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Use the `%left', `%right' or `%nonassoc' declaration to declare a
token and specify its precedence and associativity, all at once. These
are called "precedence declarations". *Note Operator Precedence:
Precedence, for general information on operator precedence.
The syntax of a precedence declaration is the same as that of
%left <TYPE> SYMBOLS...
And indeed any of these declarations serves the purposes of `%token'.
But in addition, they specify the associativity and relative precedence
for all the SYMBOLS:
* The associativity of an operator OP determines how repeated uses
of the operator nest: whether `X OP Y OP Z' is parsed by grouping
X with Y first or by grouping Y with Z first. `%left' specifies
left-associativity (grouping X with Y first) and `%right'
specifies right-associativity (grouping Y with Z first).
`%nonassoc' specifies no associativity, which means that `X OP Y
OP Z' is considered a syntax error.
* The precedence of an operator determines how it nests with other
operators. All the tokens declared in a single precedence
declaration have equal precedence and nest together according to
their associativity. When two tokens declared in different
precedence declarations associate, the one declared later has the
higher precedence and is grouped first.
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