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
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
#
#
# Nimrod's Runtime Library
# (c) Copyright 2010 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## The ``gentabs`` module implements an efficient hash table that is a
## key-value mapping. The keys are required to be strings, but the values
## may be any Nimrod or user defined type. This module supports matching
## of keys in case-sensitive, case-insensitive and style-insensitive modes.
import
os, hashes, strutils
type
TGenTableMode* = enum ## describes the table's key matching mode
modeCaseSensitive, ## case sensitive matching of keys
modeCaseInsensitive, ## case insensitive matching of keys
modeStyleInsensitive ## style sensitive matching of keys
TGenKeyValuePair[T] = tuple[key: string, val: T]
TGenKeyValuePairSeq[T] = seq[TGenKeyValuePair[T]]
TGenTable*[T] = object of TObject
counter: int
data: TGenKeyValuePairSeq[T]
mode: TGenTableMode
PGenTable*[T] = ref TGenTable[T] ## use this type to declare hash tables
const
growthFactor = 2
startSize = 64
proc len*[T](tbl: PGenTable[T]): int {.inline.} =
## returns the number of keys in `tbl`.
result = tbl.counter
iterator pairs*[T](tbl: PGenTable[T]): tuple[key: string, value: T] =
## iterates over any (key, value) pair in the table `tbl`.
for h in 0..high(tbl.data):
if not isNil(tbl.data[h].key):
yield (tbl.data[h].key, tbl.data[h].val)
proc myhash[T](tbl: PGenTable[T], key: string): THash =
case tbl.mode
of modeCaseSensitive: result = hashes.hash(key)
of modeCaseInsensitive: result = hashes.hashIgnoreCase(key)
of modeStyleInsensitive: result = hashes.hashIgnoreStyle(key)
proc myCmp[T](tbl: PGenTable[T], a, b: string): bool =
case tbl.mode
of modeCaseSensitive: result = cmp(a, b) == 0
of modeCaseInsensitive: result = cmpIgnoreCase(a, b) == 0
of modeStyleInsensitive: result = cmpIgnoreStyle(a, b) == 0
proc mustRehash(length, counter: int): bool =
assert(length > counter)
result = (length * 2 < counter * 3) or (length - counter < 4)
proc newGenTable*[T](mode: TGenTableMode): PGenTable[T] =
## creates a new generic hash table that is empty.
new(result)
result.mode = mode
result.counter = 0
newSeq(result.data, startSize)
proc nextTry(h, maxHash: THash): THash {.inline.} =
result = ((5 * h) + 1) and maxHash
proc RawGet[T](tbl: PGenTable[T], key: string): int =
var h: THash
h = myhash(tbl, key) and high(tbl.data) # start with real hash value
while not isNil(tbl.data[h].key):
if mycmp(tbl, tbl.data[h].key, key):
return h
h = nextTry(h, high(tbl.data))
result = - 1
proc RawInsert[T](tbl: PGenTable[T], data: var TGenKeyValuePairSeq[T],
key: string, val: T) =
var h: THash
h = myhash(tbl, key) and high(data)
while not isNil(data[h].key):
h = nextTry(h, high(data))
data[h].key = key
data[h].val = val
proc Enlarge[T](tbl: PGenTable[T]) =
var n: TGenKeyValuePairSeq[T]
newSeq(n, len(tbl.data) * growthFactor)
for i in countup(0, high(tbl.data)):
if not isNil(tbl.data[i].key):
RawInsert[T](tbl, n, tbl.data[i].key, tbl.data[i].val)
swap(tbl.data, n)
proc hasKey*[T](tbl: PGenTable[T], key: string): bool =
## returns true iff `key` is in the table `tbl`.
result = rawGet(tbl, key) >= 0
proc `[]`*[T](tbl: PGenTable[T], key: string): T =
## retrieves the value at ``tbl[key]``. If `key` is not in `tbl`,
## default(T) is returned and no exception is raised. One can check
## with ``hasKey`` whether the key exists.
var index = RawGet(tbl, key)
if index >= 0: result = tbl.data[index].val
proc `[]=`*[T](tbl: PGenTable[T], key: string, val: T) =
## puts a (key, value)-pair into `tbl`.
var index = RawGet(tbl, key)
if index >= 0:
tbl.data[index].val = val
else:
if mustRehash(len(tbl.data), tbl.counter): Enlarge(tbl)
RawInsert(tbl, tbl.data, key, val)
inc(tbl.counter)
when isMainModule:
#
# Verify tables of integer values (string keys)
#
var x = newGenTable[int](modeCaseInsensitive)
x["one"] = 1
x["two"] = 2
x["three"] = 3
x["four"] = 4
x["five"] = 5
assert(len(x) == 5) # length procedure works
assert(x["one"] == 1) # case-sensitive lookup works
assert(x["ONE"] == 1) # case-insensitive should work for this table
assert(x["one"]+x["two"] == 3) # make sure we're getting back ints
assert(x.hasKey("one")) # hasKey should return 'true' for a key
# of "one"...
assert(not x.hasKey("NOPE")) # ...but key "NOPE" is not in the table.
for k,v in pairs(x): # make sure the 'pairs' iterator works
assert(x[k]==v)
#
# Verify a table of user-defined types
#
type
TMyType = tuple[first, second: string] # a pair of strings
var y = newGenTable[TMyType](modeCaseInsensitive) # hash table where each
# value is TMyType tuple
#var junk: TMyType = ("OK", "Here")
#echo junk.first, " ", junk.second
y["Hello"] = ("Hello", "World")
y["Goodbye"] = ("Goodbye", "Everyone")
#y["Hello"] = TMyType( ("Hello", "World") )
#y["Goodbye"] = TMyType( ("Goodbye", "Everyone") )
assert( not isNil(y["Hello"].first) )
assert( y["Hello"].first == "Hello" )
assert( y["Hello"].second == "World" )
#
# Verify table of tables
#
var z: PGenTable[ PGenTable[int] ] # hash table where each value is
# a hash table of ints
z = newGenTable[PGenTable[int]](modeCaseInsensitive)
z["first"] = newGenTable[int](modeCaseInsensitive)
z["first"]["one"] = 1
z["first"]["two"] = 2
z["first"]["three"] = 3
z["second"] = newGenTable[int](modeCaseInsensitive)
z["second"]["red"] = 10
z["second"]["blue"] = 20
assert(len(z) == 2) # length of outer table
assert(len(z["first"]) == 3) # length of "first" table
assert(len(z["second"]) == 2) # length of "second" table
assert( z["first"]["one"] == 1) # retrieve from first inner table
assert( z["second"]["red"] == 10) # retrieve from second inner table
for k,v in pairs(z):
echo( "$# ($#) ->" % [k,$len(v)] )
#for k2,v2 in pairs(v):
# echo( " $# <-> $#" % [k2,$v2] )
echo()
|