Variable bound check (#72)

* bound check implemented

* bound check reimplemented

Author: sshin23

src/nlp.jl

@@ -8,6 +8,7 @@ struct ConstraintNull <: AbstractConstraint end
 
 struct Variable{S,O} <: AbstractVariable
     size::S
+    length::O
     offset::O
 end
 Base.show(io::IO, v::Variable) = print(
@@ -245,13 +246,33 @@ function ExaModel(c::C; prod = nothing) where {C<:ExaCore}
     )
 end
 
-@inline Base.getindex(v::V, i) where {V<:Variable} =
+@inline function Base.getindex(v::V, i) where {V<:Variable}
+    _bound_check(v.size, i)
     Var(i + (v.offset - _start(v.size[1]) + 1))
-@inline Base.getindex(v::V, i, j) where {V<:Variable} = Var(
-    i +
-    j * _length(v.size[1]) +
-    (v.offset - _start(v.size[1]) + 1 - _start(v.size[2]) * _length(v.size[1])),
-)
+end
+@inline function Base.getindex(v::V, is...) where {V<:Variable}
+    @assert(length(is) == length(v.size), "Variable index dimension error")
+    _bound_check(v.size, is)
+    Var(v.offset + idxx(is .- (_start.(v.size) .- 1), _length.(v.size)))
+end
+
+function _bound_check(sizes, i::I) where I <: Integer
+    __bound_check(sizes[1], i)
+end
+function _bound_check(sizes, is::NTuple{N,I}) where {I <: Integer, N}
+    __bound_check(sizes[1], is[1])
+    _bound_check(sizes[2:end], is[2:end])
+end
+_bound_check(sizes, is) = nothing
+_bound_check(sizes, is::Tuple{}) = nothing
+
+function __bound_check(a::I,b::I) where I <: Integer
+    @assert(1<= b <= a, "Variable index bound error")
+end
+function __bound_check(a::UnitRange{Int},b::I) where I <: Integer
+    @assert(b in a, "Variable index bound error")
+end
+
 
 function append!(backend, a, b::Base.Generator, lb)
     b = _adapt_gen(b)
@@ -332,12 +353,13 @@ function variable(
 
 
     o = c.nvar
-    c.nvar += total(ns)
+    len = total(ns)
+    c.nvar += len
     c.x0 = append!(c.backend, c.x0, start, total(ns))
     c.lvar = append!(c.backend, c.lvar, lvar, total(ns))
     c.uvar = append!(c.backend, c.uvar, uvar, total(ns))
 
-    return Variable(ns, o)
+    return Variable(ns, len, o)
 
 end