babelfish-for-postgresql / babelfish_extensions / 11331010303

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Support unary '+' operators for strings (#3013)


The T-SQL grammar allows an arbitrary number of unary + operators to precede an expression,
but PG only supports that for numeric expressions. For string expressions, the + will be parsed fine by the T-SQL ANTLR parser, but these will raise an error in PG.
In SQL those unary + string operators may look like they are additional concatenation operators, like: SELECT 'a' ++ 'b'. Expressions such as +++(+++@v)) are also valid syntax according to the T-SQL grammar even though they look unusual.
In this fix we remove such unary + operators, which are redundant anyway.
However we do not touch numeric constants (e.g. +123) since the +, though still redundant, may
have been included for code clarity (e.g. +123 as opposed to -123).

Signed-off-by: Rob Verschoor rcv@amazon.com

Issues Resolved
BABEL-1924 Support unary '+' operator for string expressions

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