pegen_restore_token.c

expr_ty _PyPegen_produce_string(Parser *p, expr_ty a) {
    int start = -1, end = -1, length = 0, seen_walrus = 0, mark;
    for (mark = p->mark; start == -1; --mark) {
        Token* token = p->tokens[mark];
        if (token->end_lineno == a->end_lineno
            && token->end_col_offset == a->end_col_offset)
        {
            end = mark;
        }
        if (token->lineno == a->lineno
            && token->col_offset == a->col_offset)
        {
            start = mark;
        }
        if (end != -1) {
            length = length + PyBytes_GET_SIZE(token->bytes);
            if (IS_KEYWORD(token) || token->type == NUMBER) {
                length = length + 2;
            } else if (token->type == COLONEQUAL) {
                seen_walrus = 1;
            }
        }
    }

    assert(start != -1 || end != -1);
    char* buffer = PyMem_Calloc(length + seen_walrus * 2, sizeof(char*));
    for (mark = start; mark <= end; ++mark) {
        int is_start = mark == start;
        Token* token = p->tokens[mark];
        char *value = PyBytes_AS_STRING(token->bytes);
        if (IS_KEYWORD(token) || token->type == NUMBER) {
            const char *format;
            char new_value[strlen(value) + 2];
            if (is_start) {
                format = "%s ";
            } else {
                format = " %s ";
            }
            value = PyMem_Malloc(sprintf(new_value, format, value) + 1);
            strcpy(value, new_value);
        }
        if (mark == start) {
            if (seen_walrus) {
                strcpy(buffer, "(");
                strcat(buffer, value);
            } else {
                strcpy(buffer, value);
            }
        } else {
            strcat(buffer, value);
        }
    }
    if (seen_walrus) {
        strcat(buffer, ")");
    }
    PyObject *res = PyUnicode_FromString(buffer);
    PyMem_Free(buffer);
    if (res == NULL) {
        return NULL;
    }
    if (PyArena_AddPyObject(p->arena, res) < 0) {
        Py_DECREF(res);
        return NULL;
    }

    return Constant(res, NULL, a->lineno, a->col_offset, a->end_lineno, a->end_col_offset,
                    p->arena);
}