1 | #include <Parsers/ASTWithAlias.h> |
2 | #include <IO/WriteBufferFromOStream.h> |
3 | #include <IO/WriteHelpers.h> |
4 | |
5 | |
6 | namespace DB |
7 | { |
8 | |
9 | void ASTWithAlias::writeAlias(const String & name, const FormatSettings & settings) const |
10 | { |
11 | settings.ostr << (settings.hilite ? hilite_keyword : "" ) << " AS " << (settings.hilite ? hilite_alias : "" ); |
12 | settings.writeIdentifier(name); |
13 | settings.ostr << (settings.hilite ? hilite_none : "" ); |
14 | } |
15 | |
16 | |
17 | void ASTWithAlias::formatImpl(const FormatSettings & settings, FormatState & state, FormatStateStacked frame) const |
18 | { |
19 | /// If we have previously output this node elsewhere in the query, now it is enough to output only the alias. |
20 | /// This is needed because the query can become extraordinary large after substitution of aliases. |
21 | if (!alias.empty() && !state.printed_asts_with_alias.emplace(frame.current_select, alias, getTreeHash()).second) |
22 | { |
23 | settings.writeIdentifier(alias); |
24 | } |
25 | else |
26 | { |
27 | /// If there is an alias, then parentheses are required around the entire expression, including the alias. |
28 | /// Because a record of the form `0 AS x + 0` is syntactically invalid. |
29 | if (frame.need_parens && !alias.empty()) |
30 | settings.ostr << '('; |
31 | |
32 | formatImplWithoutAlias(settings, state, frame); |
33 | |
34 | if (!alias.empty()) |
35 | { |
36 | writeAlias(alias, settings); |
37 | if (frame.need_parens) |
38 | settings.ostr << ')'; |
39 | } |
40 | } |
41 | } |
42 | |
43 | void ASTWithAlias::appendColumnName(WriteBuffer & ostr) const |
44 | { |
45 | if (prefer_alias_to_column_name && !alias.empty()) |
46 | writeString(alias, ostr); |
47 | else |
48 | appendColumnNameImpl(ostr); |
49 | } |
50 | |
51 | } |
52 | |