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Merge pull request #2503 from ReneSac/arrowLike

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Restrict arrow-like operators to those ending with `->`, `~>` or `=>`
This commit is contained in:
Andreas Rumpf 2015-04-15 19:24:44 +02:00
commit b4e938ca21
4 changed files with 29 additions and 9 deletions
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17
doc/manual/syntax.txt
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@ -15,8 +15,6 @@ Associativity
Binary operators whose first character is ``^`` are right-associative, all
other binary operators are left-associative.
Operators ending in ``>`` but longer than a single character are
called `arrow like`:idx:.
Precedence
@ -33,9 +31,12 @@ as ``(@x).abc`` whereas ``$x.abc`` is parsed as ``$(x.abc)``.
For binary operators that are not keywords the precedence is determined by the
following rules:
Operators ending in either ``->``, ``~>`` or ``=>`` are called
`arrow like`:idx:, and have the lowest precedence of all operators.
If the operator ends with ``=`` and its first character is none of
``<``, ``>``, ``!``, ``=``, ``~``, ``?``, it is an *assignment operator* which
has the lowest precedence.
has the second lowest precedence.
Otherwise precedence is determined by the first character.
@ -43,14 +44,14 @@ Otherwise precedence is determined by the first character.
Precedence level Operators First character Terminal symbol
================ =============================================== ================== ===============
10 (highest) ``$ ^`` OP10
9 ``* / div mod shl shr %`` ``* % \ /`` OP9
8 ``+ -`` ``+ ~ |`` OP8
9 ``* / div mod shl shr %`` ``* % \ /`` OP9
8 ``+ -`` ``+ - ~ |`` OP8
7 ``&`` ``&`` OP7
6 ``..`` ``.`` OP6
5 ``== <= < >= > != in notin is isnot not of`` ``= < > !`` OP5
5 ``== <= < >= > != in notin is isnot not of`` ``= < > !`` OP5
4 ``and`` OP4
3 ``or xor`` OP3
2 ``@ : ?`` OP2
2 ``@ : ?`` OP2
1 *assignment operator* (like ``+=``, ``*=``) OP1
0 (lowest) *arrow like operator* (like ``->``, ``=>``) OP0
================ =============================================== ================== ===============
@ -67,7 +68,7 @@ is still parsed as ``1 + (3 * 4)``, but ``1+3 * 4`` is parsed as ``(1+3) * 4``:
.. code-block:: nim
#! strongSpaces
if foo+4 * 4 == 8 and b&c | 9 ++
if foo+4 * 4 == 8 and b&c | 9 ++
bar:
echo ""
# is parsed as