py/objstrunicode: str_index_to_ptr: Implement positive indexing properly.
Order out-of-bounds check, completion check, and increment in the right way.
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@ -149,26 +149,29 @@ const byte *str_index_to_ptr(const mp_obj_type_t *type, const byte *self_data, s
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}
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}
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++s;
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} else if (!i) {
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return self_data; // Shortcut - str[0] is its base pointer
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} else {
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// Positive indexing, correspondingly, counts from the start of the string.
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// It's assumed that negative indexing will generally be used with small
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// absolute values (eg str[-1], not str[-1000000]), which means it'll be
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// more efficient this way.
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for (s = self_data; true; ++s) {
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s = self_data;
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while (1) {
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// First check out-of-bounds
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if (s >= top) {
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if (is_slice) {
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return top;
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}
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nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_IndexError, "string index out of range"));
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}
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// Then check completion
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if (i-- == 0) {
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break;
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}
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// Then skip UTF-8 char
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++s;
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while (UTF8_IS_CONT(*s)) {
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++s;
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}
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if (!i--) {
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return s;
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}
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}
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}
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return s;
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