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Copy pathoperator.lua
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209 lines (182 loc) · 4.15 KB
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--- Lua operators available as functions.
--
-- (similar to the Python module of the same name)
--
-- There is a module field `optable` which maps the operator strings
-- onto these functions, e.g. `operator.optable['()']==operator.call`
--
-- Operator strings like '>' and '{}' can be passed to most Penlight functions
-- expecting a function argument.
--
-- @module pl.operator
local strfind = string.find
local operator = {}
--- apply function to some arguments **()**
-- @param fn a function or callable object
-- @param ... arguments
function operator.call(fn,...)
return fn(...)
end
--- get the indexed value from a table **[]**
-- @param t a table or any indexable object
-- @param k the key
function operator.index(t,k)
return t[k]
end
--- returns true if arguments are equal **==**
-- @param a value
-- @param b value
function operator.eq(a,b)
return a==b
end
--- returns true if arguments are not equal **~=**
-- @param a value
-- @param b value
function operator.neq(a,b)
return a~=b
end
--- returns true if a is less than b **<**
-- @param a value
-- @param b value
function operator.lt(a,b)
return a < b
end
--- returns true if a is less or equal to b **<=**
-- @param a value
-- @param b value
function operator.le(a,b)
return a <= b
end
--- returns true if a is greater than b **>**
-- @param a value
-- @param b value
function operator.gt(a,b)
return a > b
end
--- returns true if a is greater or equal to b **>=**
-- @param a value
-- @param b value
function operator.ge(a,b)
return a >= b
end
--- returns length of string or table **#**
-- @param a a string or a table
function operator.len(a)
return #a
end
--- add two values **+**
-- @param a value
-- @param b value
function operator.add(a,b)
return a+b
end
--- subtract b from a **-**
-- @param a value
-- @param b value
function operator.sub(a,b)
return a-b
end
--- multiply two values __*__
-- @param a value
-- @param b value
function operator.mul(a,b)
return a*b
end
--- divide first value by second **/**
-- @param a value
-- @param b value
function operator.div(a,b)
return a/b
end
--- raise first to the power of second **^**
-- @param a value
-- @param b value
function operator.pow(a,b)
return a^b
end
--- modulo; remainder of a divided by b **%**
-- @param a value
-- @param b value
function operator.mod(a,b)
return a%b
end
--- concatenate two values (either strings or `__concat` defined) **..**
-- @param a value
-- @param b value
function operator.concat(a,b)
return a..b
end
--- return the negative of a value **-**
-- @param a value
function operator.unm(a)
return -a
end
--- false if value evaluates as true **not**
-- @param a value
function operator.lnot(a)
return not a
end
--- true if both values evaluate as true **and**
-- @param a value
-- @param b value
function operator.land(a,b)
return a and b
end
--- true if either value evaluate as true **or**
-- @param a value
-- @param b value
function operator.lor(a,b)
return a or b
end
--- make a table from the arguments **{}**
-- @param ... non-nil arguments
-- @return a table
function operator.table (...)
return {...}
end
--- match two strings **~**.
-- uses @{string.find}
function operator.match (a,b)
return strfind(a,b)~=nil
end
--- the null operation.
-- @param ... arguments
-- @return the arguments
function operator.nop (...)
return ...
end
---- Map from operator symbol to function.
-- Most of these map directly from operators;
-- But note these extras
--
-- * __'()'__ `call`
-- * __'[]'__ `index`
-- * __'{}'__ `table`
-- * __'~'__ `match`
--
-- @table optable
-- @field operator
operator.optable = {
['+']=operator.add,
['-']=operator.sub,
['*']=operator.mul,
['/']=operator.div,
['%']=operator.mod,
['^']=operator.pow,
['..']=operator.concat,
['()']=operator.call,
['[]']=operator.index,
['<']=operator.lt,
['<=']=operator.le,
['>']=operator.gt,
['>=']=operator.ge,
['==']=operator.eq,
['~=']=operator.neq,
['#']=operator.len,
['and']=operator.land,
['or']=operator.lor,
['{}']=operator.table,
['~']=operator.match,
['']=operator.nop,
}
return operator