diff --git a/py/objstr.c b/py/objstr.c
index 73de7b5da25e6e5e06a7336a9f0de99e6d9e76d7..c0f8c23b941ed07549b4cccc45134c45e25732ca 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -34,6 +34,7 @@
#include "py/objlist.h"
#include "py/runtime0.h"
#include "py/runtime.h"
+#include "py/stackctrl.h"
STATIC mp_obj_t str_modulo_format(mp_obj_t pattern, mp_uint_t n_args, const mp_obj_t *args, mp_obj_t dict);
@@ -848,16 +849,12 @@ STATIC NORETURN void terse_str_format_value_error(void) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "bad format string"));
}
-mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
- assert(MP_OBJ_IS_STR_OR_BYTES(args[0]));
-
- GET_STR_DATA_LEN(args[0], str, len);
- int arg_i = 0;
+vstr_t mp_obj_str_format_helper(const char *str, const char *top, int *arg_i, mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
vstr_t vstr;
mp_print_t print;
vstr_init_print(&vstr, 16, &print);
- for (const byte *top = str + len; str < top; str++) {
+ for (; str < top; str++) {
if (*str == '}') {
str++;
if (str < top && *str == '}') {
@@ -886,7 +883,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
vstr_t *field_name = NULL;
char conversion = '\0';
- vstr_t *format_spec = NULL;
+ const char *format_spec = NULL;
if (str < top && *str != '}' && *str != '!' && *str != ':') {
field_name = vstr_new();
@@ -927,9 +924,16 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
// '{:d}'.format(True) returns '1'
// So we treat {:} as {} and this later gets treated to be {!s}
if (*str != '}') {
- format_spec = vstr_new();
- while (str < top && *str != '}') {
- vstr_add_byte(format_spec, *str++);
+ format_spec = str;
+ for (int nest = 1; str < top;) {
+ if (*str == '{') {
+ ++nest;
+ } else if (*str == '}') {
+ if (--nest == 0) {
+ break;
+ }
+ }
+ ++str;
}
}
}
@@ -957,7 +961,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
const char *field = vstr_null_terminated_str(field_name);
const char *lookup = NULL;
if (MP_LIKELY(unichar_isdigit(*field))) {
- if (arg_i > 0) {
+ if (*arg_i > 0) {
if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
terse_str_format_value_error();
} else {
@@ -970,7 +974,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "tuple index out of range"));
}
arg = args[index + 1];
- arg_i = -1;
+ *arg_i = -1;
} else {
for (lookup = field; *lookup && *lookup != '.' && *lookup != '['; lookup++);
mp_obj_t field_q = mp_obj_new_str(field, lookup - field, true/*?*/);
@@ -986,7 +990,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
vstr_free(field_name);
field_name = NULL;
} else {
- if (arg_i < 0) {
+ if (*arg_i < 0) {
if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
terse_str_format_value_error();
} else {
@@ -994,11 +998,11 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
"can't switch from manual field specification to automatic field numbering"));
}
}
- if ((uint)arg_i >= n_args - 1) {
+ if ((uint)*arg_i >= n_args - 1) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "tuple index out of range"));
}
- arg = args[arg_i + 1];
- arg_i++;
+ arg = args[(*arg_i) + 1];
+ (*arg_i)++;
}
if (!format_spec && !conversion) {
conversion = 's';
@@ -1037,7 +1041,10 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
// precision ::= integer
// type ::= "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"
- const char *s = vstr_null_terminated_str(format_spec);
+ // recursively call the formatter to format any nested specifiers
+ MP_STACK_CHECK();
+ vstr_t format_spec_vstr = mp_obj_str_format_helper(format_spec, str, arg_i, n_args, args, kwargs);
+ const char *s = vstr_null_terminated_str(&format_spec_vstr);
if (isalignment(*s)) {
align = *s++;
} else if (*s && isalignment(s[1])) {
@@ -1084,8 +1091,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
"invalid format specifier"));
}
}
- vstr_free(format_spec);
- format_spec = NULL;
+ vstr_clear(&format_spec_vstr);
}
if (!align) {
if (arg_looks_numeric(arg)) {
@@ -1288,6 +1294,15 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
}
}
+ return vstr;
+}
+
+mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
+ assert(MP_OBJ_IS_STR_OR_BYTES(args[0]));
+
+ GET_STR_DATA_LEN(args[0], str, len);
+ int arg_i = 0;
+ vstr_t vstr = mp_obj_str_format_helper((const char*)str, (const char*)str + len, &arg_i, n_args, args, kwargs);
return mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
}
diff --git a/tests/basics/string_format.py b/tests/basics/string_format.py
index 7fb53cb491343a32d71161e29d7093261be0b2aa..e07f0d953340b233308172f251f8545ca5e58c91 100644
--- a/tests/basics/string_format.py
+++ b/tests/basics/string_format.py
@@ -66,6 +66,14 @@ test("{:>20}", "foo")
test("{:^20}", "foo")
test("{:<20}", "foo")
+# nested format specifiers
+print("{:{}}".format(123, '#>10'))
+print("{:{}{}{}}".format(123, '#', '>', '10'))
+print("{0:{1}{2}}".format(123, '#>', '10'))
+print("{text:{align}{width}}".format(text="foo", align="<", width=20))
+print("{text:{align}{width}}".format(text="foo", align="^", width=10))
+print("{text:{align}{width}}".format(text="foo", align=">", width=30))
+
print("{foo}/foo".format(foo="bar"))
print("{}".format(123, foo="bar"))
print("{}-{foo}".format(123, foo="bar"))