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# XML-database conversion
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import copy
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import re
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from xml.dom import Node
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import exc
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import Parser
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import sql
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import sql_gen
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import strings
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import util
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import xml_dom
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import xml_func
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import xpath
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def name_of(node): return re.sub(r'^.*\.', r'', node.tagName)
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ptr_suffix = '_id'
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def is_ptr(node_name): return node_name.lower().endswith(ptr_suffix)
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def ptr_type_guess(node_name):
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    assert is_ptr(node_name)
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    return node_name[:-len(ptr_suffix)]
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def ptr_target(node):
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    assert is_ptr(name_of(node))
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    return xml_dom.value_node(node)
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def find_by_name(node, name):
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    for parent in xml_dom.NodeParentIter(node):
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        if name_of(parent) == name: return parent
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        else:
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            for child in xml_dom.NodeElemIter(parent):
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                child_name = name_of(child)
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                if is_ptr(child_name):
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                    target = ptr_target(child)
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                    if target.tagName == name: return target
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                elif child_name == name: return child
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    return None
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def get(db, node, limit=None, start=None):
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    def pkey(table): return sql.pkey(db, table)
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    node = node.firstChild
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    table = name_of(node)
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    pkey_ = pkey(table)
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    fields = []
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    conds = {}
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    for child in xml_dom.NodeElemIter(node):
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        child_name = name_of(child)
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        if xml_dom.is_empty(child): fields.append(child_name)
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        elif xml_dom.is_text(child): conds[child_name] = xml_dom.value(child)
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        else: raise Exception('Joins not supported yet')
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    id_ = xml_dom.get_id(node)
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    if id_ != None: conds[pkey(table)] = id_ # replace any existing pkey value
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    if fields == []: fields.append(pkey_)
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    return sql.select(db, table, fields, conds, limit, start)
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def put(db, node, row_ct_ref=None, on_error=exc.raise_, pool=None,
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    store_ids=False, parent_id=None):
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    '''store_ids enables searching the tree for missing fields'''
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    def pkey(table): return sql.pkey(db, table, True)
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    def put_(node, parent_id=None):
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        args = (db, node, row_ct_ref, on_error, pool, store_ids, parent_id)
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        if parent_id != None and pool != None: pool.apply_async(put, args)
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        else: return put(*args)
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    def on_error_(e):
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        exc.add_msg(e, 'node:\n'+str(node))
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        on_error(e)
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    table = name_of(node)
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    try: pkey_ = pkey(table)
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    except sql.DatabaseErrors, e: on_error_(e); return None
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    row = {}
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    children = []
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    # Divide children into fields and children with fkeys to parent
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    for child in xml_dom.NodeElemIter(node):
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        child_name = name_of(child)
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        if xml_dom.is_empty(child): row[child_name] = None
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        elif xml_dom.is_text(child):
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            row[child_name] = strings.to_unicode(xml_dom.value(child))
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        elif is_ptr(child_name): row[child_name] = put_(ptr_target(child))
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        else: children.append(child)
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    try: del row[pkey_]
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    except KeyError: pass
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    # Add fkey to parent
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    if parent_id != None:
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        parent_ptr = node.getAttribute('fkey')
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        if parent_ptr == '': parent_ptr = pkey(name_of(node.parentNode))
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        row[parent_ptr] = parent_id
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    # Insert node
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    try:
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        for try_num in xrange(2):
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            try:
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                id_ = sql.put(db, table, row, pkey_, row_ct_ref)
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                if store_ids: xml_dom.set_id(node, id_)
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                break
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            except sql.NullValueException, e:
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                col = e.cols[0]
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                if try_num > 0: raise # exception still raised after retry
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                if store_ids and is_ptr(col):
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                    # Search for required column in ancestors and their children
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                    target = find_by_name(node, ptr_type_guess(col))
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                    if target == None: raise
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                    row[col] = xml_dom.get_id(target)
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                else: raise
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    except sql.DatabaseErrors, e: on_error_(e); return None
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    # Insert children with fkeys to parent
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    for child in children: put_(child, id_)
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    return id_
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class ColRef:
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    '''A reference to a table column'''
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    def __init__(self, name, idx):
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        self.name = name
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        self.idx = idx
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    def __str__(self): return self.name
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input_col_prefix = '$'
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put_table_special_funcs = set(['_simplifyPath'])
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def put_table(db, node, in_table, in_row_ct_ref=None,
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    row_ins_ct_ref=None, limit=None, start=0, on_error=exc.raise_,
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    parent_ids_loc=None, next=None):
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    '''
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    @param node The XML tree that transforms the input to the output. Similar to
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        put()'s node param, but with the input column name prefixed by
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        input_col_prefix in place of the column value.
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    @return (table, col) Where the pkeys (from INSERT RETURNING) are made
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        available
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    '''
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    in_table = sql_gen.as_Table(in_table)
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    in_table.set_srcs(sql_gen.src_self, overwrite=False)
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    # Subset in_table
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    if limit != None or start != 0:
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        full_in_table = in_table
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        in_table = copy.copy(in_table) # don't modify input!
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        in_table.set_srcs([full_in_table])
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        sql.run_query_into(db, sql.mk_select(db, in_table, limit=limit,
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            start=start), into=in_table)
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            # in_table will be shadowed (hidden) by the created temp table
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        sql.add_pkey(db, in_table)
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    def pkey(table): return sql.pkey(db, table, True)
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    def put_table_(node):
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        return put_table(db, node, in_table, None, row_ins_ct_ref,
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            on_error=on_error, parent_ids_loc=parent_ids_loc, next=next)
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    is_func = xml_func.is_func(node)
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    out_table = name_of(node)
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    # Divide children into fields and children with fkeys to parent
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    row = {}
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    children = []
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    for child in xml_dom.NodeElemIter(node):
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        child_name = name_of(child)
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        if xml_dom.is_empty(child): row[child_name] = None
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        elif xml_dom.is_text(child):
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            row[child_name] = strings.to_unicode(xml_dom.value(child))
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        else:
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            child_value = xml_dom.value_node(child)
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            if is_func or is_ptr(child_name) or xml_func.is_func(child_value):
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                row[child_name] = child_value
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            else: children.append(child)
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    # Special handling for structural XML functions
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    if out_table == '_simplifyPath':
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        # Parse args
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        def wrap_e(e): raise xml_func.SyntaxError(e)
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        try:
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            next = row['next'] # modifies outer next var used by put_table_()
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            require = row['require']
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            path = row['path']
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        except KeyError, e: wrap_e(e)
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        try: next = xpath.parse(next)
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        except Parser.SyntaxError, e: wrap_e(e)
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        try: next = next[0].name
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        except IndexError, e: wrap_e(e)
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        return put_table_(path)
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    # Remove any explicit pkey
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    try: del row[pkey(out_table)]
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    except KeyError: pass
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    # Add fkey to parent
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    if parent_ids_loc != None:
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        parent_ptr = node.getAttribute('fkey')
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        if parent_ptr == '': parent_ptr = pkey(name_of(node.parentNode))
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        row[parent_ptr] = parent_ids_loc
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    # Divide fields into input columns and literal values
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    parent_ids_loc = None # applies to this section
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    in_tables = [in_table]
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    for out_col, value in row.iteritems():
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        # Handle forward pointers
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        if xml_dom.is_node(value): row[out_col] = value = put_table_(value)
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        # Translate values
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        if isinstance(value, sql_gen.Col): # value is temp table column
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            in_tables.append(value.table)
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        elif util.is_str(value) and value.startswith(input_col_prefix):
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            # value is input column
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            row[out_col] = sql_gen.Col(strings.remove_prefix(input_col_prefix,
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                value), in_table)
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        else: # value is literal value; should only be string or None
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            assert util.is_str(value) or value == None
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            row[out_col] = sql_gen.NamedCol(out_col, value)
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    # Insert node
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    pkeys_loc = sql.put_table(db, out_table, in_tables, row, row_ins_ct_ref,
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        None, next, is_func, on_error)
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    # Insert children with fkeys to parent
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    parent_ids_loc = pkeys_loc # applies to this section
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    for child in children: put_table_(child)
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    # Count # rows and update in_row_ct_ref once all columns have been processed
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    if in_row_ct_ref != None:
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        in_row_ct_ref[0] += sql.table_row_count(db, in_table)
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    return pkeys_loc
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