blob: 543518356f7438af6a5ed18eb6f126a528b473d5 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
|
--!A cross-platform build utility based on Lua
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
-- http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
-- Copyright (C) 2015-present, Xmake Open Source Community.
--
-- @author ruki
-- @file queue.lua
--
-- load modules
local object = require("base/object")
-- define module
local queue = queue or object {_init = {"_first", "_last"}} {1, 0}
-- clear all elements
function queue:clear()
self._first = 1
self._last = 0
end
-- push an item to the back of the queue
--
-- @param item the item to push
--
function queue:push(item)
local last = self._last + 1
self._last = last
self[last] = item
end
-- pop an item from the front of the queue
--
-- @return the popped item, or nil if empty
--
function queue:pop()
local first = self._first
if first > self._last then
return nil
end
local value = self[first]
self[first] = nil
self._first = first + 1
return value
end
-- get the queue size
--
-- @return the number of elements
--
function queue:size()
return self._last - self._first + 1
end
-- is the queue empty?
--
-- @return true if empty
--
function queue:empty()
return self._first > self._last
end
-- peek the first item without removing
--
-- @return the first element, or nil if empty
--
function queue:first()
if self._first > self._last then
return nil
end
return self[self._first]
end
-- peek the last item without removing
--
-- @return the last element, or nil if empty
--
function queue:last()
if self._first > self._last then
return nil
end
return self[self._last]
end
-- iterator for all items (forward)
--
-- e.g.
--
-- for item in queue:items() do
-- print(item)
-- end
--
function queue:items()
local index = self._first - 1
local last = self._last
return function()
index = index + 1
if index <= last then
return self[index]
end
end
end
-- iterator for all items (reverse)
function queue:ritems()
local index = self._last + 1
local first = self._first
return function()
index = index - 1
if index >= first then
return self[index]
end
end
end
-- clone the queue
--
-- @return the cloned queue
--
function queue:clone()
local q = queue.new()
for i = self._first, self._last do
q:push(self[i])
end
return q
end
-- create a new FIFO queue
--
-- @return the queue instance
--
function queue.new()
return queue()
end
-- return module: queue
return queue
|
