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Add ^ operator for power #26

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Add ^ operator for power #26

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2763f09
Add ^ operator for power.
osaris Jul 12, 2015
d08ba38
Fix coding style.
osaris Jul 13, 2015
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6 changes: 5 additions & 1 deletion Arithmetic.pp
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,7 @@
%token minus \-|−
%token times \*|×
%token div /|÷
%token pow \^
%token constant [A-Z_]+[A-Z0-9_]+
%token id \w+

Expand All @@ -65,7 +66,10 @@
ternary() ( ::times:: #multiplication expression() )?

ternary:
term() ( ::div:: #division expression() )?
quaternary() ( ::div:: #division expression() )?

quaternary:
term() ( ::pow:: #power expression() )?
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Are we sure that ^ has not the same priority (precedence) than an other existing operator?

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According to many sources found on Google (!!), ^ priority is lower than multiplication and division operators.

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Since PHP5.6, we have the ** operator with the following precedence: http://php.net/manual/en/language.operators.precedence.php. It is a right associative operator. Is it the case here?

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As said here,

  • the common ^ operator is left associative (according to my mind and my calculator (2^3^2=64))
  • the PHP ** operator is right associative (2 ** 3 ** 2 == 512).

What about Hoa\Math ^ operator ?

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It's right associative here (2^3^2 == 512) like the ** operator.

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Ok, it seem my mind and my college calculator were wrong ;)
https://en.wikipedia.org/wiki/Order_of_operations#Special_cases

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So, do we have the same associativity than in PHP? If yes, why not using **? We will be able to fix test suites directly too.


term:
( ::bracket_:: expression() ::_bracket:: #group )
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6 changes: 5 additions & 1 deletion Test/Unit/Arithmetic.pp
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Expand Up @@ -51,6 +51,7 @@
%token minus \-
%token times \*
%token div /
%token pow \^
%token constant [A-Z_]+[A-Z0-9_]+
%token id \w+

Expand All @@ -64,7 +65,10 @@
ternary() ( ::times:: #multiplication expression() )?

ternary:
term() ( ::div:: #division expression() )?
quaternary() ( ::div:: #division expression() )?

quaternary:
term() ( ::pow:: #power expression() )?

term:
( ::bracket_:: expression() ::_bracket:: #group )
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11 changes: 11 additions & 0 deletions Visitor/Arithmetic.php
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Expand Up @@ -209,6 +209,17 @@ public function visit(

break;

case '#power':
$children[0]->accept($this, $a, $eldnah);

$acc = function ($b) use ($a, $acc) {
return $acc(pow($a(), $b));
};

$children[1]->accept($this, $acc, $eldnah);

break;
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CS: An empty new line is missing before the break statement.

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Can you explain this part please?

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Short answer, no. Longer, I have basically copy/pasted what is done for #multiplication and updated the operation ?

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Ok. Are tests green?

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Funny: 147a38d.


case '#fakegroup':
case '#group':
$children[0]->accept($this, $a, $eldnah);
Expand Down