98 lines
2.4 KiB
Lua
98 lines
2.4 KiB
Lua
--[[
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This file is part of Ice Lua Components.
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Ice Lua Components is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Ice Lua Components is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with Ice Lua Components. If not, see <http://www.gnu.org/licenses/>.
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]]
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function collect_new_prioq(fn_compare)
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local this = {} this.this = this
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local DEBUG_HEAP_ASSERT = false
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function this.clear()
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this.q = {}
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end
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local function prv_debug_check_heap(idx)
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local cidx = idx*2
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if cidx > #(this.q) then return end
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if fn_compare(this.q[cidx], this.q[idx]) then error("heap check failed") end
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prv_debug_check_heap(cidx)
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if cidx+1 <= #(this.q) then
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if fn_compare(this.q[cidx+1], this.q[idx]) then error("heap check failed") end
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prv_debug_check_heap(cidx+1)
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end
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end
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local function prv_sift_down(idx)
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while idx*2 <= #(this.q) do
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-- find highest prio child
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local cidx = idx*2
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if cidx+1 <= #(this.q) and fn_compare(this.q[cidx+1], this.q[cidx]) then
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cidx = cidx + 1
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end
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-- swap if necessary
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if fn_compare(this.q[cidx], this.q[idx]) then
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this.q[idx], this.q[cidx] = this.q[cidx], this.q[idx]
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idx = cidx
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else
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break
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end
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end
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end
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function this.push(v)
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local idx = #(this.q)+1
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this.q[idx] = v
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-- sift up
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while idx > 1 do
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-- check parent
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local pidx = math.floor(idx/2)
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if fn_compare(this.q[idx], this.q[pidx]) then
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this.q[idx], this.q[pidx] = this.q[pidx], this.q[idx]
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idx = pidx
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else
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break
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end
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end
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-- sift down
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prv_sift_down(idx)
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if DEBUG_HEAP_ASSERT then prv_debug_check_heap(1) end
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end
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function this.pop()
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local qlen = #(this.q)
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if qlen == 0 then return nil end
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local v = this.q[1]
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this.q[1] = this.q[qlen]
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this.q[qlen] = nil
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if this.q[1] then prv_sift_down(1) end
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if DEBUG_HEAP_ASSERT then prv_debug_check_heap(1) end
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return v
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end
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function this.empty()
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return #(this.q) == 0
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end
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this.clear()
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return this
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end
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