Reduce code duplication in traceback module

Author: jepler

py/obj.c

@@ -143,7 +143,7 @@ void mp_obj_print(mp_obj_t o_in, mp_print_kind_t kind) {
 }
 
 // helper function to print an exception with traceback
-void mp_obj_print_exception(const mp_print_t *print, mp_obj_t exc) {
+void mp_obj_print_exception_with_limit(const mp_print_t *print, mp_obj_t exc, mp_int_t limit) {
     if (mp_obj_is_exception_instance(exc) && stack_ok()) {
         size_t n, *values;
         mp_obj_exception_get_traceback(exc, &n, &values);
@@ -156,16 +156,38 @@ void mp_obj_print_exception(const mp_print_t *print, mp_obj_t exc) {
             #endif
             const compressed_string_t *block_fmt = MP_ERROR_TEXT(", in %q\n");
 
+            // Set traceback formatting
+            // Default: Print full traceback
+            limit = limit * 3;
+            mp_int_t i = n - 3, j;
+            if (limit > 0) {
+                // Print upto limit traceback
+                // entries from caller's frame
+                if ((unsigned)limit > n) {
+                    limit = n;
+                }
+                limit = n - limit;
+            } else if (limit < 0) {
+                // Print upto limit traceback
+                // entries from last
+                if ((unsigned)-limit > n) {
+                    limit = -n;
+                }
+                i = 0, limit = limit + 3;
+            }
+
             // Print the traceback
             mp_cprintf(print, MP_ERROR_TEXT("Traceback (most recent call last):\n"));
-            for (int i = n - 3; i >= 0; i -= 3) {
+
+            for (; i >= limit; i -= 3) {
+                j = (i < 0) ? -i : i;
                 #if MICROPY_ENABLE_SOURCE_LINE
-                mp_cprintf(print, frame, values[i], (int)values[i + 1]);
+                mp_cprintf(print, frame, values[j], (int)values[j + 1]);
                 #else
-                mp_printf(print, frame, values[i]);
+                mp_cprintf(print, frame, values[j]);
                 #endif
-                // the block name can be NULL if it's unknown
-                qstr block = values[i + 2];
+                // The block name can be NULL if it's unknown
+                qstr block = values[j + 2];
                 if (block == MP_QSTRnull) {
                     mp_print_str(print, "\n");
                 } else {
@@ -178,6 +200,10 @@ void mp_obj_print_exception(const mp_print_t *print, mp_obj_t exc) {
     mp_print_str(print, "\n");
 }
 
+void mp_obj_print_exception(const mp_print_t *print, mp_obj_t exc) {
+    mp_obj_print_exception_with_limit(print, exc, 0);
+}
+
 bool PLACE_IN_ITCM(mp_obj_is_true)(mp_obj_t arg) {
     if (arg == mp_const_false) {
         return 0;

py/obj.h

@@ -888,6 +888,7 @@ mp_obj_t mp_obj_cast_to_native_base(mp_obj_t self_in, mp_const_obj_t native_type
 void mp_obj_print_helper(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind);
 void mp_obj_print(mp_obj_t o, mp_print_kind_t kind);
 void mp_obj_print_exception(const mp_print_t *print, mp_obj_t exc);
+void mp_obj_print_exception_with_limit(const mp_print_t *print, mp_obj_t exc, mp_int_t limit);
 
 bool mp_obj_is_true(mp_obj_t arg);
 bool mp_obj_is_callable(mp_obj_t o_in);

shared-module/traceback/__init__.c

@@ -27,61 +27,5 @@
 #include "shared-module/traceback/__init__.h"
 
 void shared_module_traceback_print_exception(mp_obj_exception_t *exc, mp_print_t *print, mp_int_t limit) {
-    // Print traceback
-    if (exc->traceback != NULL) {
-        size_t n = exc->traceback->len;
-        size_t *values = exc->traceback->data;
-        if (n > 0) {
-            assert(n % 3 == 0);
-            // Decompress the format strings
-            const compressed_string_t *traceback = MP_ERROR_TEXT("Traceback (most recent call last):\n");
-            #if MICROPY_ENABLE_SOURCE_LINE
-            const compressed_string_t *frame = MP_ERROR_TEXT("  File \"%q\", line %d");
-            #else
-            const compressed_string_t *frame = MP_ERROR_TEXT("  File \"%q\"");
-            #endif
-            const compressed_string_t *block_fmt = MP_ERROR_TEXT(", in %q\n");
-
-            // Set traceback formatting
-            // Default: Print full traceback
-            limit = limit * 3;
-            mp_int_t i = n - 3, j;
-            if (limit > 0) {
-                // Print upto limit traceback
-                // entries from caller's frame
-                if ((unsigned)limit > n) {
-                    limit = n;
-                }
-                limit = n - limit;
-            } else if (limit < 0) {
-                // Print upto limit traceback
-                // entries from last
-                if ((unsigned)-limit > n) {
-                    limit = -n;
-                }
-                i = 0, limit = limit + 3;
-            }
-
-            // Print the traceback
-            mp_cprintf(print, traceback);
-            for (; i >= limit; i -= 3) {
-                j = (i < 0) ? -i : i;
-                #if MICROPY_ENABLE_SOURCE_LINE
-                mp_cprintf(print, frame, values[j], (int)values[j + 1]);
-                #else
-                mp_printf(print, frame, values[j]);
-                #endif
-                // The block name can be NULL if it's unknown
-                qstr block = values[j + 2];
-                if (block == MP_QSTRnull) {
-                    mp_print_str(print, "\n");
-                } else {
-                    mp_printf(print, block_fmt, block);
-                }
-            }
-        }
-    }
-    // Print exception
-    mp_obj_print_helper(print, exc, PRINT_EXC);
-    mp_print_str(print, "\n");
+    mp_obj_print_exception_with_limit(print, exc, limit);
 }