop_iolist_fold(term t, interop_iolist_fold_fun fold_fun, void *accum)
 {
     if (term_is_binary(t)) {
-        *size = term_binary_size(t);
-        return InteropOk;
+        return fold_fun(t, accum);
     }
 
     if (UNLIKELY(!term_is_list(t))) {
         return InteropBadArg;
     }
 
-    unsigned long acc = 0;
-
     struct TempStack temp_stack;
     if (UNLIKELY(temp_stack_init(&temp_stack) != TempStackOk)) {
         return InteropMemoryAllocFail;
@@ -200,9 +197,14 @@ InteropFunctionResult interop_iolist_size(term t, size_t *size)
     }
 
     while (!temp_stack_is_empty(&temp_stack)) {
-        if (term_is_integer(t)) {
-            acc++;
-            t = temp_stack_pop(&temp_stack);
+        if (term_is_integer(t) || term_is_binary(t)) {
+            InteropFunctionResult result = fold_fun(t, accum);
+            if (UNLIKELY(result != InteropOk)) {
+                temp_stack_destroy(&temp_stack);
+                return result;
+            } else {
+                t = temp_stack_pop(&temp_stack);
+            }
 
         } else if (term_is_nil(t)) {
             t = temp_stack_pop(&temp_stack);
@@ -214,10 +216,6 @@ InteropFunctionResult interop_iolist_size(term t, size_t *size)
             }
             t = term_get_list_head(t);
 
-        } else if (term_is_binary(t)) {
-            acc += term_binary_size(t);
-            t = temp_stack_pop(&temp_stack);
-
         } else {
             temp_stack_destroy(&temp_stack);
             return InteropBadArg;
@@ -226,60 +224,45 @@ InteropFunctionResult interop_iolist_size(term t, size_t *size)
 
     temp_stack_destroy(&temp_stack);
 
-    *size = acc;
     return InteropOk;
 }
 
-InteropFunctionResult interop_write_iolist(term t, char *p)
+static inline InteropFunctionResult size_fold_fun(term t, void *accum)
 {
-    if (term_is_binary(t)) {
-        int len = term_binary_size(t);
-        memcpy(p, term_binary_data(t), len);
-        return InteropOk;
-    }
-
-    struct TempStack temp_stack;
-    if (UNLIKELY(temp_stack_init(&temp_stack) != TempStackOk)) {
-        return InteropMemoryAllocFail;
-    }
-
-    if (UNLIKELY(temp_stack_push(&temp_stack, t) != TempStackOk)) {
-        temp_stack_destroy(&temp_stack);
-        return InteropMemoryAllocFail;
+    size_t *size = (size_t *) accum;
+    if (term_is_integer(t)) {
+        *size += 1;
+    } else if (term_is_binary(t)) {
+        *size += term_binary_size(t);
     }
+    return InteropOk;
+}
 
-    while (!temp_stack_is_empty(&temp_stack)) {
-        if (term_is_integer(t)) {
-            *p = term_to_int(t);
-            p++;
-            t = temp_stack_pop(&temp_stack);
-
-        } else if (term_is_nil(t)) {
-            t = temp_stack_pop(&temp_stack);
-
-        } else if (term_is_nonempty_list(t)) {
-            if (UNLIKELY(temp_stack_push(&temp_stack, term_get_list_tail(t)) != TempStackOk)) {
-                temp_stack_destroy(&temp_stack);
-                return InteropMemoryAllocFail;
-            }
-            t = term_get_list_head(t);
-
-        } else if (term_is_binary(t)) {
-            int len = term_binary_size(t);
-            memcpy(p, term_binary_data(t), len);
-            p += len;
-            t = temp_stack_pop(&temp_stack);
+InteropFunctionResult interop_iolist_size(term t, size_t *size)
+{
+    *size = 0;
+    return interop_iolist_fold(t, size_fold_fun, size);
+}
 
-        } else {
-            temp_stack_destroy(&temp_stack);
-            return InteropBadArg;
-        }
+static inline InteropFunctionResult write_string_fold_fun(term t, void *accum)
+{
+    char **p = (char **) accum;
+    if (term_is_integer(t)) {
+        **p = term_to_int(t);
+        (*p)++;
+    } else if (term_is_binary(t)) {
+        int len = term_binary_size(t);
+        memcpy(*p, term_binary_data(t), len);
+        *p += len;
     }
-
-    temp_stack_destroy(&temp_stack);
     return InteropOk;
 }
 
+InteropFunctionResult interop_write_iolist(term t, char *p)
+{
+    return interop_iolist_fold(t, write_string_fold_fun, (void *) &p);
+}
+
 term interop_map_get_value(GlobalContext *glb, term map, term key)
 {
     return interop_map_get_value_default(glb, map, key, term_nil());

src/libAtomVM/interop.h

@@ -53,6 +53,8 @@ typedef struct
     int i_val;
 } AtomStringIntPair;
 
+typedef InteropFunctionResult (*interop_iolist_fold_fun)(term t, void *accum);
+
 char *interop_term_to_string(term t, int *ok);
 char *interop_binary_to_string(term binary);
 char *interop_list_to_string(term list, int *ok);
@@ -65,6 +67,7 @@ term interop_map_get_value_default(GlobalContext *glb, term map, term key, term
 
 NO_DISCARD InteropFunctionResult interop_iolist_size(term t, size_t *size);
 NO_DISCARD InteropFunctionResult interop_write_iolist(term t, char *p);
+NO_DISCARD InteropFunctionResult interop_iolist_fold(term t, interop_iolist_fold_fun fold_fun, void *accum);
 
 /**
  * @brief Finds on a table the first matching atom string.