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57 lines
1.7 KiB
C++
57 lines
1.7 KiB
C++
#include <Parsers/ASTWithAlias.h>
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#include <IO/WriteHelpers.h>
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#include <IO/Operators.h>
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namespace DB
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{
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static void writeAlias(const String & name, const ASTWithAlias::FormatSettings & settings)
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{
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settings.ostr << (settings.hilite ? IAST::hilite_keyword : "") << " AS " << (settings.hilite ? IAST::hilite_alias : "");
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settings.writeIdentifier(name);
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settings.ostr << (settings.hilite ? IAST::hilite_none : "");
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}
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void ASTWithAlias::formatImpl(const FormatSettings & settings, FormatState & state, FormatStateStacked frame) const
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{
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/// If we have previously output this node elsewhere in the query, now it is enough to output only the alias.
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/// This is needed because the query can become extraordinary large after substitution of aliases.
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if (!alias.empty() && !state.printed_asts_with_alias.emplace(frame.current_select, alias, getTreeHash()).second)
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{
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settings.writeIdentifier(alias);
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}
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else
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{
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/// If there is an alias, then parentheses are required around the entire expression, including the alias.
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/// Because a record of the form `0 AS x + 0` is syntactically invalid.
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if (frame.need_parens && !alias.empty())
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settings.ostr << '(';
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formatImplWithoutAlias(settings, state, frame);
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if (!alias.empty())
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{
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writeAlias(alias, settings);
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if (frame.need_parens)
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settings.ostr << ')';
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}
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}
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}
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void ASTWithAlias::appendColumnName(WriteBuffer & ostr) const
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{
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if (prefer_alias_to_column_name && !alias.empty())
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writeString(alias, ostr);
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else
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appendColumnNameImpl(ostr);
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}
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void ASTWithAlias::appendColumnNameWithoutAlias(WriteBuffer & ostr) const
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{
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appendColumnNameImpl(ostr);
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}
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}
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