py/objstr: For str.format, add nested/computed fields support.
Eg: '{:{}}'.format(123, '>20')
@pohmelie was the original author of this patch, but @dpgeorge made
significant changes to reduce code size and improve efficiency.
This commit is contained in:
pohmelie
Damien George
parent
2bd758fe96
commit
e3a29de1dc
53
py/objstr.c
53
py/objstr.c
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@ -34,6 +34,7 @@
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#include "py/objlist.h"
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#include "py/runtime0.h"
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#include "py/runtime.h"
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#include "py/stackctrl.h"
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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);
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@ -848,16 +849,12 @@ STATIC NORETURN void terse_str_format_value_error(void) {
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nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "bad format string"));
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}
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mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
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assert(MP_OBJ_IS_STR_OR_BYTES(args[0]));
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GET_STR_DATA_LEN(args[0], str, len);
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int arg_i = 0;
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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) {
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vstr_t vstr;
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mp_print_t print;
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vstr_init_print(&vstr, 16, &print);
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for (const byte *top = str + len; str < top; str++) {
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for (; str < top; str++) {
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if (*str == '}') {
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str++;
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if (str < top && *str == '}') {
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@ -886,7 +883,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
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vstr_t *field_name = NULL;
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char conversion = '\0';
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vstr_t *format_spec = NULL;
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const char *format_spec = NULL;
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if (str < top && *str != '}' && *str != '!' && *str != ':') {
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field_name = vstr_new();
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@ -927,9 +924,16 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
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// '{:d}'.format(True) returns '1'
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// So we treat {:} as {} and this later gets treated to be {!s}
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if (*str != '}') {
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format_spec = vstr_new();
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while (str < top && *str != '}') {
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vstr_add_byte(format_spec, *str++);
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format_spec = str;
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for (int nest = 1; str < top;) {
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if (*str == '{') {
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++nest;
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} else if (*str == '}') {
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if (--nest == 0) {
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break;
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}
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}
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++str;
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}
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}
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}
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@ -957,7 +961,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
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const char *field = vstr_null_terminated_str(field_name);
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const char *lookup = NULL;
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if (MP_LIKELY(unichar_isdigit(*field))) {
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if (arg_i > 0) {
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if (*arg_i > 0) {
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if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
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terse_str_format_value_error();
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} else {
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@ -970,7 +974,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
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nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "tuple index out of range"));
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}
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arg = args[index + 1];
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arg_i = -1;
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*arg_i = -1;
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} else {
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for (lookup = field; *lookup && *lookup != '.' && *lookup != '['; lookup++);
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mp_obj_t field_q = mp_obj_new_str(field, lookup - field, true/*?*/);
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@ -986,7 +990,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
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vstr_free(field_name);
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field_name = NULL;
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} else {
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if (arg_i < 0) {
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if (*arg_i < 0) {
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if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
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terse_str_format_value_error();
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} else {
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@ -994,11 +998,11 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
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"can't switch from manual field specification to automatic field numbering"));
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}
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}
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if ((uint)arg_i >= n_args - 1) {
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if ((uint)*arg_i >= n_args - 1) {
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nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "tuple index out of range"));
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}
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arg = args[arg_i + 1];
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arg_i++;
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arg = args[(*arg_i) + 1];
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(*arg_i)++;
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}
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if (!format_spec && !conversion) {
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conversion = 's';
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@ -1037,7 +1041,10 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
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// precision ::= integer
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// type ::= "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"
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const char *s = vstr_null_terminated_str(format_spec);
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// recursively call the formatter to format any nested specifiers
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MP_STACK_CHECK();
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vstr_t format_spec_vstr = mp_obj_str_format_helper(format_spec, str, arg_i, n_args, args, kwargs);
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const char *s = vstr_null_terminated_str(&format_spec_vstr);
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if (isalignment(*s)) {
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align = *s++;
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} else if (*s && isalignment(s[1])) {
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@ -1084,8 +1091,7 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
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"invalid format specifier"));
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}
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}
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vstr_free(format_spec);
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format_spec = NULL;
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vstr_clear(&format_spec_vstr);
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}
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if (!align) {
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if (arg_looks_numeric(arg)) {
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@ -1288,6 +1294,15 @@ mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs
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}
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}
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return vstr;
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}
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mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
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assert(MP_OBJ_IS_STR_OR_BYTES(args[0]));
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GET_STR_DATA_LEN(args[0], str, len);
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int arg_i = 0;
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vstr_t vstr = mp_obj_str_format_helper((const char*)str, (const char*)str + len, &arg_i, n_args, args, kwargs);
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return mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
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}
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@ -66,6 +66,14 @@ test("{:>20}", "foo")
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test("{:^20}", "foo")
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test("{:<20}", "foo")
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# nested format specifiers
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print("{:{}}".format(123, '#>10'))
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print("{:{}{}{}}".format(123, '#', '>', '10'))
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print("{0:{1}{2}}".format(123, '#>', '10'))
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print("{text:{align}{width}}".format(text="foo", align="<", width=20))
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print("{text:{align}{width}}".format(text="foo", align="^", width=10))
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print("{text:{align}{width}}".format(text="foo", align=">", width=30))
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print("{foo}/foo".format(foo="bar"))
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print("{}".format(123, foo="bar"))
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print("{}-{foo}".format(123, foo="bar"))
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