Add sequential next item strategies

Author: Frankie Robertson

src/next_item_rules/NextItemRules.jl

@@ -39,6 +39,7 @@ export ExpectationBasedItemCriterion, AbilityVarianceStateCriterion, init_thread
 export NextItemRule, ItemStrategyNextItemRule
 export UrryItemCriterion, InformationItemCriterion
 export RandomNextItemRule
+export PiecewiseNextItemRule, MemoryNextItemRule, FixedFirstItemNextItemRule
 export ExhaustiveSearch
 export catr_next_item_aliases
 export preallocate
@@ -60,6 +61,7 @@ include("./prelude/preallocate.jl")
 
 # Selection strategies
 include("./strategies/random.jl")
+include("./strategies/sequential.jl")
 include("./strategies/exhaustive.jl")
 
 # Combinators

src/next_item_rules/strategies/sequential.jl

@@ -0,0 +1,51 @@
+"""
+$(TYPEDEF)
+$(TYPEDFIELDS)
+
+This is the most basic rule for choosing the next item in a CAT. It simply
+picks a random item from the set of items that have not yet been
+administered.
+"""
+@kwdef struct PiecewiseNextItemRule{BreaksT, RulesT} <: NextItemRule
+    # Tuple of Ints
+    breaks::BreaksT
+    # Types of NextItemRules
+    rules::RulesT
+end
+
+#tuple_len(::NTuple{N, Any}) where {N} = Val{N}()
+
+function current_rule(rule::PiecewiseNextItemRule, responses::TrackedResponses)
+    for brk in 1:length(rule.breaks)
+        if length(responses) < rule.breaks[brk]
+            return rule.rules[brk]
+        end
+    end
+    return rule.rules[end]
+end
+
+function best_item(rule::PiecewiseNextItemRule, responses::TrackedResponses, items)
+    return best_item(current_rule(rule, responses), responses, items)
+end
+
+function compute_criteria(rule::PiecewiseNextItemRule, responses::TrackedResponses)
+    return compute_criteria(current_rule(rule, responses), responses)
+end
+
+"""
+"""
+@kwdef struct MemoryNextItemRule{MemoryT} <: NextItemRule
+    item_idxs::MemoryT
+end
+
+function best_item(rule::MemoryNextItemRule, responses::TrackedResponses, _items)
+    return rule.item_idxs[length(responses) + 1]
+    # XXX: A few problems with this:
+    # 1. Could run out of `item_idxs`
+    # 2. Could return an item not in `items`
+    # TODO: Add some basic error checking -- can only panic
+end
+
+function FixedFirstItemNextItemRule(item_idx::Int, rule::NextItemRule)
+    PiecewiseNextItemRule((1,), (MemoryNextItemRule((item_idx,)), rule))
+end