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|
classdef richc
% Rich nested comparison syntax, Python like.
%
% A chain of cmp operators comparions is flattened lazily. Exemples of
% chains: 1 < x < y >= 2 1 < 2 < x
% This is a linear chain. distant arguments are never compared directly,
% only adjacent operand are compared (left to right reduce)
%
% * Typical Matlab syntaxes
% if richc: 1< 2 >1.5 -> cast to bool via self.boolean
% container(richc: 1< 2 >1.5) -> cast to bool via self.subsindex
% richc: 1< 2 >1.5 :richc -> cast to bool via closing colon (:) instance
% richc: 1< 2 >1.5 -> NOT casted to bool
% richc: 1< 2 >1.5 & (true|False) -> cast to bool via external logical operators &|
%
% The colon <:> allows beginning a rich comp with a light syntax, thanks to
% its higher priority
%
% * Warning, NEVER do this
% richc: (1< 2 >1.5) -> parentheses force matlab basic dummy evaluation of
% (1< 2 >1.5)
%
% * Impl.
% - The ternary column seems to have lower priority than the binary :
% workaround: use a closing instance with another colon
% TODO: add boolean operator in a lazy way (current impl. forces evaluation)
% but this requires harder evaluation due to priorities
properties
datas= {};
operators= {};
not_= false;
% CLSNAME= mfilename;
is_left_op= false;
end
methods
function self= colon(self,b,varargin)
% Used for light syntax richc: x<y<z, colon has higher priority
% Used as an autoassign constructor
% the last c in colon could be used for recasting (to bool?) after
% all comparisons are done, but the syntaxe wont allow it wo ()
% NO: even with (), richc:(expr):cast => expr is evaluated before
% :, hence in the builtin stupid way.
if isa(b,mfilename); % closing colon
b.is_left_op= true;
tmp= self; self= b; b= tmp;
end
assert(isempty(self.datas))
self.datas{1}= b;
end
%% ----------- Forcing evaluation
function results= evalme(self)
% Forces evaluation of the boolean value of self
assert(~isempty(self.operators),...
'You probably have used the wrong parentheses richc:(...). Remove them please')
results= true;
if isa(self.datas{end},mfilename)
% Treats a closing colon instance
assert(self.datas{end}.is_left_op);
self.datas{end}= self.datas{end}.datas{1};
end
for k=1:length(self.operators)
op= self.operators{k};
if isequaln(op,@not)
% Implemented with self.not_, this changes the priority of
% NOT to lowest !
else
results= results & op(self.datas{k},self.datas{k+1});
end
if not(any(results)); break; end
% TODO[optim]: restreindre les cmp ultérieurs aux éléments qui sont
% toujours true ?
end
if self.not_; results= not(results);end
end
function results= subsindex(self,A)
% forces the evaluation
% Careful if A overloads subsref
results= find(self.evalme()) -1; % zero based integers !
end
function results= logical(self,A)
% if/while casting
results= self.evalme();
end
function results= double(self,A)
results= self.evalme();
end
%% ----------- lazy cmp operators
function self= check_closing_colon(self)
% Allows RC: .. :RC to evaluate automatically
if isa(self.datas{end},mfilename)
self= self.evalme();
end
end
function self= le(self,b)
self.datas{end+1}= b;
self.operators{end+1} = @le;
self= self.check_closing_colon();
end
function self= ge(self,b)
self.datas{end+1}= b;
self.operators{end+1} = @ge;
self= self.check_closing_colon();
end
function self= lt(self,b)
self.datas{end+1}= b;
self.operators{end+1} = @lt;
self= self.check_closing_colon();
end
function self= gt(self,b)
self.datas{end+1}= b;
self.operators{end+1} = @gt;
self= self.check_closing_colon();
end
function self= eq(self,b)
self.datas{end+1}= b;
self.operators{end+1} = @eq;
self= self.check_closing_colon();
end
function self= ne(self,b)
self.datas{end+1}= b;
self.operators{end+1} = @ne;
self= self.check_closing_colon();
end
function self= not(self)
% remain lazy, priority changed to lowest
self.not_= ~(self.not_);
end
%% ----------- external boolean operators
% Forces evaluation
% TODO: lazy operators, but this would complicate evaluation with priorities
function z= any(self,varargin)
z= any(self.evalme(),varargin{:});
end
function z= all(self,varargin)
z= all(self.evalme(),varargin{:});
end
% DONE: weird behaviour on (richc: 1<2) & (richc: 2<3)
% self was changed to boolean after self.evalme(), in THIS stack !!
% Maybe handle class wouldn't
% FIXED: b.evalme() fixes it
function z= and(self,b)
if isa(b,mfilename); b= b.evalme(); end
z= and(self.evalme(),b);
end
function z= or(self,b)
if isa(b,mfilename); b= b.evalme(); end
z= or(self.evalme(),b);
end
% function horzcat()
%
% end
% function vertcat()
%
% end
end
%%
end
%%
function DEMO
% demo datas
v= 1:10;
vv= 10*rand(1,10);
vv= sort(vv);
w= rand(1,10)<0.5;
%-- Nested comparisons syntax. the <:> allows a light syntax
richc: 3<= v < 7 % remains an instance, not evaluated yet
% A constructor could use heavier syntaxe, not done yet
% richc(3) <= v< 7
%-- logical casting (=> dim 1)
if richc : 1<2<3; disp('ok');end
if richc : 3>2<4; disp('ok');end
if richc : 1<2>3; disp('ok');end
%-- Indexing (via subsindex)
% this is dangerous if the indexed class overloads subsref
v(richc: 3<= v< 7)
v(richc: 3< v<= vv <= 8)
v(richc: 3< v > vv )
v(richc: 3<= v< 8 < 5+vv)
%-- External boolean operator
richc: 3<= v< 7 & true % casts to logical
% no simpler way to do it since unary op have higher priority ....
% SOLUTION; closing colon
richc: 3<= v< 7 | v>=9
any(richc: 3< v< 7)
all(richc: 3< v< 7 | v<=10)
v(richc: w== 1)
v(richc: w~= 1)
% + indexing
v(richc: 3<= v< 7 & v<6)
v(~richc: 3<= v< 7 & v<6) % unary not is lazy, with lowest priority!
v(richc: 3<= v< 7 | v>=9)
% other indexing (cell, matrices)
m= reshape(1:100,[10 10]);
m(richc: 2<= v< 7 ,:)
m(:, richc: 2<= v< 7)
m(richc: 2<= v< 7)
c= num2cell(m);
c(richc: 2<= v< 7,:)
c(richc: 2<= v< 7)
c{richc: 2<= v< 7}
find(richc: 2<= v< 7) %fails
find(richc: 2<= v< 7:richc)
% (richc: 2<= v< 7).find()
% rguments to the closing instance could denote subsindexing !
% la simple présence de cette ligne fait bugger la classe
% !!!!!!!!!!!!!!!!!!!!!!!!!!
% richc: 2<= v< 7:richc(1:3,:) % malheuresement, : et end ne sont pas des arguments valide !
%
end
function SOLUTION_TO_SYNTAXE_ISSUES
% DONE: use a left richc colon operand to close the evaluation and cast to
% bool
richc: 3<v<7: richc
richc: 3<= v < 7 > 1 : richc
richc: 1+2<= 1*v-0 < 7^1 > 1 : richc
end
function OTHER_INTERACTIONS
0+ richc:3<v<7: richc % bad priority, require overload +
0+ (richc:3<v<7: richc) % work around
[richc:3<v<7: richc, richc:3<v<7: richc] % works, cat priority is lower
cat(1,richc:3<v<7:richc, richc:3<v<7:richc) % works, cat priority is lower
cat(1,richc:3<v<7, richc:3<v<7) % struct array concatenation
[richc:3<v<7, richc:3<v<7] % struct array concatenation
evalme([richc:3<v<7, richc:3<v<7]) % fails
end
function TODO
richc:3<v<7:richc('find')
richc:3<v<7:richc('subsindex') % mais pas de : et end :(
end
function BUGGED_SYNTAXES
% Never do this
richc: (3<= v < 7) % supid classic evaluation of (3<= v < 7)
% TODO: we could force some operator to occur before final evaluation to avoid
% this user error
% * tres bizarre
% <and> => self.evalme(), qui a changé self en sortant !!!
% Maybe a handle class could fix it ?
% FIXED by converting other operand to bool !
(richc: 1<2) & (richc: 2<3)
richc: 1<2 & richc: 2<3 % priorities ok !
(richc: 3<= v< 7) & (richc: 3<= v< 7)
%% BUGGED ternary colon syntaxes
% what can we do of the 3rd colon arg ?
% tries to cast once all comparisons are done, but...
richc:3<v<7:@logical % fails, priority issue (ternary : is lower than binary : ???)
richc: (3< v< 7) : @logical % wrong, silent error, (3< v< 7) is evaluated before
(richc: 3< v< 7) : @logical % this works, but error prone syntax with tedious ()!
richc: @logical: 3<v< 7 % syntaxe ok, mais inutile. on ne le sait pas assez tard pour convertir
end |
Rich comparison operators
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