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operator precedence changed: assignment like operators are supported; escaping of operators with \ is supported

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Araq 2011-11-09 01:42:05 +01:00
commit 68be801f63
7 changed files with 64 additions and 26 deletions
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doc/manual.txt
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@ -387,13 +387,25 @@ This section lists Nimrod's standard syntax in ENBF. How the parser receives
indentation tokens is already described in the `Lexical Analysis`_ section.
Nimrod allows user-definable operators.
Binary operators have 9 different levels of precedence. For user-defined
operators, the precedence depends on the first character the operator consists
of. All binary operators are left-associative, except binary operators starting
with (or only consisting of) ``^``.
Binary operators have 10 different levels of precedence.
All binary operators are left-associative, except binary operators starting
with (or only consisting of) ``^``.
For operators that are not keywords the precedence is determined by the
following rules:
An operator symbol's *relevant character* is its first
character unless the first character is ``\`` and its length is greater than 1
then it is the second character.
If the operator ends with ``=`` and its relevant character is none of
``<``, ``>``, ``!``, ``=``, ``~``, ``?``, it is an *assignment operator* which
has the lowest precedence.
Otherwise precedence is determined by the relevant character.
================ =============================================== ================== ===============
Precedence level Operators First characters Terminal symbol
Precedence level Operators Relevant character Terminal symbol
================ =============================================== ================== ===============
9 (highest) ``$ ^`` OP9
8 ``* / div mod shl shr %`` ``* % \ /`` OP8
@ -403,7 +415,8 @@ Precedence level Operators First charact
4 ``== <= < >= > != in not_in is isnot not of`` ``= < > !`` OP4
3 ``and`` OP3
2 ``or xor`` OP2
1 (lowest) ``@ : ?`` OP1
1 ``@ : ?`` OP1
0 (lowest) *assignment operator* (like ``+=``, ``*=``) OP0
================ =============================================== ================== ===============